West, Ian M. 2017. Select bibliography of petroleum geology of Wessex, southern England. http://www.southampton.ac.uk/~imw/Oil-South-Bibliography.htm. Version: Revised: 17th August 2017.
Select Bibliography - Petroleum Geology of Wessex, southern England

By Dr. Ian West,

Romsey, Hampshire,
and Visiting Scientist at:

Faculty of Natural and Environmental Sciences,
Southampton University,
Webpage hosted by iSolutions, Southampton University
Website archived at the British Library

Associated Webpages:

|Petroleum Geology of the South of England

|The Petroleum Geology of the Portland - Isle of Wight Offshore Basin

|Petroleum Geology of the Western Weald and South Downs (Shale Oil etc.)

Other webpages:

|Kimmeridge - Oil Shale |Kimmeridge Bibliography. |Lyme Regis | Lyme Regis to Charmouth, with Liassic source rock. | West Bay, Bridport - Bridport Sands Reservoir Rock| Osmington - Oil Sand in Bencliff Grit| Sidmouth and Ladram Bay - Sherwood Sandstone Reservoir Rock.

Click here for the full LIST OF WEBPAGES
(You can download this educational site to SurfOffline or similar software to keep an offline copy, but note that updating of the live version takes place periodically.)

Related web page:
Petroleum Geology of the South of England

Petroleum Geology - Balcombe and the Central Weald

The Petroleum Geology of the Portland - Isle of Wight Offshore Basin


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(This paper is not on south of England, but is briefly quoted for comparision on certain aspects)

Abdul Khair, H. 2013. Mapping fracture networks key for efficient extraction of unconventional gas. Institute for Energy and Mineral Resources, Adelaide University. Newsletter, February 2013.
[See: University of Adelaide, Institute for Energy and Mineral Resources, Newsletter, Feb. 2013]
Extracts:
"It is difficult to extract gas from shales as the shale is often impermeable. We have to create our own permeability by hydraulic fracturing in order to release the gas - this is why the gas resource is termed unconventional.
Natural fractures in the rock can be used to improve fracture stimulation and new fractures may also initiate and propagate when stimulated. To improve the effectiveness of fracture stimulation and ultimately the efficiency of gas collection, it is vital to have as much information as possible about the natural fracture network within the resource and the magnitude and orientation of the stresses that it experiences."

Abul Khair H, Backe G, King R, Holford S, Tingay M and Cooke D. 2012. Factors influencing fractures networks within Permian shale intervals in the Cooper Basin, South Australia. AAPEA Journal, vol. 52: pp. 213-228.
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Abraham, K. 1990. Wytch Farm development stresses environmental responsibility. Abraham, Kurt World Oil, Houston, TX, United States. World Oil, vol. 210 no. 4p. 85-86, 88-92, 94. 1990.
Offline, not accessible to the public for copyright reasons">
Privately held at archive:
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Ainsworth, N.R., Braham, W., Gregory, F.J., Johnson, B. and King, C. 1998. The lithostratigraphy of the latest Triassic to earliest Cretaceous of the English Channel and its adjacent areas. Pp. 103-164. In: Underhill, J.R. (Editor) 1998. The Development, Evolution and Petroleum Geology of the Wessex Basin. Published by the Geological Society of London. In Geological Society Special Publication, No. 133. 420 pp. [The key publication on the petroleum geology of the Wessex Basin is highly recommended. It is a substantial paper 61 pages long with 26 diagrams. It is very good with much information, including facies and thickness maps, diagrams showing sea-level changes etc. It is easily readable by anyone who already knows the general geological succession and zonal schemes of the Dorset Coast.]
Authors - Nigel R. Ainsworth, William Braham, F. John Gregory, Ben Johnson and Christopher King.
Abstract:
The stratigraphy of the latest Triassic through to the earliest Cretaceous of the Portland - Wight Basin and its adjacent area may be subdivided using petrophysical (gamma ray and interval transit time) criteria, in association with gross lithology to allow a total of 50 lithological units to be recognised. Three units occur within the latest Triassic, 46 in the Jurassic and one in the earliest Cretaceous. The lithostratigraphy can be integrated into a biostratigraphic template using published data and subsequent observations based on micropalaontology (ostracods, foraminiferids) and palynology (dinocysts, miospores). Throughout the study area recognition of major lithostratigraphic and biostratigraphic events enables the chronostratigraphic framework of the basin to be determined, which has aided identification of regional stratigraphic breaks throughout much of the Portland - Wight Basin, including haiti in proximity to the Pliensbachian - Toarcian and the Aalenian - Bajocian boundaries, and also within the late Oxfordian. Although the majority of the lithostratigraphic events have been deduced to be isochronous, a number of lithological units exhibit significant diachroniety. These specifically include the Frome Clay and the Great Oolite, the Kellaways Sand Member and Clay Member, and the Sandsfoot Grit Formation and the Ampthill Clay Equivalent.

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Allan , J.J. and Gardiner, H. 1995. Operating experience with ESP's and permanent downhole flowmeters in Wytch Farm from extended-reach wells. Journal of Petroleum Technology, 47, 902.


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Allen , F., Tooms, P., Conran, G., Lesso, B. and Van de Slijke. 1997. Extended Reach Drilling: Breaking the 10km Barrier. Oil Review, Winger 1997, 47pp with colour diagrams and colour photographs. [re. an extended reach borehole at Goathorn Peninsula, Wytch Farm Oil Field, Dorset, into the Sherwood Sandstone Reservoir]. Available as a pdf file: Extended Reach Drilling: Breaking the 10km Barrier.

Summary:
Geosteering, torque reduction and casing flotation have all contributed to record-breaking extended-reach drilling achievements. The limits of directional drilling continue to be pushed back as horizontal reservoir sections greater than 2500m are being drilled, cased, cemented and completed to tap reserves at extreme distances from surface wellsites.

[Further notes from this article:
Wytch Farm - Europe's largest onshore oilfield - 467 million bbl - 74 million cubic metres.
Three reservoirs: Frome at 800m; Bridport at 900m; Sherwood Reservoir at 1600m
Bridport in production since 1979. For Sherwood, first plan was an offshore island (Hook Island), second was Extended Reach. The latter cost half and accelerated production by three years. The main part of the article discusses the technology of the extended reach borehole.]
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AMOCO (U.K.) Exploration Company. 1983. The start of work on the Hoe Lane Exploratory Borehole, North Baddesley, near Romsey, Hampshire, - involved a planning application to the Test Valley Council:
Application: TVS.3459/1 Exploratory work in search of hydrocarbons, involving drilling of a borehole and subsequent testing of any discovery at - Hoe Farm, Hoe Lane, North Baddesley. Temporary Permission subject to conditions valid until - 31/01/83, Granted - 22/03/82. Ref. No: TVS.03459/1 | Status: Permission subject to conditions and notes

Online, if clicked, the following message appears: Planning Application details not available. This application is no longer available for viewing. It may have been removed or restricted from public viewing. [See also, quoted in a North Baddesley Planning Document, probably just repetition of the above: Application: TVS.3459/1 Exploratory work in search of hydrocarbons, involving drilling of a borehole and subsequent testing of any discovery at - Hoe Farm, Hoe Lane, North Baddesley. Temporary Permission subject to conditions valid until - 31/01/83, Granted - 22/03/82. (Further details not found). Ref. No: TVS.03459/1 | Status: Permission subject to conditions and notes.]


AMOCO (U.K.) Exploration Company, Ultramar Exploration Company. 1985. Larkwhistle Farm Oil Discovery: Consultative Document Describing the Appraisal Programme. Unpublished document. Cope Special Collection, Southampton University. [Amoco]

AMOCO (U.K.) Exploration Company, Ultramar Exploration Company. 1987. Furzedown: Consultative Document Describing the Exploration Proposals. Unpublished document. Cope Collection, Southampton University. [Amoco]

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ANDREWS, I.J. 2014. [British Geological Survey] THE JURASSIC SHALES OF THE WEALD BASIN: GEOLOGY AND SHALE OIL AND SHALE GAS RESOURCE ESTIMATION. (MAIN REPORT - APPENDICES SEPARATE BELOW) 79 pp. BGS and DECC. British Geological Survey; Department of Energy and Climate Change. With 52 figures and 12 tables. Available online as a pdf file. [A summary is given below.]

Go to: BGS Weald Basin Jurassic Shale Reports

Summary of the main report: The Jurassic Shales of the Weald Basin report: geology and shale oil and shale gas resource estimation. Page 1 et seq.
Following the publication of shale gas resource estimates for the Carboniferous Bowland-Hodder shales (Andrews 2013), this report is the second to address the potential distribution and in-place resources of unconventional oil and gas contained in the shales beneath the UK. It summarises the background geological knowledge and methodology that have enabled a preliminary in-place oil resource calculation to be undertaken for the Weald Basin and adjacent areas in southern Britain (Figure 1). No significant shale gas resource is recognised in the Jurassic of the Weald Basin.
Marine shales were deposited in the Weald Basin at several intervals during the Jurassic (c. 145-200 Ma). The basin is composed of several fault-controlled sub-basins, which form part of a wider basin that extended into northern France. It is geologically distinct from the Wessex Basin which lies to the southwest, outside of the study area.
Five units within the Jurassic of the Weald Basin contain organic-rich, marine shale: the Mid and Upper Lias Clays (Lower Jurassic) and the Oxford Clay, Corallian Clay and Kimmeridge Clay (Upper Jurassic). These attain gross shale thicknesses of up to 300 ft. ( 90 m.), 220 ft. (67 m.), 500 ft. (150 m.), 260 ft. (80 m.) and 1,800 ft (550 m.) respectively in the Weald Basin depocentre, and they contain varying amounts of organic matter. Coventional oil and gas fields in the basin attest to the capability of some of these units to produce hydrocarbons. It is possible that oil could have been generated from any or all of the five shales, but in the current model even the deepest Jurassic unit is not considered to have been sufficiently buried to have generated significant amounts of gas. Some gas has been generated in association with oil and shallow biogenic gas may also be present.
Organic-rich shales occur at two levels in the Lias (Lower Jurassic) of the Weald; these have direct equivalents in the Paris Basin, although in the Weald they fail to reach the richness found in France. In a third Lias unit, the Blue Lias (Lower Lias), total organic carbon (TOC) reaches 8% further west in the shales of the Wessex Basin, where it sources the Wytch Farm oilfield, but organic carbon contents are typically well below 2% in the equivalent limestones and shales of the study area. This contrast in organic content may result from differences in palaeogeography and organic input or preservation between the basins. The most significant organic-rich shales in the Weald Basin occur in the lowermost Oxford Clay (TOC up to 7.8%) and middle Kimmeridge Clay (TOC up to 21.3%) and these represent potential 'sweet-spots' worthy of further investigation.
None of the Jurassic shales analysed by Rock-Eval methodology has an 'oil saturation index' (SI*100/TOC) of greater than 50, i.e. much of the "oil" may be physically associated with kerogen, rather than present in pore space. This is low in comparison to shale oil producing areas in North America, so it may be tha only limited amounts of shale within the Jurassic of the Weald Basin have any potential to produce oil in commercial quantities. However, after correcting fro the evaporation of light hydrocarbons since the sample was taken, it may be that some horizons within the Mid and Upper Lias, lower Oxford Clay and Kimmeridge Clay exceed the 100 required for the oil to be 'producible'. Also the fact that oil has migrated inot conventional reservoirs suggests that optimum conditions are reached at least locally within the basin. Interpreting the presence of producible oil in the organic-rich shales allows for an in-place resource volume to be calculated wth a broad range of probabilities.
The maturity of the shales is a function of burial depth, heat flow and time. In this study, the Jurassic shales are considered mature for oil generation (vitrinite reflectance, Ro values between 0.6% and 1.1%) at depths between approximately 7,000 - 8,000 ft. (2130m. - 2440m.) and 12,000 - 13,000 ft. (3660m. - 3960m.)(where there has been minimal uplift). However, southern Britain experienced a phase of significant uplift in Cenozoic times, due to basin inversion, that has raised the mature shales by up to 6,750 ft (2060m.) to shallower present day depths than would otherwise be expected. Howver, even the Lias shales are unlikely to have attained sufficient maturity to allow for significant gas generation.
Where they have been buried to a sufficient depth for the organic material to generate oil, all five prospective shales are considered to to have some potential to form a shale oil resource analogous, but on a smaller scale, to the producing shale oil provinces of North America (e.g. Barnett, Woodford and Tuscaloosa).
Hybrid conventional/shale oil plays, with low porosity and impermeable rocks juxtaposed against mature shales may also represent favourable exploration target in the Weald Basin; these have also proven successful in the the North America (e.g. the Bakken oil system). The oil resources potentially present in these plays are not included in the in-place oil volumes in this report.
The total volume of potentially productive shale in the Weald Basin was estimated using a 3D geological model generated using seismic mapping, integrated with borehole information. This gross volume was then reduced to a net mature organic-rich shale volumen using a maximum, pre-uplift burial depth corresponding to a vitrinite reflectance cut-off of 0.6% (modelled at 7,000 ft./ 2130m., and 8,000 ft/ 2440m. The volume was further truncated upwards at two alternative levels - firstly at a depth of c. 3,300 ft. (1000m.) (as proposed by USEIA 2013) and secondly at a depth of c. 5,000 ft. (1,500m.) below land surface (as proposed by Charpentier and Cook, 2011 for shale gas). This is a regionally applied cut-off; the depth to which shale oil (or shale gas) productivity because an issue in terms of pressure and hydrogeology will need to be addressed locally.
The volumes of potentially productive shale and average oil yields were used as the input parameters for a statistical calculation (using a Monte Carlo simulation) of the in-place oil resource (see Appendix A). Two scenarios were modelled for each shale unit (Table 1).
[Table 1 follows, but it is not shown here. See the original.]
[Most optimistic estimate for the Kimmeridge Clay is 4.77 billion barrels using top of oil window at 7,000 ft. (2130m) or a much lower figure of 1.44 billion barrels using top of oil window at 8,000 ft. (2440 m) maximum burial depth. These figures are remarkably different.
The Mid Liassic Clay figures for most optimistic estimates is fairly uniform with 1.43 and 1.15 billion barrels. There is obviously much uncertainly about the Kimmeridge Clay.
Figures for all Jurassic clay are 2.2 - 4.4 - 8.6 billion barrels, with the last figure being the most optimistic.]
This study offers a range of total in-place oil resource estimates for the various Jurassic shales of the Weald Basin of 2.2 - 4.4 - 8.6 billion bbl 0.29 - 0.59 - 1.14 billion tonnes) (P90 - P50 - P10) (Table 1). It should be emphasised that these 'oil in place' figures refer to an estimate for the entire volume of oil contained in the rock formation, not how much can be recovered. It is still too early to use a more refined methodology, like the USGS's Technically Recoverable Resource "top down" estimates, which require production data from wells. In time, the drilling and testing of new wells will give an understanding of achievable, sustained production rates. The combined with other non-geological factors such as oil price, operating costs and the scale of development agreed by the local planning system, will allow estimates of the UK's producible oil reserves to be made.
There is a high degree of uncertainty in these figures. Indeed, there is a chance that there may be little or no 'free oil', given that the 'oil saturation index' is considerably less than 100 (see Jarvie 2012b) and what oil there is could be located entirely within the kerogen particles and would heating/retorting to extract it. In these circumstances, the resource could no longer be categorised in terms of 'shale oil'. The potential for hybrid plays in which oil might have migrated into tight reservoirs adjacent to mature shale is acknowledged, but the potential volumes of oil trapped in such plays in not addressed in this report.
Introduction to shale gas, shale oil and resource estimation:
Shales have long been recognised as the source rocks from which most oil has been generated. This mechanism allows for a proportion of the generated oil and gas to be expelled and to migrate into conventional reservoirs over geological time. The fact that some hydrocarbons, particularly oil, are retained in the fine-grained lithologies has now taken on a new significance. Some of these hydrocarbons occur as free oil in the shale, whilst some remain bound with the kerogen and require the shale to be retorted (i.e. heated to >350 degrees C) to extract it. This is the basic distinction between shale oil and oil shale (see Section 2.2 below).
The terms 'shale oil' and 'oil shale' are both applied to organic-rich source rocks, but the hydrocarbons are present in very different scenarios. Shale oil is mature and can be found in association with shale gas plays if the source rocks have been buried to sufficient depths. On the other hand, oil shale is immature and can either be mined at or near the surface or retorted in situ at depth. Such oil shale extraction techniques make it very unlikely that it might be exploited at depth in the Weald Basin. [bottom of p.4, continues with a table]
[end of example extract from the main report]


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Andrews, I.J. 2014. Appendices to the Jurassic Shales of the Weald basin: Geology and Shale Oil and Shale Gas Resource Estimation: BGS, DECC. See also these important and extensive Appendices:

Appendix A: Andrews, I.J., Sankey, M.J. and McCormac, M. 2014. Appendix A. Estimation of the total in-place oil resource in Jurassic shales in the Weald area, southern England. Appendix A to: Andrews, I. J. 2014. The Jurassic Shales of the Weald Basin: Geology and Shale Oil and Shale Gas Resource. 13 pp. Available online as a pdf file.

Example text from the Introduction to this Appendix.
"The aim of this study is to estimate the P90-P50-P101 range of potential total oil in place volumens for the main Jurassic shales units across the Weald area of southern Britain. This analysis forms an appendix to the main Weald report, which provides the detailed geological background to this shale oil play. This specific study applies a Monte Carlo simulation to a suite of input parameters, some of which come from the geology-based methodology described in the main report, and others which are based on information from published analogues. range of potential total oil-in-place volumes for the main Jurassic shale units across the Weald area of southern Britain.
2. Introduction:
In the case of the Weald Basin, the paucity of geochemical data precludes a full understanding of free oil contents that should be necessary to estimate in-place resources. However, with regards to the use of S1 to estimate oil-in-place, it is reasonable to model two end members:
1. Use Jarvie (2012b) and as '(S1/TOC) x 100' is less than 100, assume that most/all of the measured S1 is associated with kerogen. In this scenario, the free oil density will be negligible.
2. Assume that the sorbed oil is restricted to S2 and that all the S1 is free oil. It is then possible to correct the S1 for evaporative loss (see Michael et al. 2013) and use this as the free oil density.
3. Equations 2. This report converts the S1 data from Rock-Eval analyses to an estimation of free oil yield to determine oil in-place (see Section 9.2), using Michael et al.'s (2013) equation:
[continues in this style, with values used etc].

Appendix B: Smith, N.J.P., Vane, C., Moss-Hayes, V. and Andrews, I.J. 2014. Appendix B. Rock-Eval geochemical analysis of the 103 shale samples from wells in the Weald area: results and interpretation. Appendix B to: Andrews, I. J. 2014. The Jurassic Shales of the Weald Basin: Geology and Shale Oil and Shale Gas Resource. 7pp plus tables.

Appendix C: Kemp, S.J., Mounteney, I and Chagger, A. 2014. Appendix C. Mineralogical analysis of fine-grained sedimentary rock samples from Weald Basin boreholes. Appendix C to: Andrews, I. J. 2014. The Jurassic Shales of the Weald Basin: Geology and Shale Oil and Shale Gas Resource. 19pp plus tables.

Appendix D: Gent, C.M.A., Hannis, S.D. and Andrews, I.J. 2014. Appendix D. Estimation of total organic carbon in the Jurassic shales of the Weald area by log analysis. 76 pp. [Important record, with much borehole detail]
"This appendix documents the calculation of total organic carbon (weight percent (TOCwt%)) from geophysical logs across the Jurassic shale formations of interest in southern England. Geophysical data were available from wells drilled in the 1980s and stored in the British Geological Survey database. These were extracted, verified and analysed using the Passey sonic method to give vertically continuous wt% TOC curves for each well. Estimated clay volume curves were also calculated to apply dicriminators to the tabulated outputs. Intervals with clay volume values greater than 0.5 (50%) were considered 'net' for the average wt% TOC and net to gross (N/G) calculations, and intervals with greater than 2wt% TOC were considered organic-rich 'pay' in the pay to gross (P/G) values calculated for each of the Jurassic clay units listed: Kimmeridge Clay, Corallian Clay, Oxford Clay, Upper Lias Clay, Mid Lias Clay and Lower Lias Limestone-Shale Unit." [continues]

Appendix E: Stratigraphic data from key wells penetrating Jurassic shales in the Weald area. 2 pp. [Albury 1, Ashdown 2, Ashington 1, Ashour 1, Balcombe 1, Baxter's Copse 1, Biddenden 1, Bletchingley 1, Bolney 1, Bordon 1, Brightling 1, Brockham 1, Chilworth 1, Clanfied 1 - and so on. This givesd Top Kimmeridge, Top Corallian, Top Oxford Clay, Top Upper Lias Clay, Top Mid Lias Clay, in a table]

Appendix F: Andrews, I.J. 2014. Detailed correlation of Jurassic strata between selected key wells in the Weald area. There is much valuable data here in these correlative borehole diagrams. [However, if printed directly as shown, without enlargement, there is too much details to see clearly. This is undoubtedly a valuable resource. For example a log of Balcombe 1 well is given, but you cannot read the details without enlargement.]

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Armitage, P.J., Worden, R.H., Faulkner, D.R., Aplin, A.C., Butcher, A.R. and Espie, A.A. 2013. Mercia Mudstone Formation caprock to carbon capture and storage sites: petrology and petrophysical characteristics. Journal of the Geological Society, London, vol. 170, no. 1, pp. 119-132.
Abstract:
Porous rocks in the subsurface are now used for carbon capture and storage (CCS), to help ameliorate the effects of greenhouse gas emissions. These porous reservoir rocks require a caprock to retain the CO2. It is important to characterize caprock quality and its stability in the presence of elevated partial pressures of CO2. Lower Triassic sandstones are common in the UK and NW Europe and are being considered for future CCS projects. The caprock to these sandstones is the Middle and Upper Triassic Mercia Mudstone Group. We have studied the Mercia Mudstone using mineralogy, petrology and mercury injection porosimetry to assess its caprock quality. Detrital minerals are dominated by quartz, K-feldspar, illite and chlorite; diagenetic pore-filling minerals are dominated by calcite, dolomite and gypsum. In samples with abundant clay minerals, there are only small quantities of pore-filling diagenetic cements. Porosity is broadly uniform for both clay-rich and clay-poor samples. The cleaner (clay-poor) samples had their initial pore spaces filled with early diagenetic pore-filling carbonates and gypsum. Despite the broadly uniform porosity, mean pore throat diameter displays a strong inverse correlation with clay content whereas threshold capillary entry pressure shows a strong positive correlation with clay content. The more clay-rich samples represent much better caprock than the coarser-grained samples that contain abundant pore-filling cement. The samples could support potential column heights of supercritical CO2 between 70 and 540 m and have calculated permeabilities between 10-20 and 10-19 m2; leakage would occur only on geological time scales, assuming that these samples are representative of the whole caprock. Because caprock quality correlates with illite content and illite will be relatively immune to elevated partial pressures of CO2, the Mercia Mudstone probably represents a durable caprock for future Lower Triassic sandstone CCS projects.
Notes: - Location of Investigation Site.
Sample material has been obtained from core kept by the British Geological Survey (BGS) at Keyworth, Nottinghamshire. Six samples have been recovered from depths between 300 and 310 m from the Willow Farm borehole in the East Midlands near Nottingham [BGS map reference SK7543429483 or SK72NE/41]. These six samples are from the Ladinian to Carnian Sidmouth Mudstone Formation. A burial history relating to the East Midlands shelf (McKinley et al. 2012) indicates that these rocks have been buried to a maximum depth equivalent temperature of c. 80 degrees C (Fig. 2).
Notes: - Mention of Wytch Farm.
"Potential has been identified to store CO2 in the Sherwood Sandstone Group reservoirs in the East Irish Sea Basin (Gough and Shackley 2006; Gough et al. 2006; Heinemann et al. 2012) within existing petroleum fields and structures that do not contain petroleum, but that could feasibly trap sequestered CO2. The Sherwood Sandstone Group forms the main reservoir rocks in the east Irish Sea. A storage capacity of 1047.6 M tons has been calculated for sequestered CO2 (Gough et al. 2006), the equivalent of 243 years of production from the nearby Connah's Quay power plant onshore on the Dee estuary. The Mercia Mudstone Group also forms an effective seal to petroleum reservoirs in the south of England (Wytch Farm). There is a renewed need to characterize caprocks when CO2 is being injected as part of a carbon capture project."


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Anonymous . 1982. North Baddesley Borehole. Hoe No. 1. Hoe Lane. Amoco. Some preliminary notes only.

Anonymous. 1990. BP: Furious residents block road. The Purbeck Independent, 31st October, 1990, p.2. [re proposed gas borehole in the Isle of Purbeck, re Anvil Point, Durlston Head, Swanage quarries, etc. - see later work re California Quarry and InfraStrata]

Anonymous. 1990. (Editorial) Wytch Farm - Western Europe largest oil field. Erdol Kohle Erdgas Petrochemie, vol. 43, No. 3, p. 92 only.

Anonymous. 1991. Kelt unveils major onshore field boost from horizontal well. F.T North Sea Newsletter. 785, 16 pp., pl. 9 only. [Horndean Oilfield near Portsmouth]

Anonymous. 1992. BP to produce from Wytch Farm Frome Reservoir. Oilman Weekly News Letter. 23rd May, p. 6-7.

Anonymous. 1992. Wytch Farm wells to tap fields other wells cannot reach. F.T. North Sea Newsletter. 837 (29th Jan) p. 14 only.

Anonymous. 1992. Extended reach eyed for Wytch Farm. Source: Oil and Gas Journal (United States), vol. 90: 1. Publication Date: 6 Jan 1992 pp. 24-27.

Anonymous, 1993. Inverted well for Wytch Farm. Oilman Weekly News Letter, 23rd Jan, p. 5-6.

Anonymous, 1994. Wytch Farm produces at record rate. Financial Times N. Sea Letter. No. 942, 16th Feb. p.9 only. (British Geological Abstracts)

Anonymous. 1996. Map of blocks in Dorset region with notes on discoveries. [Note 9.6 mmcfpd of gas east of Swanage. Wytch Farm - oil 312 mmbbl, gas 38 bcf.]

Anonymous. 1996. Map of blocks in Dorset region with notes on discoveries. [re gas in the Isle of Purbeck]

Anonymous. 2008. More black gold than ever before - but please keep the noise down. Midhurst and Petworth Observer, online - Thursday 25th September, 2008. Published Date: 11 September 2008.
Black gold will be pouring from an oilfield site in woodland near Singleton after plans to extend it were approved. Providence Energy will be increasing the one-hectare site by 0.3 hectares and installing four new jet pumps. The site, to the left of the A286, currently has six wells, five 'nodding donkeys' (pump beams) and a jet pump well. The on-shore site produces 450 barrels of oil per day, but the expansion will increase production to between 850 to 1,000 barrels per day. Singleton Oilfield has been drilling for oil since 1990 and has expanded several times over the past 18 years. West Sussex County Council's planning committee has given the site temporary permission to drill for oil until December 31, 2016, to tie in with the end of the current planning permission. Councillors were concerned about the amount of noise produced by the site, which has increased from 27 decibels to 33. Resident Michael Allison, who lives in Broadham House, the nearest property to the site, said he had lived there for many years. He had no objections to the expansion, but hoped all reasonable action would be taken to keep noise levels to a minimum. "If the wind is blowing from the south-west the noise is at a minimum. If it's from the north-east the noise is considerably increased," he said. "When there are leaves on the trees it is considerably reduced. When the leaves fall off the trees, the noise is increased. With modern technology, I would have thought the noise would be reduced, not increased." Officers said the limit of 33 decibels would be policed. The expansion will involve felling around 100 trees, some of which will be replaced as part of a landscaping and compensatory woodland management scheme. Once work at the site ends, the area will be restored to its original state.
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Aplin , A.C. and Coleman, M.L. 1995. Sour gas and water chemistry of the Bridport Sands reservoir, Wytch Farm, UK. In: The Geochemistry of Reservoirs, Geological Society Special Publication No. 86, pp. 303-314. By Andrew C. Aplin and Max L. Coleman. Special Publication No. 86, The Geochemistry of Reservoirs. Available online from the Lyell Collection of the Geological Society, London.
Abstract:
Co-produced waters and gaseous H2S were sampled at four wells at Wytch Farm oil field, UK, over a one year period. The chemical and stable isotopic (H, O) compositions of the waters were determined, plus the sulphur isotopic composition of dissolved sulphate and gaseous sulphide. Formation waters contain about 70 000 mg 1-1 total dissolved solids (TDS) and are evolved meteoric waters; there is a 10% fieldwide variation in TDS. H2S was formed by (bacterial?) reduction of formation-water sulphate. A high but variable fraction of the sulphide has been subsequently lost, perhaps by reaction with abundant Fe-bearing minerals. At least some, and possibly a significant fraction, of the sulphide in the reservoir is dissolved in formation water. Simple mass-balance models show that when reservoir sulphide is predominantly within formation water, the concentration of H2S in produced gas will increase dramatically with increasing water cuts. In this case, increasing concentrations of H2S in produced gas do not necessarily imply that souring has been caused by production practices. Seawater breakthrough is recognized and quantified in one well using chemical and stable isotopic data. K, Mg and SO 4 are all lost from injected seawater during its passage through the reservoir. Geochemical modelling and isotopic data fail to identify the fate of the missing sulphate,, although the isotopic data tentatively suggest that some may have been converted to sulphide. However, the levels of sulphide produced from the breakthrough well are no higher than in other wells, suggesting that reduction of seawater sulphate contributes a small percentage of fieldwide H2S production.

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Arthus, J.D., Bohm, B. , Coughlin, B.J., Layne, M. 2008. Evaluating the Environmental Implications of Hydraulic Fracturing in Shale Gas Reservoirs. (i.e. re "Fracking")
Available online as a pdf file:
Evaluating the Environmental Implications of..

ArthurHydrFracPaperFINAL.pdf
Authors: J. Daniel Arthur, P.E., ALL Consulting; Brian Bohm, P.G., ALL Consulting; Bobbi Jo Coughlin, EIT, ALL Consulting; Mark Layne, Ph.D., P.E., ALL Consulting
Abstract:
Exploration, drilling and production of shale gas plays such as the Barnett, Fayetteville, and Haynesville have transformed the unconventional gas industry. These and other existing and developing plays have had unimaginable economic impacts to many regions, created tens of thousands of jobs, and have generated royalty payments to a variety of state and local governments as well as many individuals. At the core of shale gas development are two key technologies: horizontal drilling and hydraulic fracturing. Techniques used to hydraulically fracture horizontal wells completed in shale reservoirs often require larger volumes of fracturing fluid than might be common for conventional, vertical well stimulations. The rapid development of shale gas across the country has created concerns on issues such as the use of infrastructure and environmental impacts. Specifically, the common practice of hydraulic fracturing of these shales has attracted critical interest regarding risks potentially posed to groundwater and surface water. This paper will present a summary and evaluation of the environmental implications of hydraulic fracturing in shale gas reservoirs, with examples from multiple basins.

This paper is of interest in that it briefly discusses various formations including the Haynesville Shale of Kimmeridgean age in Louisiana (although this Jurassic unit is much more thermally mature than the Kimmeridge Clay of Balcombe).

The paper discusses the stages in hydraulic fracturing, including the following:

Drilling and Data Collection; Model Simulations, Bringing Hydraulic Fracturing Equipment On-site; Bringing Fluids On-site; Acid Treatment (taking place at Balcombe 2013); Flush and Initiate Formation Breakdown; Perforate Production Tubing (planned for Balcombe); Rig-Up Piping; Pump Slickwater Pad; Pump Proppant Stages; More Proppant Stages; Well Flush.

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Barker, J.A. [et al.?] 1988. Monitoring and modelling of the Southampton geothermal reservoir: progress report [first progress report]. (2 copies in Southampton University, Hartley Library, Cope Collection, Quarto, SOU 66.5.)

Barker, J.A. [et al.?] 1989. Monitoring and modelling of the Southampton geothermal reservoir: progress report [second progress report?]. (2 copies in Southampton University, Hartley Library, Cope Collection, Quarto, SOU 66.5.)

Barker, J.A., Bird, M.J. and Darling, W.G. 1989. Monitoring and modelling of the Southampton geothermal reservoir, 3 : third progress report. By J.A. Barker, M.J. Bird, and W.G. Darling. British Geological Survey, Hydrogeology series; 89/31. 19pp. (2 copies in Southampton University, Hartley Library, Cope Collection, Quarto, SOU 66.5.)

Barker, J.A., Rowe, W.G.E., Bird, M.J. and Darling W.G. 1991. Monitoring and modelling of the Southampton geothermal reservoir, 4: Final Report. By J.A. Barker, Rowe, W.G.E, Bird, M.J. and Darling, W.G.. British Geological Survey, Hydrogeology series. 71pp. (2 copies in Southampton University, Hartley Library, Cope Collection, Quarto, SOU 66.5.)
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BBC. 2015. New licences for UK shale gas exploration. BBC online, 17th December 2015. The Oil and Gas Authority has awarded a raft of new licences to explore for oil and gas on the mainland of the UK. The 93 licences to explore 159 blocks of land could pave the way fro more controversial hydraulic fracturing, known as fracking. Large parts of North East and North West of England have been opened up for exploration. There are also licence blocks in the Midlands, the South of England and Wales. About 75 percent of the exploration licencess relate to shale oil and gas, which typically requires fracking. The Oil and Gas Authority6 said a total of 95 applications for licences were received from 47 companies, covering 295 Ordnance Survey Blocks. Among the biggest winners were Ineos, with 21 licences, Cuadrilla, IGas and Southwestern Energy. Ineos said it was "committed to full consultation with all local homeowners, landowners and communities close to its shale gas wells".... This week, MPs voted to allow fracking for shale gas below national parks and other protected sites. ....." [See the map of new licences and current licences] -- [continues]
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Beeley, H.S. and Norton, M.G. 1998. The structural development of the English Channel High, constraints from section restoration. In Underhill, J.R. (Ed.) Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publications, No. 133, pp. 283-298. With 13 Figures. H. Beeley from Phillips Petroleum Company and M.G. Morton from Coleraine Road, London.
Abstract: The Central Channel High is an east-west trending asymmetric, south-facing, anticlinal structure which forms the southern boundary of the Central Channel Basin. Upper Jurassic rocks are exposed at seabed in the core of the structure, while Tertiary strata are preserved immediately to the south. Elsewhere in the Wessex - Channel basins structures of this overall form are interpreted as linear inversion structures formed during the mid-Tertiary by the reactivation of Mesozoic extensional faults, themselves formed by the partial reactivation of Variscan thrust ramps. Projection of the eroded sequence over the high using the geometry of the preserved section indicates the original presence of an approximately symmetrical Upper Jurassic - Lower Cretaceous sub-basin formed in the hanging wall of a north-dipping Mesozoic extensional structure, the Central Channel Fault. Seismic velocities from wells over the high are consistent with the implied post-Cretaceous relative uplift of up to 1500m. The deeper geometry of the Central Channel Fault has been determined using the restored hanging wall geometry and the main internal aspects of the inversion structure have been recreated by forward modelling. The internal structure of the Central Channel High is consistent with a moderately steep fault near surface which passes relatively abruptly inot a lower-angle fault. this is interpreted to indicate the presence of a Variscan backthrust at depth which has been partially reactivated during both Mesozoic extension and mid-Tertiary inversion.
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Berger, B.D. and Anderson, K.E. 1978. Modern Petroleum; a Basic Primer of the Industry. PennWell Books, Tulsa, Oklahoma. 293 pp. [This book has no special relevance to the south of England. However, it is light, interesting reading with many good diagrams, particularly those that explain old techniques and petroleum exploration history. I have used it for a beam pump diagram.]
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BERR, Department for Business, Enterprise and Regulatory Reform. 2008. The Hydrocarbon Prospectivity of Britain's Onshore Basins . 85pp. This was previously available online at: BERR - Hydrocarbon Prospectivity Reports.

However it is now out-of-date and no longer available. If you click on it you receive a "Stop" warning. There is a redirection to:

British Government, Department of Energy and Climate Change - Oil and Gas.

[The following notes are from the original report]
This report has been produced under contract by the British Geological Survey (BGS). It gives contacts for requests and enquiries to Geoff Swann, Senior Geologist - UK Onshore, and Joy Gray, Senior Geoscientist - Energy and Resources Development Unit, BERR. The specific pdf file is obtainable at: The Hydrocarbon Prospectivity of Britain's Onshore Basins. [This is a concise report, with references, that has sections on the Geological Overview, Wessex Basin, the Weald Basin, the Cheshire Basin, and the Cleveland Basin.] Example extract: "The Department of Trade and Industry's (DTI) onshore licence area includes some offshore areas, specifically estuaries e.g. in the Solway and seas between islands e.g. the Minch between the inner and outer Hebrides, NW of Scotland (Fig. 1.1). Geographical coordinates of these areas may be found here. A map showing the current onshore licensing situation is available here. Northern Ireland issues its own Licences to cover its onshore area, contact the Department of Enterprise, Trade and Investment's Energy Division, tel: 028 9052 9900 for more details. For the purposes of describing hydrocarbon prospectivity, the onshore United Kingdom can be divided into productive basins, potentially productive basins and those where the prospectivity is less attractive. On figure 1.1 productive basin names and provinces are shown in red, potentially productive in blue and adjacent offshore basins in black. The productive or historically productive basins are: Wessex (section 2), Weald (3), West Lancashire (5), Cleveland (6), the East Midlands oil province (7, also known as Carboniferous Pennine Basin) and the Midland Valley of Scotland (8). The potentially productive basin reviewed is the Cheshire Basin (4). The Wessex and Weald basins both extend offshore into the English Channel, but only their onshore components are described. Similarly, the West Lancashire Basin is the eastern, onshore margin of the more extensive East Irish Sea Basin, and the Cleveland Basin is essentially the onshore extension of the Southern North Sea gas basin. The productive basins have been explored for about 100 years and are now essentially at a mature stage of exploration. The average oilfield size is 2.1 million barrels (excluding Wytch Farm Oilfield, Fig. 1.2). Saltfleetby is the largest producing gas field, with recoverable reserves of 2.08 bcm (Fig. 1.3). Detailed statistics for producing fields are available here. [There follows a plot of a list of oilfields in order of discovery with million tonnes of oil (recoverable reserves) from each]
Keddington, Cold, West Firsby, Goodworth, Long Clawson, Whisby, Scampton, Beckingham Storrington (Sussex), Farley's Wood, Palmer's Wood, Welton, Wareham (Dorset), Apleyhead, Torksey, Gainsborough, Corringham, Langar, Plungar, Caunton, Formby, Midlothian, Coalport Fields"
[Wytch Farm is off the scale in terms of recoverable reserves, but is indicated next to Wareham.]

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BERR. 2002?.Wytch Farm. Summary data on oil field in production - BP-Amoco. Wytch Farm, (BP-Amoco). Onshore oil field in production. Block and licence number: L97/10, PL.089. Grid reference: 2 degrees 00 W, 50 degrees 40 N. [continues as a table, with data on licencees and company interests etc.].


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Bigge, M.A. and Farrimond, P. 1998. Biodegradation of seep oils in the Wessex Basin- a complication for correlation. By M. Ashley Bigge and Paul Farrimond. [at Fossil Fuels and Geochemistry (NRG), University of Newcastle upon Tyne. In: Underhill, J.R. (editor) Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publication, No. 133, pp. 373-386.
Abstract: A detailed organic geochemical investigation of seep oils from the Dorset coast has revealed notable variation in both the extent and pathways of biodegradation. All the seep samples analysed from Mupe Bay, Stair Hole (near Lulworth Cove) and Osmington Mills have had their n-alkanes and acyclic isoprenoid alkanes removed, but some samples are more extensively degraded, with partial loss of steranes and/or hopanes. At Mupe Bay (conglomerate matrix samples; see Parfitt and Farrimond 1997 this volume) the hopanes have been preferentially attacked, whilst at Stair Hole the steranes appear heavily degraded although there has been no alteration to the hopane distribution. 25-Norhopanes were not detected in any of the samples. Biological marker distributions of seep oils which have suffered no hopane or sterane biodegradation are compared with those of three reservoired oils from the area (Wytch Farm and Kimmeridge fields). Molecular parameters indicate significant variation in source rock facies and maturity within the oils of the Wessex Basin.


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Bitterli, P. 1960. Bituminous Posidonianschiefer (Lias epsilon) of Mont Terri, Jura Mountains. Bulletin der Vereinigung Schweiz. Petroleum-Geologen und - Ingenieure, Volume 26, 1959-1960, Heft 71. pp. 41-48, available online as a pdf [in English].
Introduction [no English abstract is given]: In the course of an extended field investigation of bituminous rocks, a number of surface and well sections, covering the Lias epsilon (lower Toarcian) or at some places the whole Lias, were studied in Western Europe. Natural outcrops of complete Lias sections being rare, the Posidonienschiefer of the Mont Terri in NW Switzerland proved an invaluable link between the excellent Lias outcrops of Aubachle in Wurttemberg and of Fontaneilles near Millau in S France. During the summer of 1957, a survey of the Swiss table and folded Jura found the best profiles exposed to occur in the Mont Terri area and the following locality was chosen at the south flank of this anticline: the co-ordinates are 578,76/247,91 of the Landeskarte der Schweiz, 1 : 50,000, Blatt 222, Clos du Doubs. The location lies 7 km SE of Porrentruy, about 1 km S of Mont Terri and 250 m due N of Pt. 857. At this place, locally referred to as Les Efougelles, the Posidonienschiefer is developed as bituminous shale 17 m thick and a complete section between the underlying Spinatus-Obliqua beds and the overlying Jurensis marl could be exposed along a small creek with little digging. A. Schneider carried out the field survey and collected 43 samples from this locality. At the laboratory, in Delft, most of the rock specimens were studied sediment-petrographically by A. Fehr and eight selected samples were analysed geochemically by J. A. Gransch and P. A. Schenk under the supervision of E. Eisma. Micropalaeontologic investigation was done by J. Brouwer, while the palynological studies were carried out by Miss M. Brosius. In the following, a brief account of the results of these studies is given (see fig. 1), comparing some of them with the information obtained from other Lias sections in western Europe which were investigated by S. B. Spijer, R. M. M. Moullard, H. F. Jansen and P. Bitterli during 1957-59. [end of Introduction] [Relevance to UK - bituminous shales, 17m thick occur near the Pliensbachian-Torcian boundary. In the Portsdown borehole, Sussex, a small amount of bituminous shale in recorded in the Lias near the Pliensbachian-Toarcian boundary,]
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Bjorkum , P.A. and Walderhaug, O. 1993. Isoptopic composition of a calcite-cemented layer in the lower Jurassic Bridport Sands, southern England: implications for formation of laterally extensive calcite-cemented layers. Journal of Sedimentology, 63, 678-682.
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Black Rock Oil & Gas PLC . 2004. Acquisition of Wildlook Enterprises Pty Ltd. Proposed issue of 1 warrant for every 5 existing ordinary shares. Exploration update Notice of EGM. See: Black Rock, 2004 - pdf file.

Selected extracts relevant to West Weald oilfields:
PEDL 125 Black Rock interest: 10%.
PEDL 125 is situated adjacent to the Horndean and Singleton Fields in Southern England, geologically within the Weald-Wessex Basins. There is a lead located in PEDL 125 where an oil play may have been bypassed in the Great Oolite in the Hedge End 1 well. Seismic analysis near the well suggests considerable updip potential and initial estimates of potential recoverable mean volumes are 3 to 9 million barrels of oil. A second follow-up lead, Eastleigh, is also located in this block.
PEDL 126 Black Rock interest: 10%
PEDL 126 is situated adjacent to the Horndean and Singleton Fields in southern England, geologically within the Weald-Wessex Basins. Six potential structures have been identified in PEDL 126, between and adjacent to the known fields. Wells in the area have similar oil water contacts within the Great Oolite reservoir, indicating that the prospects may be connected. The High Copse and Hylters prospects lie between the two fields and have estimated recoverable volumes of 1.1 to 3.3 and 3 to 9 million barrels of oil, respectively. Three additional prospects extend southwest from the Singleton Field. The Chilgrove, Hasler's Steading and Walderton prospects each have estimated recoverable volumes in the range of 0.6 to 1.9 million barrels of oil, 3.8 to 11.4 million barrels of oil and 1.6 to 5 million barrels of oil, respectively. Northwest and updip of the oil-water contact in the Horndean Field is a broad low relief closure, known as Hinton Manor Extension, which possibly links the Horndean Field and Hinton Manor. To the north of these is a further prospect named Clanfield. These prospects have estimated recoverable volumes in the range of 0.4 to 1.3 million and 1.0 to 3.2 million barrels of oil, respectively. Although these structures have great potential because of the postulated single oil water contact, further work needs to be carried out on the play prior to drilling.

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Black Rock Oil and Gas PLC. 2004. Site preparation for Sandhills 2 well site has commenced. [Brief notes on the website:] Black Rock Oil and Gas Plc (the "Company") today [7 December 2004] announces that site preparation began yesterday at the Sandhills 2 well (PEDL 113) on the Isle of Wight. The Company has a 5 percent free carry in this project. The Sandhills 2 well location is expected to be drill-ready by January 2005 and is required to enable the drilling of the well. This well is one of 5 projects that the Company has an interest in near the Isle of Wight (PEDL 098 - 5 percent; PEDL 099 - 5 percent; PEDL 113 - 5 percent; PEDL 151 - 2.5 percent; PEDL 152 - 5 percent). [no further information here on this topic. The following website gives the same limited information:] Rigzone Com , your gateway to the oil and gas industry.    
There is further information on location in the following:
IW Tests for Black Gold Begin. By Suzanne Pert. The first test for oil on the Island for a decade has got under way in woodland between Shalfleet and Yarmouth. Behind the venture is Northern Petroleum who, with partners, aim to drill for black gold in the Porchfield area and will soon be submitting a planning application to sink a trial borehole in a drilling area known as Sandhills 2. The company also intends to make a second application for a borehole in a separate area of the West Wight. But there were some gaps in the seismic information and it was felt that new techniques would provide more vital information before planning applications were submitted. Two huge seismic vibrators were brought to the Island - one to be used as a back-up - and surveys were carried out under guidance from the company's chief geophysicist, Jerry Field, on Forestry Commission land at Bouldnor Copse. The information obtained from the 16-ton, four-wheel articulated vehicles will be sent to a process centre and it will take about a month before a picture emerges of the seismic section surveyed. That data will be interpreted by Mr Field. He said the last seismic survey was carried out on the Island in 1992 by Brabant and prior to that British Gas, Sun Oil and Clyde Petroleum had all acquired their own data... [continues, with photograph].
[For estimates of reserves see the following:]
Drilling for Black Gold. by Echo Reporter. 2003. Some extracts only: "Humble Porchfield could become the Island's answer to Dallas after a major oil company announced it will investigate drilling for crude oil beneath the small rural village. Northern Petroleum plc, which has a 40 per cent interest in the licence covering the area, has told its shareholders that there could be almost ten million barrels of oil beneath agricultural land around the village in a field known as the Sandhills-1 oilfield. The company is preparing a planning application asking the Isle of Wight Council for permission to sink a borehole. ..Northern Petroleum said the cost of the exploratory well is likely to be between 600,000 pounds and 1m pounds. The company has told shareholders the Sandhills project was capable of transforming the perceived value of the company. It says: "It has been independently evaluated at 9.8 million barrels of `probable' oil reserves." This would make it bigger in terms of reserves than Humbly Grove in Hampshire, which is nearing the end of its productive life and has netted about eight million barrels. The exact site of the borehole has not been identified, but it is likely to be close to a previous test well on land to the west of Whitehouse Road, at Youngwoods Farm. "We are very certain the oil is in the ground, more than 90 per cent certain, but the issue is can we get it to the surface at a rate of production which is economic?" said Mr Musgrove..." [continues].
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Bleakley , W. B. 1986. BP active onshore UK. Petroleum Engineer International, vol. 58, no. 3 March 1986 pp. 70-72.
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Bloch, S. 1981. Modes of Formation of Anomalously High Radioactivity in Oil-Field Brines. American Association of Petroleum Geologists Bulletin (Geologic Notes), vol. 65 (1981). By Salman Bloch and Robert M. Key.
Many oil-field brines contain anomalously high radium concentrations. A theoretical model proposed here suggests that such concentrations can be a function of the geochemical environments of petroleum reservoirs or can be caused by uranium occurrences associated with oil pools. The model suggests that, on a triangular diagram with barium, radium-228, and radium-226 as the axes, brines associated with uranium occurrences will plot relatively far toward the radium-226 corner. Radium-rich brines associated with "normal" mineral assemblages will fall relatively close to the Ba/Ra-228 side of the diagram. Geochemical differentiation of the radium source may provide a useful tool in exploration for uranium accumulations in petroliferous areas.
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Bowman, M.B.J., McClure, N.M. and Wilkinson, D.W. 1993. Wytch Farm oilfield: deterministic reservoir description of the Triassic Sherwood Sandstone. In: Parker, J.R. (ed), Petroleum Geology of Northwest Europe: Proceedings of the 4th Conference. The Geological Society, London, 1513-1518.
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Bournemouth Bay Group. 1986. Geology of the Wessex Basin. Unpublished company report. Re the 9th Round of Licencing. Many maps and diagrams. About 100 pages, softbound. This is an old, out-of-date oil company report on Poole Bay etc.. Some of the maps and diagrams are useful. Kindly donated to me by the late Dr. Stan Cockett
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Bow Valley Energy Ltd . 2000. Bow Valley Energy Ltd. - A Solid Foundation. (The following link to a website is no longer functioning: Bow Valley Energy Ltd.- A Solid Foundation. )
Many of the people involved with Bow Valley Energy Ltd. played a part in the success of the original Bow Valley. From its modest beginnings in the late 1940's, Bow Valley Industries, with Doc Seaman as Chairman, had become a large diversified international corporation by the early 1980's. Bow Valley's primary revenues came from oil and gas production, principally from fields in Canada, the United Kingdom, Indonesia, the United States, Norway and Abu Dhabi. In oilfield services, the Company's drilling subsidiary was one of Canada's largest drilling contractors, both onshore and offshore. Bow Valley was also active in other business sectors: coal mining and minerals exploration; manufacturing of transportation, heating, ventilating and air conditioning equipment; design and manufacturing of environmental monitoring equipment; as well as the ownership and operation of a hazardous waste disposal facility... and an exploration program has been launched onshore in Dorset.

Bow Valley Energy Ltd. - Research Report, 2000. This was available as a pdf file but is not functioning now. (Bow Valley Energy Ltd.- Research Report. )
See: P.7 - Part Two: Onshore Properties; The Wessex Licenses.
"Bow Valley hold operated interests in three contiguous UK licences - PL 090 (41.67), PEDL 048 (45 percent) and PEDL 072 (37.5 percent). .....they cover all the western and central parts of the prominant horst feature known as the Central Wessex High, the natural trap for oil migrating from the major oil kitchen to the south, which rises, as one moves further west, closer to the surface -1100m, compared with 1600m. at the eastern end, where is to be found the 450m. barrels plus Wytch Farm field, the most prolific producer among onshore oilfields in western Europe, plus numerous small satellite accumulations including Wareham (largely depleted) and Stoborough (still to be developed). Contained within PL 090 is a more remote and yet-to-be-appraised satellite discovery, Waddock Cross, but following recent seismic this is considered too small to be developed at this time.
Wytch Farm, when first discovered, was a moderate-sized oil accumulation in the Bridport (Jurassic), sourced from the Liassic (Lower Jurassic), the major source rock for southern England. A model for the juxtaposition of the Liassic with a thick section of the older Sherwood (Triassic) reservoir rock, across a major regional fault, during the main period of oil migration (Lower Cretaceous to Tertiary) encouraged then-operator British Gas to deepen one of the Bridport producers into the Sherwood. The astonishing success of this exercise turned Wytch Farm into the UK's most abundant source of easily-accessible oil supply and the enforced sale of the British Gas share therein, the first of the Thatcher administration's privatisation moves, was the making of junior UK independents Carless Capel, Clyde, Goal and Tricentrol, none of whom have survived the subsequent consolidation periods of the industry.
Attempts to discover on-trend analogues, both on and offshore, proved abortive, the majority of the wells not even recording oil shows, a surprising outcome given that the Wytch Farm Sherwood structure is full to spill point and oil migrating through the region should in theory have been trapped somewhere nearby. Recent reinterpretation of well data and previous seismic has however suggested that all previous wells in the area were drilled either off-structure or in petroleum-migration shadows; in some cases, velocity-conversion problems meant that wells testing apparent highs were in reality located in synclines or other structural lows. The BVX-led consortium has identified a dozen Sherwood closures with reserve potential of up to 60m barrels individually and 300m barrels collectively on its licences, none of which have ever been tested by the drill bit. Two (Woolcombe Farm and Townhill Farm) are ready to drill, subject to the granting of full planning permission.
Of these, the larger is Woolcombe Farm, with the potential for recoverable reserves of more than SOm. barrels; on current plans, this will be drilled in the first quarter of 2001. The prospect lies towards the western end of the horst block, and hence at the ultimate point of the migration route - only the adjoining Powerstock fault block is further to the west and it is possible that the two might be in communication, in which case the reserve potential would be in the region of BOm. barrels. The prospectivity of Woolcombe Farm is enhanced by the possibility of additional sourcing from the south. Recent exploration in Dorset has proceeded on the assumption that the oil kitchen was confined to an area to the south of Wytch Farm, but there is ample evidence of past oil-generation, as far west as the Chesil Bank, in the existence of numerous surface seeps (e.g. Osmington Mills) and significant shows in five of the six previously-drilled wells between Woolcombe Farm and the coast. Between Abbotsbury, at the northwestern end of the Chesil Bank, and Swanage there is a zone of significant inversion - uplift in the Oligocene-Miocene periods - whose surface manifestation is the Purbeck Hills. This had the effect of bursting the Bridport structures closer to the coast, allowing the trapped oil to escape, but was too far south to affect the Central Wessex High.
Success with Woolcombe Farm -1 would, by confirming the validity of the migration theory, greatly improve the likelihood of similar finds in the other dozen mapped Sherwood prospects extending across the three licences. These collectively have reserve potential of Wytch Farm proportions."
[end of section on: The Wessex Licences; continues with "The Paris-Basin Blocks"]
See also the publicly available Planning Application for West Compton Well, with diagrams as below.
"Proposed Exploratory Borehole, West Compton, Dorset. Supporting Statement to the Application. (2000 or 2001?).

Seismic line through the West Compton Prospect, Dorset, 2000

Prognosis for the West Compton Well, Dorset, prior to drilling, 2000

Location and Access:
The proposed wellsite is located 2 km north of the A35 Bridport to Dorchester Trunk Road in the Parish of Litton Cheney on arable farmland 800 metres south of West Compton. (see dwg. no. BV/04). Access to the wellsite is proposed from the unclassified County Road known as White Way via a proposed 1.25 km new access track across open farmland. The extent of the land the subject of the planning application, amounting to 3.07 hectares (7.59 acres), is shown on dwg. no. BV/05.
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Bowman , M.B.J., McClure, N.M. and Wilkinson, D.W. 1993. Wytch Farm oilfield: deterministic reservoir description of the Triassic Sherwood Sandstone. Petroleum Geology of North West Europe: Proceedings of the 4th Conference, 1993, edited by J.R. Parker, pp. 1513-1517. Available online from the Lyell Collection of the Geological Society, London.
Abstract:
The Triassic Sherwood Sandstone is the principal reservoir in the Wytch Farm Field, located in Dorset, southern England. Composed of predominantly arkosic alluvial sandstones, it has excellent reservoir qualities but includes significant mudstone, calcrete and calcrete conglomerate baffles which affect the vertical passage of fluids. The identification of 'flow units' within this sequence has helped to determine appropriate layers for use in the reservoir simulation model. These flow units were defined using core data from 24 of the 48 wells and by log correlation. The well information was supplemented by outcrop data to help elucidate the geometry of individual layers.
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Bray, R.J., Duddy, I.R. and Green, P.F. Multiple heating episodes in the Wessex Basin: implications for geological evolution and hydrocarbon generation. In: Underhill, J.R. (editor). Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society of London, Special Publication, No. 133, pp. 199-213. By Richard J. Bray (Geotrack International UK Office, 5 Linen Yard South Street, Crewkerne, Somerset, UK), Ian R. Duddy, (Geotrack International UK Office, Crewkerne) and Paul F. Green (Geotrack International Pty Ltd., 37 Melville Road, Brunswick West, Australia).
Abstract:
The timing of maturity development and hydrocarbon generation with respect to structuring is a primary factor controlling oil and gas accumulation. Hydrocarbon generation is largely a temperature-dependent process and in order to predict accumulation it is necessary to reconstruct thermal history. In this study of the Wessex Basin and adjacent areas, direct thermal history data are obtained from Apatite Fission Track Analysis (AFTA) on samples from wells, shallow boreholes and outcrops, enabling the key facets of a complex thermal and tectonic history to be reconstructed. Several distinct styles of thermal history are recognised, with clelar differences across the region in the time of cooling from maximum palaeotemperatures. Areas of east Devon show evidence of an early thermal expisode, sometime after mid-Triassic and before approximately 170 million years. The cause remains uncertain at present. In the area of the 'Wytch Farm Block' maximum palaeotemperatures were reached prior to cooling in the early Cretaceous, in the range approximately 140 to 100 million years, due mainly to uplift and erosion. This area remained relatively high through the rest of its history compared to areas to the north and south. The Lias (early Jurassic) was not heated sufficiently to cause significant generation and any that occurred effectively ceased in the early Cretaceous. South of the Portland - Isle of Wight faults, maximum palaeotemperatures were reached prior to cooling due to uplift and erosion in the mid and late Tertiary at about 40 million years and at about 20 million years respectively. Tertiary uplift and erosion affected a wide region. Maximum erosion occurred immediately to the south of the Purbeck structure where maturation of Lias source rocks continued through peak oil and into the gas generation phase until terminated by the Tertiary cooling. In most wells AFTA and vitrinite reflectance data define low and or non-linear palaeogeothermal gradients indications of an element of heating due to fluid movement in addition to heating due to burial, making quantitative estimation of erosion difficult, but any reasonable model requires kilometre-scale uplift and erosion over a wide region. West of Portland in Lyme Bay, a key question is whether maturation history is dominated by early Cretaceous or by mid- to late Tertiary events. At present there are not sufficient data to extrapolate confidently from the area of well control east of Portland. No parts of the basin are currently generating hydrocarbons, implying that surface seepages are previously reservoired accumulations.

[This is a key paper. This is an excellent discussion of the tectonic and corresponding thermal events. Most of it is compatible with the general theories re the basin history, but there are some anomalies.]

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British Geological Survey [BGS]. 2017 [and open data for various years]. The BGS Lexicon of Named Rock Units: Great Oolite Group. [Computer Code - GOG, Mapping Code GtO]. Available online, free of charge.
Extract notes: The Great Oolite Group is Middle Jurassic, Bathonian to Bajocian age. Inferior Oolite Group is below. The Kellaways Formation is above. The thickness is about 20m through Lincolnshire and the Midlands (East Midlands Shelf), thickening south through the Cotswolds (60 to 90m) to 100 to 200m in Somerset and Dorset, and in the Weald subcrop (Green, 1992; Sumbler, 1996) [actually it can be about 60m in places]. Offshore English Channel up to 224m (Hamblin et al., 1992). continues

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BP - BRITISH PETROLEUM


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BP Petroleum Development Ltd. 1984. A Consultative Document; the Proposed Overall Development Scheme for Wytch Farm Oilfield.
26pp with fold-out maps, and with an Appendix 1, Dorset County Structure Plan, and Appendix 2, Glossary of Terms.
Foreword - Why Further Development at Wytch Farm?
The original development at Wytch Farm was designed to produce oil at the optimum rate (4,000 barrels a day) from the Bridport Reservoir. This has been successful and the production rate from this reservoir could remain at about that level for several years to come.
The proposal is to develop the underlying Sherwood Reservoir, which has substantially greater reserves of oil and natural gas and to determine the limits of the the Bridport Reservoir. To do this properly it is necessary to drill a number of new wells, to provide new gathering facilities and to transport the produced oil and gas out the Purbeck area.
The proposed scheme has to balance the need for good reservoir management with the need to avoid damage and unnecessary disturbance to the ecology of the area. Therefore to avoid constructing a new gathering station it is proposed to modify and extend the existing plant at Wytch Heath. The additional rail loading facilities can be fitted into the existing Furzebrook site and many of the new wells can be drilled on existing well sites. Two new sites would be required on Furzey Island and a third in the vicinity of the Studland peninsula [the application for the well under the South Haven Peninsula ran into sustained opposition, and in 1982, Shell Bay had become National Trust land].
BP is receptive to alternative ideas and suggestions but has chosen to put forward a clear proposal rather than put forward a possibly confusing number of option.
The scheme described in this consultative document is based primarily on BP's studies and our shared experience with Gas Council (Exploration) since the initial exploration began in 1973.


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BP Petroleum Development Ltd . 1985. Oil from Dorset. A Consultative Document. BPPD, Dorset.

BP Petroleum Development Ltd. 1987 (March). Exploratory Drilling in 98/7 - Consultative Document.

BP Petroleum Development Ltd. 1988. BP's Plans for Further Drilling in Poole Bay. (Consultative Document). BPPD, Dorset.


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BP Exploration. 1991. Hook Island - Poole Bay: Private Bill - Environmental Study. (re a proposed artificial island off Sandbanks). Compiled by Brocklehurst, M.S., Whitehead, A., Martin, D.E. with assistance from Turnbull, B.J., Rodgers, D.C., Stevenson, S. and members of the Wytch Farm Development Project, Hydraulics Research, Nicholas Pearson Associates and Southampton University. On behalf of BP Petroleum Development Ltd., Arco British Ltd., Premier Oil Dorset Ltd., Kelt Energy PLC, Clyde Petroleum (Dorset) Ltd., Goal Petroleum plc. February 1991. 120 pages. [This is with regard to the original plans to build an artificial island offshore from the Sandbanks peninsula and to use this island as a base from which to drill into the Wytch Farm, oil field reservoirs. In later years extensive horizontal drilling became feasible. Thus this became the main procedure for the extraction of oil from the Wytch Farm offshore oil field. Drilling took place from the Goathorn Peninsula. The plans for the artificial island, Hook Island, were then abandoned.]

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BP Exploration. (undated, about 1992). Oil at Wytch Farm. Colour brochure of 27 pp.
[Extract from page 5, part of: "The History of Britain's Onshore Oil."]
"Natural seepages of oil and, more often, outcrops of oil-bearing shale have been used in Britain since Iron Age times. In the late 18th century and throughout the 19th century, shale was distilled on a commercial scale in various parts of Britain including Dorset. Mining for shale in Britain reached its peak during the First World War, but then went into rapid decline, unable to compete with growing imports of cheap oil from more prolific sources abroad.
However, it was recognised that certain areas of Britain were made up of sedimentary rocks which might contain oil. The Government encouraged an exploration programme and the first British oil well was drilled at Hardstoft, Derbyshire, in 1918. The Hardstoft Well was later deepened by BP, and had produced over 30,000 barrels of oil by the end of its useful life in 1945.
Renewed interest in the search for British oil in the 1930s led to the Petroleum (Production) Act 1934. This declared all oil and gas reserves to be the property of the Crown, with exploration and production licences issued by the government to suitable operators. It was about this time that D'Arcy Exploration, later to be become BP Exploration, started looking for oil in the UK.
It took until 1939 for the first commercial discovery onshore to be made - at Eakring in Nottinghamshire. Smallr finds followed nearby. Eakring alone supplied two million barrels of oil during the Second World War. D'Arcy Exploration started its search for Dorset oil with a shallow well drilled at Broadbench, in Kimmeridge Bay in 1936. Other wells were drilled at Poxwell, Ringstead, and Lulworth, and between Worbarrow and Mupe, all without success. Surveys in the 1950s shifted attention to a structure known as the Weymouth Anticline, and so BP drilled at Radipole in 1958. Analysis suggested that a deeper well should be drilled at Kimmeridge, and so oil was discovered there in March 1959. Production started in September 1960 and the Kimmeridge well continues to produce about 100 barrels of oil per day. (The barrel is used worldwide by the oil industry as a standard measure. Originally an actual barrel, it now related to a standard unit of 35 imperial gallons or 159 litres).
In 1973 following a seismic survey of the area between Wareham and the Purbeck Hills, British Gas, in partnership with BP, began exploratory drilling into the Bridport Sands formation under Wytch Farm. Oil was discovered early in 1974, 920m. (3000 feet) below the surface in what became known as the Bridport reservoir. Production began in 1979 and by the mid-1980s produced some 5500 barrels per day. Meanwhile in 1978 additional deeper wells had been drilled from Wytch Farm's existing wellsites and much larger reserves were discovered in the Sherwood Sands formation at 1585 metres (5200 feet). From the beginning of 1988 to the end of 1990, Stage II in the development of the Wytch Farm Oilfield took place. The expanded facilities prudce an annual average of 65,000 barrels per day. [This was the figure in about 1992]

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Example, partial page extract from BP Exploration brochure - Oil Within Reach, An Onshore Development Concept for the Wytch Farm Reserves under Poole Bay, 1992

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BP Exploration. (1992). Oil Within Reach. An Onshore Development Concept for the Wytch Farm Reserves under Poole Bay.
Brochure of six pages, unnumbered, written just prior to the development of Extended Reach Drilling. This is brief but it is very informative in a concise manner and has very good diagrams.
"This brochure outlines a new concept for the development of the Wytch Farm oilfield reserves which lie under Poole Bay, by drilling long reach wells from an onshore site. The scheme eliminates the need for an island in the bay [Hook Island, an artificial island, was at one stage planned to be built on Hook shoal, just off Sandbanks] and also avoids disturbance to the Studland [South Haven] penisula[there had been plans for a well near Redhorn Quay or at Shell Bay ferry location, but these did not receive planning approval]. It provides a simpler and less intrusive means of completing the development of the oilfield.
In January 1990, BP presented various concepts for recovering these offshore reserves. Two years ago, the options were onshore sites on the Sandbanks or Studland peninsulas, or offshore methods such as subsea wellheads, conventional steel platforms or concrete caissons, a gravity-based structure or an artificial island. Throughout that year, BP consulted many organisations representing local and national interests. The island was selected as the most acceptable development solution and further studies were concentrated on that proposal.
BP is a worldwide organisation and technical achievements on other oilfield developments are always monitored to see if they are applicable to Wytch Farm. Following the recent successful drilling of a series of extended-reach wells in the North Sea and elsewhere, BP and its partners are now confident that well can be drilled to a distance of five kilometres from an onshore site on the Goathorn Peninsula, or a site on farmland outside of the Studland nature reserve. This would enable the bulk of the oil in the offshore section of the Wytch Farm Sherwood reservoir to be recovered.... [continues]
[In fact the Extended Reach Drilling procedure took place successfully and it still continues. It can do so by Perenco UK until 2037. At the time of writing this webpage the wells have reached more than 11 km out into Poole Bay, so their original estimate of 5 km has been well exceeded. Hook Island never had to be built, and this was probably a considerable relief to the inhabitants of Sandbanks, even though oil and gas has been produced from beneath their houses! The BP programme was very successful, and is now being continued by Perenco UK]

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BP Exploration. (undated, about 1992, or possibly 1993 - not up-to-date). Extended Reach Drilling [ERD] Under Poole Bay. Brochure of 4 pages with colour photographs and diagrams. [produced at a date when ERD drilling into the Sherwood Reservoir was to 6 km.; subsequently it extended to 10.5 km.
The Wytch Farm oilfield, with its estimated 300 million barrels of recoverable oil [note - estimate at the time, and not including the Beacon Field], is a valuable asset to the industry and to the local and national economy. It currently [at that date, but much less in 2013] produces around 90,000 barrels (3,150,000 gallons) of oil a day. The oilfield comprises two major reservoirs, the shallower Bridport reservoir at 900 metres below the surface, and the larger, more productive Sherwood reservoir about 1500 metres underground. To date [about 1990] nine operational wellsites have been constructed and some 70 wells drilled into the reservoirs. However, one third of the recoverable Sherwood reserves lie in the offshore sector under Poole Bay. ....
BP Exploration and its partners are proud of their record in developing Europe's largest onshore oilfield in an Area of Outstanding Natural Beauty set in the heart of the Purbecks. This development has only been possible with the co-operation of local planning authorities, environmental organisations, various interested parties and, of course, the public. This successful partnership within Dorset has resulted in several environmental awards being received, including winning in 1991 the Management category of the RSA Better Environmental Awards for Industry and the National Landscape Award of trhe British Association of Landscape Industries and in 1992, a commendation in the European Better Environmental Awards for Industry and winner of the Sponsorship Award of the British Archaeological Wards. BP's commitment to the environment and to the people of Dorset will continue throughout the life of the oilfield. Unfortunately, however, BP Exploration suffered major financial problems because of the Deepwater Horizon oil spill that began in April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect, the largest accidental marine oil spill in the history of the petroleum industry. In 2010 it sold the Wytch Farm Oilfield to Perenco UK. Thus in reality BP will not be committed to the environment and the people of Dorset throughout the life of the oilfield. Perenco UK have successfully applied in 2013 to continue the operation of the oilfield for about another twenty years.

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BP. 2003. Asset Portfolio - Wytch Farm. Pdf file available online at: BP Asset Portfolio - Wytch Farm. The UK Upstream Asset Portfolio is published by BP Exploration. Farburn Industrial Estate, Dyce, Aberdeen AB21 7PB. BP Exploration, 2003.
Wytch Farm is located in Dorset approximately 17 miles from Poole, 6 miles from Wareham. Wytch Farm oil field comprises three separate oil reservoirs that lie under Poole Harbour and Poole Bay in Dorset. The Bridport reservoir is 900 metres below the surface and lies above the Sherwood reservoir, which extends eastwards under Poole Bay at a depth of 1600 metres. Further exploration discovered the 7.5 million barrel Frome reservoir in clay/limestone at 750 metres. Total estimated recoverable reserves have risen to 480 million barrels of which over 90 percent lie in the Sherwood reservoir making it the sixth largest in the UK. Wytch Farm has been developed by BP to be Western Europe's largest onshore oil field in one of the most environmentally sensitive areas of the UK. It is in an Area of Outstanding Natural Beauty, featuring: Sites of Special Scientific Interest (SSSI)... [continues]

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BP. 2004. Wytch Farm Environmental Statement - 2004. A pdf file obtainable from IEMA, Institute of Environmental Management and Assessment. IEMA Reading Room - online.
[Example extract:]
Key Environmental Issues for 2004
Drilling Programme and Production - Production of approximately 35,063 barrels of oil per day was achieved in 2004. The drilling programme continued to undertake a programme of well maintenance and infill drilling in the offshore part of the reservoir with the new B92 drilling rig on Goathorn Peninsula.
LPG (Liquid Petroleum Gas) Road Loading - Planning permission was obtained for the construction and operation of a facility at the Gathering Station to enable export of LPG [Liquid Petroleum Gas] by road. This will replace the current system of export by rail from Furzebrook Rail Terminal. Construction work began in 2004 and road export is due to start mid 2005. Pipeline Integrity - Pipeline monitoring was continued through 2004. This work provides assurance on the state of the pipeline and identifies any areas where further investigation may be necessary.
Naturally Occurring Radioactive Material (NORM) occurs at Wytch Farm, mainly in the Sherwood Sandstone Reservoir. BP had begun to use the new facilities commissioned by RWE Nukem Ltd., at Winfrith, to clean NORM contaminated drilling equipment.
Land Management - In discussion with Dorset County Council and English Nature, extensive clearance of rhododendron and gorse was completed on Furzey Island. This was carried out to improve the SSSI habitat whilst maintaining sufficient tree cover to keep the wellsites out of sight.
Gas Turbines - One of Wytch Farm's two gas turbines was upgraded in 2004 to a more efficient model. This subsequently produced additional power with only a small increase in gas consumption. The second turbine was to be upgraded in 2005.
[continues, and contains various tables, in addition to text]

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BP. 2007. Wytch Farm Oil Field.
Wytch Farm is located in Dorset approximately 17 miles from Poole, 6 miles from Wareham. Wytch Farm oil field comprises three separate oil reservoirs that lie under Pool harbour and Poole Bay in Dorset; The Bridport reservoir is 900 metres below the surface and lies above the Sherwood reservoir, which extends eastwards under Poole Bay at a depth of 1600 metres. Further exploration discovered the 7.5 million barrel Frome reservoir in clay/limestone at 750 metres. Total estimated recoverable reserves have risen to 480 million barrels of which over 90% lie in the Sherwood reservoir making it the sixth largest in the UK. [continues]

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BP Oil International Limited. 2008. [and some later, 2016, Perenco data]Assay of Wytch Farm Crude .
Crude - Wytch Farm, Location - UK, Load Terminal - Hamble, Parcel Sizes - Up to 650,000 barrels, API° - 41.2. [continues]. From Perenco - API Gravity - 40.6.

[Further information from Perenco 2016, online:
Wytch Farm is a light ultra low sulfur paraffinic Crude Oil, that yields 18 % Naphtha for reforming and Mid -Distillates with good cold properties and excellent cetane index. Naphtha 29 % yield is interesting as isomerization and Reforming unit feedstock. Kerosene Good cold properties, high smoke and aniline point makes our kerosene excellent for hydro treating to produce jet fuel. Gasoil Remarkable cold properties and excellent cetane Index. VGO Wytch farm VGO can be used as fuel due to his high Heating value and remarkably low Sulfur, or as thermal fluid. Residue can be dewaxed to produce high quality Wax or can be used as Asphalt base.]

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BP. 2009. See: DECC. Department of Energy and Climate Change (British Government). 2009. Relinquishment Document by BP - Old Harry - 1 Prospect. To DECC, Department of Energy and Climate Change. Licence determination of surrender document filed to DECC, November, 2009. Re. Old Harry - 1 Prospect. (Details given in the DECC section, and in the Petroleum Geology, South of England, webpage.). As the name implies this was an offshore prospect fairly near (southeast of) Old Harry Rock, Studland.

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BP. 2010. BP Exploration and Operating Co. Ltd. Presented by Erwin Wahidiyat. 2010. Update on ESP [Electrical Submersible Pumps]operation at BP Wytch Farm Oilfield. Presented at the European Lift Forum, 17th - 18th February, 2010.

Although primarily concerned with ESPs this paper provides much interesting information on the Sherwood Sandstone Reservoir. A cross-sectional diagram on p.4 proves much details on the Sherwood lithology. [ESPs are, according to Wikipedia: "An electric submersible pump (ESP) is a device which has a hermetically sealed motor, close-coupled to the pump body. The whole assembly is submerged in the fluid to be pumped. The main advantage of this type of pump is that it prevents pump cavitation, a problem associated with a high elevation difference between pump and the fluid surface. Submersible pumps push fluid to the surface as opposed to jet pumps having to pull fluids. Submersibles are more efficient than jet pumps."
An overall summary of the Sherwood Sandstone Reservoir is given as follows:
Triassic sandstone reservoir, with top reservoir at ca. 1585 m. TVDSS [true vertical depth subsea] with a maximum 110 m. column of oil-bearing sand above the oil water contact.
Upper reservoir: Zones 10-40, Lower reservoir: Zones 50-100. Zones 20, 40, and 60 (muddier intervals) act as barriers.
Three main oil bearing zones: Zones 30, 50 and 70 (decreasing permeability and net to gross in the upper zones). PI [Production index] ranges from 1 to 100+ BPD [barrels per day]/psi [pressure].
The western part of the field lies onshore (below Poole Harbour and surrounding area) and the eastern part of the reservoir lies offshore.
Over half of the Sherwood reserves lie in the offshore area which necessitated the drilling of ERD [Extended Reach Drilling] wells beginning 1993.
Production from the Sherwood reservoir accounts for 85 percent of total WYF production.
Reservoir conditions relatively benign for operating ESPs [electrical submersible pumps].
Normally Occurring Radioactive Material (NORM) is present with the produced fluids and causes complications when retrieving downhole completion and the handling of retrieved ESPs during teardown [i.e. the pumps become radioactive]. [Natural radioactivity is a feature of Permo-Triassic rocks in southern England and the occurrance of radioactive, uranium-vanadium nodules in the Permian Littleham Mudstone of Littleham Cove, near Budleigh Salterton, Devon is well-known. See the associated Budleigh Salterton webpage.]

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BP. 2012. BP UK Asset Portfolio: Wytch Farm. BP Asset Portfolio, pp. 1-8.

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FURTHER INFORMATION ON WYTCH FARM OILFIELD

See - Perenco UK. The Wytch Farm Oilfield was sold to Perenco UK from BP in the year 2011.

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BGS - BRITISH GEOLOGICAL SURVEY

[See also: Andrews (2014), for Jurassic Shales of the Weald Basin - a BGS report with appendices.]
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BRITISH GEOLOGICAL SURVEY (BGS)

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British Geological Survey, GEOLOGY OF BRITAIN VIEWER [online]. Borehole Location Maps and Details.

See:
Geology of Britain Viewer; Borehole Locations and Scans.

This is a highly recommended and important resource from which you can find and zoom in on boreholes in any part of Britain. It is quick and easy to use and contains a mass of geological data. It states whether boreholes are 0-10m, 10-30m, 30m+, unknown, or confidential or restricted.

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BGS. British Geological Survey . 2006. Onshore Oil and Gas. Mineral Planning Factsheet. 16pp. Available online as a pdf file - mpfoilgas-1.pdf.
This factsheet was produced and updated by the British Geological Survey for the Department of Communities and Local Government as part of the research project DCLG-BGS Joint Minerals Information Programme. It was compiled by David Evans and David Highley (British Geological Survey) and John Cowley (Mineral and Resource Planning Associates) with the assistance of Niall Spencer and Deborah Rayner. This factsheet provides an overview of Onshore oil and gas supply in the UK. It is one of a series on economically-important minerals that are extracted in Britain and is primarily intended to inform the land-use planning process.

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British Geological Survey (BGS). (Compiled by M.A. Woods) 2011. Geology of South Dorset and South-East Devon and its World Heritage Coast.

The cover of the 2011 South Dorset Memoir of the British Geological Survey

An example page from the British Geological Survey, South Dorset Memoir, 2011

Special Memoir for 1:50,000 geological sheets 328 Dorchester, 342 West Fleet and Weymouth and 342/343 Swanage and parts of sheets 326/340 Sidmouth, 327 Bridport, 329 Bournemouth and 330 Newton Abbott. Compile by M.A. Woods. By Barton, C.M., Woods, M.A., Bristow, C.R., Newell, A.J., Westhead, R.K., Evans, D.J., Kirby G.A., and Warrington, G. Contributors: Biostratigraphy - J.B. Riding; Stratigraphy - E.C. Freshney; Economic Geology - D.E. Highley and G.K. Lott; Engineering Geology - A. Forster and A. Gibson. British Geological Survey, Keyworth, Nottingham, 2011. 161 pp. This is the new version of the Geological Survey Memoir for the Dorset Coast etc. and replaces Arkell (1947) and the earlier memoir by Strahan (1898). It covers a wider area than these old memoirs, though, and includes all of "Jurassic Coast", UNESCO World Heritage Coast. It is a key reference work. Available from BGS Online Bookshop at 24 pounds stirling (in Jan. 2012).

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British Geological Survey, BGS, 1998. Shephard-Thorn, E.R et al. 1998. . Geology of the Country around Ramsgate and Dover. Memoir for the 1:50,000 geological sheets 274 and 290 (England and Wales). British Geological Survey, London, Her Majesty's Stationery Office. 49 pp. Contributors: Bisson, G., Harding, P.E., Warren, S., Hughes, M.J., Mitchell, M., Wood, C.J., Dangerfield, J., Strong, G.E., Wheatley, C.W. and Howells, E.A.
This memoir is relevant to petroleum geology, because it shows and discusses the subcrop of the Coal Measures of the Kent Coalfield. This old coalfield might yield coal mine methane, coal bed methane and provide targets for hydraulic fracturing ("fracking"). Beneath the Coal Measures the Dinantian Carboniferous Limestone has been proved in several borehole. It is of interest that some limestone have small drusy cavities lined by sparry calcite, with apparently oily inclusions. Note that there are many oilfields and some gas fields in the Westphalian (Coal Measures) of the East Midlands on the north side of the London-Brabant Massif. Welton Oilfield is the third largest oilfield onshore in the UK, after Wytch Farm, the largest, and Stockbridge, the second largest. By analogy, some oil in addition to gas might be discovered in the Kent coalfield.

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British Geological Survey, BGS. McEnvoy et al. 2003. Hampshire (Comprising the City of Portsmouth and the City of Southampton) Mineral Resources Information in Support of National, Regional and Local Planning. Mineral Resources. Scale 1:100,000. Compiled by McEnvoy, F.M., Bloodworth, A.J., Cameron, D.G., Simpson, C., Lott, G.K., Evans D.J. and Highly, D.E. (Project Leader: D.E. Highly). Available online as a pdf files; go to : hampshireMap.pdf.

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British Geological Survey, BGS. Andrews, I.J. 2014. [British Geological Survey] The Jurassic Shales of the Weald Basin: Geology and Shale Oil and Shale Gas Resource Estimation. 79 pp. BGS and DECC. British Geological Survey; Department of Energy and Climate Change. With 52 figures and 12 tables. Available online as a pdf file.
Go to: BGS Weald Basin Jurassic Shale Reports
Go to: Andrews, I.J. (2014) for the full abstract of this publication. See also the associated Appendices A-F.

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BP. 1989. [BP, British Petroleum, drilled seaward from Southard Quarry on the downs near Durlston Head, Swanage, Dorset. They found indications of oil but lost pressure during the drilling operation. It was said that drilling fluid was lost (presumably due to an open fault or joint?). The well was abandonned. See InfraStrata, re plans to drill from another quarry nearby, California Quarry (a short distance further east). Search re InfraStrata, BP, Frack Free Dorset etc. There is useful information on the newly proposed borehole available online in InfraStrata webpages.]
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Bratton, T., et al. 2006. The Nature of Naturally Fractured Reservoirs. By Tom Brannon, Dao Viet Canh, Nguyen Van Que, Nguyen V. Duc, Paul Gilespie, David Hunt, Bingjian Li, Richard Marcinew, Satyaki Ray, Bernard Montaron, Ron Nelson, David Schoderbek and Lars Sonneland. Oilfield Review. 23 pp., available online as a pdf file. naturally_fract_reservoirs.pdf.
Naturally fractured reservoirs present a production paradox. They include reservoirs with low hydrocarbon recovery; these reservoirs initially may appear highly productive, only to decline rapidly. They are also notorious for early gas or water breakthrough. On the other hand they represent some of the largest, most productive reservoirs on Earth. The paradoxical nature of this class of reservoirs is the impetus behind the industry's effort to learn more about them and model them with reasonable amount of certainty.
[paper continues and here is extract from p.4 : "This article examines the impact of natural fractures on hydrocarbon reservoirs at different stages of reservoir development. The classification of natural fractures and naturally fractured reservoirs (NFRs) are reviewed, along with factors that affect NFR behaviour. We describe methods used over a range of scales to identify and characterise natural fractures and to model the influence of fracture systems on production. Case studies from around the world highlight various approaches.
... The stress state is important in NFRs because the stress state largely dictates whether fractures are open to conduct reservoir fluids. In addition the magnitude and direction of horizontal stresses, play critical roles in hydraulic fracture design, the primary stimulation method for NFRs... "]

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Bristow , C.R., Freshney, E.C. and Penn, I.E. 1991. Geology of the Country around Bournemouth. Memoir for 1:50,000 geological sheet 329 (England and Wales). British Geological Survey, London, 116 p.
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Bromehead, C.E.N. 1923. The oil horizons of England. Geological Magazine, vol. 60, p. 297. Of historic interest
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Brooks , J.R.V. 1983. Geological information from hydrocarbon exploration on the United Kingdom continental shelf. In Brooks, J. 1983. Petroleum Geochemistry and Exploration of Europe. Geological Society Special Publication, No. 12, 343-356. List of boreholes released at that date.

Brooks, J. and Glennie, K., Petroleum Geology of North West Europe, Graham and Trotman, London. vol. 1, 598p + xxiii, See also volume 2 .
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Brunstrom, R.G.W. 1963. Recently discovered oilfields in Britain. In: Sixth World Petroleum Congress, Frankfurt June 1963, Section 1, Paper 49, 1-10.

Brunstrom, R.G.W. 1966. Indigenous petroleum and natural gas in Britain. Institute of Petroleum, 5-27.
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Bryant, I. D.; Kantorowicz, J. D.; Love, C. F., 1988. Origin and recognition of laterally continuous carbonate-cemented horizons in the Upper Lias sands of southern England. Marine and Petroleum Geology, vol. 5 No. 2, May 1988, pp. 108-133.
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Buchanan , J.G. 1998. The exploration history and controls on hydrocarbon prospectivity in the Wessex basins, southern England, UK. In: Underhill, J.R. (ed), The Development, Evolution and Petroleum Geology of the Wessex Basin, Geological Society, London, Special Publications, 133, 19-37. By James G. Buchanan (formerly of British Gas and Production Ltd. Listed in the paper as at Conoco Inc. Houston, Texas).

Abstract:
The Wessex basins were formed during the Mesozoic extension and were subsequently modified by Cretaceous uplift and Alpine inversion events. The basin geometry and evolution of the area is strongly controlled by the long-lived fault systems which cross the area.
Two primary plays are recognised within the Wessex basins, the Triassic Sherwood Sandstone and the Jurassic Bridport Sandstone. These plays contribute to the vast majority of recoverable reserves in the area. The Triassic play consists of a Sherwood Sandstone Group reservoir, a Liassic mudstone source rock and a Mercia Mudstone Group regional seal. Hydrocarbons were generated from Late Jurassic to Tertiary in the main kitchen area and migrated into a range of fault-related traps. The main risks on the play are reservoir quality together with the timing and the route of hydrocarbon migration into valid traps.
The Jurassic play consists of the Bridport Sandstone Formation which is also sourced from Liassic mudstones and top seal is provided by the Fuller's Earth Formation. The dominant risk on this play is the extent and quality of reservoir facies. In the onshore domain trap definition, using two-dimensional seismic data is an additional risk on both plays.
The basins of southern England have been explored for hydrocarbons for over 50 years. The initial phase of exploration focussed on the onshore and tested anticlinal structures which had also been mapped at surface. Onshore activity reached a peak in the successful drilling by British Gas of the Jurassic and Triassic reservoirs in the Wytch Farm Field in 1973 and 1977 respectively.
The first offshore well in the United Kingdom Continental Shelf (UKCS) was drilled off Lulworth Cove by BP in 1963. More recently, offshore exploration concentrated on fault-related traps within or on the edges of the Portland-Wight Basin. Although offshore activity has been reduced in the last five years [this was in 1998], the 14th UK Licencing Round rekindled interest in the area as companies were awarded previously unlicensed acreage for exploration. [now at 26th Round, 2012, and on]
Successful future exploration in the Wessex basins will require a more complete understanding of reservoir development dna three-dimensional basin evolution. Future drilling will focus on untested fault-bounded prospects and stratigraphic traps with suitable reservoir quality. [end of abstract].
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Butler, M., and Pullan, C.P. 1990. Tertiary structures and hydrocarbon entrapment in the Weald Basin of southern England. In: Hardman, R.F.P. and Brooks, J. (eds), Tectonic Events Responsible for Britain's Oil and Gas Reserves, Geological Society, London, Special Publications, vol. 55, 371-391.
Abstract:
The Weald Basin of southeast England was formed by rapid subsidence associated with thermal relaxation following early Mesozoic extensional block faulting. The basin appears initially to have taken the form of an easterly extension of the Wessex Basin but became the major depocentre during the Upper Jurassic and Lower Cretaceous, with associated active faulting. These movements appear to have ceased prior to Albian times and a full Upper Cretaceous cover is believed to have been deposited in a gentle downwarp which extended far beyond the confines of the Weald and Wessex Basins. Major inversion of the Weald Basin took place in the Tertiary, with both gentle regional uplift, which in the eastern part of the basin is estimated to have exceeded 5000 feet (1525 metres), and intense local uplift along pre-existing zones of weakness, which led to the formation of compressional features such as tight folds and reverse faults. Zones of Tertiary deformation appear to have been strongly influenced by underlying, particularly Hercynian, structural trends.
Lower Jurassic source rocks reached maturity in the early Cretaceous and initial migration occurred at this time, often over long distances, into traps closed by pre-Aptian faults. Tertiary tilting and uplift led to the breaching of many of these pre-existing traps and the formation of large folded closures. A second phase of hydrocarbon migration, particularly of gas, took place at this time, with significant vertical migration along fault zones. Major reservoirs located to date occur in Middle Jurassic carbonates and Upper Jurassic sandstones, but deep burial in the basin has caused considerable destruction of primary reservoir characteristics; changes in the temperature and pressure regimes and the mobilization of fluids within the basin resulting from the Tertiary uplift caused further diagenetic changes, particularly in the carbonate reservoirs.
Exploration of the Weald Basin remains at a very early stage, with a low drilling density to date. The more recent drilling has focussed on earlier structures, but traps formed or modified during the Tertiary movements represent important exploration objectives, although general deterioration in reservoir quality towards the centre and east of the basin makes large fold closures in these areas less attractive.

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Butler, M. 1998. The geological history of the Wessex Basin - a review of new information from oil exporation. In: Underhill, J. R. (Editor), 1998. Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publication, No. 133, 67-86. By Malcolm Butler. [A key paper by Malcolm Butler, including information from Brabant Petroleum Limited.]
Abstract:
Mapping of intervals between the base of the Aylesbeare Mudstone (Permian or early Triassic) and the top of the Penarth Group (early Jurassic) in the Dorset - Isle of Wight area indicates that the deposition of these formations was influenced strongly by northwest-southeast trending faults, probably related to underlying Variscan elements. There are significant differences between the distribution of the Aylesbeare Mudstone and that of the later Triassic formations. An unconformity is recognised within the Sherwood Sandstone Group, separating the syn-rift sequences of Aylesbeare Mudstone, and overlying Budleigh Salterton Pebble Beds and anhydrites from the post-rift Otter Sandstone and Mercia Mudstone (middle-late Triassic). It is postulated that the top of the Sherwood Sandstone Group becomes progressively younger from the Mid Dorset Platform towards the Isle of Wight, steadily replacing the Mercia Mudstone. Halite beds are present within the middle Mercia Mudstone of Dorset, although they are absent over much of the Mid Dorset Platform and areas to the east of Wytch Farm. East-west trending faults became dominant in the Jurassic, and there is strong seismic evidence for syn-depositional movement on these faults during the Lias across the entire Dorset - Isle of Wight area. In Dorset, many of these east-west faults are listric, hading out into the Mercia Mudstone halite and creating very different structural styles above and below the salt. Major syn-depositional movement is thought to have taken place along these faults during Kimmeridgian and Portlandian times, creating a series of rollover anticlines in the hanging walls. Seismic evidence indicates that the early Cretaceous sequences of the Portland - South Wight Trough thinned rapidly onto the footwalls of these east-west faults and that very little deposition took place north of the Purbeck disturbance, either in Dorset or on the Isle of Wight. Several of these east-west faults reversed their throw during compression associated with the mid-Tertiary inversion. Reverse displacement estimates range from 50 m on the Litton Cheney Fault to 1350 m. on the Purbeck disturbance in the Isle of Wight. Offsets of the inversion trends may be related to underlying northwest - southeast trending Variscan faults which influenced the margins of the Jurassic and early Cretaceous basins, but strike-slip movements may have accentuated some of these offsets during the Tertiary. These offsets appear to be dextral to the west of the Wytch Farm oilfield and sinistral in the area to east. Structural styles suggest that there may also have been strike-slip movements along east-west trending faults.
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[The following paper is included, although it is on carbonate diagenesis in the Jurassic strata of the Paris Basin. This is because it considers Late Cimmerian processes etc. and may be relevant to the south of England Jurassic carbonates and their cementation.]

Carpentier C. et al. 2014. Impact of basin burial and exhumation on Jurassic carbonates diagenesis on both sides of a thick clay barrier (Paris Basin, NE France). Marine and Petroleum Geology, online 22nd February, 2014.
[Authors: Carpentier, C., Brigaud, B., Blaise, T., Vincent, B., Durlet, C., Boulvaise, P., Page, M., Hibsch, C., Yven, B., Lacha, P., Cathelineau, M., Boirona, M., Landrein, P and Buschaert, S. 2014.]
Abstract:
Several diagenetic models have been proposed for Middle and Upper Jurassic carbonates of the eastern Paris Basin. The paragenetic sequences are compared in both aquifers to propose a diagenetic model for the Middle and Late Jurassic deposits as a whole. Petrographic (optical and cathodoluminescence microscopy), structural (fracture orientations) and geochemical (delta 18 O, delta 13 C, REE) studies were conducted to characterize diagenetic cements, with a focus on blocky calcite cements, and their connection with fracturation events. Four generations of blocky calcite (Cal1 to Cal4) are identified. Cal1 and Cal2 are widespread in the dominantly grain-supported facies of the Middle Jurassic limestones (about 90% of the cementation), whereas they are limited in the Oxfordian because grain-supported facies are restricted to certain stratigraphic levels. Cal1 and Cal2 blocky spars precipitated during burial in a reducing environment from mixed marine-meteoric waters and/or buffered meteoric waters. The meteoric waters probably entered aquifers during the Late Cimmerian (Jurassic/Cretaceous boundary) and Late Aptian (Early Cretaceous) unconformities. The amount of Cal2 cement is thought to be linked to the intensity of burial pressure dissolution, which in turn was partly controlled by the clay content of the host rocks. Cal3 and Cal4 are associated with telogenetic fracturing phases. The succession of Cal3 and Cal4 calcite relates to the transition towards oxidizing conditions during an opening of the system to meteoric waters at higher water/rock ratios. These meteoric fluids circulated along Pyrenean, Oligocene and Alpine fractures and generated both dissolution and subsequent cementation in Oxfordian vugs in mud-supported facies and in poorly stylolitized grainstones. However, these cements filled only the residual porosity in Middle Jurassic limestones. In addition to fluorine inputs, fracturation also permitted inputs of sulphur possibly due to weathering of Triassic or Purbeckian evaporites or H2S input during Paleogene times.

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Carless Exploration Ltd. 1985. Statement and Plans to Accompany a Planning Application to Drill an Exploratory Borehole from Land south of Prew's Hanger near Horndean, Hampshire. Unpublished planning application.

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CELTIQUE ENERGIE

Celtique Energie, 2013. Our Project at Fernhurst, Sussex.
A internet pdf version of a public presentation regarding a drilling exploration project at Fernhurst (about half way between Midhurst and Haslemere, on the A286 road, north of Chichester). This particular part of Sussex is covered by Celtique Energie's Exploration Licence PEDL 231. Celtique Energie has its core activity in Exploration Licences PEDL 231, 234, and 243.
Celtique has identified a structure beneath the surface at Nine Acre Copse about 1 mile west of the the village of Fernhurst, that may contain a large oil or gas accumulation, and is keen to investigate it by drilling an exploration well. The well would be drilled to a depth of approximately 2.6km (8,600ft) below ground level.

"The primary reason for drilling this well is to test the conventional Kimmeridge Limestones [i.e. Kimmeridge Clay Micrites] and the Great Oolite stratigraphic trap. These limestones contain natural porosity and permeability and the hydrocarbons have migrated from from the Kimmeridge or Liassic shales beneath.
The work that has been done to understand the basin, which is based on existing information, indicatesd that there may be unconventional shale oil and shale gas resources in Sussex. Celtique wishes to acquire information about the Jurassic shales to better understand and evaluate any unconventional potential."

[continues]

Celtique Energie. 2013. Wisborough Green. "Celtique Energie" (Celtique Energie Weald Ltd., the oil and gas exploration company with its joint investment partner Magellan Petroleum (UK) Ltd. has applied to set up a temporary well site near the villages of Kirdford and Wisborough Green, Sussex. The proposal is to use a screened area of land. Theses notes come a Press Statement of 2nd September 2013. It is available online. Search for "Celtique Energie, Wisborough Green".
The test is for the presence of commercial oil or gas in the: Kimmeridge Limestone (the "Kimmeridge Micrite") and The Great Oolite (a conventional oil reservoir at Storrington and elsewhere in the western Weald region). This application does not include hydraulic fracturing. There was a public consultation for two days in May 2013 at which 154 people attended. ... [continues].

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Chadwick, R.A. 1986. Extension tectonics in the Wessex Basin. Journal of the Geological Society of London, 143, 465-488.
The Permian to Cretaceous tectonic evolution of the Wessex Basin was controlled by horizontal and vertical isostatic forces within the lithosphere. The gross morphology of its constituent structures were governed by the location of Variscan thrust and wrench faults in the upper and middle crust, which suffered extensional reactivation in tensional stress fields orientated approximately NW-SE. Several episodes of crustal extension can be resolved, in early Permian, early Triassic, early Jurassic and late Jurassic/early Cretaceous times. These were characterised by the rapid subsidence of fault-bounded basins and commonly by erosion of adjacent upfaulted blocks. Superimposed upon the fault-controlled subsidence, dominant during periods of fault quiescence, and becoming increasingly important with time, a component of regional subsidence is considered to have a thermal origin. This suggests that crustal extension was accompanied by some form of, not necessarily uniform, lithospheric thinning. Subsidence analysis assuming local Airey isostasy give cumulative crustal extension factors of 20-28% beneath the grabens. A more reasonable assumption of regional Airey compensation indicates basinwide crustal extension of 13-17%, which is consistant with BIRPS offshore deep seismic reflection data.
[Comment by IMW: This is an excellent paper explaining how the Wessex Basin has a "Steer's Head" profile. Permian to Late Cretaceous crustal extension was by extensional faulting over Variscan structures. It is important to note that at this phase there were elevated isotherms! This is actually crucial with regard to thermal maturity of the source rocks. Higher Cretaceous burial temperatures have been discussed elsewhere. Some calculated thermal maturity figures may need modification. In other words the source rocks may be more mature than always assumed.]

Chadwick , R.A. 1993. Aspects of basin inversion in southern Britain. Journal of the Geological Society, London, 150, 311-322.

Chadwick R.A. and Evans D.J. 2005. A Seismic Atlas of Southern Britain. 180 pp. British Geological Survey, ISBN No. 0852725124. Price 30 pounds from BGS. The following summary is from BGS Bookshop online. ISBN No. 0852725124
Over the past two hundred years, the numerous and varied structural features of southern Britain have been mapped on the basis of outcrop information. Until relatively recently, the detailed nature of these structures at depth has remained conjectural. This atlas, however, illustrates some of the best seismically imaged geological features of the region. Each of the features illustrated is described and a detailed development history is provided. This gives a unique insight into the subsurface structure of southern Britain and has transformed our understanding of the processes involved in structural development - the role of the major faults in basin evolution and sediment distribution, and the relationship of faults to folds in the sedimentary cover. Images are also provided of igneous intrusions, major basement structures and the deep crust, and a review of the tectonic evolution of England and Wales includes the Caledonian, Variscan and Cimmerian-Alpine cycles. This provides a context for the more detailed description of the subsurface features. This book will be of interest to students, structural geologists and researchers. The book also includes a CD of the text. 180pp, plus references and index.

Chadwick, R.A., Kenolty, N. and Whittaker, A. 1983. Crustal structure beneath southern England from deep seismic reflection profiles. Journal of the Geological Society, London, vol. 140, pp. 893-911. (a key paper).
Seismic reflection events from recently acquired profiles in southern England are interpreted in terms of stratigraphic and structural interfaces between rock units. In particular, evidence is brought forward that a series of reflection events, dipping between 22 degrees and 27 degrees with azimuth averaging 160 degrees, represent two major thrust zones occurring in the Variscan floor beneath Mesozoic cover. A geological model based on borehole information and regional geological considerations is presented. The tentative recognition of crystalline basement overlain and overstepped by late Proterozoic rocks of variable thickness suggests that the basement in this area was unstable from late Precambrian times. The Mesozoic structural evolution can be related to tectonic re-activation of major concealed thrust zones in the Palaeozoic "basement".
[See particularly fig. 12 (a and b). The Mere Fault and the Pewsey Fault are interpreted as reactivation and reversal of listric Variscan thrust zones. This explains Mesozoic growth faulting in both cases. These diagrams are relevant to other structures in the region.]

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Clayton, C.J., Myers K.J. and Fleet A.J. 1988. Petroleum source rocks of southern England. (BP Research International, Sunbury-on-Thames). PESBG/BRG Meeting London, September 1988. Regional Geology of the Southern United Kingdom. Petroleum Exploration Perspectives.

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Cobald, P. [Peter Cobbold], Zanella, A., Fourbdan, B., Neraudeau, D. and Gouttefangeas, F. 2015. Natural hydraulic fractures in the eastern Paris Basin. Cobbald-et-al-2015-AGBP-text.pdf
Keywords : Paris Basin, Lorraine, veins of calcite 'beef'. Abstract: Within hydrocarbon-producing sedimentary basins it is not uncommon to find bedding-parallel veins of fibrous calcite ('beef'). They tend to be abundant within source rock that has reached the oil window. Good examples occur in the Wessex Basin (England) and the Neuquen Basin (Argentina), where calcite crystals have inclusions of oil, gas or bitumen. We interpret such veins as having resulted from natural hydraulic fracturing, as a result of overpressure during maturation of organic matter. In the Paris Basin, notably in Lorraine, certain geologists (Marcel Denaeyer and Pierre Maubeuge) had described outcrops bearing fibrous calcite veins, especially within Toarcian shale, but also within older layers (Triassic) or younger ones (Bajocian or Oxfordian). On searching for such outcrops, we found beef veins in (1) Triassic strata at Blainville and (2) Liassic Schistes - Carton at Gelaucourt. At other localities, we found fibrous veins of calcite, which had less diagnostic forms, or even resembled fossil bivalves (Trichites). Key-words : Paris Basin, Lorraine, veins of calcite, beef, oil, petroleum, fibrous, organic.

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Cole, D.C. and Harding, I.C. 1998. Use of palynofacies analysis to define Lower Jurassic (Sinemurian to Pliensbachian) genetic stratigraphic sequencess in the Wessex Basin, England. Pp. 165-185 in Underhill, J. (editor, 1998. Development, Evolution and Petroleum Geology of the Wessex Basin), Geological Society, London, Special Publication No. 133, pp. 165-185. By David C. Cole and Ian C. Harding, address at the time, Department of Geology, University of Southampton, Southampton Oceanography Centre, Empress Dock, Southampton, SO14 3ZH. Now (2016) Faculty of Natural and Environmental Sciences (geology takes place not within a separate department but within the broader Faculty, and still at what is now known as the National Oceanography Centre building.)
Abstract: Quantitative palynological and palynofacies analyses allow the Lower Jurassic succession of the Dorset coast (Wessex Basin, southern England, UK) to be placed tihing a genetic sequence stratigraphic framework. The multifaceted approach employed utilizes various palynological criteria adopted from previous publications (e.g. both relative and absolute particle abundance data, allochthonous versus autochthonous palynomorphs ratios, phytoclast type etc.) and suggests new parameters which may be studied in this context (e.g. ratio of acritarch spine length). Interpretation of palynofacies trends within the studied succession enables the identification of eight genetic sequences informally described as Genetic Stratigraphic Sequences I - VIII (1 - 8). Genetic stratigraphic sequence boundaries are placed at the following horizons: Mongrel, Grey Ledge, Pavior, the Coinstone, Hummocky, the Belemnite Stone, Day's Shell Bed and the margaritatus Stone. These results compare well with sequence stratigraphic frameworks published for the British Jurassic interval both in Dorset and elsewhere, suggesting that the maximum flooding events are likely to have been of inter-regional extent.
[With 10 figures or diagrams, several of them vertical stratigraphic plots, through the Blue Lias, Shales-with-Beef and Black Ven Marls. Dorset Coast localities discussed include Pinhay Bay, Lyme Regis, Charmouth, Golden Cap, Seaton, Thorncombe Beacon and Eype's Mouth. Stages of the Lower Jurassic that are discussed are mainly Sinemurian and Pliensbachian.]


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Coe, A. L. 1992. Unconformities within the Upper Jurassic of the Wessex Basin, Southern England. D.Phil. thesis. Oxford University.

Coe , A.L., Hesselbo, S.P., Jenkyns, H.C., Morgans Bell, H. and Weedon, G.P. 2001. Kimmeridge Clay Formation composite graphic log for coastal exposures, near Kimmeridge, Dorset. Part of Supplementary Publication No. SUP 90490, British Library. Associated with paper by Morgans-Bell, Coe, Hesselbo, Jenkyns, Weedon, Marshall, Tyson and Williams (2001). By Angela L. Coe of the Open University and others.
This log is available on the internet at Integrated stratigraphy of the Kimmeridge Clay Formation (Upper Jurassic) based on exposures and boreholes in south Dorset, UK. [This is an excellent log and very useful with bed numbers and much detail. Printing it out is very worthwhile but this uses much paper and ink, and takes time, unless you have a special printer for large sheets. It is about 3 metres long. It is very good and incorporates the previous work of Gallois and others; it is likely to be standard basis for further research on the cliff section. The Swanworth and Metherhill logs of Kimmeridge Clay boreholes are also available from this website.]

For the full log go to:
Rapid Global Geological Events. 2001. The Rapid Global Geological Events (RGGE) Project. A Natural Environment Research Council (NERC) Special Topic. [although you may not successfully obtain this, now]


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Colter, V.S. and Havard, D.J. 1981. The Wytch Farm Oil Field, Dorset. In: Illing, L.V. and Hobson, G.D. (eds), Petroleum Geology of the Continental Shelf of Northwest Europe, Institute of Petroleum Geology, London, 494-503. By V.S. Colter and D.J. Havard of the British Gas Corporation, 59 Bryanston St., Marble Arch, London, W1A 2AZ, UK.
In April 1968, a number of Production Licences were granted in the Wessex Basin to BP/Gas Council partnership, which was operated by BP. Oil had already been discovered by BP at Kimmeridge in the 100 percent BP ML5 and production was established from fractured rocks in the Cornbrash. Subsequently in 1964, BP drilled the Wareham No.1 Well, which found oil in thin fractured Inferior Oolite, but which was not production tested until 1970. A study of the Wessex Basin carried out by Gas Council (Exploration) (GC(E)) Ltd. in 1972 concluded that the Bridport Sands offered better and more predictable reservoir properties than the fractured rocks believed to be producing in Kimmeridge No.1 and Wareham No.1. On the assumption by GC(E) of the operatorship of the BP/GC(E) group, the Wytch Farm No.1 Well was proposed to test a structure found on seismic data obtained by a BP seismic party. The well was spudded in December 1973, and found light oil in the Bridport Sand, trapped in an east-west - trending anticline, downfaulted to the south. Subsequent studies on the structural history of the area, together with geochemical data, suggested that the oil originated south of the Purbeck - Isle of Wight Disturbance from Jurassic sources, and could also have migrated into the Triassic Sherwood ("Bunter") Sandstone of the Wytch Farm structure. To test this view, the Wytch Farm D5 Well was spudded in December 1977, and found light oil in the Triassic reservoir. To date [1981], in addition to the wells mentioned, three delineation wells, six production wells and three water injection wells at Bridport Sands level have been completed, and a well has been drilled to the pre-Permian basement at location X14. Further delineation of the Triassic Sandstone accumulation is in progress [in 1981].
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Cornford, C. 1988. Geochemistry and Volumetrics of Dorset Oil Seeps. Chris Cornford Integrated Geochemical Interpretational Ltd., Hallsannery Field Centre, Bideford, Devon EX39 5HE. Tel: 0237271749. Regional Geology of the southern United Kingdom; Petroleum-explanation perspectives; held in London September 1988.
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Cope, J.C.W. 2012. Geology of the Dorset Coast. Geologists' Association Guide, No. 22. 232pp., with many colour photographs and diagrams. New edition by John C.W. Cope. (See also the earlier editions by House, M.R. 1989 and 1993.)
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Cooper, M.A. and Williams, G.D. (eds) 1989. Inversion Tectonics. Geological Society, London, Special Publications, 44, 375pp.
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Cornford, C., Christie, O., Endresen, U., Jensen, P. and Myhr, MB. 1988. Source rock and seep oil maturity in Dorset, Southern England. Advances in Organic Geochemistry 1987, 13, Part I, Organic geochemistry in petroleum exploration; proceedings of the 13th international meeting on organic geochemistry. Mattavelli, L. (editor); Novelli, L. (editor), 13th international meeting on organic geochemistry, Venice, Italy, Sept. 21-25, 1987, Organic Geochemistry, vol. 13, no. 13 pp. 399-409.


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Cowan, G. 1993. Identification and significance of aeolian deposits within the dominantly fluvial Sherwood Sandstone Group of the East Irish Sea Basin, UK. By Greig Cowan. British Gas Exploration and Production, Reading. In North, C.P and Prosser, D.J. (Editors). Characterisation of Fuvial and Aeolian Reservoirs, Geological Society of London, Special Publication. vol. 73, pp. 231-245.
Abstract:
The Triassic Sherwood Sandstone Group sediments of the East Irish Sea Basin are over 4000 ft thick and comprise medium - to coarse-grained sandstones and rare thin mudstones. Facies models developed during production drilling on the South Morecambe Field show that deposition occurred in a braided fluvial setting with minor aeolian episodes. The major facies associations present are: (A) major channel fill; (B) ephemeral channel fill; (C) non-channelized sheetflood deposits; (D) and (E) non-reservoir fines (abandonment and playa respectively); (F) aeolian dune and sand-sheet. Volumetrically, the major channel (A) and sheetflood (C) facies dominate, and the alternation of these facies associations is correlatable across the field. The aeolian sandstones form units varying in thickness from a few grain diameters up to 3 m thick. The sand-sheet and dune deposits can be correlated over considerable distances and show pressure communication on RFT logs. Although the aeolian sandstones comprise only 5 to 10 percent of the reservoir they have very high porosities and permeabilities (up to 30 percent and 10 darcies) and make disproportionate contributions to flow into the wellbore. The depositional criteria used to differentiate between aeolian and fluvial deposition in the South Morecambe Field are pinstripe lamination, good sorting and lack of rounded clay clasts, but these criteria are not definitive. As a result of the dissolution of an early diagenetic cement, aeolian sandstones have very high porosities compared to fluvial sandstones. This high porosity is reflected in high sonic transit times and allows aeolian sandstones to be identified tentatively in uncored wells by use of sonic logs.

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Cox , B.M. and Gallois, R.W. 1981. Stratigraphy of the Kimmeridge Clay of the Dorset type area and its correlation with some other Kimmeridgian sequences. Report of the Institute of Geological Sciences, No. 80/4, 144.
The Kimmeridge Clay of the type area crops out in cliff sections at Kimmeridge, Osmington Mills, Ringstead Bay and Wyke Regis in south Dorset. At Kimmeridge, the sections, although continuous, expose only the upper part of the formation. At Osmington Mills and Ringstead Bay, a section through the lower part of the Kimmeridge Clay and through a part of the remainder of the formation can be determined, although only in isolated exposures which are separated from one another by landslips and complicated by tectonic structures. At Wyke Regis, only the basal beds are exposed. Descriptions and graphic sections are given for the exposed sequences.
Comparison of the Dorset succession with those elsewhere in England has shown that the lithological and faunal sequences are similar throughout the country. A number of distinctive thin marker-bands have been recognised in Dorset, and these are correlated with similar bands recorded from the Warlingham Borehole, Surrey, and from boreholes in East Anglia.
The ammonite faunas are discussed and the zonal scheme in current use is reviewed. It is suggested that the abundance of Gravesia has been underestimated in the past and that consideration should be given to the introduction of a new zone of Gravesia spp. The base of such a zone would mark the Lower-Upper Kimmeridgian boundary. It would also form an important link with Tithonian and Volgian sequences elsewhere in Europe.
Relationships among the Kimmeridgian, Portlandian, Tithonian and Volgian stages are discussed. It is recommended that the most of the Kimmeridge Clay of the type area should be included in the Kimmeridgian Stage, and that the use of the term Kimmeridgian sensu gallico (which places only the Lower Kimmeridge Clay in the Kimmeridgian Stage) should be abandoned. [end of abstract]
[This is an important publication for details of Kimmeridge Clay stratigraphy at Kimmeridge and elsewhere. It is a key work essential for field studies of the Kimmeridge cliffs and cliffs of Kimmeridge Clay elsewhere. It may be obtainable from the British Geological Survey.]

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Cuadrilla Resources (main webpage). 2012 Cuadrilla Resources. (relevant to Balcombe, Sussex)
"Cuadrilla is a UK company based in Staffordshire. Formed in 2007 as a privately owned exploration and production company, our focus is on bringing together experts to recover natural resources, such as those found in Lancashire. Members of Cuadrilla's management team have each played leading roles in the drilling and/or hydraulic fracturing of more than 3,000 natural gas and oil wells across the world. Cuadrilla is aiming to be a "model company" for unconventional exploration in the UK. It is acutely aware of the responsibilities this brings, particularly with regard to safety, environmental protection and working with local communities. Although exploration for natural gas from shale is still in its infancy in this country, the Government believes that the UK is well placed to become the leading player in an emerging energy industry. Natural gas from shale could increase the country's self-sufficiency and secure investment and jobs for local communities across the country. In the United Kingdom we are pioneering natural gas exploration, recovering gas from shale rock. We currently have a number of exploration sites in the Bowland Shale basin in Lancashire. In addition, we also have a production site at Elswick which has been generating electricity from natural gas since 1993." ... [continues]

Cuadrilla Resources - Balcombe. 2012. Cuadrilla Resources - Balcombe. Balcombe, West Sussex.
"The existing Balcombe oil well was drilled by Conoco in Autumn 1986 and was plugged and abandoned after the evaluation. We have a planning permission from West Sussex County Council for further exploratory drilling, but have no plans to do so at present."

Cuadrilla Resources Limited. 2010. Appendix - B. Seismic Interpretation. 6 pages, including 3 figs. Available online as: Cuadrilla Resources pdf File - Lower Stumble Hydrocarbon Exploration Site; Planning Application 2010. Prepared by Phil Mason. A short account but with some structural maps and a summary borehole log. The log which only extends into the uppermost Lias and has a TD or total depth at 5560 feet (1695m.); it provides no information on Lower Lias shales. It is of interest in showing 7m of Purbeck anhydrite. The Kimmeridge Clay is 1864ft thick or 568m compared to about 508m at Kimmeridge. Thus, regarding the Kimmeridge Clay here, this is obviously a very thick, basinal facies, more so than on the Dorset coast. Is the Lower Lias similarly thick and basinal?
Planning Application: Appendix B - Seismic Interpretation. Extract from this document:
"Geological Summary Lower Stumble Prospect: The Lower Stumble prospect forms on an east-west trending anticline of Alpine origin in the centre of the Weald Basin. The location is approximately 8km south-east of Crawley and 5km north-west of Hayward's Heath near the village of Balcombe. It lies on the downthrow side of the Borde Hill Fault and dip closure is present to the east and west at Upper Jurassic level. Stratigraphic thinning of the Upper Jurassic towards the east reduces the amount of structural closure at deeper stratigraphic levels and little or no structural closure is observed below the Middle Jurassic (geological and seismic cross sections Fig. BO1 and BO2). The well is located at the same place as the Balcombe 1 well drilled by Conoco in 1986. The geological column encountered in the Balcombe-1 well is shown in Fig. BO3. The original objectives were the Portland sandstone, Ashdown Sands and Kimmeridge Sandstones. A number of oil and gas shows were recorded in the well but none proved to be economic. The target formation for the Lower Stumble well is the Middle to Upper Jurassic including the Corallian Sandstone, Kimmeridge and Portland Sandstone. The Cuadrilla exploration plan is to drill vertically through the Middle to Upper Jurassic sequence, recover core and drill to a total depth of 4700 feet (below surface) in the Great Oolite. If the result of the core analysis and geological investigations appear promising we may choose to drill a horizontal well section to further test the presence of hydrocarbons." [.. continues]

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Cuadrilla Resources Ltd. 2013. Non-Technical Summary of an Environmental Permit Application to Drill Balcombe 2 and 2Z Wells for conventional oil exloration activity only. Application to the Environment Agency. This is a a clearly-written and easily-readable, Non-Technical Summary of an Environmental Permit Application made in June 2013 to drill a vertical borehole at Balcombe with a sidetrack into micrite (fine-grained limestone) of the Kimmeridge Clay. The drilling of this borehole has now (Aug. 2013) commenced. The Non-Technical Summary is available online: Go to the Environment Agency Website regarding Balcombe at: Permit Application from Cuadrilla Balcombe Limited at their Lower Stumble Hydrocarbon Exploration Site. Click, as indicated, to download the 474kb document of nine pages of text with a diagram of a simplified vertical section through the planned borehole (Fig. 1).
An Environmental Permit application has been made on the 11th June 2013 for Cuadrilla to drill conventionally into a micrite within the Kimmeridge Clay Formation. An introductory summary is as follows" "Cuadrilla Balcombe Limited (hereinafter "Cuadrilla") has prepared an Environmental Permit application to operate a Mining Waste Facility and that covers the management of non-inert, non-hazardous and hazardous extractive waste.This operation is for conventional oil drilling. No hydraulic fracturing is being proposed for the prospecting activity."

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Dafter , R. 1982. Wytch Farm revalued at £400m. Financial Times, 11.01.1982.


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Davies, R.J., Mathias, S.A., Moss, J., Hustoft, S. and Newport, L. 2012. Hydraulic fractures: how far can they go?. Marine and Petroleum Geology, Volume 37, Issue 1, November 2012, pp. 1-6. Review Article. Published by Elsevier Ltd. Available online as a pdf file. Article by By Richard, J. Davies, Durham Energy Institute, Department of Earth Sciences, Durham University, Simon A. Mathias, Jennifer Moss, Steiner Hustof and Leo Newport.
Available online at Hydraulic fractures: how far can they go?
Abstract
The maximum reported height of an upward propagating hydraulic fracture from several thousand fracturing operations in the Marcellus, Barnett, Woodford, Eagle Ford and Niobrara shale (USA) is approximatly 588m. Of the 1170 natural hydraulic fracture pipes imaged with three-dimensional seismic data offshore of West Africa and mid-Norway it is approximately 1106 m. Based on these empirical data, the probability of a stimulated and natural hydraulic fracture extending vertically >350 m is approximately 1% and approximately 33% respectively. Constraining the probability of stimulating unusually tall hydraulic fractures in sedimentary rocks is extremely important as an evidence base for decisions on the safe vertical separation between the depth of stimulation and rock strata not intended for penetration.
[Regarding Dorset, but not discussed in this paper, note that the Kimmeridge Oil Shale or Blackstone in south Dorset (where it is fully developed) could not be subjected to hydraulic fracturing, without breaching this 600m theoretical limit. In fact the southern part of the Isle of Purbeck would probably be eliminated, as would the Isle of Portland and the Portesham area. In any case 600m fractures upward from the Kimmeridge Blackstone would allow gas entry into the porous Portland Freestone.]

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Davies, R.J., Almond, S, Ward, R.S., Jackson, R.B., Adams, C., Worrall, F., Herringshaw, L.G., Gluyas, J.G. and Whitehead, M.A. 2014. Oil and gas wells and their integrity: implications for shale and unconventional resource exploitation. Marine and Petroleum Geology, vol. ?, pp. 1-16. (Accepted 1st March 2014). By Richard J. Davies, Sam Almond, Robert S. Ward, Robert B. Jackson, Charlotte Adams, Fred Worrall, Liam G. Herrington, Jon G. Gluyas and Mark A. Whitehead. (Richard J. Davies and some other authors are at Durham Energy Institute, Department of Earth Sciences, Durham University).
Abstract: Data from around the world (Australia, Austria, Bahrain, Brazil, Canada, the Netherlands, Poland, the UK and the USA) show that more than four million onshore hydrocarbon wells have been drilled globally. Here we assess all the reliable databases (25) on well barrier and integrity failure in the published literature and online. These datasets include production, injection, idle and abandoned wells, both onshore and offshore, exploiting both conventional and unconventional reservoirs. The datasets vary considerably in terms of the number of wells examined, their age and their designs. Therefore the percentage of wells that have some form of well barrier or integrity failure is highly variable (1.9% - 75%). Of the 830 wells targeting the Marcellus shale inspected in Pennsylvania between 2005 and 2013, 6.3% of these have been reported to the authorities for infringements related to well barrier or integrity failure. In a separate study of 3533 Pennsylvania wells monitored between 2008 and 2011, there were 85 examples of cement or casing failures, 4 blowouts and 2 examples of gas venting. In the UK, 2152 hydrocarbon wells were drilled onshore between 1902 and 2013 mainly targeting conventional reservoirs. UK regulations, like those of other jurisdictions, include reclmation of the well site after abandonment. As such there is no visible evidence of 65.2% of these well sites on the land surface today and monitoring is not carried out. The ownership of up to 53% of wells in the UK is unclear; we estimate that between 50 and 100 are orphaned. Of 143 active wells that were producing at the end of 2000, one has evidence of well integrity failure.
[With regard to the Weald area, see particularly this section on p. 6:
"The two pollution incidents at Singleton Oil Field (now operated by IGas but operated by a different company when the incidents occurred) occurred in the early 1990s, and were caused by failure of cement behind the conductor and the 9 and 5/8th - inch casing. This was identified as a result of five groundwater monitoring boreholes installed at the Singleton Oil Field in 1993. The leak was from the well cellar (cement lined cavity in which the well head sits) via the pre-installed conductor and the 9 and 5/8th inch casing, both of which appear not to have been adequately cemented in situ in at least one well. A thorough investigation commenced in 1997, including the drilling of a number of (>11) additional boreholes, and the carrying out of tracer tests and CCTV examination under the auspices of, and in consultation with, the UK Environment Agency. The leak paths, once identified and verified, were remediated. Monitoring has continued since that time and the observed levels have remained below those set by the Environment Agency as requiring further action."

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Dawson , Charles (of the Piltdown Forgery)

Dawson, C. 1897. Discovery of a large supply of 'natural gas' at Waldron, Sussex. Nature, London, 57, 150-151.

Dawson, C. 1898. On the discovery of natural gas in East Sussex. Quarterly Journal of the Geological Society, London, 64, 564-572.

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DECC - DEPARTMENT FOR ENERGY AND CLIMATE CHANGE

(See also: Royal Society (2012). Shale Gas Extraction in the UK: a review of hydraulic fracturing. ["fracking"])

MAJOR DOCUMENTS

(Scan down for more DECC documents!)
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DECC; Department of Energy and Climate Change. 2010. THE HYDROCARBON PROSPECTIVITY OF BRITAIN'S ONSHORE BASINS.
Promote UK 2011. 86pp. Available online as a pdf file at: The Hydrocarbon Prospectivity of Britain's Onshore Basins.

"Foreword:
This report has been produced under contract by the British Geological Survey (BGS). It is based partly on BGS confidential reports compiled for the Department of Energy (now Department of Energy and Climate Change) during the 1980s and partly on more recent analysis, together with published data and interpretations. Additional information is available at the Department of Energy and Climate Change (DECC) website. This includes licensing regulations, maps, monthly production figures, basic well data and where to view and purchase released well data and seismic data. Onshore seismic data and stratigraphic tops for wells are available at Onshore data.
DECC has now published the technical reports etc acquired or produced for Landward licences following the expiration of the confidentiality period provided for by the licence together with the "Appendix B" licence application documents submitted for the 1st to 8th Landward licensing rounds. Also now available are Field Development Plans and the Annual Field Reports for fields where the confidentiality period provided for by the relevant licence has expired. The 9th to 11th Landward licensing round data should be included by the end of 2010. This information can be purchased from Mosaic Informations Solutions (email: ian@mosaicis.com). Relinquishment reports fro Landward licences can be found on the DECC website for download free of charge at DECC Reliquishment Reports"... [almost the end of Foreword]

Now see particularly:

Wessex Basin - pp. 6-17.
Weald Basin - pp. 18-25.
Overall Conclusions - p. 76 only.
References - pp. 78-86 (a good list)

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DECC; Department of Energy and Climate Change. 2011a. Promote: United Kingdom 2011. THE PROSPECTIVITY OF THE ENGLISH CHANNEL .

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DECC (Department of Energy and Climate Change) 2013.
The Unconventional Hydrocarbon Resources of Britain' Onshore Basins - Shale Gas. 34 pp, including a reference list. With coloured geological maps and diagrams. A key publication regarding fracking.

"This document offers a geologic framework to examine the potential for shale gas exploration in the UK. Since the USGS has recognised a large increase in American natural gas reserves from shale resources, there has been a growing interest in European potential for shale gas. UK potential is as yet untested. Shale has not previously been considered a hydrocarbon reservoir rock in the UK, but instead its organic-rich shales have been studied as world-class source rocks in which oil and gas matured before migrating into conventional fields. Gas shows are commonly observed while drilling through shale stratigraphy, but they are rarely flow tested. The UK shale gas industry is in its infancy, and ahead of more drilling, fracture stimulation and testing there are no reliable indicators of potential productivity. The analogies presented in this report may ultimately prove to be invalid. However, by analogy with similar producing shale gas plays in America, the UK shale gas reserve potential could be as large as 150 bcm (5.3 TCF) - very large compared with 2-6 bcm estimate of undiscovered gas resources for onshore conventional petroleum. The technologies needed to explore for shale gas are only recently available in the UK, and mitigating the environmental impacts of stimulation technology and to large scale development are subject to local authority consent."
[continues]

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DECC, Department of Energy and Climate Change. 2011b. OFFSHORE OIL AND GAS LICENSING, 26TH SEAWARD ROUND, CENTRAL ENGLISH CHANNEL, Blocks 97/14, 97/15, 98/06b, 98/07b, 98/08, 98/11, 98/12, 98/13 and 98/14. Appropriate Assessment (AA) [environmental assessment], May 2011. 91 pp. This is an environmental, conservation assessment regarding the potential oil production blocks. It is a pdf file available on line.

Summarised notes from "Background and Purpose":

On the 27th January 2010, the Secretary for State for the Department of Energy and Climate Change (DECC) invited applications for licences in the 26th Seaward Licensing Round. The Secretary of State undertook a screening exercise on whether the Blocks would be likely to have a significant effect on a relevant European conservation site. This is the "Appropriate Assessment" (AA), that is an environmental assessment regarding conservation, for the Central English Channel petroleum licensing blocks.

This report is largely a report on possible environmental impact and ecological effects. There is very little geological information in this particular publication. The map showing the locations of the blocks is useful to geologists, however, and a version is reproduced below.

Licence Block map, Offshore Oil and Gas Licensing, Central English Channel, 26th Seaward Round, May 2011

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DECC; Department of Energy and Climate Change. 2011c. Promote UK 2011. THE UNCONVENTIONAL HYDROCARBON RESOURCES OF BRITAIN'S ONSHORE BASINS, . 33pp.

[Example extracts - see the full report online}

5. SHALE GAS PROSPECTIVITY - UK JURASSIC SHALE FORMATIONS

Lias
The Lower Jurassic Lias (Toarcian) of the Yorkshire coast consists of a shale facies containing 40% illite, 30% kaolinite, 25% mixed layer clays and 5% chlorite (Morris 1979). Hallam (1960) distinguished four lithologies within the Blue Lias of Dorset and Glamorgan by their differing carbon contents - its bituminous shales contain from 3.9-7% carbon, its laminated marls 8% carbon, and its other marls and limestone less than 1.9% carbon. Lias oil-shale is present at Kilve on the southern side of the Bristol Channel (Shatwell et al. 1924). Both shores of the Channel are immature for oil (Cornford 1986). Though probably lying in the oil window offshore, the Lias is immature for shale gas in all of these areas.

.....

Kimmeridge Clay
The Kimmeridge Clay Formation of onshore eastern and southern England (Fig. 21) is a potentially prospective shale (for oil and probably biogenic gas) because it contains ubiquitous oil-shale beds (Gallois 1979). Its background shale has TOC up to about 10%, its bituminous shale has TOC values up to 30% and its oil-shales have TOCs reaching 70% (e.g. the Blackstone Bed, Stocks & Lawrence 1990) [70% is actually the total organic matter, not the total organic carbon!]. Five basins show thickening of the formation in response to syn-sedimentary faulting (Weald, Wessex, English Channel, Cleveland and Lincolnshire- Norfolk).

The Kimmeridge Clay Formation is immature for thermogenic gas generation onshore (Scotchman 1991) and it is only marginally mature for oil generation in the Weald Basin depocentre. Its carbonate content varies from 12% (oil-shales) to 94% (limestones, Farrimond et al. 1984). Scotchman (1991) showed that high TOCs and sedimentation rate result in high phytane/TOC values. The low maturity is confirmed by TMAX 403-437 degrees C on pyrolysis. Samples confirmed kerogen of Type II or mixed Type II-III on the Van Krevelen diagram (Tissot et al 1974).

Exploration for oil-shale deposits was conducted in Dorset at Corton after World War 1 (Strahan 1920).

....

Exploitation of these Kimmeridge Clay oil-shale beds was uneconomic because of the thinness of the beds and high sulphur content. This may be overcome by horizontal drilling, and future exploration could be a combination of coal bed methane-type exploration (in relatively thin oil-shale beds), and shale gas exploration in the formation as a whole.

The English Channel Basin, particularly south of Purbeck and on the southern Isle of Wight, contains more mature source rocks at all levels than in the area near Wytch Farm oil field (Colter & Havard 1981), because of Alpine inversion. There are already precedents for deviating wells from the onshore to the offshore (Amoco's Down Barn (Fig. 5) and the Wytch Farm development wells in Dorset) to access the main part of the basin for shale gas.

Weald Basin

[There is hydrocarbon source rock potential regarding the Lias, the Oxford Clay and the Kimmeridge Clay within the deep Weald Basin. Most mature is the Lias. This is of interest in 2012 because of the possibilities of hydraulic fracturing to realise hydrocarbons. See online discussion regarding Cuadrilla, although these reports, at present, do not necessarily give details or refer to the Lias.]

"The Lower Jurassic Lias rocks, particularly the Lower Lias, are rich in organic material (Hallam 1960), with TOC in the range of 0.5 % to 2.1% (Butler & Pullan 1990). Some shales contain up to 7 wt per cent TOC (Ebukanson and Kinghorn 1985). The interval does show considerable vertical and lateral variation in richness, deteriorating in quality in the eastern part of the Weald Basin. Basin modelling (TTI) predicts that the Lias falls within the zone of oil generation over much of the Weald Basin, being perhaps overmature in the deepest parts of the basin (Penn et al., 1987). The Lower Lias is probably immature over the Hampshire Dieppe High (Penn et al., 1987). VR values for the Lias at Penshurst in the centre of the basin vary between 0.8 - 0.9ƒs (Ebukanson, & Kinghorn, 1986), being in the main phase of oil generation and supporting the maturity predictions. The same authors show that the Lower Lias is marginally mature at Henfield, Warlingham and Winchester, around the periphery of the basin. Oil generation from Lias source rocks probably began during deposition of Lower Cretaceous sediments and peaked at about the middle of the Cretaceous (Penn et al. 1987)."

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DECC - OTHER DOCUMENTS
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DECC. Department of Energy and Climate Change (British Government). 2009. Relinquishment Document by BP - Old Harry - 1 Prospect. [Re an offshore prospect fairly near Old Harry Rock, Studland, Dorset.] To DECC, Department of Energy and Climate Change. Licence determination of surrender document filed to DECC, November, 2009. Re. Old Harry - 1 Prospect. Available online as a PDF file. Go to:
decc.gov.uk
Relinquishment Document - Old Harry - 1 Prospect.

[some summary extracts follow]. (The document includes of the prospect in relation to faults and other oilfields. See also a section on the Old Harry Prospect in: Petroleum Geology, South of England.)
License P1022 (Block 98/11); Awarded out of round 1999
Licence Type: Production, Block 98/11 Operator/Partner %: Operator: BP (50.48%), Partners: Maersk (32.19%), Premier (12.38%), Talisman (4.95%). Work Programme Summary: 1 firm well targeting Old Harry exploration prospect
Well drilled. L98/06-M18 and L98/06-M18Z (Old Harry-1) - Plugged and Abandoned.
Drilled from Wytch Farm onshore M Site [Goathorn Extended Reach Drilling Derrick] in Jan 2000. Drilled 60mTVT of Sherwood from 1738mSS. Encountered shaley zone in top 9m (Wytch Farm Zones 10, 20). Good 6m HC sand at 1748 - 1754m TVD, Sw 40 - 55 percent. Thinner sands below with net SW 40 percent in shaley matrix. Overall 60m interval is N/G of 0.29 with Sw 50 percent cut off. Possible OWC at 1753m TVDSS, structural spill point on post well remapping is 1750-1760m. Individually trapped HC's in thin sands below this level, down to 1788m TVDSS
May be gas or oil, no oil shows in Sherwood, but OBM and disaggregated samples would work against shows. Oil is assumed, see Comments. This well had no RFT runs despite low Sw and good reservoir zones, and no DST's were run.
Reason for failure - Top Sherwood 40m deeper than prognosed due to higher than predicted Chalk velocity. Logs show oil or gas migration to this structure

Old Harry Prospect (Well 98/06-M18), Pre Drill.
The objective was the Sherwood Sandstone, footwall anti-clinal structure, one fault block south of Wytch Farm.
Well and Post Drill
This prospect was drilled by BP L98/06 -18Z in Jan 2000 (Old Harry), but the structure was 40m deep to prognosis. There were good HC indications on logs, SW's down to 40 percent, indicating a valid closure, probably oil bearing, but no tests were carried out, RFT or DST. The reservoir quality was poor due to the absence of good channel sands in Zones 30, 40, which are present in Wytch Farm. Old Harry is off the main Sherwood sand channel axis. There was a good quality 6m HC bearing sand at the top of Zone 30. Below this thin individual HC bearing sands occur in a low N/G sequence, extending to TD at some 44m below the mapped spill point. These are probably individually stratigraphically trapped, but if they are part of a connected reservoir body, a fault linkage would be needed to seal a structure down to at least 1800mSS, below the water level in 98/11-1 to the east.



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Department of Energy (DOE) . UK land well records (microfiche). [Re. Wytch Farm.]

Department of Energy and Climate Change, 2010.
British Government, Department of Energy and Climate Change - Oil and Gas.
Contents: Oil and Gas.

EMS - Environmental Statement Reports for Operations carried out during 2009.
UKCS Production Projections.
26th Seaward Licensing Round.
Significant Offshore Discoveries in date order to end 2009.
UK Fallow Assets and Process - 2010.
2009 Drilling Activity.
UK Oil and Gas Reserves and Resources - 2009.

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Donovan, D.T. and Stride, A.M. 1961. An acoustic survey of the sea floor south of Dorset and its geological interpretation. Philosophical Transactions of the Royal Society, London, Series B, Biological Sciences, Vol. 244, No. 712, pp. 299-330, 23rd November, 1961. An important and classic publication.

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DORSET COUNTY COUNCIL


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Dorset County Council report of 1979 on the then-proposed oil well F at Goathorn Peninsula, Wytch Farm Oilfield, Dorset

Dorset County Council. 1979. Wytch Farm Oilfield. Goathorn Peninsula. Report of Working Party on the environmental implications of an exploration well site for oil or gas. May 1979, 75pp with various maps and plans. [This is concerned with the old F site on Goathorn Peninsula, not the major M site, now used for ERD boreholes]

Introduction:
1.1. Following the discovery in 1973 of a commercially viable oil field at Wtych Farm, Gas Council (Exploration) Limited - GC(E) - are now developing facilities at the various well sites, gathering station and railhead at Furzebrook. (Map 1).

1.2. During exploration of the Wytch Farm field [i.e. Bridport Reservoir], a second deposit [i.e. Sherwood Reservoir] of oil was found in 1977 which lies beneath and probably displaced to the east of the original field.

1.3. To further investigate both deposits of oil GC(E) submitted a planning application to drill two evaluation wells on Goathorn peninsula. Following advertisement of the applications, objections wer received by Dorset County Council, many of which relate to environmental factors. ...

1.10. [The Studland Well was proposed but this development never happened and was probably refused permission; it is just mentioned here out of interest.] The working party were also asked to to pay regard to the possibility of a similar proposal being made on the Studland peninsula at some time in the future and to consider any relevant interactions between the two proposals [a map is given showing the possible location of the Studland (South Haven Peninsula) well site. The Studland well was to be at approximately SY 027855, 0.5km west of Redhorn Quay and on the heath just on the northwest side of Ferry Road. On page 43, there is further discussion of the, then-considered, Studland well. It was to be positioned on the west side of the Studland Toll Road (Ferry Road), but it is mentioned that a site east of the Toll Road may be possible.]

26.5 [p. 35. An item of interest on blow-outs. No blow-out has actually occurred and there has been only one known oil leak (in 2010). The safety procedures are mentioned below.]

1. The maximum formation pressure likely to be encountered will be accurately estimated.

2. The well will be circulated with a suitable quantity of properly conditioned and weighted mud to compensate for this pressure.

3. The rig will be fitted with "blow-out" preventer equipment, which consists of three valves fitted one above the other. They are hydraulically operated and can be activated locally or remotely. (These valves are tested daily and pressure-tested weekly). [Note that in the case of flowing wells, as opposed to pumped wells, there is a also a downhole safety valve which can automatically close.]

4. Estimates by GC(E) engineering staff indicates by comparison with Wytch Farm that, in the unlikely event of a "blow-out", then a flow in the region of 3,000 barrels of oil per day could result. The holding capacity of the well site within the bund wall is 17,500 barrels. This would allow a period of about 5 and a half days to to bring in any additional measures needed to control the pollution. [reference is made on p. 40 to the safety record of BP for having drilled 10,000 wells on land for some ten years without the occurrence of a "blow out". The failure of a "blow-out" preventer is estimated at 1 in a million. The "blow-out" risk at Wytch Farm is estimated at 1 in a million. In fact from 1973 to 2013, forty years, there has never been a "blow-out" at Wytch Farm.

Oil Pollution in Poole Harbour in 1961, not from an oil well (see map 12), page 41:
"In the first incident, 6000 gallons (170 barrels) of oil escaped from a land installation at Holton Heath [adjacent to Poole Harbour] covering the Spartina in that area, but fortunately did not spread very far. The second incident, which occurred on 25 January [1961] was much more serious. On this date an oil tanker and another ship collided in the area between the mouth of the harbour and Brownsea Island releasing 61,561 gallons (1,750 barrels) of oil at about the time of low water. Easterly winds drifted the oil on the flood tide towards Brownsea Island, Goathorn Point and the island shores to the west, to approximately the area labelled "heavily polluted" on the map (map 12). As a result of heavy rain and south-west gale force winds which developed two days after the collision, spring tides flooded above their predicted levels, and the oil, caught temporarily by the stems of Spartina, was lifted again and spread far afield. Fortunately, it soon became trapped and this time held by Spartina, so that by 2 February [1961] when the tide was 1 ft. above predicted levels the oil was submerged and very little was seen floating. Relatively few birds frequent Spartina marsh, and the oil was safer there than on the water, on the beaches or on the mudflat feeding grounds.
At least 300 birds of 32 different species are known to have been affected by the oil pollution and at least 148 birds of 28 different species are known to have died as a result of it. .... [continues on to p. 42.]

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Dorset County Council. 1980. Onshore Oil in Dorset: A Consultative Document. Dorset County Council, Alan Swindall, County Planning Officer, County Hall, Dorchester, November, 1980. 22p.

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Downing, R.A., Edmunds, W.M. and Gale, I.N. 1987. Regional groundwater flow in sedimentary basins in the U.K. Pp 105-125 in: Goff, J.C. and Williams, B.P.J. 1987. Fluid Flow in Sedimentary Basins and Aquifers. Geological Society Special Publication No. 34, 230 p.

Downing, R.A. and Penn, I.E. 1992. Groundwater flow during the development of the Wessex Basin and its bearing on hydrocarbon and mineral reserves. B.G.S. [British Geological Survey] Research Report SD/91/1. 30 p. ISBN - 0 - 85272-203-6.
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Dranfield , P. Langley, G.O., McLean, F. and Scotton, G. 1986. Wytch Farm oilfield development; geological, geophysical and reservoir engineering considerations. BP Petroleum Development Ltd.

Dranfield , P., Begg, S.H. and Carter, R.R. 1987. Wytch Farm Oilfield: reservoir characterisation of the Triassic Sherwood Sandstone for input into reservoir simulation studies. In: Brooks, J. and Glennie, K. (eds), Petroleum Geology of North West Europe, Graham & Trotman, London, 494-503.
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Dorset County Council. 1980. Onshore Oil in Dorset: A Consultative Document. Dorset County Council, Alan Swindall, County Planning Officer, County Hall, Dorchester, November, 1980. 22p.

Dorset County Council. 1986. Oil and Gas in Dorset: Policy and Practice. Dorset County Council, Dorchester. ISBN 085216 3819.
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Drill or Drop? 2016. Independent Journalism on Fracking, Onshore Oil and Gas and the Reactions to it.
Drill or Drop? [online articles].
Environment Agency calls for refusal of Markwells Wood oil production plans over risk to water. By Ruth Hayhurst on November 3rd, 2016. The Environment Agency has objected to plans for 20 years of production at Markwells Wood in the South Downs National Park because of concerns about pollution of the chalk aquifer. "Portsmouth Water has objected to proposals for 20 years of oil production in the South Downs National Park because of concerns about contamination to drinking water. People living near a proposed oil production site in the South Downs National Park voted almost unanimously against the scheme."
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DTI (Department of Trade and Industry) . 2003. The Hydrocarbon Prospectivity of Britain's Onshore Basins. pdf file:
The Hydrocarbon Prospectivity of Britain's Onshore Basins.
See Wessex Basin, pp. 6-17, and Weald Basin pp. 18-25. There are summary accounts of the various oil fields; Wytch Farm, for example, is discussed in concise form on p. 16.
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Dunn, C.E. 1974. Identification of sedimentary cycles through Fourier analysis of geochemical data. [on Kimmeridge Clay bituminous sediments of Kimmeridge, Dorset]Chemical Geology, 13, 217-232. By Colin E. Dunn, at the time at: Department of Mineral Resources, Saskatchewan Government, Regina, Sark, Canada. Based on a doctoral thesis at Kingston Polytechnic (now university), supervised by Dr. R.C.L. Wilson.
Abstract:
Trace elements are sensitive to slight shifts in the chemical equilibrium of a body of water, and as a result they can be expected to reflect cyclical events in the earth's history. Geochemical data [trace elements, total organic matter and CO
2 ] from a section of Upper Jurassic (Kimmeridgian) bituminous sediments [Upper Kimmeridge Clay, wheatleyensis - hudlestoni, around the Blackstone or main Kimmeridge oil shale], in [Dorset coast] Great Britain, 20m. thick, have been examined by single Fourier series analysis, thereby permitting an objective assessment of sedimentary cycles. Subjectivity only enters into the final interpretative stage.
Assumptions made as to the rate of deposition of these sediments have indicated several superimposed periodicities with respective durations of (?)200,000, 100,000, 40,000 [the obliquity or axial tilt cycle], and 11,000 years [tectonic or climatic?]. Comparison is made with long-term cyclic durations estimated by other workers. Several of the these periods are coincident with the duration of the astronomical phenomenon which could could cause climatic fluctuations.
[Related webpage: Kimmeridge Clay - Oil Shale at Clavell's Hard - by Ian West]
[Related references: Weedon]

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Durham University, News. 2012. Durham's Richard Davies speaks at Geological Society Briefing on fracking and hydraulic fractures. (21 June 2012).
Available online at: Richard Davies - at the Geological Society.
[See the article for a video link]
The probability of hydraulic fractures, such as those produced in 'fracking' for shale gas, contaminating shallow aquifers is minimal, according to a study which was discussed at a recent open meeting of the Geological Society.
The research, published earlier this year in the journal Marine and Petroleum Geology, suggests that particularly for areas where fracking is being carried out for the first time a minimum distance of 600 metres should be maintained between the fracture zone and an aquifer. The maximum upward propagation of a stimulated hydraulic fracture which has been recorded is 588 metres, in the USA. Nevertheless, data presented in the study suggests that their probability of extending beyond 350 metres is around 1%.
With UK fracking typically occurring at distances of between two and three kilometres below the surface, the data suggests the risk of contamination to aquifers is minimal.
The paper's lead author, Professor Richard Davies from Durham University, was speaking as part of an public briefing meeting held at the Geological Society on 18 June 2012.

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Durkin, J. 2011a. News: Dorset oil leak is a crude "wake up call" for BP. By Jim Durkin, Daily Echo; Bournemouth Echo, Friday 28th April 2011.
Green campaigners say that the oil leakage that prompted a two-month shutdown at BP's Wytch Farm oilfield should be viewed as a "wake-up call for potential disaster in Dorset". ........ The Wytch Farm plant normally produces an average of 18,000 barrels a day, but since the leak ... no oil has been pumped at the Purbeck site, a situation costing BP millions in lost revenue.
Dr. Suzie Baverstock, Wytch Farm's communications and land management team leader, assured the Daily Echo that the leak, occurring at one of the well sites was small and there was no contamination to surrounding water or countryside. "It was contained and dealt with very promptly by ourselves" she said. "No oil left the site whatsoever." BP say that after the initial shutdown, they took the opportunity to carry out maintenance work across the plant. Operations are due to re-start at Wytch Farm with the next few days (i.e. after Friday 28th January 2011).

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Durkin, J. 2011b. BP strikes deal with Perenco for Wytch Farm oilfield. Daily Echo; Bournemouth Echo. Wednesday 18th May 2011. By Jim Durkin
Extract: "Energy giant BP has announced the sale of its Wytch Farm oilfield in a deal worth a staggering 10 million dollars. The Purbeck plant, the largest onshore oilfield in Western Europe, has been sold to Perenco UK Ltd, the British arm of an Anglo-French independent oil and gas company with interests in 16 countries. It is expected that all employees based at the Wytch Farm plant will continue to work for the new company. An immediate 500m dollarss payment has already been made, with a further $55m to be paid on completion, expected at the end of 2011. The remaining 55 million dollars is contingent on submission of Perenco's future development of the Beacon field and on oil prices in 2011-13. BP sold off Wytch Farm - which taps into three separate oil reservoirs under Poole Harbour and Poole Bay - so that it can invest more capital into its North Sea operations.....
Wytch Farm, which is sited in one of the most environmentally-sensitive areas of the UK, produces around 15,000 barrels of oil a day. However, at its peak production was closer to 110,000 barrels. Mr Garlick said: "We are pleased to have reached this agreement with Perenco. Perenco is committed to investing in and developing Wytch Farm beyond BP's plans, ultimately providing a longer-term future for the asset and the people who work there. Ensuring continued safe operation of Wytch Farm will continue to be our priority as we support employees through the transition process which we will now follow."

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Durrance, E.M. 1984. Uranium in the New Red Sandstone of southeast Devon. Proceedings of the Ussher Society, January 1984, pp. 108-115. This is relevant to the problem of radioactivity in the Sherwood Sandstone Reservoir of the Wytch Farm oil field. Pipes and pumps can become too radioactive to handle. A special cleaning procedure is in operation and has been for many years. Radioactivity of more than one origin is usual in the Permo-Triassic strata of the south of England.

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Ebukanson and Kinghorn
Dr. E.J. Ebukanson, deceased, late of the Department of Geology, the University of Port Harcourt, Port Harcourt, Nigeria. Dr. Robert Kinghorn, deceased, 1942-2007. A member of research, academic and administrative staff at Imperial College London, 1969-2006.

Ebukanson, E.J. 1984. An Investigation of Some Potential Hydrocarbon Source Rocks of Southern England. Ph.D. Thesis, University of London, 450pp.

Ebukanson , E.J. and Kinghorn, R.R.F. 1985. Kerogen facies in the major Jurassic mudrock formations of southern England and the implication of the depositional environments of their precursors. Journal of Petroleum Geology, 8, 435-462.

Ebukanson, E.J. and Kinghorn, R.R.F. 1986a. Maturity of organic matter in the Jurassic of southern England and its relation to the burial history of the sediments. Journal of Petroleum Geology, 9, 259-280.

Ebukanson , E.J. and Kinghorn, R.R.F., 1986b. Oil and gas accumulations and their possible source rocks in southern England. Journal of Petroleum Geology, 9, 413-428.

Ebukanson, E.J. and Kinghorn, R.R.F. 1986. Maturity of organic matter in the Jurassic of southern England and its relation to the burial history of the sediments. Journal of Petroleum Geology, vol. 9, part 3, pp. 259-280. Abstract: An investigation of the maturity levels of organic matter in the major potential Jurassic hydrocarbon source rock units in Southern England (i.e. the Lower Lias, Oxford Clay and Kimmeridge Clay) using sporomorph colouration and alkane distribution patterns shows that the Oxford Clay and the Kimmeridge Clay organic materials are immature in most parts of the area. They are mature only in the central parts of the Mesozoic Wealden Basin... The distribution of mature Lower Lias sections is found to be more extensive. Attempted reconstructions of the burial history of the Jurassic sections across Southern England, and the application of the Lopatin method of theoretical organic maturity prediction, seem to support the observed maturity trends and suggest that the present maturity levels of Jurassic organic matter at any given locality are dependent on the structural development of the area through time.
[end of abstract]
[further notes regarding maturity]
p. 265 - Organic maturity of Kimmeridge Clay etc. -
"Kerogens in all outcrop samples are immature. In Dorset kerogens in the outcrop samples of the Kimmeridge Clay to the south of the Purbeck - Isle of Wight Disturbance (i.e. the Kimmeridge Bay area) are relatively more mature than to the north of that line (i.e. in the Ringstead Bay area).
In the Arreton - 2 Borehole of the Isle of Wight, kerogen samples from the lower parts of the Kimmeridge Clay and the whole of the Oxford Clay are marginally mature (estimated R0 0.50 to less than 0.60%), while those from the Penshurst Well in the Central Weald have entered the main phase of oil generation (i.e. estimated R0: 0.60%). Thus the two most mature contemporaneous organic matter in the Kimmeridge Clay and the Oxford Clay occur in two parts of southern England: the Isle of Wight area to the south of the line of disturbance and the central Weald. ....
However, Lower Lias samples in the main phase of oil generation are encountered only at Arreton 2, Henfield, Winchester 1 and Penshurst. The most mature Lower Lias sections occur at Arreton-2 (estimated R0: up to 0.90%) and Penshurst (estimated R0: up to 0.85%) wells - the same localities where the most mature Kimmeridge Clay and Oxford Clay samples are identified. In the Penshurst Well the thickness of the Jurassic is about 4,130ft (1.259m). In areas of the central Weald where the Jurassic attains thicknesses of 5,000ft (1.524m) such as the northern part of West Sussex and southern Surrey (Gallois, 1965), it is very likely that the organic matter in these three Jurassic formations has attained higher maturity levels than those reported for the Penshurst borehole....
[p. 270].The Arreton No. 2 Well (Isle of Wight).
.. it is noted that the base Lias attained a TTI value of 3 or 0.50% R0in the Aptian/Albian (Early Cretaceous), a TTI value of 10 or 0.60 percent R0 in the Late Cretaceous, and a TTI value of 15 or 0.65 percent R0 in the Paleocene. ... [there is interesting discussion about over-estimation for eroded Cretaceous and Tertiary - a very valid point because there is independent evidence for early erosion of Tertiary from the southern Isle of Wight]....
Despite the small disparity the Lopatin method does show that the Lower Lias evolved into the catagenesis stage (top = 0.50 R0) in the Early Cretaceous, although the onset of the main phase of oil generation was not achieved until the Late Cretaceous.

Ebukanson, E.J. and Kinghorn, R.R.F. 1990. Jurassic mudrock formations of southern England: lithology, sedimentation rates and organic carbon content. Journal of Petroleum Geology, vol. 13, part 2, pp. 221-228.
Abstract:
The Jurassic mudrock formations of southern England, especially the Lower Lias, Oxford Clay and Kimmeridge Clay, show great variations in lithology, organic content and rates of sedimentation. It is here suggested that the varying sedimentation rates of these formations have been a major contributary factor, resulting in differences in the organic richness observed between these fine-grained Jurassic rock units. Variations in lithology have only a minor effect on the organic richness of these sediments, compared to the marked influence of sedimentation rate. [end of abstract]
[further notes from the paper - Depositional Environment and Organic Carbon Content]
"In the Lower Lias, as well as the Kimmeridge Clay, it has been noted that the laminated mudrocks, which represent anoxic depositional conditions, are much higher in organic matter compared with the non-laminated varieties, which represent the oxidising depositional environments (Hallam, 1960; Gallois, 1976). This agrees with findings of other workers, who report that bioturbated sediments contain significantly less organic matter than laminated ones (Pratt, 1984; Savarda et al. 1984).
Total organic carbon values as high as 35.1 percent (Williams and Douglas, 1980) and over 50% (Tyson et al. 1979) have been reported for the Kimmeridge Clay, whilst maximum values of lower than 10 percent have been reported for both the Lower Lias and the Oxford Clay (Hallam, 1960; Bitterli, 1963; Morris, 1980). [continues with Materials Sampled]


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Egdon Resources Plc. [InfraStrata] 2006. Portland Gas Storage Project Update, 28th June 2006. Available online. [see also InfraStrata, a later name for the company. The Portland gas storage project never took place, although an initial borehole was drilled and the distribution of Kimmeridge oil shale on the sea floor around the area was also surveyed. InfraStrata have also been involved in a proposal of 2016 to drill a borehole from California Quarry, Swanage, in the direction of the well-known gas seep at Anvil Point, near Durlston Head, Swanage. This drilling operation did not actually take place in 2016. There were protests from "green" organisations.]
Egdon Resources Plc (AIM : EDR), the onshore UK focused energy company, today provides an update on its gas storage project on the Isle of Portland in Dorset. Portland Gas Limited ('Portland Gas'), a wholly owned subsidiary of Egdon Resources Plc, is pleased to report that drilling operations for the Portland-1 borehole have been completed and the BDF Rig 28 is expected to be released within the next 24 hours. A total drilled depth of 2929 metres was reached in the Triassic Sherwood Sandstone on 21st June 2006. The Portland-1 borehole on the Isle of Portland, Dorset was drilled to confirm that a halite sequence with a low insoluble content (called 'S7' by Portland Gas), within a Triassic salt sequence ('Saliferous Beds') of the Wessex Basin, was suitable for the creation of caverns to store natural gas. Initial technical analyses of the data acquired from the borehole, by Portland Gas consultant DEEP. Underground Engineering GmbH ('DEEP') of Germany, indicates that individual caverns of approximately 250,000 cubic metres could be created within the S7 sequence at the Isle of Portland location. This is the same volume used in the pre-feasibility work for the project prior to the drilling of the Portland-1 borehole. The Saliferous Beds were encountered with a thickness of 470 metres (41 metres thicker than forecast). The top of the target S7 interval was penetrated at a depth of 2365 metres and was found to have a thickness of 135 metres (43 metres thinner than forecast). DEEP will coordinate the completion of further laboratory work on core samples over the S7 sequence and computer simulation of the proposed cavern leaching programme. Final confirmation of project feasibility is expected in August 2006... [continues]

Egdon Resources Plc . 2008. Further details of New Licences Onshore UK. 24th June 2008.
[Extract:]
Egdon Resources plc (AIM:EDR), the UK-based exploration and production company primarily focused on the hydrocarbon-producing basins of the onshore UK and mainland Europe, is pleased to provide further details of the licences offered to it in the UK 13th Landward licensing round. As previously reported the Department for Business Enterprise and Regulatory Reform has offered Egdon a total of six operated Petroleum Exploration and Development Licences ("PEDL's"). These licences are located within two of the Company's focus areas, the East Midlands Petroleum Province and the Wessex Basin of Dorset. All licence awards are subject to the usual regulatory approvals. Egdon and its joint venture partners have been offered PEDL237 within the Wessex Basin in Dorset, Southern England. Egdon will hold a 45 percent interest in the licence with partners First Oil Expro Ltd (26.25 percent), Sterling Resources (UK) Ltd. (18.75%) and Dorset Exploration Limited (10 percent). The licence is contiguous to existing licences PEDL048 and PL090. The area contains a number of high potential oil prospects identified on proprietary reprocessed 2-Dimensional ("2D") seismic data. The main plays within the block are the Sherwood Sandstone and Bridport Sandstone which are productive at the Wytch Farm oil field located some 20 kilometres to the east. Egdon have mapped best estimate gross prospective resource potential of 70 million barrels of oil ("mmbo") within the licence. The work programme will comprise of pre-stack depth migration of existing 2D seismic data prior to making a drill or drop decision on the licence.

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Egdon Resources U.K. Limited. [InfraStrata] 2010? Sherwood Sandstone Play Farm-in PL090 and PEDL237 Wessex Basin, Onshore UK. Egdon Resources U.K. Limited, on behalf of its co-venturers, wishes to farm out part of their interest in Wessex Basin licences PL090 and PEDL237 in return for a carry through a small 3D seismic programme (including some PSDM reprocessing) and the drilling of a well. These licences contain prospects with a total of 200mm bbl STOIIP The farm-in excludes the Waddock Cross oil discovery in PL090.
Summary
Opportunity to test Wytch Farm reservoir in updip, offset location
Opportunity to test Wytch Farm reservoir in updip, offset location
Initial test of Winfrith Prospect with estimated prospect reserves of up to 6.3 mmbo (unrisked)
Requires small 3Dseismic survey to refine target location
2009 well (subject to planning and rig availability)
Several other leads/prospects at several levels containing STOOIP of up to 200 mmbbl.
Licence Summary
Egdon has interests in three licences in the Wessex Basin - PL090 and the recently awarded 13th Round license PEDL 237.
PL090 was awarded to Gas Council Exploration and BP in 1968 (expiry 31 March 2014). All commitments were met by the original Licencees. Brabant, Yates & Canyon farmed in during 1993 and drilled West Stafford -1 in 1994. Bow Valley purchased interests from Brabant & Canyon in early 1999. Bow Valley then assigned interests under an AMI Agreement to Sterling Resources & Egdon. Egdon purchased Bow Valley's interest in March 2003 and drilled Waddock Cross-2 in 2003/04 and - 3 in 2005. Following a number of deals current interests are Egdon 45%, First Oil Expro 26.25 percent, Sterling Resources 18.75 percent and Dorset Exploration 10 percent. PEDL237 was awarded in the 13th Round of Licensing, 2008 to the same company group. [continues]

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Emerton, S., Muxworthy, A.R. and Sephton, M. A. 2013. A magnetic solution to the Mupe Bay mystery. Marine and Petroleum Geology, vol. 46, pp. 165-172. September 2013. By Stacey Emmerton, Adrian R. Muxworthy and Mark A. Sephton. Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
[This is an important paper regarding oil migration in the Wessex Basin.]

Highlights:
The clasts hold a magnetic signal unlike the matrix indicating two phase staining.
The clasts show similar directions and thus were soft when deposited into the bed.
The clasts indicate the onset of oil migration in the Early Cretaceous.
The matrix is consistent with today's magnetic field and is an active oil seep.

Abstract:
An outcrop of Wealden beds at Mupe Bay (UK) is associated with a key piece of evidence for the timing of hydrocarbon migration in the Wessex Basin. A conglomeratic bed contains oil-stained clasts and matrix that appear different upon superficial observation. Conventional interpretations assign differences to the erosion and transport of oil-cemented clasts by Wealden rivers before their incorporation into a later stained conglomeratic bed. This scenario constrains the onset of oil migration in the basin to the Early Cretaceous; however, arguments have been put forward for single phase staining.
Magnetic information may provide new ways to examine the Mupe Bay record of oil migration. Migrating fluids such as hydrocarbons have been shown to cause chemical conditions suitable for the alteration or formation of authigenic magnetite resulting in associated chemical remanent magnetization (CRM). Magnetic characterization reveals both the matrix and clasts contain multi-domain magnetite but abundant hematite only exists within the clasts. Hysteresis parameters show the matrix has more multi-domain and likely larger magnetic grains than the clasts.
Magnetic directions are different in the clasts and matrix supporting a two-phase oil-staining event. Moreover, paleomagnetic directions for the clasts after tilt correction (82.6°N and 155.2°E) are consistent with biodegradation processes in the Early Cretaceous. Consistent directions in separate clasts imply the biodegradation and magnetite formation took place following transportation and incorporation of the oil-cemented clasts into the conglomerate bed. Magnetic directions reveal that the Mupe Bay matrix has a remanent magnetization corresponding to today's magnetic field, confirming the matrix represents an active oil seep.
This study represents an unprecedented use of magnetic data to date the onset of oil migration in a basin. The classic two-stage oil-staining scenario, which constrains the onset in the Wessex Basin to the Early Cretaceous, is supported by our data.

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Evans, D.J. and Chadwick, R.A. 2009. Underground Gas Storage: Worldwide Experiences and Future Development in the UK and Europe. 1st June 2009. Special Publication of the Geological Society, 283pp. Price 90 pounds, Fellow's price 45 pounds, higher prices on Amazon.
"Generally the thickness of individual units of pure halite range from 21 to 40m., but can exceed 60m. in thickness, as proved in the Martintown, Chickerell and Southard Quarry [near Durlston Head, Swanage] Boreholes." "Depth to the uppermost halite bed - 2141m. at Southard Quarry."
[Harvey and Stuart (1998, pp. 242-244 and fig.3), have given some further limited information regarding the Southard Borehole, Swanage. It would seem that this was a deep well and it penetrated the Triassic salt deposits. It seems to have shown that the salt thickness was about 320 m. in thickness, south of the major, mid-Durlston Bay fault (downthrowing south). This compares with estimates for zero under Swanage town and with more than 400m. in Lyme Bay.]
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Evans , J., Jenkins, D. and Gluyas, J. 1998. The Kimmeridge Bay oilfield: an enigma demystified. In: Underhill, J.R. (Ed.) Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publications, 133, 1-18. 407-413. Abstract: The Kimmeridge oilfield was the first commercial discovery in the Wessex Basin. It was discovered in 1959 and is still producing from a single well. To date over 3 million barrels of oil have been extracted. Production is likely to continue into the next century. Oil is trapped in the fractured Cornbrash Limestones in an anticline close to the main inversion axis. The Kimmeridge accumulation remains the only producing field in the hanging wall to the Purbeck Disturbance, making it an intriguing enigma within the basin. Many myths have been perpetuated regarding the size of the field and the results from drilling elsewhere within Kimmeridge Bay. By presenting data on the field here, we hope to dispel some of these myths.

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Falcon , N.L. and Kent, P.E. 1950. Chalk Rock of Dorset - more evidence of salt? Geological Magazine, 87, 302-303.

Falcon, N.L. and Kent , P.E. 1960. Geological Results of Petroleum Exploration in Britain 1945-1957. Geological Society of London, Memoir No. 2, 56pp + foldout diagrams. By Norman Leslie Falcon, M.A. F.R.S., Chief Geologist, The British Petroleum Company Limited, and Percy Edward Kent, D.Sc., Ph.D., Geological Advisor, BP Exploration (Canada). London, 4th August, 1960.

[Example extract]
2. General Exploration:
(a) Southern England (Table I):
(i) Dorset and the Hampshire Basin:
The extent of oil shows at outcrop in Dorset marginal to the Hampshire basin has continued to attract our interest. The borehole at Poxwell originally proved the complexity of the movements in pre-Albian times (Taitt & Kent 1939), and holes drilled through the Chalk at Chaldon Down, north of Lulworth, passed directly from Albian to Kimmeridge Clay, showing that strong local pre-Albian uplift continued eastwards from outcrop (Arkell 1947B). Telluric surveys carried out over this area showed a number of anomalies but their interpretation was uncertain, and seismic and gravity surveys south of the Tertiary syncline of Wareham failed to give clear-cut results beneath the Chalk blanket.
The next stage, in progress at the time of writing, has included further investigation of outcropping structures in Dorset and seismic work in the less strongly disturbed area north of the Ballard Down fault in Dorset and in the Tertiary basin in Hampshire. The first of the outcropping structures to be drilled was the fold at Chaldon Herring, which had a superficial appearance of simplicity (Arkell 1947B). Four boreholes in a N.-S. line across the culmination proved it to be a structure of Poxwell type, flanked by a fault with a large pre-Albian throw, with the additional complication that the fault plane had been sharply distorted by the final phase of folding. An account by M. R. House is in the press. Further operations on outcropping structures are planned on the Weymouth anticline near Langton Herring (see Postscript Note, p. 49) and also at Broadbench, where an earlier hole found a minor oil show in the Corallian.
Within the Tertiary outcrop two areas have received detailed attention by seismic reflection survey. The first is near Wareham, where gravity and seismic refraction survey had proved an anomaly. The second is the Ringwood gravity high in Hampshire (White 1949), where reflection survey has detailed a sub circular crest maximum in the Jurassic; the shape and size of this structure suggest that it could be an uplift caused by a local intrusion of Triassic salt at depth, analogous to the domal uplift of Compton Valence (Falcon & Kent 1950).
Footnote:
Since this account was prepared, drilling of Fordingbridge No. 1 [in the New Forest] has shown that this structure is pre-Albian, like those of Dorset, for Gault rests directly on Kimmeridge Clay, with elimination of the thick Portland, Purbeck, Wealden and Lower Greensand (see Postscript Note). Also, a test well drilling near Bere Regis, north-west of Wareham, at the time of going to press, located on a seismic reflection high, has proved Oxford Clay immediately below the Gault.

[Additional example extract - Fordingbridge No. 1 Well at Ogdens in the New Forest]
(c) Fordingbridge, Hampshire
Latitude. 500 54' 17.7; longitude. 010 43' 59.6; elevation 229 feet O.D.
The section of Fordingbridge No 1, drilled on a gravity and seismic high at Ogdens Inclosure (Hasley Hill, and near the Latchmore Brook), near Fordingbridge, is still being worked out, but the following brief account may be given.
Drilling began in the Tertiary beds of the Hampshire basin; the Chalk was reached at 678 feet and. the Upper Greensand and Gault penetrated from 1997 to 2251 feet. Beneath the Gault the well passed directly into Kimmeridge Clay, shown by a core 20 feet below the top to be Lower Kimmeridge (with Aulacostephanus, etc.). Only 210 feet of Kimmeridge Clay remained beneath the Gault. The unconformity eliminates the Lower Greensand, Wealden, Purbeck, Portland and Upper Kimmeridge, measuring approximately 4000 feet in eastern Dorset (the nearest outcrops) and some 2700 feet at Portsdown on the other side of the same Tertiary basin. This represents a very considerable pre-Albian uplift.
Beneath the Kimmeridge the boring proved a normal sequence of Corallian (about 170 feet), Oxford Clay (about 430 feet), Cornbrash (35 feet) and Great Oolite Series (404 feet). The last-named was mainly limestone, with only a minor development of argillaceous beds which could be ascribed to the Fuller's Earth, in marked contrast to recent borings nearer the Dorset coast (see the account of the Radipole borings). Below, 118 feet of sandy and ferruginous limestones and ironstones are ascribed to the Inferior Oolite, and beneath this the well proved an Upper Lias development of Bridport Sands type, 250 feet thick. The remainder of the Lias was normal, except that the Middle and Lower subdivisions totalled only about 450 feet and rested upon 60 feet of beds ascribed on fossil evidence to the Rhaetic. The well was completed at 4487 feet, 106 feet into the Keuper [Mercia Mudstone]. [continues with details of Radipole No. 1 borehole, Weymouth]


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Farrimond , P., Comet, P., Eglinton, G., Evershed, R.P., Hall, M.A., Park, D.W. and Wardroper, A.M.K. 1984. Organic geochemical study of the Upper Kimmeridge Clay of the Dorset type area. Marine and Petroleum Geology, 1, 340-354.

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Fishman, N.S., Lowers, H.A, Hackley, P.C., Hill, R.J. and Egenhoff, S.O. 2012. --- Porosity in Shales of the Organic-Rich Kimmeridge Clay Formation (Upper Jurassic), Offshore United Kingdom.
By Neil S. Fishman, Heather A. Lowers, Paul C. Hackley, Ronald J. Hill and Sven O. Egenhoff. Search and Discovery Article No. 50620 (2012), Posted June 11, 2012. Adapted from an oral presentation at AAPG Annual Convention and Exhibition, Long Beach, California, April 22-25, 2012.
Available online at:
Porosity in Shales of the Organic-Rich Kimmeridge Clay Formation.
Abstract:
Petrographic, SEM, and RockEval pyrolysis analyses of organic-rich shale samples from 6 wells that penetrated the Upper Jurassic Kimmeridge Clay Formation (KCF), offshore United Kingdom, were performed to evaluate the nature (physical and chemical) of the organic material and to document changes in organic porosity as a function of increasing thermal maturity. The formation is at depths ranging from ~6,100 ft to ~15,300 ft (subsea). It is thermally immature to marginally mature in the shallowest core samples, where total organic carbon (TOC) contents are as high as 10 wt%, vitrinite reflectance (Ro) values are ~0.6%, and hydrogen indices (HI ) are high (>400 mg hydrocarbon/g rock). In contrast, it is thermally mature in the deepest core (Ro values ~1.2%), with high TOC contents (as much as 8 wt%) but low HI values (less than 30 mg hydrocarbon/g rock). In addition, the KCF has intermediate HI and Ro values in other core samples. At least four distinct types of organic components were observed in petrographic and SEM analyses, which are, in decreasing abundance: 1) amorphous organic material admixed with clay platelets (as much as 20 im [?] long); 2) elongate (up to 300 im mat-like masses (micro-algal mat?) with small (less than 0.5 im) quartz, feldspar, and clay entrained within it; 3) discrete particles (possibly alginate?); and 4) Tasmanites microfossils. Regardless of depth and thermal maturity, the following observations were made of porosity in shales of the KCF. On ion-milled surfaces, there are irregular-shaped micropores and nanopores (0.1-0.01 im across) in some mat-like masses, whereas regularly shaped micropores (up to 1 im across) are in the discrete organic particles. Other types of pores, particularly interparticle (i.e., between illite flakes or platelets as well as between authigenic quartz euhedra), and intraparticle (i.e., between crystallites in framboidal pyrite) are also present and are noteworthy because they compose much of the observable porosity in the KCF shales.
No systematic increase in organic porosity was observed in any organic material within the KCF with increasing depth and thermal maturity. As such, organic porosity does not contribute significantly to overall pore volume in the KCF, even in organic-rich shales that are thermally mature. Therefore, the petroleum storage potential in the formation appears to reside largely within interparticle and intraparticle pores between or within inorganic components of the shales, respectively.
[This now continues with a very good, well-illustrated and interesting presentation!]

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Fontenot B.E. et al., 2013. An Evaluation of Water Quality in Private Drinking Water Wells Near Natural Gas Extraction Sites in the Barnett Shale Formation (USA). Environmental Science and Technology Letters. ACS Publications, Washington, D.C. [Re environmental aspects of Shale Gas Fracking (Hydraulic Fracturing). Arsenic etc has been found near shale gas fracking wells. There is a review of this article on the BBC New, website, August 2013.]
[Full list of authors: Fontenot, B.E., Hunt, L.R., Hildenbrand, Z.L., Carlton, D.D., Okka, H. Walton, J.L., Hopkins, D., Osorio, A., Bjorndal, B., Hu, Q.H. and Schug, K.A. 2013.]
Natural gas has become a leading source of alternative energy with the advent of techniques to economically extract gas reserves from deep shale formations. Here, we present an assessment of private well water quality in aquifers overlying the Barnett Shale formation of North Texas. We evaluated samples from 100 private drinking water wells using analytical chemistry techniques. Analyses revealed that arsenic, selenium, strontium and total dissolved solids (TDS) exceeded the Environmental Protection Agency’s Drinking Water Maximum Contaminant Limit (MCL) in some samples from private water wells located within 3 km of active natural gas wells. Lower levels of arsenic, selenium, strontium, and barium were detected at reference sites outside the Barnett Shale region as well as sites within the Barnett Shale region located more than 3 km from active natural gas wells. Methanol and ethanol were also detected in 29% of samples. Samples exceeding MCL levels were randomly distributed within areas of active natural gas extraction, and the spatial patterns in our data suggest that elevated constituent levels could be due to a variety of factors including mobilization of natural constituents, hydrogeochemical changes from lowering of the water table, or industrial accidents such as faulty gas well casings.


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Frack Free Somerset. 2013. Website of an organisation protesting about possible hydraulic fracking for coal bed methane in the Bristol-Somerset Basin (Somerset Coal Field and beyond). Go to: Frack Free Somerset, available online.)
Example extract: "Latest information as of March 2013: At a public debate in Bath on 14th March 2013 between UK Methane Ltd and Frack Free Somerset, company UK Methane confirmed that they have been working on plans in the Ston Easton area and also around Compton Martin for their next test drilling sites. They have said they intend to apply to apply for permission for full production in Keynsham towards the end of 2013." [the website is quite large with several pages of information.]

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Gallois, R.W. 1965. The Wealden District. British Regional Geology. 4th Edition. Institute of Geological Sciences.

Gallois , R.W. 1976. Coccolith blooms in the Kimmeridge Clay and origin of North Sea Oil. Nature, London, 259, 473-475.

Gallois, R.W. 1978. A pilot study of oil shale occurrences in the Kimmeridge Clay. Institute of Geological Sciences, Report 78/13, H.M.S.O. 26 pp. Author and contributor: Ramues W. Gallois, B.Sc., C Eng, FIMM ; R.J. Merriman, B.Sc. (clay mineralogy section). By Dr. Ramues Gallois.
Summary:
This report describes the stratigraphical and analytical results obtained from four continuously cored boreholes drilled at Donington on Bain, Lincolnshire; North Runcton, Norfolk; Swindon Wiltshire and West Lavington, Wiltshire to examine the nature and occurrence of oil shales in the Kimmeridge Clay. These oil shales have been shown to be concentrated at five levels throughout southern England and detailed correlations have been made between each group of seams in the boreholes and with those at outcrop in the type section at Kimmeridge, Dorset. Potential oil yields have been determined for each group of seams: the results show that, with mechanical enrichment, some levels of Kimmeridge Clay could provide a richer retorting material than some of the oil shales which have been worked in the past. The clay mineralogy of the raw and spent oil shales has been examined using X-ray diffraction, and posssible uses of the spent shale are discussed. The raw shale has also been examined for possible trace element enrichment. The geophysical characters and engineering properties of the Kimmeridge Clay are briefly discussed since these have a bearing on future exploration and possible methods of working respectively...
[end of abstract]

Gallois, R.W. 1978a. What price oil shales? New Scientist, 23 February, 1978, pp. 490-493. The world's largest reserves of liquid hydrocarbons are bound up in extensive deposits of oil shales. This article takes a look at their economic potential and the technical difficulties of their exploitation. The Department of Energy has recently commissioned the Institute of Geological Sciences to carry out a detailed study of Britain's Jurassic oil shales.

Gallois, R.W. 1998. The stratigraphy and well-completion reports for the Swanworth Quarry No.1 and No.2 and Metherhills No. 1 boreholes (RGGE Project), Dorset. British Geological Survey Technical Report, WA/97/91.

Gallois, R.W. 2000. The stratigraphy of the Kimmeridge Clay Formation (Upper Jurassic) in the RGGE Project boreholes at Swanworth Quarry and Metherhills, south Dorset. Proceedings of the Geologists' Association, 111, 265-280. Abstract: Three continuously cored boreholes were drilled in the Kimmeridge Clay Formation in south Dorset to provide unweathered samples for a multidisciplinary study of late Jurassic rhythmic sedimentation and its possible causes. Taken together, the borehole cores provide the first complete sequence through the Kimmeridge Clay and the Kimmeridgian Stage in the type area. The cores have been correlated in detail with the succession exposed in the nearby Kimmeridge cliffs and other sections in south Dorset, as well as with those proved in borehole sections elsewhere in southern and eastern England. The cores have enabled the current chronostratigraphical classification of the Kimmeridge Clay to be extended to the top of the formation, covering strata that are poorly exposed at outcrop. Four types of small-scale rhythm are present within the formation, each of which can be related to the sequence stratigraphy. Only one of these is organic rich and of importance as an oil-source rock. End of abstract. (Additional notes: This is a key paper for providing stratigraphical information on the top and bottom of the Kimmeridge Clay Formation. Types of rhythms are shown diagrammatically. There is some lateral variations in stone beds (actually mostly dolomite). Some notable Kimmeridge Clay horizons include - the Hobarrow Bay Fluidised Bed of seismic shock origin and the Chapman's Pool Pebble Bed. For the unexposed section beneath Kimmeridge Bay there are new names for stone bands - Metherhills SB, Swanworth A, B, C, and D stone bands. The Kimmeridge Cliffs thickness is 7 percent greater than that at Swanworth Quarry. RGGE stand for "Rapid Global Geological Events", a special research topic to examine rhthmicity and its possible causes in the Kimmeridge Clay. This was initiated by NERC in 1995.).

Gallois, R.W. 2005. On the Kimmeridgian (Jurassic) succession of the Normandy coast, northern France. Proceedings of the Geologists' Association, 116, 33-43. Abstract: Kimmeridgian rocks crop out on the Normandy coast north and south of the Seine Estuary at Le Havre in a series of small foreshore and cliff exposures separated by beach deposits and landslips. A total thickness of about 45 m of richly fossiliferous strata is exposed, ranging from the base of the Baylei Zone to the middle part of the Eudoxus Zone. The sections are mostly unprotected by sea-defence works and are subject to rapid marine erosion and renewal. Taken together, the Normandy exposures currently provide a more complete section through the low and middle parts of the Kimmeridgian Stage than any natural English section, including those of the Dorset type area. Descriptions and a stratigraphical interpretation of the Normandy sections are presented that enable the faunal collections to be placed in their regional chronostratigraphical context. The Kimmeridgian succession at outcrop on the Normandy coast contains numerous sedimentary breaks marked by erosion, hardground and omission surfaces. Some of these are disconformities that give rise to rapid lateral variations in the succession: biostratigraphical studies need, therefore, to be carried out with particular care. [This includes a brief mention of the main Dorset localities with references.]

Gallois, R. 2012. The Norfolk Oil Shale Rush, 1916-1921. Proceedings of the Geologists's Association, London, vol. 123, January 2012, pp. 64-73. By Dr. Ramues Gallois. Gallois Geological Consultancy, Exeter.
Available online at:
The Norfolk Oil Shale Rush, 1916-1921.
Abstract:
Oil shales are one of those naturally occurring resources that require so much costly treatment to convert them into useful products that they are only worked on a large scale at times when the availability of cheaper alternatives is restricted. The need to find secure UK supplies during the First World War led to attempts to exploit the potential oil reserves contained in the more organic-rich parts of the Jurassic Kimmeridge Clay Formation. The most costly of these was that carried out in west Norfolk by the privately funded English Oilfields Ltd. (EOL) in 1916–1921 under the direction of Dr. William Forbes-Leslie M.D., FGS. Extensive treatment works were constructed on the Kimmeridge Clay outcrop at Setchey, five miles south of King's Lynn, but very little oil shale was worked or retorted. An extensive drilling programme claimed to have proved sulphur-free oil shales, hundreds of millions of tons of free oil, a 21-m thick seam of natural paraffin wax (ozokerite), and an abundance of metalliferous minerals. At its peak in 1920, the stock-market value of the company was several hundred million pounds at present-day prices. The turning point came in 1921 when samples of shale oil from Setchey and the products derived from them by distillation were shown to have no commercial value because of their high sulphur contents. There was, at that time, no commercially viable method of reducing the sulphur contents to an acceptable level. The free oil, ozokerite and metalliferous minerals only existed in the reports to the shareholders.

[See also Cox and Gallois and Gallois, R.W. 1981. Stratigraphy of the Kimmeridge Clay of the Dorset type area and its correlation with some other Kimmeridgian sequences. Report of the Institute of Geological Sciences, No. 80/4, 144. [Important publication for details of Kimmeridge Clay stratigraphy at Kimmeridge and elsewhere]

Gallois R.W. and Cox, B.M. 1976. The stratigraphy of the Lower Kimmeridge Clay of eastern England. Proceedings of the Yorkshire Geological Society, 41, 13-26.

Gallois, R. and Etches, S. 2001. The stratigraphy of the youngest part of the Kimmeridge Clay Formation (Upper Jurassic) of the Dorset type area. Proceedings of the Geologists' Association, 112, 169-182. By Ramues Gallois (Exeter) and Steve Etches (Kimmeridge). Abstract: The stratigraphy of the youngest part of the Kimmeridge Clay Formation (Upper Jurassic) of the Dorset type area. The lithostratigraphy of the youngest part of the Kimmeridge Clay of the stratotype section at Houns-tout/Chapman's Pool in south Dorset is described in detail for the first time, and is the correlated with other current exposures in south Dorset and with borehole sequences in more distant areas. The stratotype section, albeit deeply weathered in part, is the only complete succession in Britain through this late Jurassic interval. It remains of key importance to international correlation of the Boreal, Sub-boreal and Tethyan faunal provinces at this stratigraphical level and to the resolution of the debate concerning the boundaries of the Kimmeridgian, Tethyan and Bolonian stages. [Houns-tout is also known as Hounstout.]

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Gallois, R.W. and Worssam, B.C. 1993. Geology of the Country Around Horsham; Memoir for 1:50,000 geological sheet 302 (England and Wales). British Geological Survey, Her Majesty's Stationery Office. 130pp. Contributors: Stratigraphy and Structure: R.G. Thurrell and I.E. Penn, Palaeontology: F.W. Anderson, Hydrogeology: R.A. Monkhouse. NERC 1993. ISBN 0 11 884480 6.
Introduction:
The Horsham district is situated within the western part of the Weald. It includes the western end of the High Weald on the Hastings Beds outcrop and part of the surrounding Low Weald, on the northern Weald outcrop. The district is mostly in Sussex, but its northernmost fringe is in Surrey (Fig. 1). The natural vegetation of the district in early postglacial times like that of the rest of the central Weald, was dominated by oak forests. The tiny 'microlith' flint implements of the Mesolithic hunters have been found in large numbers locally, on higher groundon both the Hastings Beds and the Weald Clay outcrops. The forests seem to have deterred large-scale Neolithic, Bronze Age or Iron Age (including Romano-British) settlement. Stane Street, the Roman road between London and Chichester, crossed the northwest corner of the district, running through Ockley and west of Slinfold, and is still followed in part by the modern A29..... [continues].

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gasdrillinginbalcombe website. 2013. Gas Drilling in Balcombe website. (Regarding the Lower Stumble drill site, 2013.)
This webpage contains a copy of a short text report, presumably a compnay report from Cuadrilla, dealing with testing and, in passing, with some geological matters. Because it is of geological interest and thus is reproduced below. Go to the Gas Drilling in Balcombe website for more details and discussion. Some extracts from the Testing Procedure statement are given below:
Testing Procedure:
"The main aim of the Lower Stumble Exploratory well is to test for natural gas/oil trapped in the thin sandstone layers of the Upper Jurassic Formations which lie directly on the crest of the Bolney (Lower Stumble) Anticline. The company might test the Portland Sandstone if shows of gas are witnessed during the final stages of drilling. This would be a short test known as a drill stem test (or "DST") and is carried out with the drilling rig on site for a short period of up to 2-8 hours. Testing the Portland would take a lesser priority than to test an discovered shale formations and would only be tested if the shald was not present during drilling. If it was decided to test the Portland then a typical DST would follow the example test procedure detailed below and depicted in the test equipment photographs No.s 11 and 12 under Appendix 1.
Testing the shale layers [presumably subdivisions of the Kimmeridge Clay Formation](known as stages) will be the main purpose of the Lower Stumble exploratory drilling operation and will only take place if sufficient gas or oil is encountered in each stage of the drilling operation.
Testing the stage or stages would take between 5 - 12 days and is generally carried out during daylight hours. The Company are expecting to encounter between three and six shale stages and would expect to see sufficient shows in at least three that would warrant testing within the 28 day period. This type of testing, i.e. several stages, is generally carried out in the United States within 14 days. The testing time scale is governed by the amount of stages encountered, rock porosity (pore space in the rock), permeability (ease of movement of natural gas through the pore space), and natural fractures in the formation. Both the porosity and permeabiligy within the Lower Stumble structure are considered to be poor to good, but the natural fractures are expected to be good to very good, i.e. the wells should flow unstimulated. In any event the test would be complete within the usual 28 days requested to test a conventional hydrocarbons discovery, i.e. the period generally requested within a temporary drilling exploration planning application.
There may be a need to stimulate a stage which flows gas/oil but at a low rate to ascertain if the gas was being held back by poor porosity or permeability or lack of natural fracture or a combination of all three. Stimulation is carried out by pumping water under pressure into the natural fractures [joints?] in the shale formations to open them up to allow the gas to flow more freely. In some cases silicone sand is then pumped in to hold open the fractures once the water is removed. The recovered water is retained on site for use on other stages orn removed and disposed of if not needed. Testing of each stage will take up to two 10 hour days including any necessary stimulation. The water and sand will be brought to site by road using water tankers and 20 tonne tipper lorries. The amount of water and sand will depend on the permeability, i.e., the gas flow rate of a stage and with the permeability via fractures expected to be good to very good the stimulation required will be none or small and therefore the number of water and sand deliveries are expected to be few.
Any produced gas during testing will be flared using a screened low volume/pressure ground flare (see appendix C) and is generally carried out during daylight hours."
[end of page 1 of 2. - not continued here]

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Gautier, D.L. 2005. Kimmeridgian Shales Total Petroleum System of the North Sea Graben Province. U.S. Geological Survey Bulletin, 2204-C, 24pp. By Donald L. Gautier. With 8 figures and 1 table, and with reference list. Available online: Kimmeridge Shales, North Sea Graben.
Abstract:
The North Sea Graben of northwestern Europe, World Energy Project Province 4025, is entirely offshore within the territorial waters of Denmark, Germany, the Netherlands, Norway, and the United Kingdom. Extensional tectonics and failed rifting are fundamental to the distribution of oil and gas in the province. Accordingly, the geologic history and reservoir rocks of the province are considered in the context of their temporal relationship to the principal extension and rifting events. The oil and gas accumulations of the province are considered part of a single petroleum system: the Kimmeridgian Shales Total Petroleum System (TPS). Source rocks of the Kimmeridgian Shales TPS were deposited in Late Jurassic to earliest Cretaceous time during the period of intensive extension and rifting. The Kimmeridgian Shales contain typical "type II" mixed kerogen. Oil and gas generation began locally in the North Sea Graben Province by Cretaceous time and has continued in various places ever since.

Reservoirs are found in strata with ages ranging from Devonian to Eocene. Pre-rift reservoirs are found in fault-block structures activated during rifting and can be of any age prior to the Late Jurassic. Syn-rift reservoirs are restricted to strata actually deposited during maximum extension and include rocks of Late Jurassic to earliest Cretaceous age. Post-rift reservoirs formed after rifting and range in age from Early Cretaceous to Eocene. Seals are diverse, depending upon the structural setting and reservoir age. Pre-rift reservoirs commonly have seals formed by fine-grained, post-rift sedimentary sequences that drape the Late Jurassic to earliest Cretaceous structures. Contemporaneous shales such as the Kimmeridge Clay seal many syn-rift reservoirs. Fields with post-rift reservoirs generally require seals in fine-grained Tertiary rocks. In most of the North Sea Graben, source rocks have been continuously buried since deposition. Structural trap formation has also taken place continuously since Mesozoic time. As a result, oil and gas are present in a wide variety of settings within Province 4025.

Assessment units for the World Energy Project were defined geographically in order to capture regional differ-ences in exploration history, geography, and geological evolution. Three geographic areas were assessed. The Viking Graben, in the northern part of the province, includes both United Kingdom and Norwegian territorial areas. The Moray Firth/Witch Ground in the west-central part of the province is entirely in United Kingdom. waters. The Central Graben in the southern part of the province includes territorial areas of Denmark, Germany, the Netherlands, Norway, and the United Kingdom. The North Sea Graben is estimated to contain between 4.3 and 25.6 billion barrels (BBO) of undiscovered, conventionally recoverable oil. Of that total, the Viking Graben is believed to contain 2.2 to 14.8 BBO of undiscov-ered oil, the Moray Firth/Witch Ground may contain between 0.3 and 1.9 BBO, and the Central Graben was estimated to contain undiscovered oil resources of 1.7 to 8.8 BBO. Province 4025 was also estimated to hold between 11.8 and 75 trillion cubic feet (TCF) of undiscovered natural gas. Of this total, 6.8 to 44.5 TCF is thought to exist in the Viking Graben, 0.6 to 3.4 TCF is estimated to be in the Moray Firth/Witch Ground, and 4.5 to 27.1 TCF of undiscovered gas is estimated to be in the Central Graben.



Geertsma, J. 1973. Land Subsidence Above Compacting Oil and Gas Reservoirs. Society of Petroleum Engineers. Journal of Petroleum Technology, vol. 2, No.6, pp. 734-744. Date June 1973.
Preview
Notable subsidence above producing oil and gas fields is the exception rather than the rule. A simple procedure is outlined to single out the exceptional but real problem areas. This exercise in potential-problem analysis shows that the huge Groningen gas field in The Netherlands is a candidate for causing subsidence troubles in a lowland area.
Introduction.
During the last 20 years, the Royal Dutch/Shell Group has conducted extensive investigations into the phenomenon of reservoir compaction and subsidence. These have included research projects to study subsidence above Bolivar Coast oil reservoirs in Venezuela and to examine the huge Groningen gas reservoir in The Netherlands. The latter investigation was conducted by a team of specialists from both the Koninklijke/Shell Exploratie en Produktie Laboratorium (KSEPL) and BV Nederlandse Aardolie Maatschappij (NAM), the latter being the producing company owned jointly by Shell and Esso. Details of the Groningen investigation are published elsewhere but as it may have consequences for other operating companies working in lowland and other subsidence-prone areas, we shall consider here the causes of subsidence above hydrocarbon-producing reservoirs in a more general way, and review the state of the art of its prediction. A simple method will be presented for estimating the order of magnitude of both compaction and the accompanying subsidence. Application of this method, which can be used to explore the need for an investigation in depth, requires hardly any specialist knowledge. The objective is twofold: to demonstrate that land subsidence due to hydrocarbon production seldom leads to serious subsidence, and production seldom leads to serious subsidence, and to pinpoint the few potential problem areas.
Earlier Field Observations.
The literature on subsidence deals mainly with a few notable examples, such as the Goose Creek oil and gas field in Harris County, Tex., where dramatic subsidence occurred between 1918 and 1925, and the Wilmington field below Long Beach, Calif., where almost 10 m of subsidence was experienced in 1960. Further subsidence could be avoided in this latter case after unitization and pressure maintenance as a result of water injection. More recently, a search for additional, documented surface depressions over oil and gas fields in the U. S. was reported by Yerkes and Castle. This search revealed only a few other significant cases, mainly fields close to Wilmington, such as those at Buena Vista, Huntington Beach, and Inglewood. From this concentration of subsidence bowls, it may be inferred that such events are somehow related to a similarity in reservoir conditions. Shell has been confronted only once with a major land-subsidence problem. It is related to the production of oil and gas in Venezuela, where subsidence above a number of important oil reservoirs bordering Lake Maracaibo is a constant phenomenon, and huge dykes have been built to protect the coastal area from flooding. Its cause is discussed by Van der Knaap and Van der Vlis. Subsidence data for oil and gas fields outside the Americas are very scarce indeed. Okumara and Hirono describe a case from the Niigata district of Japan that results from the production of methane dissolved in water. In Italy, AGIP has been accused of contributing to subsidence in the Po Delta by producing from a number of gas fields.


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Gibbs , A.D. 1987. Basin Development. Examples from the U.K. and comments on the hydrocarbon prospectivity. Tectonophysics, vol. 73, pp. 189-198.
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Giffard , H.P.W. 1923. The recent search for oil in Great Britain. Transactions of the Institution of Mining and Metallurgy, vol. 55, p. 221.
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Gent, Harris and Andrews. In Andrews 2014. Jurassic Shales of the Weald Basin. Geology and Shale Oil and Shale Resource Estimation. Main Appendices are separate. Available online as a pdf file. Go to Andrews, 2014, above, in this reference list
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Gluyas , J. G. and Hichens, H.M. (eds.) 2003. United Kingdom Oil and Gas Fields. Commemorative Millenium Volume, Geological Society of London, Memoir 20.

Gluyas, J.G., Evans, I.J. and Richards, D. 2003. The Kimmeridge Bay Oilfield, Dorset, UK Onshore. Pp. 943-948 in: Gluyas, J. G. and Hichens, H.M. (eds.) 2003. United Kingdom Oil and Gas Fields. Commemorative Millenium Volume, Geological Society of London, Memoir 20.
Abstract: The Kimmeridge Oilfield is the oldest commercial discovery of petroleum in the Wessex Basin. The field was discovered in 1959. The discovery well was completed for production and that same well continues to produce today, more than forty years after discovery. More than three million barrels of oil have been produced. Oil is trapped in fractured, Middle Jurassic, Cornbrash limestones in an anticline. The anticline is a product of Alpine inversion tectonics. Moreover the Kimmeridge accumulation is unusual insofar as it is the only inversion structure to contain a commercial quantity of petroleum and the only producing field in the hanging wall of the Purbeck Disturbance.
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Goode, T.W. 2013. Razorback PEDL 239. Student Exercise for Petroleum Geology Course at Southampton University [not to be taken literally, but a very good short, concise, student project, with some valid points and some good figures - but with some reliance on Wessex Exploration reports on Razorback PEDL [a real prospect of Wessex Petroleum] as a basis. See these.]. Evaluation of Chessel - 1 and potential investment in the Razorback prospect [Isle of Wight - hypothetic borehole etc]. S.T.A.G. Exploration [hypothetical]. By Thomas Goode, 18th January 2013.
[pseudowell 1 is situated NE of Mottistone Manor and pseudowell 2 is situated NE of Brighstone in licence block PEDL 239 and both are hypothetical. They are southeast of the real Chessel - 1 Well.]
Example extract:
"Jurassic Lower Lias source rock:
335m thick, TOC approx 3.4%, predominantly Type II/III kerogen.
Entered oil window at 100 Ma, during burial within the Wessex - Channel Basin (WCB)[i.e the Portland-Wight Basin] to depths of 2,000 to 2,500m.
Total hydrocarbon potential: 34.4 mmbls/km2.
Regional WCB (170.4km2) hydrocarbon potential: 5862 mmbls [ p.5 - "however, due to the relatively small timescale of hydrocarbon generation (Fig.3), on a percentage of the potential would have been reached"]."
continues.

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Gray, L. 2013. The town where 'fracking' [hydraulic fracturing] is already happening.[re Wytch Farm Oil Field and Perenco, UK]
The Daily Telegraph, Article of 10th August 2013. Available online, Wednesday 11th September 2013. By Louise Gray, Environment Correspondent.
Go to: The town where 'fracking' is already happening. [Some extracts only, follow; see the full article.]
"Fracking might be causing mass protests in Middle England, but for the community living around one of the hundreds of wells already "fracked" in the UK, the locals hardly seem to notice. Wytch Farm in Dorset is in the heart of an Area of Outstanding Natural Beauty. But you would be forgiven for not knowing the largest oilfield in western Europe is even there. Nestled in a pine forest near a nature reserve and on islands off Poole Harbour, the oilfield owned by French company Perenco has been quietly producing thousands of barrels a day since the late 1970s.
At one point the oilfield had the longest horizontal drill in the world and has regularly pumped water into wells to "fracture" the rock and force out oil and gas. Academics say that this so-called "fracking" has been used on 200 wells across the UK over the last 20 years or so.
Now the controversial technology is making headlines around the world. In Balcombe, West Sussex, locals have staged weeks of protests, ending in more than 30 arrests. In contrast, the local community around Wytch Farm are unaware the technology is being used and appear relaxed about the "discreet" operations happening in the heart of their community....
In Wareham, which is a few miles from Wytch Farm, the concern seems to be more about a proposed wind farm in East Stoke and a massive offshore development off the Jurassic Coast. Even Frack Free Dorset admit that Wytch Farm has not caused environmental problems so far. But they insist that the long term risk from fracking is a serious concern as drilling for oil and gas in the area massively expands and more "shale gas" is discovered.
Peter Style, Professor in Applied and Environmental Geophysics at Keele University, said that fracking first happened in the UK in Lincolnshire in 1988. He said fracking was mostly used in the UK to get the last out of old oil and gas wells. "It is not a new technology, we have had 200 wells fracked in England and no one has even noticed."'.......
Perenco refused to give details of fracking at Wytch Farm but admitted that hydraulic fracturing happened at the oilfield after it was highlighted in a Royal Society report. "Well stimulation techniques, and produced water and seawater injection have been used at Wytch Farm for many years, said a spokesman...
Richard Davies, Professor of Energy at Durham University, agreed fracking has been going on in the UK for decades. He said the risk is fracking for shale gas.
"The oil industry is correct in saying they have been fracking for some time. What is new is the widespread deployment and possible fracking for shale gas." Prof Davies explained that unlike fracking for conventional oil and gas, fracking for shale gas requires multiple wells and has only happened in Lancashire so far, where it caused a small earthquake.... [continues]


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Green , B. 1886. Kimmeridge Shale: its Origin, History and Uses. London. Hatchett, C. Observations on bituminous substances, with a description of the varieties of elastic bitumen. Transactions of the Linnaean Society, vol. 4, p. 129.

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Groundsure Energy. 2015. Groundsure Location Intelligence. [for the UK] This is the website of a commercial firm, who for a fee (25 pounds?) provide information on fracking sites, conventional oil well sites etc within 25km. of a specific location. [Go to: https://www.groundsure.com/wp-content/uploads/2015/10/Groundsure-Energy-Commercial.pdf - for a pdf explanatory account. ]
This database shows all existing and historic licensed oil, gas, shale gas and coalbed methane extraction sites, and is supplied by the Department of Energy and Climate Change. The exact type of extraction site is shown in the 'Type' field in the data table above. It shows all wells which hold, or have formerly held, a UK Petroleum Exploration and Development License (PEDL) or its historical equivalent. These wells may have been licensed in any one of the 14 licensing rounds which have been undertaken by the Department of Energy and Climate Change (DECC) or any of its predecessors. The data within this section of the report shows wells which were licensed as far back as 1910. This dataset is obtained from DECC and Groundsure will endeavour to update this on a monthly basis. The presence of a well in this database does not mean that any active exploration or production is occurring, and homebuyers may wish to check whether the well is noted to have a 'completed by' date within the data, which would indicate that no further activity is likely to take place at the site.

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Hamblin , R.J.O., Crosby, A., Balson, P.S., Jones, S.M., Chadwick, R.A., Penn, I.E. and Arthur, M.J. 1992. The Geology of the English Channel. British Geological Survey, United Kingdom Offshore Regional Report, London, H.M.S.O., 106 pp.
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Hancock , F.R.P. and Mithern, D.P. 1987. The geology of the Humbly Grove Oilfield, Hampshire, UK. In: Brooks, J. and Glennie, K. (eds), Petroleum Geology of North West Europe, Graham and Trotman, London, 161-170.


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Harvey, F. 2014. Cuadrilla scraps plan to frack at Balcombe site. The Guardian [newspaper and online], theguardian.com, Thursday 23 January 2014. By Fiona Harvey, Environment Correspondent.
"Natural fractures in shale rock rules out need for hydraulic fracking, company says. Cuadrilla is to scrap plans to use controversial fracking technology near the village of Balcombe in Sussex – but only because the rocks at its site already contain natural fractures...
... the company ... released a statement saying that it was applying for an extension to its planning permission for an exploratory well, but added: "The analysis of the samples we obtained from the exploration well confirmed that the target rock underneath Lower Stumble is naturally fractured. The presence of these natural fractures and the nature of the rock means that we do not intend to hydraulically fracture the exploration well at Lower Stumble now or in the future."
Cuadrilla's statement said: "In 2013, Cuadrilla drilled a conventional exploration well at the Lower Stumble site, drilling horizontally for some 1,700 feet through the Micrite formation (a type of limestone) at a depth of approximately 2,350 feet below ground level. The company was expecting to and did indeed find oil in the Micrite. However, without flow testing Cuadrilla cannot be sure at what rate the oil may flow to the surface. The new application to flow test includes revised planning boundary lines showing the extent of the horizontal well being tested, and will effectively cover the same well testing work scope that was permitted activity in Cuadrilla's previous planning permission. These proposed flow testing operations are significantly smaller in scope than drilling operations. The main testing operations would last some three to five weeks after which the well would be closed in and monitored for up to 60 days."

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Hardman, R. F. P. 1982. Chalk reservoirs of the North Sea. Bulletin of the Geological Society of Denmark, vol. 30, pp. 119-137, Copenhagen, September 1st, 1982.
In the North Sea, chalk became a reservoir for oil and gas by a combination of fortunate circumstances. Shortly after burial chalk in general has a high porosity, but a low permeability. It is a micropore reservoir. For fluids to enter the pore space, pressure is necessary. North Sea Chalk hydrocarbon fields are all located over thick areas of Kimmeridge and Oxford Clay source rocks on structures which grew during the Tertiary. Structural growth caused fracturing allowing hydrocarbons, which were generated from as early as Oligocene times onwards, to build up in the fracture systems within structural closures in the Chalk. In this way hydrocarbons were able, by their buoyancy or by the pressure generated from the shales below, to enter chalk reservoirs. In areas where Paleocene sands are present, a closed pressure system was not present and no saturation of the Chalk was possible. Chalk is composed of the debris of coccolithophorids, which being composed of low magnesian calcite is of great chemical stability. Although early diagenetic effects such as compaction by dewatering and loss of aragonite are recognised, burial diagenesis does not start until approximately 1000 m below surface. In the case of North Sea Chalk reservoirs, diagenesis, which will normally reduce porosity from approximately 50% at the sea bed to 10% at between 3000 and 4000 m burial depth, is arrested by three factors; the pressure generated, as mentioned above, which partially or wholly supports the overburden, thus reducing or preventing pressure solution; oil or gas in the pore space, which, as a chemically inert fluid also largely prevents pressure solution; magnesium ions, present in sea water and in greater concentrations in the pore-waters of up-domed beds overlying Zechstein evaporites, which poison sites of nucleation of calcite retarding diagenesis. As a result all Chalk fields show anomalously high values of porosity. Valhall Field for instance has values of 50% porosity at a depth of 2500m. Chalk reservoir quality is controlled by a variety of factors, but four factors predominate; the purity in terms of calcium carbonate of the sediment; the rate of deposition of the Chalk which in turn determines the degree of early frame-work cement; the tectonic setting of the field area during Chalk deposition; and the size distribution of the coccoliths being deposited. To these four factors nearly all reservoir quality variation can be related. The best Chalk reservoir in the North Sea is undoubtedly the Tor Formation because of its purity, but the Lower Hod Formation and, in places where allochtonous sheets of Tor Formation have slid in during its deposition, the Ekofisk Formation, can act as very satisfactory North Sea Chalk reservoirs.

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BBC
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Harrabin, R. [Roger Harrabin, BBC Environment Analyst]. FRACKING: Shale rock professor says UK gas reserves 'hyped'.
1.1 INTRODUCTION - AN OVERVIEW FROM PROFESSOR UNDERHILL, AUGUST 2017 - REPORTED IN BBC NEWS (BY ROGER HARRABIN)
Reference: Harrabin, R. 2017. BBC NEWS ARTICLE - Business section. Available online:
Fracking: Shale rock professor says UK gas reserves 'hyped'.
[This is a statement from the top expert on the Petroleum Geology of south and southeastern England. See his various research papers and for much useful background information read the book he contributed to and edited some years back):
Underhill, J.R. 1998. Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, Special Publication, No. 133. 420pp.

The BBC Article by Roger Harrabin, 2017 (17th August).
[just some brief extracts - see the full article]

Fracking: Shale Rock Professor says UK Gas Reserves 'Hyped'

"The gas reserves in shale rock in the UK have been "hyped", a geology professor has warned. Professor John Underhill from Herriot-Watt Universit said UK shale deposits were formed 55 million years too late to trap substantial amounts of gas."
[presumably this is a reference to Upper Jurassic, Kimmeridge Clay oil shale and it really means - actually too late, not like the Lower Jurassic and not sufficiently deeply buried to produce by burial heat substantial amounts of gas. The general implication here is obvious. Not discussed here and not likely at present is pyrolysis - which means setting the oil shale on fire - there is work in China on this method, but it is very unlikely to be used in the UK].

"He said the government would be wise to formulate a Plan B to fracking for future gas supplies."

"But the fracking firm Cuadrilla said it would determine how much gas was present from its test drilling" [there have already been numerous boreholes through the Kimmeridge Clay in the Weald!]

"Hydraulic fracturing, or fracking, is a technique designed to recover gas and oil from oil shale, a sedimentary rock found worldwide. The amount of shale gas available in the UK is acknowledged to be a great unknown. Cuadrilla said estimates from the British Geological Survey (BGS) indicated a large potential gas reserve.
Reference, below, to a British Geological Survey Statement of Andrews, I.J. 2014 The Jurassic shales of the Weald Basin: geology and shale oil and shale gas resource. British Geological Survey (this is the main report, but there is also a large Appendix.)

p.54. "This study concludes that there is no significant Jurassic shale gas potential in the Weald Basin. Even the deepest Lias shales are unlikely to have attained sufficient maturity to allow for significant gas generation. However, gas is encountered in many wells in the basin and there are several significant gas fields, some not associated with oil ----"

(go to the original for further discussion on possible sources of gas in the Weald - yes, there is gas in the Weald but it may not necessarily be directly associated with Jurassic oil shale; the gas might even be of Carboniferous origin; there is a gas question. BGS did not conclude that the gas had come from the oil shales.).
[this topic warrants further study but will left here until the full report of John Underhill is available.]

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Harvey, M.J. and Stewart, A.S.A. 1998. Influence of salt on the structural evolution of the Channel Basin. In Underhill, J.R. (editor). Development and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publications, No. 133, pp. 241-266. By Michael J. Harvey and Simon A. Stewart. Michael J. Harvey [originally from Imperial College, London] subsequently at Nederlandse Aardolie Maatschpppij, 9400HH Assen, The Netherlands. Simon A. Stewart at Amerada Hess Ltd., 33 Grosvenor Place, London, SW1X 7HY, UK.
Abstract:
The north margin of the Channel Basin is defined in Dorset and the Isle of Wight by Mesozoic extensional faults which were reversed during Tertiary contraction, causing forced folding of the Albian-Oligocene post-rift cover. The resulting contractional structures (the Purbeck and Isle of Wight Monoclines and the reversed Abbotsbury - Ridgeway Fault) have previously been used as type examples of inversion tectonics. The Jurassic-Cretaceous basin margin crosses the eastern edge of a Triassic salt basin (Dorset Halite, Upper Triassic Mercia Mudstone Group) near Swanage. Detachments in Triassic salt around Weymouth resulted in extension and inversion styles which differ from the better known basement-linked structures to the east. The Abbotsbury-Ridgeway Fault is listric and unlike the Tertiary hangingwall folds to the east the Weymouth Anticline formed as an extensional rollover, onlty tightened during inversion.
Seismic and well data and structure maps are used to illustrate for the first time the increasing effects of salt on structural style as the fault thickens westwards. The onset of detachment on the basin margin is placed at Ringstead, where a north-stepping shift in the margin at pre-salt levels defines a relay zone. Here extension was accomodated on many basement faults and the ratio of basement fault diplacement to salt thickness was reduced sufficiently to allow the post-salt section to detach through extension (Abbotsbury - Ridgeway Fault). Tight Tertiary compressional folds in this area may result from linkage of the pre- and post-salt sections during inversion, a consequence of salt welds developed during the last stages of extension.
In the western part of the Channel Basin (Lyme Bay) the Triassic salt is sufficiently thick to ave detached the pre- and post-salt sections over a wide area. North-south shortening during basin inversion may been accomodated in the Lyme Bay post-salt section by displacements on conjugate, northwest-southeast- and northeast-southwest orientated, strike-slip faults such as the Mangerton Fault. The Dorset Halite [Dorset Salt] is complex sequence of halite and mudstone interbeds, different from the 'pure' halites seen in the North Sea Basin, and its influence on structural styles differs accordingly. Variation in salt tectonics style between the Weymouth area (salt swells and rollers) and Lyme Bay (salt rollers only) may reflect lateral facies variation and hence rheology in the Dorset Halite Formation.
[See Fig. 3 showing more than 300m. of salt in the Trias at the Southard Quarry Borehole of BP, near Durlston Head, Swanage. A new borehole has been proposed at the nearby Californian Quarry Borehole, near Durlston Head, Swanage, Dorset, but this has not been drilled yet, by November 2016.]

Harvey, T. and Gray, J. 2010. The hydrocarbon prospectivity of Britain onshore basins. Promote UK, 2011, pp. 1-17.
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Hawkes , P.W., Fraser, A.J. and Einchcomb, C.C.G. 1998. The tectonostratigraphic development and exploration history of the Weald and Wessex Basins, southern England. In: Underhill, J.R. (ed.), The Development, Evolution and Petroleum Geology of the Wessex Basin, Geological Society, London, Special Publication 133, [hardbound book], pp. 39-65. By P.W. Hawkes of Enterprise Oil, Trafalgar Square, London and A.J. Fraser of BP Exploration Inc., Houston, and C.C.G. Einchcomb of BP Exploration, Chertsey Road, Sunbury on Thames, Middlesex, England. [an important paper]
Abstract: Exploration drilling for hydrocarbons in southern England commenced over 50 years ago prompted by numerous seepages along the Dorset coast and gas shows in water boreholes. The two main depocentres, the Weald and Wessex basins, exhibit many similarities in both tectonic and stratigraphic evolution through Early Triassic - Tertiary times, reflecting the regional influences of Atlantic Margin rift-subsidence processes and subsequent Tertiary (Alpine) inversion tectonics. Given these similarities, the development of the hydrocarbon play system in both these areas can be compared using a common tectono-stratigraphic framework which has been identified and calibrated using well and seismic data. In detail, facies variability recognised within individual depositional units highlight differences in both source and reservoir distribution between the Weald and Wessex areas, which have in turn exerted fundamental controls on the hydrocarbon prospectivity of the two basins. These differences are influenced by the position of major basin-bounding fault systems and by the changing importance of the Cornubian-Armorican and the London-Brabant Massifs as clastic provenance areas through time. Sequence isopachs illustrate the same discrete episodes of rift-related subsidence in both areas. These rifting episodes led to the development of extensional trapping geometries particularly during Late Jurassic - Early Cretaceous times. Subsequent Late Cretaceous thermal subsidence led to the formation of mature source kitchen areas focussed within the hanging walls of the earlier extensional faults. Hydrocarbon expulsion from the source kitchen areas ceased during Tertiary uplift and subsequent cooling. Inversion movements on the old extensional faults led to the development of hanging wall anticlines which rely upon remigration mechanisms, including the exsolution of gas from uplifted Liassic source rocks, to receive hydrocarbon charge. To date [1998] over 300 million barrels of oil and 100 billion cubic feet of gas have been discovered.
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Heasley , E.C.; Worden, R.H. and Hendry, J.P. 2000. Cement distribution in a carbonate reservoir; recognition of a palaeo oil-water contact and its relationship to reservoir quality in the Humbly Grove Field, onshore, UK. Marine and Petroleum Geology, 17, 639-654.
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Hesselbo, S. 1998. Basal Wealden of Mupe Bay; a new model. In Underhill, J.R. (editor), Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London. Special Publications, 133, pp. 349-353. By Stephen P. Hesselbo, address at that date: Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR.
Abstract: Angular stratal relationships associated with the Mupe Bay [east of Lulworth Cove] palaeo-oilseep in the Lower Cretaceous Wealden Group of South Dorset have previously been viewed as evidence of angular unconformity. An alternative (preferred) interpretation is that the succession represents rotational channel bank collapse at the margin of a large Early Cretaceous fluvial channel. The new interpretation explains observed bedding-plane orientations and palaeocurrent directions.

Hesselbo , S.P. and Allen, P.A. 1991. Major erosion surfaces in the basal Wealden Beds, Lower Cretaceous, South Dorset. Journal of the Geological Society of London, 148, 105-113.
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Hinde , P. 1980. The development of the Wytch Farm oilfield. Communication 1133, Inst. Gas Engineers, London ., 11-33.
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Hinchcliffe , J.C. 1978. Death stalks the secret coast. [Natural gas seep at Durlston Head, near Anvil Point, Swanage, see also related InfraStrata Borehole plans ] Triton , Vol. 23, no. 2, Feb. 78, p. 56-57. By the diver - John C. Hinchcliffe. Triton Magazine was published by Ecton Publications, 55 High Street, Teddington, TW11 8HA. [about the offshore methane gas seep at Durlston Head, near Anvil Point] "On the seabed directly beneath Durlston Castle, above whose cliffs is poised the giant stone globe of the world, a further curious phenomenon is found. Here the seabed is bubbling. in 10 metres of water, long columns of bubbles ascend. Some sources are continuous, some spasmodic. I recently collected a sample of this gas and it proved to be an inflammable natural gas. An even more curious phenomenon here is the large numbers of huge bass and pollock which tend to swim about near these bubbles. Do they mistake the hydrocarbon gas for oxygen?

Mike Markey, a diving enthusiast, drew my attention to this article. He reported (7th Dec. 1990) that the gas seep was still bubbling at that time. He had also found a similar gas seep on the Lulworth Banks (near the axis of the anticline, which has been drilled).

[See also Judd, A.G. 2004. Natural seabed gas seeps as sources of atmospheric methane. Environmental Geology, vol. 46, No. 8, November, 2004. "Gas bubbles lose methane to the water as they rise, so deep water seeps are unlikely to contribute to the atmosphere. However, bubbles break the surface above some shallow water seeps."]
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Hogg , A.J.C., Evans, I.J., Harrison, P.F., Meling, T., Smith, G.S., Thompson, S.D. and Watts, G.F.T. 1999. Reservoir management of the Wytch Farm oil field, Dorset, UK; providing options for growth into later field life. In: Fleet, A.J., Boldy, S.A.R. (eds). Petroleum geology of Northwest Europe; proceedings of the 5th conference. The Geological Society of London, 1157-1172.
Abstract:
The Wytch Farm Oil Field, currently on plateau [note - on plateau in 1999, but later in 2010 with much lower production and much more water-cut - see Wahidiyat (2010)], produces up to 110 times 103 BOPD, 17.6 to, es 106 SCF gas and 725 tonnes LPG per day. Original reserves are 450 times 106 BBL with a proven 230 times 106 BBL oil equivalent remaining. The Triassic fluvio-lacustrine Sherwood Sandstone, at 1535m TVDSS (true vertical depth, subsea), is the largest and most prolific reservoir. Approximately half the reserves are in an offshore extension being developed by extended reach drilling (ERD) at step-outs of up to 10.1 km from onshore Poole Harbour. Projects to increase reserves, extend plateau and slow decline include: additional ERD wells; infill drilling; miscible gas injection; and pattern water flooding of the low nett-to-gross Upper Sherwood all whilst maintaining reservoir pressure.
Reservoir description is central to realizing these opportunities for growth. Structural uncertainty has been reduced through acquisition of the first transition-zone 3D seismic survey in the UK. An extensive RFT (repeat formation test) and production log database has been acquired in the onshore and ERD wells. These dynamic data, together with static data from core and outcrop studies, and >21km of ERD formation evaluation logs, are used to develop a high-resolution, fluvio-lacustrine sequence architecture of the Sherwood. The deterministic model enhances predictability of flow barriers, baffles and high permeability intervals. This understanding of fluid flow and recovery provides the framework for economic evaluation, which, with clear communication of uncertainty across disciplines, is the key to successful management of the reservoir into later field life.

Hogg, A.J.C, Mitchell, A.W. and Young, S.1996. Predicting well productivity from grain-size analysis and logging while drilling. BP Exploration Operating Co Ltd, Blackhill Rd, Holton Heath, Poole BH16 7lS, Dorset, England. BP Exploration Operating Co Ltd, Sunbury TW16 7lN, Middx, England. Petroleum Geoscience, 2, No. 1, 1-15.

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Holloway , S., Milodowski, A.E., Strong, G.E. and Warrington, G. 1989. The Sherwood Sandstone Group (Triassic) of the Wessex Basin, southern England. Proceedings of the Geologists Association, 100, 383-394. Data from released wells indicate that the subdivision of the Sherwood Sandstone Group into the Budleigh Salterton Pebble Beds and the Otter Sandstone Formation is equally applicable in both the outcrop and subcrop of the Group in the Wessex Basin. The Sherwood Sandstone Group was deposited largely from braided streams but an inland sabkha may have occupied the depocentre during deposition of the lower parts of the Otter Sandstone Formation. The Budleigh Salterton Pebble Beds may have been removed from parts of the Wessex Basin by erosion prior to deposition of the Otter Sandstone Formation. [See also Morton, A., Knox. R. and Frei, D. 2016, Heavy mineral and zircon age constraints on provenence of the Sherwood Sandstone Group (Triassic) in the eastern Wessex Basin, UK. Proceedings of the Geologists' Association, vol. 127, pp. 515-516.
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Hopton , R. 1711. An account of an eruption of a burning spring at Brosely, Shropshire. Philosophical Transactions. [Not seen, given as a reference in BERR 2008. "One gas seep near Broseley was an early tourist attraction (Hopton, 1711) and, when it ceased, exploration was conducted again, eventually proving successful (Mason, 1747)" (BERR, 2008, Cheshire Basin Chapter)][relevant to the Durlston Head gas seep?]
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House , M.R. 1989. Geology of the Dorset Coast. Geologists' Association Guide, 169pp, 39 text-figs and 34 monochrome plates. September 1989. Paper-back. ISBN 0 7073 0485 7.

House, M.R. 1993. Geology of the Dorset Coast. Geologists' Association Guide No. 22. 2nd edition, 164pp., 43 text-figs (mostly cliff diagrams and maps) and 32 plates, some in colour. Paper-back. ISBN 0 7073 0485 7. Extract from Preface: "This guide aims to provide a general introduction to what may may be seen and where. Emphasis is placed on the localities and the precise discrimination of the stratigraphic successions. It is hoped that in this way new observations can be better integrated with earlier work and thus form a more scientific basis for individual study, thought and interpretation and argument. Most emphasis is placed on the Jurassic rocks because these are such an international standard. Rather less detail is given on the Cretaceous and Tertiary rocks because these rocks are as well or better seen elsewhere, and the Dorset Chalk cliffs, being mostly vertical, are also dangerous. In any case, with such a wealth of geology to describe, some selection has been essential. The introductory sections on Sedimentology and Palaeontology have been added by request to introduce specialist terms to the general reader. "
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Hunsdale , R. 1996. The application of geological techniques in fault investigation and characterisation: examples from southern England. University of Southampton Faculty of Science Geology, Ph.D Thesis, 171pp. and Appendix.

Hunsdale, R. and Sanderson, D.J. 1998. Fault size distribution analysis - an example from Kimmeridge Bay, Dorset, U.K. In Underhill, J.R. (editor), Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publication, No. 133, pp. 299-310. By R. Hunsdale, formerly University of Southampton, since at Phillips Petroleum, Norway, and Professor D.J. Sanderson, Southampton University.
Abstract: Fault displacement data wer measured over four orders of magnitude for a fault set cross-cutting Upper Jurassic rocks exposed along the Dorset coast [southern England]. Fault data were subdivided into three data-sets, based on data source and field character. Distribution analysis showed that these faults conform to a power law. The scaling relationship is, however, not constant over the entire displacement range of the faults. Faults with displacements greater than 2 metres are characterised by a negative power law, having an exponent of approximately 0.96, while faults with displacement of less than 1 metre are related by a negative exponent of approximately 0.7. The change of scale is interpreted as being a product of the influence of lithological heterogeneity on fracture initiation amd growth. [with 7 figures and 1 table].
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Hunt, J. 2016. Unusual aircraft over the Isle of Wight. By Joanna Hunt. Isle of Wight County Press Online. Wednesday, September 14, 2016.
Unusual planes have been spotted flying over the Isle of Wight this afternoon (Wednesday). The two Boeing 727 jets have been flying over the Needles and Tennyson Down as part of an exercise to deal with potential oil spills. Oil Spill Response (OSRL) said the crew was practising dealing with an oil spill on the other side of the world. Southampton-based OSRL stressed that it was only an exercise and the aircraft were spraying water to simulate a response to a real incident.
[Added note. The major, thermally mature, oilfield of the English Channel, the Jurassic source of the oil of Wytch Farm, is located directly south of the Needles and Tennyson Down, and in late 2015 the southern Isle of Wight was licenced for oil exploration. The oil importance of the area to the south may be just a coincidence. An offshore oil leak there is probably unlikely anyway, since the oil shale could probably be easily accessed by lateral drilling from the on-land, southwest coast of the Isle of Wight, (i.e. like Wytch Farm in reverse). An oil spill there is not expected and very unlikely, although the possibility in the future is not zero, of course. An oil spill from shipping is more likely. Incidently, bitumen has been washed up in such quantities on Hurst Spit directly to the north of the Needle area, that a bitumen factory, producing floor tiles once existed on the spit. The bitumen occurrence has not been explained, nor observed recently.]

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Hurren, C. and Hancock, I. 2009. Humbly Grove Gas Storage. London Evening Lecture at the Geological Society, Burlington House, London. Tuesday 14th April 2009. By the Petroleum Exploration Society of Great Britain, PSGB, sponsored by Star Energy. The event is over, but the summary is published online by PSGB. It occupies two pages of printed small text. It is available from the Petroleum Exploration Society webpage: http://pesgb.org.uk/events-39/....
Some small, shortened extracts only are given here; see the full account.
The Humbly Grove reservoir was discovered in 1980. It is located in rural Hampshire, 5km from Alton. The field consists of two reservoirs, the Great Oolite and the Rhaetic, both containing saturated oil with overlying gas caps. The field was put on stream in 1984. By end 1995, field cumulative production was 6.0 MMstb of oil and 11.5 bcf of gas. At that time four horizontal wells were drilled into the Oolite reservoir gas cap and plant was installed to allow the the field to be used for gas storage. Oil production from downdip wells continued, at enhanced rates due to increased reservoir pressure. Subsequently two further horizontal wells were drilled into the Rhaetic for gas storage use. The field is currently operating as a gas store with 10 bcf working gas capacity and continuing oil production. Peak gas injection rate is 300 MMscf/d and peak production rate is 260 MMscf/d.
[Sections on Regional Geology and Present Day Structure of Humbly Grove are omitted here]
[continues on p.2]
Great Oolite Formation
Transgressive cycles in the Bathonian led to the development of a carbonate ramp and deposition of the Great Oolite Group, which forms the main reservoir in Humbley Grove. This accumulation is approximately 200ft thick and is characterised by cross-bedded oolitic limestone that can be divided into three main zones. The lowest (Humbly Grove Member) and the highest (Herriard Member) both commence with massive oolite deposition and pass upward into interbedded lithologies. The middle member (Hoddington Member) is a thin wackestone, which can act as a vertical permeability barrier.
Average porosity is in the region of 15 percent, with the main control on distribution being the result of complex diagenetic processes. Permeability ranges from less than 1 millidarcy to more than 1000 millidarcys with a pronounced bimodal distribution. Petrographic studies indicate an increase in porosity filling burial cements below -3393ft TVDSS [true vertical depth minus the elevation above mean sea level] across the field regardless of structure. Primary intergranular porosity characterises the porosity system in the high permeability zone [actually higher] (above -3393ft TVDSS), whereas intergranular microporosity and residual intergranular porosity occur in the low permeability zone [actually lower] (below - 3393ft TVDSS). This permeability interface is he result of early hydrocarbon emplacement, restricting the precipitation of carbonate cement by the palaeo-aquifer. Average permeability in the up zone is between 10 - 100 md, compared to 0.1 to 1 md in the lower zone. On average permeability decreases by two orders of magnitude below -3393ft TVDSS whereas the average porosity only decreases by 1.3 percent. Natural fracture have been recognised both in core and image logs, and are thought to significantly contribute to the performance of the reservoir.
[continues]
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Hurst , A. and Colter, V.S. 1998. A history of events in the exploration for the Wytch Farm oilfield, southern England. Petroleum Geoscience, 4, 377-379.

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Ickes , E.L. 1923. Recent exploration for petroleum in the United Kingdom. Transactions of the American Institution of Mining and Mechanical Engineering, 70, 10-53 .
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Illing , L.V. 1937. In discussion of the paper by: Lees, G.M. and Cox, P.T. 1937. The geological basis for the search for oil in Great Britain by the D'Arcy Exploration Co. Ltd. Quarterly Journal of the Geological Society, London, 93, 156-190.

Illing , L.V. and Hobson, D.G. 1981. The Petroleum Geology of the Continental Shelf of North-west Europe. Institute of Petroleum, Heyden, London, 52l pp.

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INFRASTRATA. 2012. (re Portland Gas Storage). Portland Gas, Project Description [http://www.portland-gas.com/].
Extracts from document:
"The UK needs to store gas. We have to maintain the supply to homes and businesses, and to keep gas prices down. The unique geology of South Dorset offers a chance to do this safetly, efficiently and unobtrusively. Portland Gas has been granted permission for a gas storage facility to be sited at Upper Osprey, Portland Port in Dorset. This is a brownfield site, formerly part of the HMS Osprey Royal Navy base. The storage facility will be linked to the UK's National Grid by a privately constructed underground pipeline. .. [continues]
At a depth of 2,400 metres (one and a half miles) under Portland there is a very thick layer of Triassic rock salt, 220 million years old. This salt can be dissolved safely and quickly using seawater to create secure impermable storage caverns. Portland Gas plans to create 14 of these caverns, which will provide safe storage for 1,000 million cubic metres (35 billion cubic feet) of gas, equivalent to 1% of our total annual demand - a big contribution to Britain's energy security. The caverns will be operated under a constant pressure with gas in the caverns being replaced by brine (saltwater) when it is withdrawn. The brine will be stored east of Dorchester, at Stafford Farm within a deep sandstone saltwater aquifer. Natural gas will be piped from the National Grid at Mappowder (18km. north of Dorchester) via a specially constructed 37 kilometre underground steel pipeline, 36 inches in diameter. A plastic brine pipeline, 30 inches in diameter will be laid will be laid within the trench for southerly section of the route to transport the brine to and from the brine storage site. There will be a nine-kilometre section across Weymouth Bay and the remainder of the pipeline route will be trenched below farmland. ....[continues]
... The pipeline itself will be constructed and the land restored within six months. It will be drilled deep under particularly sensitive sections, such as the cliffs on the northern shore of Weymouth Bay, leaving the UNESCO World Heritage coastline untouched.... [continues]
The brine (salt) solution created by dissolving the caverns will be piped out to sea where the strong currents will disperse it rapidly withing a very short distance from the outfall... [continues]

Further Information - 30th April 2012.
Go to:
ICIS website: UK Infrastrata set to scale down planned Portland natural gas storage site.

UK-based Infrastrata will reduce the size of its proposed Portland natural gas storage site and increase deliverability rates in order to enhance its chances of receiving investment. Primary operations had been based on storage along with a small exploration business , but there is little interest in large storage sites. The proposed 1 billion cubic metre Portland site is therefore likely to be scaled down, according to Infrastrata CEO Andrew Hindle, in favour of a smaller, more flexible site with higher injection and withdrawal rates.
"The investment climate for bigger, seasonal storage sites has cooled off recently because of tighter Summer/Winter spreads at the NBP, and none have received investment recently and that has been the case with Portland," Hindle told ICIS on Monday. ..... [continues]
Consequently, Hindle believes that the potentially smaller Portland site would appeal more to investors because greater flexibility would attract more capacity holders. "If the demand for a bigger site proved to be there later on, if the spreads widened, then it wouldn't be too hard to expand from there, as long as we have a foot in the door." No specific details on a potential new capacity were given... [continues]

[Carbon Capture and Storage]:
CCS bid
Infrastrata is also planning a bid for the UK's Carbon Capture Storage (CCS) competition.
"The change will provide stronger backing for the Portland gas storage project to submit a bid in the CCS project. The CCS would make use of existing permissions and consents for the Portland project and allow synergies with the gas storage project," Hindle said.

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INFRASTRATA. 2013. (re the Durlston Head Gas Prospect), Wessex Basin, Southern England
(Operator, 78% net interest). 26 November 2012 - Exploration Update.
Go to: Infrastrata Webpage - 2012 .
[Extract re Durlston Head gas prospect, offshore Dorset - Southard Quarry etc.]
"The P1918 licence [block 98/11 etc], offshore adjacent to the Dorset coast, covering an area of 584 square kilometres, was awarded to the Company effective February 2012. A total of seven wells have previously been drilled within the licence area, including the first UK offshore well in 1963 on Lulworth Banks. Six of these wells encountered oil or gas shows and three flowed oil or gas on test. Within and immediately adjacent to the licence area there are also a number of active oil and gas seeps. The InfraStrata led joint venture has purchased approximately 3,500 kilometres of existing 2D seismic data, and three existing 3D surveys, within or adjacent to the licence. The advances in technology and higher petroleum prices mean that the licensees are hopeful of being able to develop one of the existing discoveries profitably as a base from which to appraise the full potential of the area. Over the past two months this data has been interpreted by Geosolutions Limited on behalf of the group. The focus has been on the offshore extension of the Purbeck Prospect, an anticline in the east of the licence, up dip of the onshore well Southard Quarry-1 [Swanage], which encountered petroleum in Jurassic and Triassic reservoirs during 1989 but which was not tested. The new mapping of the Purbeck Prospect shows it covering an area of approximately 13 square kilometres at the primary target level, the majority within the P1918 licence.
An initial "most likely" estimate of the prospective resources, by the joint venture partners, for the primary reservoir objective, the Triassic Sherwood Sandstone, is approximately 100 billion cubic feet ("bcf") of gas recoverable (net 78 bcf to InfraStrata). An appraisal well is now required to test the productivity of the reservoir at a depth of approximately 2,500 metres below ground level. The well will also be designed to evaluate two Jurassic reservoirs where oil was encountered in the Southard Quarry-1 well. InfraStrata is now going to reprocess approximately 250 kilometres of 2D seismic data to further define the sub-surface target location for a new appraisal well. It is proposed to drill the well directionally from an onshore location to the offshore within Block 98/11 of licence PL91/8. The joint venture intends to submit a planning application in Q1 2013, and it is anticipated that the first appraisal well will commence drilling before the end of 2013, subject to consents and funding. Further technical work will be undertaken to refine the prospect inventory in both exploration projects and the Company propose to commission a Competent Persons Report on completion of this work during the first half of 2013.

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Infrastrata plc. 2013. Planning Application for a Wellsite at California Quarry, Swanage. BH19 2QS. (re Durlston Head gas prospect) 9th August 2013.
Temporary planning permission for the construction of a wellsite, with associated portable cabins for the storage of equipment and for staff accommodation, the drilling of an exploratory borehole, undertaking of production tests and retaining the site and wellhead valve assembly gear for evaluation of a conventional hydrocarbon reservoir.
Go to webpage: Planning Permission Application - California Quarry, Swanage.
The stated objectives [similar to comments given above]:
Drilling is planned to assess conventional sandstone reservoirs. The main objective is to evaluate the potential for gas to be produced from the Triassic Sherwood Sandstone geological formation, the same rock from which petroleum is currently produced elsewhere in Dorset, and more specifically the strata in which gas was encountered in a well drilled nearby at Southard Quarry in the 1980s.
Application Number - 6/2013/0456
Application Status/Decision -Awaiting Decision
Date Registered - 09-08-2013
Date Valid - 05-08-2013
Council - Purbeck District Council
Parish\Town - Swanage Town Council - Local Councillor
Planning Case Officer - Mr Andrew Helmore
Application Type - Minerals County Matter
Development Size - Major
Applicant - Infrastrata plc
Agent - Barton Willmore
[More notes re this planning application - summary from Energy-Pedia - Market Intelligence: UK: InfraStrata provides operational update on planned 2013/14 multi-well drilling programme.
"A planning application for drilling and testing of the California Quarry-1 well, to be drilled from onshore to offshore within Petroleum Licence P1918 (InfraStrata Operator, net interest 78%), has been submitted to Dorset County Council. Subject to the granting of planning permission by the end of 2013, InfraStrata anticipates the well will be drilled in the first half of 2014. The prospective resources for the Purbeck Prospect within the Triassic Sherwood sandstone reservoir have been estimated by the joint venture at 100 billion cubic feet (bcf) (net InfraStrata 78 bcf).

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Infrastrata - California Quarry, Purbeck (re Durlston Head gas prospect) - News 2012.
More technical details - Reported by Refinery News. Nov. 26, 2012.
InfraStrata has issued an update on its exploration plans for a license offshore southern England. The PL91/8 permit, offshore and adjacent to the Dorset coast, covers 584 sq km (225 sq mi) over the Wessex basin. The company was awarded a 78% operating interest this February. To date seven wells have been drilled by previous operators within the license area, including the UK's first UK offshore well in 1963 on Lulworth Banks. Six had oil or gas shows and three flowed oil or gas on test. Within and next to the license area there are also numerous active oil and gas seeps. The current partners have purchased 3,500 km (2,175 mi) of existing 2D seismic data, and three existing 3D surveys, over and around the acreage. Geosolutions is performing the interpretation. In light of technology advances and higher petroleum prices, the partners hope to develop one of the existing discoveries profitably and then proceed to appraise the area's full potential. The focus of interpretation has been on the offshore extension of the Purbeck prospect, an anticline in the east of the license, updip of the Southard Quarry-1 onshore well, drilled in 1989, which encountered petroleum in Jurassic and Triassic reservoirs. New mapping of Purbeck shows that it covers an area of roughly 13 sq km (5 sq mi) at the primary target level, much of this within the P1918 license. Prospective resources for the primary Triassic Sherwood sandstone objective could be 100 bcf (2.8 bcm) recoverable. An appraisal well is needed to test the productivity of the reservoir at a subsurface depth of 2,500 m (8,202 ft). This well will also evaluate two Jurassic reservoirs where oil was encountered in Southard Quarry-1. InfraStrata will reprocess 250 km (155 mi) of 2D data to further define the subsurface target location for the new well, which would likely be drilled directionally from an onshore location to the offshore within block 98/11. The partners expect to submit a planning application early in 2013, and aim to start drilling before the end of next year, subject to consents and funding.

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Ingraffea, A.R., Wells, M.T., Santoro, R.L. and Shonkoff, S.B.C. 2014. Assessment and risk analysis of casing and cement impairment in oil and gas wells in Pennsylvania, 200-2012. Proceedings of the National Academy of Sciences, vol. 111, no. 30,, pp. 10955-10960. The full text of this paper on well integrity is available at:
http://www.pnas.org/content/111/30/10955.full
Abstract:
Casing and cement impairment in oil and gas wells can lead to methane migration into the atmosphere and/or into underground sources of drinking water. An analysis of 75,505 compliance reports for 41,381 conventional and unconventional oil and gas wells in Pennsylvania drilled from January 1, 2000 - December 31, 2012, was performed with the objective of determining complete and accurate statistics of casing and cement impairment. Statewide data show a sixfold higher incidence of cement and/or casing issues for shale gas wells relative to conventional wells. The Cox proportional hazards model was used to estimate risk of impairment based on existing data. The model identified both temporal and geographic differences in risk. For post-2009 drilled wells, risk of a cement/casing impairment is 1.57-fold [95% confidence interval (CI) (1.45, 1.67); P < 0.0001] higher in an unconventional gas well relative to a conventional well drilled within the same time period. Temporal differences between well types were also observed and may reflect more thorough inspections and greater emphasis on finding well leaks, more detailed note taking in the available inspection reports, or real changes in rates of structural integrity loss due to rushed development or other unknown factors. Unconventional gas wells in northeastern (NE) Pennsylvania are at a 2.7-fold higher risk relative to the conventional wells in the same area. The predicted cumulative risk for all wells (unconventional and conventional) in the NE region is 8.5-fold [95% CI (7.16, 10.18); P < 0.0001] greater than that of wells drilled in the rest of the state.
[Extract from - Conclusion, p. 15]
"Pennsylvania state inspection records show compromised cement and/or casing integrity in 0.7 - 9.1% of the active oil and gas wells drilled since 2000, with 1.6 to 2.7 fold higher risk in unconventional wells spudded since 2009 relative to conventional well types. Hazard modelling suggests that the cumulative loss of structural integrity in wells across the state may be actually be slightly higher than this, and upward of 12% for unconventional wells drilled since January 2009. The wide range of estimates is influenced by significantly higher rates of impairment in wells spudded in the NE of the state (average of 12.5%, range 2.2 - 50%), with predicted cumulative hazards exceeding 40% (Fig. 5 and 6)."

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Ioannides , N.S., Stavrinos, G.N. and Downie, C. 1976. Kimmeridgian microplankton from Clavell's Hard, Dorset, England. Micropaleontology, 22, 443-478, plates 1-5 show microplankton. By N.S. Ioannides from Esso Production Research - European, Begles, France; G.N. Stavros, Nicosia, Cyprus and by Professor Charles Downie, University of Sheffield, England. Paper published October, 1976.
Abstract:
The present paper provides the first detailed account of the microplankton assemblages associated with the rich bituminous shale, the Kimmeridge Blackstone. Forty-nine taxa of dinoflagellate cysts and 13 of acritarchs are recorded; two genera and eighth species are regarded as new and emendation of one genus is proposed. There are brief remarks on previously described Upper Jurassic assemblages. One result of this study is the new insight given on the origin of the Kimmeridge Oil Shale, which is seen to be an essentially marine deposit, owing its unique character to an abundant supply of swamp-generated organic matter. [Although this paper is mainly concerned with the microplankton, the introductory section is also of interest in that it provides a table of combustible organic matter for the Blackstone, the Bubbicum and associated strata. The maximum recorded is 67.7% for the very base of the Best Blackstone. The Bubbicum has 52%.]
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Irwin , H., Curtis, C. and Coleman, M. 1977. Isotopic evidence for source of diagenetic carbonates formed during burial of organic-rich sediments. Nature, 269, 209-213. Abstract: Organic matter is modified by several processes operating at different depths during burial diagenesis: 1. sulphate reduction; 2. fermentation ; 3. thermally-induced decarboxylation, and so on. CO
2 , one common product of each can be distinguished by its carbon isotope composition: approximately 1. - 25, 2. +15, 3 -20 parts per thousand relative to PDB. These values are preserved in diagenetic carbonates of the Upper Jurassic Kimmeridge Clay. Independent corroboration of the relative dominance of each process within specific depth intervals is given by the isotopic composition of incorporated oxygen which is temperature dependent: 1. 0 to -2, 2. -1.5 to -5, 3. -3.5 to -7.0 parts per thousand.

Irwin, H. 1981. On calcic dolomite-ankerite from the Kimmeridge Clay. Mineralogical Magazine, 44, 105-107.

Irwin, H. 1979. On an environmental model for the type Kimmeridge Clay. Nature, London, 279, 819.

Irwin, H. 1980. Early diagenetic carbonate precipitation and pore fluid migration in the Kimmeridge Clay of Dorset, England. Sedimentology, 27, 577-591.
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iStockAnalyst . 2008. Planning Permission Granted to Drill Extension of an Oil Field in the Weald Basin, Onshore Southern England. Thursday, May 15, 2008. [Markwells Wood]
[Extract]
"Northern Petroleum, as Operator of the PEDL 126 Joint Venture, has received planning approval to drill an exploration well from a site to the north of Forestside in West Sussex, England. The Markwells Wood-1 well will target a prospect that is interpreted to be an eastward extension of the currently producing Horndean Oil Field. MPAL, its Joint Venturers and professional advisors have analysed datafrom, and between, the Horndean and Singleton oilfields lying some 15 km apartand have concluded that they are in essence the same oil accumulation. Markwells Wood is the first site of two within the license where structures have been mapped to exist above the interpreted common oil-water contact. Site construction for Markwells Wood-1 is anticipated to commence later this year, with drilling to take place shortly thereafter...
Markwells Wood-1 will be the first of several wells to be drilled by MPAL in this area of southern England over the next 12 to 18 months. Governmental approval is currently being sought to drill one well in each of licenses PEDL 099, 125, 135 and 137."


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ITV. 2015. Fracking licenses granted for sites in Wiltshire and Somerset. ITV Report, 17th December 2015 at 4.30pm. Available online.
"The government has handed out new licences for onshore oil and gas exploration in Gloucestershire, Somerset and Wiltshire. .. A large area of Somerset has been earmarked for controversial fracking [hydraulic fracturing], the process of breaking up rocks deep underground to release gas as an energy source, while Wiltshire could see the extraction of methane from coal beds. The Welsh Company [is this Coastal Oil and Gas?] awarded the licences would have to apply for planning permission before carrying out the drilling. Campaigners say the decision could open up swathes of the region to controversial fracking. Oil and Gas Authority [OGA] chief executive said: "This round enables a significant amout of the UK's shale prospects to be taken forward to be explored and tested. Andy Samuel, OGA."

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Jarvie, D.M. 1991. Source and Migration Processes and Evaluation Techniques. AAPG (American Association of Petroleum Geologists), Book by Daniel M. Jarvie. Chapter 11, Total Organic Carbon Analysis, Geochemical Methods and Exploration. AAPG Special Volumes.
See Chapter 2. Total Organic Carbon (TOC) Analysis.A shortened example extract follows:
"Total organic carbon (TOC) is a measurement of the organic richness of sedimentary rocks. .. This source is organic matter derived from a variety of biological origins which has been deposited and buried through geological time.. The bulk of petroleum is formed from the thermal decomposition of organic matter through time. The reactions resulting from increased thermal stress yield the large variety of carbon-containing compounds of which oil and gas are composed. Since the oil or gas potential of a formation is related to its carbon content, TOC analysis is typically the first screening analysis completed to evaluate the general potential of a formation to generate hydrocarbons... Organic carbon is derived from biogenic matter, whereas inorganic carbon is derived from mineral matter [e.g calcium carbonate - calcite]. Carbon constitutes 75-95 wt. % of hydrocarbons by molecular weight, with an average value near 83 wt.%."

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Jenkins , D. 1996. The technology challenge at lower oil prices. Geoscientist, vol. 6 , 5-10.
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Jenkyns, H.C. and Senior, J.R. 1991. Geological evidence for intra-Jurassic faulting in the Wessex Basin and its margins. Journal of the Geological Society, London, vol. 148, pp. 245-260.
Geological observations on Jurassic outcrops close to major faults in the Wessex Basin-Mendip area reveal the local presence of ammonite- and brachiopod-bearing sediments penetrating underlying strata. Toarcian and Bajocian neptunian dykes and particularly sills are associated with the Eypemouth Fault and Bajocian sills with the Bride Fault and Mere Fault. In the Mendip area numerous neptunian dykes of Hettangian, Sinemurian, Pliensbachian and Bajocian ages, cross-cutting Carboniferous Limestone, are recorded, typically also associated with major basement faults (e.g. Cranmore and Leighton Faults). These periods of assumed sediment injection are taken as indicating times of displacement along the faults in question.
Variations in facies (Hettangian-Sinemurian, Toarcian, Bajocian, uppermost Oxfordian, Kimmeridgian) spatially linked to faults are documented from some areas, and boreholes reveal considerable fault-controlled thickness changes in Hettangian-Sinemurian, Bajocian and Kimmeridgian sediments. The timing of Jurassic faulting in the Wessex Basin-Mendip area thus polarizes into two intervals: Hettangian-Bajocian and latest Oxfordian onwards, correlating with the early rifting phases of the Central and North Atlantic respectively.
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Jokanola, O. 20??. Porosity, Permeability and Capillary Pressure Properties of the Kimmeridge Clay Formation of the North Sea using Pore Size Distribution Method. M.Sc. Thesis?.
In the Kimmeridge Clay Formation (KCF), porosity and permeability decreases with depth from 24 percent -3 percent and less than 10-0.09nD between 1.5 - 5.0km depth of burial. The upper 2.3 km showed porosity and permeability decreasing with depth from 24-19 percent and 5-1.5nD respectively. Between 2.3-3.4 km, abnormally high porosity and permeability (20% and 2-9nD) occur due probably to reduced effective stress implying abnormal pore-pressure. The atypical pore size distribution pattern of the mudstones within this regional also suggests presence of coarse grained materials thought to have come from incising alluvial fans. At 3.5km, the KCF is lithologically similar, and reached mechanical compaction equilibrium resulting in best-possible pore sorting with porosity and permeability being less than 10% and 0.3-09nD respectively. The 3.5km also defines the critical depth of burial (CDB). Compared with existing mudstone data, the KCF porosity-permeability data plots in the lowest portion of the porosity -permeability profile, similar to values extrapolated from previous organic poor, fine- grained mudstones. Capillary pressure measurements shows that if "water wet", the KCF at greater than3.5km could support greater than 5km and less than .7km oil and gas respectively. Conversely, geochemical data suggest that this source rock may be "oil-wet" and may not be good capillary seals but behave more like a "permeability barrier". At the 2.3 to 3.4km band, where the KCF appears overpressured, it may be a good pressure seal. The upper 2.3 km is thought to be "water wet" and would make a good capillary seal, capable of holding up to 3.5 km and 1.3 km of oil and gas respectively. [Femi Jokanola, . Geologist-Petroleum Systems, ConocoPhillips.
Femi graduated with a PhD in Petroleum Geoscience in 2007, thesis title "Pore Pressure, Seal Risking and Column Height Predictions in Leaky Petroleum Systems: Some Case Studies". Prior to that Femi obtained his BSc in Geology from Obafemi Awolowo University, Nigeria, and an MSc in Petroleum Geochemistry from the University of Newcastle-upon-Tyne. Femi is now working as a Petroleum Systems Analyst with the Subsurface Technology Group, ConocoPhillips in Houston.]

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Judd , A.G. 2004. Natural seabed gas seeps as sources of atmospheric methane. Environmental Geology, vol. 46, No. 8, November, 2004.
Abstract Microbial and thermogenic methane migrates towards the seabed where some is utilised during microbially-mediated anaerobic oxidation. Excess methane escapes as gas seeps, which occur in a variety of geological contexts in every sea and ocean, from inter-tidal zones to deep ocean trenches. Some seeps are localised, gentle emanations; others are vigorous covering areas of more than 1 km2; the most prolific seeps reported (offshore Georgia) produce about 40 t CH4 per year. Gas bubbles lose methane to the water as they rise, so deep water seeps are unlikely to contribute to the atmosphere. However, bubbles break the surface above some shallow water seeps. Estimates of the total methane contribution to the atmosphere are poorly constrained, largely because the data set is so small. 20 Tg per year is considered a realistic first approximation. This is a significant contribution to the global budget, particularly as methane from seeps is 14C - depleted. A seep measurement programme is urgently required. [relevant to the Durlston Head and Lulworth Banks gas seeps - see Hinchcliffe (1978)].

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Kantorowicz, J.D., Bryant, I.D. and Dawans, J.M. 1987. Controls on the geometry and distribution of carbonate cements in Jurassic sandstones: Bridport Sands southern England and Viking Group, Troll Field, Norway. In: Marshall, J.D. (ed), Diagenesis of Sedimentary Sequences, Geological Society, London, Special Publications, 36, 103-118.
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Karner , G.D., Lake, S.D. and Dewey, J.f. 1987. The thermal and mechanical development of the Wessex Basin, southern England. In: Coward, M.P., Dewey, J.F. and Hancock, P.L. (eds.) , Continental Extension Tectonics. Geological Society of London, Special Publications, 28, 517-536.
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Kent , A. 1973(?). The day the earth caught fire - and Mr Cole spotted it. By Ann Kent. [Newspaper article, the newspaper is not known but might well be the Southern Evening Echo, Southampton, since another article refers to Southampton Education Committee and Redbridge School. Date probably late 1973.]
It may be chilly in city offices, but down in rural Dorset things are pretty hot. At Clavell's Hard near the seaside village of Kimmeridge, smoke is rising through cracks in . the cliffs, the ground is hot, and evil-smelling gases have killed off the grass. Deep inside, the ground is actually, on fire.
Phenomenon: The phenomenon was discovered by Douglas Cole, a 24-year-old geological research student, who was walking in the area. Mr Cole, who lives in Church Lane, Southampton, said: 'There is a 3ft. 6in. layer of oil shale underneath the rock surface which has caught fire. This is an extremely rare occurrence - the last case noted in geological records was in 1826 [but the Lyme Volcano was later]. There is a large area of dead grass on the cliff; Immediately under the loose stone the ground is red hot. If you thrust a stick into it, it would burn. I measured temperatures of just over 500deg. C. Once combustion like this starts nothing will stop it until the fuel is exhausted.' Major John Mansel, of Smedmore House, Corfe Castle, who owns the burning cliff,said 'There is a footpath running nearby and the cliffs are a popular beauty spot In the summer.'
Spontaneous: Mr Reginald Leonard, engineer for Wareham rural council. which covers the area, said 'We often hear of spontaneous combustion In rubbish tips but this is the first I have heard of it happening in oil shale.'
[see also papers etc by Cole.]
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Kent , P.E. 1949. A structure contour map of the surface of the buried Pre-Permian rocks of England and Wales. Proceedings of the Geologists' Association, London, 60, 87-104.

Kent, P.E. 1985. U.K. onshore oil exploration, 1930-1964. Marine and Petroleum Geology, 2(1), 56-64, 7 figs, 15.
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Kinghorn , R.F., Selley, R.C. and Stoneley, R. 1994. The Mupe Bay Oil Seep Demythologised. Marine and Petroleum Geology, 11, (1), p 124-125. Discussion of paper by Miles et al.
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Knox , R.W.O., Burgess, W.G., Wilson, K.S. and Bath, A.H. 1984. Diagenetic influences on reservoir properties of the Sherwood Sandstone (Triassic) in the Marchwood geothermal borehole. Clay Minerals, 19, 441-456.
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Kornacki, A.S. 2010. Integrated hydrocarbons charge evaluation of the Haynesville and Bossier Gas Shale Reservoirs, Northern Lousiana. Presentation at the 2010 GSA Denver Annual Meeting (31 October - 3 November 2010).

Gas-bearing shales in the Upper Jurassic Haynesville Formation and the overlying Bossier Formation in northern Louisiana are a new energy source. [The Haynesville Shale is the age equivalent of the Kimmeridge Clay of the UK]. These unconventional reservoirs contain gas generated by indigenous kerogen that was retained in intergranular matrix porosity and kerogen nanoporosity. We applied integrated HC charge evaluation methods to help identify shale intervals with the best commercial potential. Our study involves three complementary elements: (1) characterizing the source rock (SR) potential of Bossier and Haynesville shales; (2) analyzing the composition of gas samples obtained from different shale intervals; and (3) modeling oil and gas generation by Bossier and Haynesville SRs. We identified two good SR intervals: Upper Haynesville/Basal Bossier shales contain ~1.5-5.0 wt% total organic C (TOC); a second SR interval in the Middle Bossier Formation contains ~1.5-3.0 wt% TOC. Upper and Lower Bossier shales generally are much leaner (less than 1.5 wt% TOC). Bossier and Haynesville shales have reached such a high level of thermal maturity (VR ~ 2.0-2.8) it is difficult to determine what kind of kerogen they originally contained. But the presence of pyrobitumen in Haynesville SRs and the abundance of gas-prone and inert kerogen in lean Bossier shales indicate only the two good SR intervals contained oil-prone kerogen. Basin modeling indicates the volume of gas generated by Haynesville and Middle Bossier SRs exceeded their intrinsic storage capacity, while lean gas-prone Bossier shales generated less gas than they could retain. Excess gas expelled by good SRs probably migrated through the leaner shales via fractures and faults. The molecular and C isotopic composition of gas samples produced from Haynesville and Middle Bossier shales support these intepretations: e.g., C1/C2 ratios (~1000-2100) indicate the gas was generated at very high maturity. Systematic changes in gas composition across the study area indicate that the maturity of kerogen in each good SR largely controls gas wetness and the C isotopic composition of HC gases: i.e., the reservoirs are compartmentalized vertically and laterally. Mud gas samples from lean Bossier shales are much wetter than mud gas samples obtained from good SR intervals, suggesting Upper and Lower Bossier shales do not contribute significantly to production.

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Lake , S.D. and Karner, G.D. 1987. The Wessex Basin as an example of inversion tectonics. Tectonophysics, 137, 347-378.

Law, A. 1998. Regional uplift in the English Channel: quantification using sonic velocity. In Underhill, J.R. (Editor). Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publications, no. 133, pp. 187-197. By Dr. Adam Law, BG [British Gas] Exploration and Production Ltd. Reading Berkshire; subsequent address: Ameralda Hess Ltd., 33 Grosvenor Place, London, SW 1X 7HY, UK. Dr. Adam Law has also worked for British Gas. Dr. Adam Law is a founder of ERC Equipoise and serves as Managing Director.
Abstract: Analysis of the substantial well database held by British Gas Exploration and Production Ltd enables regional estimates of uplift for the English Channel area to be derived from anomalous measurements of downhole sonic velocity. Estimates of section uplift, or apparent erosion, can be derived from variations in sonic velocity / travel-time and depth relationship for the basin; the normal compaction relationship. These estimates are, however, extremely sensitive to errors in the normal compaction relationship, and to variations in sedimentary facies and/or diagenesis between wells. In this study, these problems have been minimized using regionally persistant, homogeneous thick facies such as shales and by carefully constraining the normal compaction relationship by 'backstripping' apparent erosion values to determine 'residual apparent erosion'.
Apparent erosion has been determined for three intervals from the Mid- and Upper Jurassic, broadly corresponding to the Fuller's Earth, Oxford Clay and Kimmeridge Clay Formations. Averaging these values and constraining them as above results in robust estimates of total uplift across the English Channel Basin, with uncertainties of around 20 percent. The results of this study suggest kilometre-scale uplift within the area, with maxima over the Purbeck - Isle of Wight Fault Zone and the Mid Channel High inversion axes. To the north of the Purbeck - Isle of Wight Fault Zone the apparent erosion calculations estimate uplift of 500 m. or less suggesting that this area may have remained relatively stable during basin inversion. When compared to equivalent estimates from AFTA/VR (apatite fission track / vitrinite reflectance) palaeotemperature data, the sonic-derived uplift is similar within errors in inverted areas. However in a more stable area such as to the north of the Purbeck - Isle of Wight Fault Zone, calculated apparent erosion indicates that little uplift has occurred, whereas estimates derived from AFTA/VR models are still significant.
[with 8 figures and 1 table. 9 references.]


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Law, P. 2009. Drilling for Oil; Hampshire sitting on Black Gold reservoir. Southern Daily Echo Newspaper, 6th August, 2009.
"An oil company is launching a new bid to drill for "black gold" within 400 metres of a Hampshire community, the Daily Echo can exclusively reveal. Northern Petroleum believes reserves worth billions of pounds lie beneath the properties.
Northern Petroleum is in advanced negotiations with owner of a secret site to erect a 118 ft. rig and drill 24 hours a day for several weeks. The move has sparked concern that the rig could be a blight on the landscape and cause traffic chaos for local residents. Oil bosses refused to reveal the exact location of the site but confirmed that it was within 400m. of homes on the outskirts of Hedge End. They believe homeowners are living above a massive oil field [this is a Middle Jurassic, Great Oolite field like those at Singleton, Humbly Grove, the Stockbridge Oilfield etc]. The development comes four years after the firm's first attempt to drill for oil in a field close to Woodhouse Lane was scuppered by a huge public outcry.
Negotiations with a farmer about a second possible site, reported by the Echo last year, also collapsed after it was decided that they were unlikely to secure planning permission. Talks were even held with Hampshire Cricket about drilling for oil next to the Rose Bowl, however, that proposal was also rejected.
The firm's exploration and technical director Graham Heard said he was confident the patch of land, north of Hedge End, would get planning permission from Hampshire County Council.
"We have gone much further afield this time, but I'd rather not say where it is until we make more progress," he said.
"We think that it is somewhere that might be suitable and we are having long discussions with the landowner. It is in the general Hedge End area, but it will require an underground 2 kilometre deviated well to get to where we want to be." -------- [continues re planning application]
In March, Northern Petroleum was given the go-ahead to start drilling an exploratory well at another Hampshire site at Leigh Park, near Havant [same Great Oolite reservoir]. Mr Heard said lessons had been learnt and assured Hedge End residents that they would be fully consulted about the plans once a lease had been agreed." [there are also brief comments by Eastleigh MP Chris Huhne and also one by Eastleigh Borough Council leader Keith House.]


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Lewin, M.D. and Hill, R. [by Michael D. Lewin and Ron Hill]. Presentation: Evaluating Oil-Shale Product Yield and Compositions by Hydrous Pyrolysis. 26th Oil Shale Symposium Presentation, 2006., at CERI, Colorado Energy Research Institute, Colorado School of Mines, Costar, Centre for Oil Shale Technology and Research. Authors from US Geological Survey, Denver, CO 80225.
This presentation is a detailed study of how to evaluate oil shale products and yields by hydrous pyrolysis. It compares Rock Eval, Fischer Assay and Hydrous Pyrolysis Oil Yields methods. A piece of the Kimmeridge Blackstone is one of the samples tested, and thus it includes Kimmeridge Blackstone data. Of 12 oil shale samples tested the Kimmeridge Blackstone sample (a marinite) had 54% wt% TOC, and was the second highest to the Glen Davis torbanite of 56% TOC (a lacustrine Botryococcus torbanite or boghead coal) from the Permian of Australia. The Devonian and Mississipian New Albany Shale of the Illinois Basin, of which their sample had only 15% TOC is a marine shale and therefore more comparable to the Kimmeridge oil shale. The Tamadit oil shale of the Cretaceous of Morocco is also a marinite, but their sample had only 9 wt% TOC.
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Lake, D. and Karner, G.D. 1987. The structure and evolution of the Wessex Basin, southern England: an example of inversion tectonics. Tectonophysics, vol. 137, pp. 347-378.
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Lallier-Verges , E., Bertrand, P., Huc, A.Y., Buckel, D. and Tremblay, P. 1993. Control of preservation of organic matter by productivity and sulphate reduction in Kimmeridgian shales from Dorset (UK). Marine and Petroleum Geology, volume, 10, pp. 600-605. [This may have followed a field trip to the Kimmeridge cliff section with Ian West, a few years before. See the Kimmeridge oil shale webpage in this website to check details.]

Lallier-Verges, E. and Tribovillard, N-C. 1995. Organic Matter Accumulation : The Organic Cyclicities of the Kimmeridge Clay Formation. In: ? Paperback (July 1995). Springer Verlag; ASIN: 0387591702.

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George Martin Lees, Military Cross, DFC, FRS, Royal Flying Corps, Assistant Political Officer in Southern Kurdistan, Advisor to Sheik Mahmoud, Royal School of Mines, Chief Geologist of the Anglo Persian Oil Company (i.e. BP). After success in Persia he initiated oil exploration in the UK. See Wikipedia for more information about this remarkable man. (also washed away in a river and survived by using his pith helmet as a float; also survived a plane crash, and escaped on horseback from a major attack!)

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Lees, G.M. and Cox, P.T. 1937. The geological basis for the search for oil in Great Britain by the D'Arcy Exploration Co. Ltd.Quarterly Journal of the Geological Society, London, 93, 156-190. By George Martin Lees, M.C. D.F.C. Ph.D. F.G.S., and Percy Thomas Cox, M.A. F.G.S. Read March 10th, 1937.


Abstract
Seepages of oil at the surface or in coal mines have been known in Great Britain for several centuries. Records of the use of oil from the Coalport seepages date from 1684. James Young in 1847 extracted wax, burning oil, and lubricating oil from a crude oil obtained in the Biddings colliery, near Alfreton in Derbyshire. In 1902, some boring was carried out in the Sussex Weald, stimulated by the accidental discovery of natural gas at Heathfield, but this enterprise was soon abandoned.
In 1918, a serious search for oil was made under the pressure of war-time conditions, and Messrs. S. Pearson and Son, Limited, between 1918 and 1921, under contract for H.M. Government, drilled 11 test-wells: seven in Derbyshire, two in Staffordshire, and two in Scotland. In every case the objective was an oil accumulation in Carboniferous beds. A small production was obtained from their first well, Hardstoft No. 1 in Derbyshire, and showings of oil were struck elsewhere, notably in the D'Arcy well in Scotland. Although the results up to that time may not have been conclusive, they were not considered sufficiently encouraging to justify further Government expenditure, and operations were suspended. Two wells were drilled later (1924–26) on the Hardstoft structure on the initiative of the Duke of Devonshire, owner of the property, but neither obtained any oil-production.
Other attempts during the last 20 years to find oil by drilling have been those at Kelham, near the site of a coal exploration borehole, which found a show.
[end of abstract]

[an example extract follows]
(c) Jurassic:
Though not so prolific in oil seepages and bitumen shows as the Carboniferous, the Jurassic system of Great Britain yields abundant evidence of oil generation within its beds. Liassic shales are bituminous, in the sense that they contain material of kerogen type, which will yield oil on heating, throughout the length of their main outcrop from northeastern Yorkshire to Dorset. The Jet Rock of Whit by and the Lower Lias outcropping near Charmouth and Lyme Regis are among the richer examples. Veinlets of hard bitumen, which must originally have been fluid, occur in the Belemnite Marls, the Black Ven Marls, and in parts of the Blue Lias of Dorset. Analysis has proved traces of soluble oil, up to 0.1 per cent, in Liassic shales and sandstones of the south coast exposures. In Kent, at Chilham, boring is reported to have found bitumen along joints in Liassic limestones. In the Eskdale and Robin Hood's Bay area of Yorkshire, small pockets of liquid oil occur, filling cavities in calcareous concretions in the outcropping Lias, and the ironstone of the Cleveland district is said to contain a trace of oil at depth (Strahan 1920, p. 62). Middle Jurassic rocks have yielded little evidence of the. presence of petroleum. Tarry matter has been recorded (Strahan 1920, p. 62) as filling joints in the Bath Oolite penetrated by borings in Kent.
The Oxford Clay contains many horizons which are comparatively rich in insoluble organic matter of kerogen type and traces of oil are known to occur in it. The following data refer to a specimen collected by Mr. C. T. Barber near Stalbridge in Dorset :
Oil yield (Imperial gallons per ton) .. 12,2
Specific gravity of oil at 60 degrees F.. 1.002 . .
Setting point of oil (rotating thermometer method) .. 52degrees F.
Sulphur .. 4.95%
Yield of oil obtainable by extraction with benzine .. 1.75%
Ash content of clay .. 71.4%
The presence of a rich impregnation of oil in the Corallian Bencliff Grits outcropping near Osmington Mills in Dorset was recently discovered by Mr. A. H. Taitt. A specimen of the sand from the exposed cliff face has given 12.1 per cent of oil, and where these beds pass below high-tide level at Bran Point there is a small but active seepage of free oil. This seepage is, so far as we are aware, a new discovery, and its existence does not appear to be known even to the local inhabitants. Following are two analyses of the oil [the second one is in brackets]:
Specific gravity at 60 degrees F. - 0.941 (0.944)
Hard asphalt - trace
Soft asphalt - 6.47 (5.90)
Soft wax - 8.11 (11.04)
Distillate to 200 degrees C. at 5 mm. Hg. pressure - 21.4 percent (19.2%)
Specific gravity of distillate - 0.907 (0.910)
Specific gravity of residue - 0.955 (0.957)
Sulphur - 0.25 percent (0.30 percent)
This Corallian oil may be indigenous to the group of beds in which it occurs or it may have been derived from another stage of the Jurassic and have lodged in this porous sandstone. The high sulphur content of oil distilled from both the Oxford and the Kimeridge clays does not favour a relationship between the Corallian oil and the kerogen material of these clays, but we are not yet able to offer a definite opinion upon this point.
The oil shales of the Kimeridgian have been described by Strahan (1920, pp. 18-40), and attempts have been made to exploit them commercially. The oil derived from this shale differs from that obtained from the Scottish shales in its higher sulphur content. Kimeridge shale oil generally contains from 2 to 7 per cent of sulphur, whereas the Scottish shales rarely yield as much as 2 per cent. Oil distilled from an Oxford clay, is, as is shown above, similar in this respect to Kimeridge oil. It is noteworthy that the free oil in the Corallian sand has less than 0.3 per cent of sulphur.
Portland beds have yielded traces of oil on analysis from outcrops at Tisbury, Portash, Portland, and Kimeridge.
The Purbeck Beds at their outcrops on the Dorset coast show a number of impressive oil indications; these include bituminous limestone, as at Peveril Point, and fractured limestones at Mupe Bay, Lulworth Cove, and Durdle Door which show oil residues on the faces of cracks and which ooze a little soft bitumen in warm weather. Strahan (1898, p. 107) recorded bituminous limestone in Purbeck beds near Holworth House and in the Chaldon anticline; oil residues similar to those of Lulworth Cove were found in Purbeck beds. Purbeck limestones outcropping at Upway gave a colour on extraction with chloroform, though they lacked visible oil content; this is also the case in the Purbeck inliers of the Weald. Lower Purbeck beds in both the Portsdown and the Henfield borings contain traces of liquid oil.
Some of the Purbeck oil and bitumen may be indigenous to that series, which also contains some oil shales. There is, further, the possibility of upward migration from the underlying Kimeridge beds, although analysis of the Purbeck residues shows that their sulphur content is generally less than 1 per cent. It is of interest in this connexion that an oil shale from the Sussex Purbeck outcrops yielded on distillation 20 gallons per ton of oil with a specific gravity of 0.878, setting point at 77 degrees F. and low sulphur content.
(d) Wealden:
The Wealden beds of the south of England, in spite of the generally accepted theory of their freshwater origin, contain a remarkable number of richly oil-impregnated sands. The senior author of this paper first discovered such impregnation in sands at Worbarrow Bay (PI. XI), and subsequently he and his colleagues found rich oil impregnation in all Wealden exposures between this place and Dungy Head (PI. XII).
At Dungy Head the lowest Wealden sandstone is richly impregnated, chocolate-brown to black in colour, and sticky, due to its oil content. This sandstone again outcrops in the cliff face between Dungy Head and Lulworth Cove at a point marked by a navigation beacon. It is here about 12 feet in thickness and is chocolate-brown in colour, but on account of its exposed position the oil content is no longer so fresh as at Dungy Head. On the western side of Lulworth Cove, a prominent black sand exposed in the cliff owes its colour to carbonaceous matter, and not to oil impregnation, but on the eastern side of the cove an oil sand occurs a short distance above a black carbonaceous bed in the lower part of the series and a second oil sand is present in the higher Wealden beds.
In Mupe Bay an especially strongly impregnated conglomera. tic sand occurs about 90 feet above the Purbeck beds, and a second oil sand towards the top of the series. Coarse sandstone boulders, of which one sample contained 7.9 per cent by weight of oil, are found in less strongly impregnated, more finely grained sand or clay of the lower horizon.
In Worbarrow Bay, where the Wealden series is well exposed~ there are several sands containing oil. Analysis of one about two-thirds up from the base of the formation showed 2.83 per cent of oil with a specific gravity of 0.96.
In the Wealden exposures of Kent and Sussex, important oil shows are rare, but at Chilley, near Pevensey, there is a sand of the Tunbridge Wells group which, on extraction with benzine, yielded 12 per cent by weight, or about 25 per cent by volume, of black, viscous oil with a specific gravity of 0.995 and a sulphur content of 0.66 per cent. Mantell, in his Geology of the South-East of England (1833, pp. 172-3) recorded that a bituminous sand containing 15.4 per cent of bitumen was struck during the excavation of a drainage trench in the marshy ground near Chilley. Tunbridge Wells sandstones exposed in an old quarry near Hailsham also give a colour on extraction with chloroform, and an auger-hole drilled some two miles farther south at Down Ash, between Hailsham and Chilley, encountered a sand lightly impregnated with oil. Colour has also been obtained from tests with chloroform of the Hastings Beds at Hastings.
The natural gas occurrences in the Heathfield district have been described by Strahan (1920, pp. 111-4), Milner (1922, pp. 148-9) and others. In the evidence given before the Royal Commission on Coal Supplies of 1904 (Second Report, p. 112), it was stated that abundant petroleum was found in wells drilled for gas in this neighbourhood, but we have no confirmation of this. The gas was obtained either from the Hastings Beds or from the upper parts of the Purbeck and may have been indigenous to one or other of these series (both of which contain a considerable amount of lignitic matter), or it may have come from a lower Purbeck or Kimeridge source- The latest analysis of this gas, quoted by Strahan (1920, p- 113), shows it to contain 2-94: per cent of ethane, 2-90 per cent of nitrogen or - other inert gas, and 1 per cent of carbon monoxide, in addition to 93-16 per cent of methane. Natural gas has been found elsewhere in the Weald, in the Hastings Beds at Cuckfield, and at Hawkhurst.
[continues with Part 4, The Exploration Programme.]

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Lees, G.M. and Taitt, A.H. 1946. The geological results of the search for oil fields in Great Britain. Quarterly Journal of the Geological Society, London, 101, 255-317. By George Martin Lees and A.H. Taitt.
Abstract: The main geological results of exploration by the British Petroleum Company Limited since 1945 are outlined, and the general basis of operations described. In the south of England new data emphasize the progressive development of the Wealden area as a Jurassic depositional basin, on a surface of mainly Devonian and Carboniferious rocks. In the East Midlands and West Yorkshire more information on the relation of Carboniferous basins is now available, and extensive occurrences of contemporary and intrusive basic igneous rocks are described. In East Yorkshire a south-easterly extension of the Permian potash basin has been proved. Post-Permian formations tend to thicken eastwards from outcrop and also inland (westwards) from the coast. The Permo-Triassic rocks of the Formby area (Lancashire) have been found to lie in a deep valley cut into Carboniferous rocks, and stratigraphic thickness variations demonstrate intra-Triassic fault movements. Further oilfields have been developed at Plungar and Egrnanton in the East Midlands, and three additional discoveries await evaluation.

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Lees , J.A., Bown, P.R., Young, J.R. and Riding, J.B. 2004. Evidence for annual records of phytoplankton productivity in the Kimmeridge Clay Formation coccolith stone bands (Upper Jurassic, Dorset, UK), Marine Micropaleontology, Special Issue, 52 (2004), pp. 29-49.

Lees, J.A., Bown, P.R. and Mattioli, E. 2005. Problems with proxies? Cautionary tales of calcareous nannofossil palaeoenvironmental indicators, Micropaleontology, 51 (2005) (4), pp. 333-343.

Lees, J., Bown, P.R. and Young, J.R. 2006. Photic zone palaeoenvironments of the Kimmeridge Clay Formation (Upper Jurassic, UK) suggested by calcareous nannoplankton palaeoecology.Palaeogeography, Palaeoclimatology, Palaeoecology, 235, Special Issue - Causes and Consequences of Marine Organic Burial Through Time, 110-134. By Jackie A. Lees (UCL), Paul R. Bown (UCL)and Jeremy R. Young (Natural History Museum, London). [See the full paper which is available on the internet through Science Direct of Elsevier]
Abstract: Nannoplankton abundance data has revealed significant and systematic population fluxes through all representative lithologies and cycle types of the Kimmeridge Clay Formation (KCF), and also through intervals in which lithology is visually homogeneous. The majority of KCF samples yielded nannofossil assemblages of low species richness (1 to 10) and marked unevenness, independent of preservational state. All samples were dominated by coccoliths of one family, the Watznaueriaceae. While assemblage unevenness is characteristic of nannofossil populations, such low species richness is atypical, particularly when compared with coeval assemblages of similar latitude. Such anomalously low nannofossil diversity may be explained as a response to nutrient-rich euphotic environments. We postulate that consistently high trophic conditions supported the eurytopic watznaueriaceans but excluded most normal open-ocean taxa. The switching of dominance within this group most likely reflects different adaptations within an r-selected ecological strategy, related to nutrient concentration. Lowest diversities were recorded in mudstone/oil-shale lithologies where Watznaueria britannica is the dominant species, suggesting adaptation to the highest nutrient concentrations. Watznaueria barnesiae/fossacincta is particularly dominant in coccolith stone bands, where diversity is slightly higher, suggesting adaptation to lower high nutrient levels. Cyclagelosphaera margerelii appears to be the most extremely r-selected species, exploiting unusual (very high trophic/lowered sea-level?) conditions that excluded even W. britannica. [end of abstract]

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Lees, G.M. and P.T. Cox, P. T. 1937. The geological basis for the search for oil in Great Britain by the D'Arcy Exploration Co. Ltd. Quarterly Journal of the Geological Society, 1937, vol. 93, pp 156-190. By: George Martin Lees, M.C. D.F.C. Ph.D. F.G.S. and Percy Thomas Cox, M.A. F.G.S. Read 19th March 1937. [old classic paper] [reload test, 6th Nov. 2016, 9.15 pm.]
Abstract
Seepages of oil at the surface or in coal mines have been known in Great Britain for several centuries. Records of the use of oil from the Coalport seepages date from 1684. James Young in 1847 extracted wax, burning oil, and lubricating oil from a crude oil obtained in the Biddings colliery, near Alfreton in Derbyshire. In 1902, some boring was carried out in the Sussex Weald, stimulated by the accidental discovery of natural gas at Heathfield, but this enterprise was soon abandoned.
In 1918, a serious search for oil was made under the pressure of war-time conditions, and Messrs. S. Pearson and Son, Limited, between 1918 and 1921, under contract for H.M. Government, drilled 11 test-wells: seven in Derbyshire, two in Staffordshire, and two in Scotland. In every case the objective was an oil accumulation in Carboniferous beds. A small production was obtained from their first well, Hardstoft No. 1 in Derbyshire, and showings of oil were struck elsewhere, notably in the D'Arcy well in Scotland. Although the results up to that time may not have been conclusive, they were not considered sufficiently encouraging to justify further Government expenditure, and operations were suspended. Two wells were drilled later (1924-26) on the Hardstoft structure on the initiative of the Duke of Devonshire, owner of the property, but neither obtained any oil-production.
Other attempts during the last 20 years to find oil by drilling have been those at Kelham, near the site of a coal exploration borehole, which found a show.

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Legg , R. 1984. Guide to Purbeck Coast and Shipwreck. Dorset Publishing Company, Milborne Port, Sherborne, Dorset,DT9 5HJ. 96 pp. ISBN 0 90212958 9. By Rodney Legg. [Includes map of the oil-shale workings at Kimmeridge.]

Legg , R. 1987. Purbeck's Heath, Claypits, Nature and the Oilfield. Dorset Publishing Co. 143pp. By Rodney Legg, notable Dorset author and historian. He has written about 25 books.

See pp. 129-143: Dorset's Texas.
Example extract from p. 129, the start of the section:

"Though the nodding donkey pump has been a familiar coastal oddity on the Kimmeridge cliffs since 1959 it is the token oil well. It was trivial at first in international terms. Then it became trivial too when the rigs came onstream in the North Sea. Now amazingly it is trivial in Purbeck terms as well. The suprise came in 1973 when petroleum production licence PL089 in the hands of the British Gas Council, hit the bullseye at Wytch Farm after years of fruitless seismic surveys and exploration failures across the county. The story unfolds in the pages that follow, into a proliferation of fast-flowing wells; a gathering station that needs a forest to hide it; underground pipelines; a special rail terminal; BP buying an island. It had the financial press talking of a 450 million pound price tag on Wytch Farm in the Thatcher government privitisation portfolio. Reserves might run to nine billion tonnes of oil. The story is an oilman's dream, with a year when more oil was found in Purbeck than the whole of Texas. It inevitably has environmental implications, though my reaction is more pragmatic than it used to be. As much oil as possible should be removed from Purbeck. The optimum with current technology is probably only about thirty-five percent. If oil is removable by present techniques then it is best for the long-term interests of the land that as little as possible is left in the ground. Otherwise a cleverer generation will come back when we are dead and tear the place apart to repeat the process."...... [continues]
The book continues with nine photographs of the oilfield and with one diagram and the original 1978 map plan for the Furzebrook Rail Terminal site, which receives oil from the Gathering Station. There is discussion about Furzey Island, Waddock Cross borehole etc. It is a very good, brief, account of the history of the Wytch Farm Oilfield up to 1987. The book is recommended and can still be obtained at low cost.
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Lowson, M.H. 1963. Oil exploration at Lulworth. Petroleum, 26, (9), 345-346. [Lulworth Banks Offshore Well]

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Macalister, T. 2013.Two-pronged Shale Search in North-West. [Also briefly discusses fracking exploration in the Weald of Sussex and Surrey, southern England] Newspaper article, The Guardian Newspaper, Saturday, 27th April, 2013.
Extract (incomplete):
IGas, partly owned by a Chinese state company, is planning to drill two wells between Manchester and Liverpool in a bid to find cheap new supplies of shale gas in Britain. Locations in Surrey and Sussex [i.e. central Weald, near the Balcombe area etc, being drilled by Cuadrilla] are also considered promising by Igas as the wider industry gears up for growth after Thursday's report from the energy and climate committee urged ministers to "get on" and support fracking. ...
IGas is 20% owned by Nexen, a Canadian company which itself was bought for 18 billion dollars by the China National Offshore Oil Exploration. Nexen is also the operator of Buzzard, the UK's largest offshore oilfield...
[Andrew Austin, chief executive of IGas] said IGas had for many years bee quietly operating 100 onshore wells around the UK, including Surrey and Sussex, where there could be potential for shale extraction.
Austin said it was too early to say whether there would be a shale gas "boom" in Britain like the one in the US which sent natural gas prices plunging. "The country deserves to know whether there is something and we are ready to press forward but we need to know what we have and whether we can obtain the right kind of flow rates," he said.
What we do know is the shale is more dense per site so we should be able to recover a lot more than in the [US shale regions] Marcellus or Bakken.

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Mansell, J.C. 1967 and later edition, about 2000. Kimmeridge, Smedmore and the Bay: Guide and History with Footpath Map. Abbotsbury Press Ltd., Bournemouth, Dorset. 30 pp. with maps, colour photographs (in later edition) etc. [Booklet written by Major J.C. Mansell, owner of Smedmore Estate and Kimmeridge, with much information on the industrial history of Kimmeridge including the oil-shale, alum and salt industries.]
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Marinex Petroleum Limited. 1980. The Location of Marinex Licences in the Regnenses Basin, Southern England. Offer for Sale by Carr, Sebag & Co. Printed, semi-colour, A4 document with several useful structural and reservoir maps. Mainly concerned with Middle Jurassic prospects. 26pp. [This document refers to "Regnenses Basin" - term not in common use in geology. The Regnenses, Regni or Regini were a British Celtic kingdom and later a civitas of Roman Britain. Their capital was Noviomagus Reginorum, known today as Chichester in modern West Sussex (from Wikpedia). Incidently, the major Stockbridge Oilfield reservoir is pumped from Larkwhistle Farm and has access from and is adjacent to a Roman Road. The name is appropriate for the oilfield area of the Hampshire-Sussex border.]
[Yarnbury, 35 miles north of Wytch Farm, objectives - Jurassic gas; Humbly Grove Prospect - map 1978; Bletchingly Gas Field map, Top Corallian, south of London, Yarnbury; Rogate Prospect, a wildcat, 51 miles northeast of Wytch Farm, Jurassic Portland Sand, Corallian and Great Oolite objectives.][Shell Lockerly Borehole and Amoco Romsey [Hoe No. 1, Hoe Lane, North Baddesley] Boreholes are in the Bathonian, shale-lime facies and not in the main Middle Jurassic Reservoir facies. There is no Middle Jurassic reservoir a few miles east of Lockerly. See the map of the Hampshire Swale on p. 10 and a redrawn version in the present website here - Oil-South-of-England. Petroleum Geology of the South of England.]
[Example extract:]
Exploration History of Southern England:
The significance of recent exploration in Southern England is that from a sparsely drilled, non-producing province, a proven petroliferous basin is emerging and is being defined areally and stratigraphically. The early wells in the area were drilled on the traditional basis of surface anticlines and oil seeps, later supplemented by gravity data and relatively primitive seismic surveys. From 1895 to 1974 about forty-five exploratory bore-holes were drilled in the search for petroleum in the Regnenses Basin [Wessex Basin etc.], a density of about one well per 140 square miles, or 1 per 90,000 acres. Although only a few minor fields of apparently marginal productivity resulted - Kimmeridge, Wareham, Bletchingly and Heathfield - most of the wells encountered oil and gas shows. Many of the shows were not tested and none is known to have been adequately tested by today's standards-with acidising, fracturing and swabbing. These methods are very expensive but are justified by the continuing escalation [at that date] in oil prices.
The Regnenses Basin is of Jurassic age and includes several sub-basins which have been recognised for many years and have been given various local geographic names - the Dorset Basin of South-Western England, the Weald Basin of South-Eastern England, the Hampshire Basin of South-Central England and the loosely defined Wessex Basin: see the map on pages 14 and 15. The significance of the Regnenses Basin has been fully appreciated only within the last few years as the inter-relationship of the subbasins has become better understood. The thickest and most prospective of the petroliferous Jurassic sediments in the basin extend from Dorset (Wytch Farm and Kimmeridge oil fields) into Hampshire and along the coastal margin of Sussex, bounded on the north by two major intra-basin positive features, the Central Wessex Platform in the west and the South Downs in the east. The South Downs anticlinorium is in the optimum position to trap oil migrating northward, updip out of the deep DorsetHampshire-East Channel Area of the Regnenses Basin. This part of the Basin is the deepest, hottest, most efficient "oil kitchen" known in North-West Europe except for the North Sea's Viking Graben. The rich source beds of the Jurassic have reached the optimum thermal maturity required to generate very large quantities of oil in the "oil kitchen". Marinex's licences XL 091-095 are up dip immediately adjacent to this rich generating area. [continues]
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[Some out-of-date discussion of the famous and successful Wytch Farm Oilfield. - not repeated here.][text now continues]
Recent exploratory results prove that significant quantities of oils have been also been generated in the Wessex-Weald sub-basin, but not necessarily in the same quantities as from the Dorset-Hampshire area. Humbly Grove is over 60 miles northeast of Wytch Farm and Kimmeridge, across the arch of the South Downs - Central Wessex Platform, and on the northern edge of the Wessex sub-basin. The oil at Humbly Grove appears to be of the same type and quality as at Wytch Farm: sweet, high gravity and slightly paraffinic. Although separated in distance by over 60 miles, and in age by 70 million years the reservoirs at both fields appear to have been filled from the same Jurassic source beds. This has important implications for the other Marinex licences shown on p. 14 and 15.
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[See the double page, spread map of the Regnenses Basin, pp. 14-15, a useful map of the Hampshire Swale (showing Middle Jurassic Reservoir Facies), structural maps of Yarnbury, Rogate, Humbly Grove and Bletchingly. Directors: Alfred John Goodfellow, Dan Weldon Williams, Andrew Roger Fish, John Charles Kinard, Grapham Randall Dowson, John Herbert Walbeoffe-Wilson.]

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Markey , M. and West, I.M. 1980s. Unpublished notes regarding the gas seep at Lulworth Banks.
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Martin , N. 1992. Wytch Farm oilfield. Stratoil Magazine, No.2, 23-25.


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Mason, R. 2011. 2011. BP Shuts UK Field after Oil Leaks. Article by Rowena Mason, Thursday, 27th January 2011. The Telegraph Newspaper. Available online. With a photograph of pumps, from Alamy, and the caption: Wytch Farm has not been producing its 25,000 barrels a day since November (2010).
[A similar report was in several other newspapers; eg. see Daily Echo, Bournemouth Echo, 28th January 2011.]
Example extracts:
"The oil giant (BP) launched a review of all its pipelines at the Wytch Farm site following the incident - less than a year since its Gulf of Mexico oil leak put the company's health and safety record under scrutiny. Wytch Farm has not been producing its 25,000 barrels per day since November and the pipeline where the leak was discovered has been undergoing maintenance ever since. Robots have been sent down into all its pipes at the site to check their condition. BP did not release any public statements at the time of the leak but on Wednesday told The Telegraph that the move to shut down the field was due to "extreme caution" because of the US spill."
"BP has suffered an oil leak in the Dorset countryside late last year, causing much concern that its biggest onshore field had been shut down for the past two months.....
The oil giant launched a review of all its pipelines at the Wytch Farm site following the incident - less than a year since its Gulf of Mexico oil leak put the company's health and safety record under scrutiny. Wytch Farm has not been producing its 25,000 barrels per day since November and the pipeline where the leak was discovered has been undergoing maintenance ever since. Robots have been sent down into all its pipes at the site to check their condition. ..........
A BP spokesman said: ' ........ It was noticed when somebody observed a small amount of oil, from a pipeline encased in concrete and sand, had risen to the surface of the sand. We've replaced that section of pipe and as a precaution we are inspecting all the key pipeline down there.'
....... The Dorset leak occurred just before warnings from the Health and Safety Executive in December about corrosion [re offshore rigs]. The HSE told companies that they had become so focussed on preventing major offshore incidents that "they are neglecting general maintenance" of their oil and gas installations.
... see the full article online: search for Telegraph, Wytch Farm Oilfield.

The oilfied was shut down for about 3 months. Shortly afterwards it was sold to Perenco UK.

[Supplementary Note 2011. Old and damaged pipelines have been the source of several leaks from BP's assets in Alaska, including the serious Prudhoe Bay spill in 2006. The Aleyska pipeline, which is half-owned by BP, sprung a leak last month, shutting down production from the North Slopes and pushing up the price of oil by almost 2 dollars a barrel. The Dorset leak occurred just before warnings from the Health and Safety Executive in December about corrosion. Go to the Telegraph website for more information.]


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Mayuga, M.N. and Allen, D.R. 1970 Subsidence in the Wilmington Oil Field, Long Beach, California, U.S.A. In: Tison, L.J., Ed., Land Subsidence, International Association of Scientific Hydrology, UNESCO, pp. 66-79.
ABSTRACT The subsidence area is in the shape of an elliptical bowl superimposed on top of California's largest oil giant, the Wilmington Oil Field. The center of the bowl has subsided over 9 meters (29 feet) since 1926. Horizontal and vertical movements have caused extensive damage to wharves, pipelines, buildings, streets, bridges and oil wells necessitating costly repairs and remedial work, including the raising of land surface areas to prevent inunda-tion by the sea. Remedial costs have already exceeded US dollars lOO million. Most investigators (i) Assistant Director and (2) Subsidence Control Engineer, Department of Oil Properties, City of Long Beach, California, U.S.A. 66 Subsidence in the Wilmington oilfield, Long Beach, California, U. S. A. agreed that the withdrawal of fluids and gas and the consequent reduction of subsurface pressures in the reservoirs caused compaction in the oil zones. A massive repressurization program, by injection of salt water into the oil reservoirs, has reduced the subsidence area from approximately 50 sq. kilometers to 8 sq. kilometers. The rate of subsidence at the historic center of the bowl has been reduced from a maximum of 75 cm (28 inches) per year in 1952 to 0.0 cm (0.0 inch) in 1968. A small surface rebound has occurred in areas of heaviest water injection.
[Might this extreme American example be a warning regarding the final stage of closure of the Wytch Farm Oilfield of Dorset in many years ahead? Or will the oilfield pressure always be maintained in the Dorset, Poole Bay and Bournemouth oil field thus preventing major subsidence? The strata at Wytch Farm is not the same at Wilmington, but much older. However, note that the Sandbanks Peninsula, largely over the Wytch Farm oilfield cannot reasonably accept even very limited subsidence because it is so low in parts and much is only a short distance above to sea level. Perhaps it is reasonable to assume that the oilfield will not be depressurised at least for many years to come. See Dorset planning applications for oilfield activities for future years. Satellite images have shown only minute surface level changes around the Wytch Farm Oilfield so far. As expected the land has risen slightly around the areas where water has been injected. Nothing at all drastic has happened and there is no indication at present that any major problem will arise; the oilfield could probably remain pressured almost indefinately, should that be necessary. No specific risk is predicted here and conditions may be very different from those at Wilmington; it is mentioned only as a matter of possible future interest and no details are known and no predictions are known.]
The article is available online as a pdf file: WilmSubGC.pdf. Other related papers may be available.


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McCann , D. M.; Baria, R.; Jackson, P. D.; Green, A., 1986. Application of cross-hole seismic measurements in site investigation surveys : Geophysics, vol. 51 no. 4 p. 914-929.
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McClure, N.M, Wilkinson, D.W., Frost, D.P. and Geehan, G.W. 1995. Planning extended reach wells in Wytch Farm Field, UK. Petroleum Geoscience, 1, 115-127.
Reservoir characterization of the Sherwood Formation in the Wytch Farm Field depended on control from 48 wells, approximately half of which had been cored. Lithotypes were denned by detailed study of a near-by outcrop, where photo mosaics were mapped to establish lithotype geometry for the reservoir model. Probe permeameter measurements were taken both at outcrop and in the laboratory to supplement existing core plug data. The key to achieving an optimum well trajectory through the reservoir is appropriate definition of the kv/kh ratio. Lithological data were assimilated to derive characteristics for input to flow simulation models. These models were developed at the single-well scale and reservoir characterizations then 'up-scaled' to full-field reservoir flow models. These studies indicated that lenses of mudstone and calcrete conglomerates have a significant effect on reservoir flow characteristics. Thus, to optimize individual well performance, a trajectory at 85 degrees to 87 degrees would be more effective than a horizontal well.
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McKie, T., Aggett, J. and Hogg, A.J.C. 1998. Reservoir architecture of the upper Sherwood Sandstone, Wytch Farm field, southern England. In: Underhill, J.R. (Ed.) Development Evolution and Petroleum geology of the Wessex Basin. Geological Society Special Publication, 133, 399-406.
The Sherwood Sandstone Group reservoir in the Wytch Farm field comprises a c. 150 m thick succession of arkosic sandstones deposited in a variety of fluvial, lacustrine and aeolian depositional systems. These systems show at least three orders of facies variability, which are interpreted to be the depositional response to climatic changes. These comprise a first-order evolutionary trend over the entire Sherwood Sandstone Group from perennial braidplain to ephemeral sheetflood systems to ephemeral lacustrine conditions. This trend culminated in deposition of the Mercia Mudstone Group, and reflects a long-term waning of sand supply and increasing 'flashiness' of the fluvial system. This trend is further subdivided into second-order cycles defined by five areally widespread floodplain and lacustrine deposits containing minimal development of fluvial sandstones. These represent widespread, episodic reductions in fluvial sediment supply and rising base level during more 'humid' climatic conditions. These horizons form the basis for the reservoir layering scheme. Each floodplain episode is increasingly more mud-rich upwards through the Sherwood section, and the sand-rich fluvial packages between become systematically more ephemeral in character. Third-order cycles are defined by thin (less than 2 m), but already widespread floodplain and lacustrine horizons which are most readily identifiable in the upper half of the Sherwood section. The sandstones between these cycles are composed of aeolian and sheetflood deposits, but are incised by coarse-grained multistorey-multilateral channel deposits. The incisions are interpreted to be the result of fluvial erosion during dry climatic conditions when lake levels fell and the alluvial plain was devegetated. These incised fluvial deposits form the principal producing intervals in the upper part of the reservoir, particularly in the eastern part of the field. Higher frequency stratigraphic cycles are locally expressed by variations in ephemeral lake levels, palaeosol development and episodic development of wind-blown sand patches. At outcrop, the stratigraphically equivalent Otter Sandstone Formation (c. 100 km to the west) shows comparable evolutionary patterns, albeit with a subtly different facies make-up. The recognition of a hierarchy of climatically driven cycles within the reservoir permits high-resolution correlation and the recognition of subtle, but important, changes in sandbody geometry and connectivity within successive cycles.
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[Key papers on Weald Oilfields]

McLimans, R. K. and Videtich, P.E. 1987. Reservoir diagenesis and oil migration: Middle Jurassic Great Oolite Limestone, Wealden Basin, Southern England. In Brooks, J. and Glennie, K. 1987. Petroleum Geology of North West Europe. Graham and Trotman, London, p. 598 + viii, pp. 119-128 (9 pages).

McLimans, R.K. and Videtich, P.E. 1989. Diagenesis and Burial History of Great Oolite Limestone, Southern England. AAPG, American Association of Petroleum Geologists, vol. 73, Issue 10 (October), pp. 1195-1205, ten pages. By Roger K. McLimans and Patricia Videtich. [An open, pay for view, PDF can be purchased for 24 dollars. The full text is available to Members of the AAPG].
Abstract: Oil is produced from the Middle Jurassic Great Oolite Limestone in he western Weald basin, England. Additional production was discovered (150 STBOPD [BOPD - barrels of oil per day], 42 API [American Petroleum Institute gravity, - Light Oil > 31.1 ] at the Conoco No.1 Well at Storrington, Sussex. The Storrington discovery is of note because the porosity in reservoir grainstones and packstones is largely primary and averages 19.4 percent, the highest value yet found for the Great Oolite. Secondary porosity is of little signficance. For all the wells studied, porosity in Great Oolite grainstones and packstones ranges between 3 and 20 percent, and there is no relationship between porosity and lithology. Locally, porosity may be largely occluded by coarse calcite spar, which fluid inclusion studies show precipitated in the deep burial environment. Exploration in the Great Oolite, therefore must seek diagenetic fairways where primary porosity has been preserved.
Limestones in the producing interval of the Great Oolite at 1 Storrington contain zoned syntaxial cements, are generally high in magnesium content, and have stable isotope composition that indicate the involvement of marine waters (relatively heavy oxygen 18 isotope). Our interpretation is that the limestones were stabilized early in a mixing zone between freshwater and marine phreatic environments.
Coarse calcite spar in the Great Oolite contains aqueous and oil inclusions. The results of geothermometry studies show that the precipitation of calcite cements occurred at depth, near maximum burial and, at certain locations, was synchronous with oil migration. Inversion of the basin was a later event. The construction of burial history diagrams that incorporate fluid inclusion and maturation data shows that oil migration was during the Late Cretaceous. A distribution pattern for oil inclusions in the Great Oolite indicates migration was mainly in the western part of the basin and initially into pre-Late Cretaceous traps.

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McKie, T., Aggett, J. and Hogg, A.J.C. 1998. Reservoir architecture of the upper Sherwood Sandstone, Wytch Farm field, southern England. In: Underhill, J.R. (Ed.) Development Evolution and Petroleum geology of the Wessex Basin. Geological Society Special Publication, No. 133, 399-406. With 5 figures. By Tom McKie and co-authors
Abstract: The Sherwood Sandstone Group reservoir in the Wytch Farm field comprises about 150m. thick succession of arkosic sandstones deposited in a variety of fluvial, lacustrine and aeolian depositional systems. These systems show at least three orders of facies variability, which are interpreted to be the depositional response to climatic changes. These comprise a first-order evolutionary trend over the entire Sherwood Sandstone Group from the perenial braidplain to epheral sheetflood systems to ephemeral lacustrine conditions. This trend culminated in deposition of the Mercia Mudstone Group, and reflects a long-term waning of sand supply and increasing 'flashiness' of the fluvial system. This trend is further subdivided into second-order cycles defined by five areally widespread floodplain and lacustrine deposits containing minimal development of fluvial sandstones. These represent widespread episodic reductions in fluvial sediment supply and rising base level during more 'humid' climatic conditions. These horizons form the basis for the reservoir layering scheme. Each floodplain episode is increasingly more mud-rich upward through the Sherwood section, and the sand-rich fluvial packages become systematically more ephemeral in character. Third order cycles are defined by thin (less than 2m.) but areally widespread floodplain and lacustrine horizons which are most readily identifiable in upper half of the Sherwood section. The sandstones between these cycles are composed of aeolian and sheetflood deposits, but are incised by coarse-grained multistorey-multilateral channel deposits. The incisions are interpreted to be the result of fluvial erosion during dry climatic conditions when lake levels fell and the alluvial plane was devegetated. These incised fluvial deposits form the principal producing intervals in the upper part of the reservoir, particularly in the eastern part of the field. Higher frequency stratigraphic cycles are locallly expressed by variations in ephemeral lake levels, palaeosol development and episodic development of wind-blown sand patches. At outcrop, the stratigraphically equivalent Otter Sandstone Formation (c. 100km to the west) shows comparable evolutionary patterns, albeit with a subtly different facies make-up. The recognition of a hierarchy of climatically driven cycles within the reservoir permits high-resolution correlation and the recognition of subtle but important chances in sandbody geometry and connectivity within successive cycles.
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McMahon, N.A. and Turner, J. 1998. The documentation of a latest Jurassic - earliest Cretaceous uplift throughout southern England and adjacent shore areas. Pp. 215-240 in Underhill, J.R. (editor), Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publications, No. 133, pp. 215-240. By Neil A. McMahon (Arthur D. Little, London) and Jonathon Turner (Department of Geology and Geophysics, University of Edinburgh). [Neil McMahon, now at Kimmeridge Energy, New York City. Nov. 2016]
Abstract: The development of the Wessex Basin, Celtic Sea Basin and the Western Approaches Trough was initiated during the break-up of Pangea with active subsidence continuing throughout the Mesozoic until the basins were inverted in the Tertiary. The Mesozoic stratigraphy in these basins is characterised by a number of unconformities. In the early Cretaceous two major erosional events can be identified, one in the Berriasian and the second in the Aptian. These unconformities have a significant bearing on both the Cretaceous stratigraphy and the hydrocarbon potential in the region.
Stratigraphic data from onshore exposures in the Wessex Basin, from over 100 boreholes, and seismic data document the evolution and erosion patterns of both unconformities. The Aptian unconformity has been well documented by previous authors, and may be related to uplift associated with the commencement of sea-floor spreading in the Bay of Biscay. However, an old unconformity can be identified as Berriasian [i.e. Purbeck, Purbeckian] in age on the basis of tracing its correlative conformity using vertical and lateral facies changes and a rapid lateral increase in the thickness of the Wealden Group. The older unconformity is herein interpreted to have been formed by a latest Jurassic - earliest Cretaceous [i.e. Purbeck, Purbeckian] uplift event and can be recognised in all basins surrounding the Cornubian Platform. The areal extent of the unconformity implies that the interpreted uplift was of regional significance, centred on the Cornubian Platform, but unlike the younger Aptian event was unrelated to any specific intra-basinal extensional event or the Apto-Albian sea floor spreading in the nearby Bay of Biscay. It effects dominated Early Cretaceous sedimentation, the results of which are demonstrated by subsidence patterns within these basins.
The thermal maturity of the Lias (Early Jurassic), the main hydrocarbon source rock in the area, has been affected by the latest Jurassic - earliest Cretaceous uplift, as well as Tertiary uplift and inversion. The latest Jurassic - earliest Cretaceous uplift, as well as Tertiary uplift and inversion. The latest Jurassic - earliest Cretaceous event resulted in the erosion of much of the Jurassic succession in the basins closest to the Cornubian Platform [i.e. southwest England] and in many areas uplifted the Lias from the top of the oil window. Only on the flanks of the uplift, where high sedimentation rates occurred during the deposition of the Purbeck [Lulworth and Durlston Formations] and Wealden Beds, were source rocks buried to depths sufficient to generate hydrocarbons. Only by understanding the tectonic evolution of the latest Jurassic - earliest Cretaceous uplift can accurate play risk modelling and prediction of the hydrocarbon fairway take place.
[With acknowledgements to John Underhill and others. With a substantial reference list.]

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Miles , J.A., Downes, C.J. and Cook, S.E. 1992. The fossil oil seep in Mupe Bay, Dorset: a myth investigated. Marine and Petroleum Geology, 10, 58-70.
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Miller , R.G. 1991. A paleoceanographic approach to the Kimmeridge Clay Formation. pp. 13-26 in: Deposition of Organic Facies (ed. A.Y. Huc). Tulsa: A.A.P.G., 234p. American Association of Petroleum Geologists, Studies in Geology, 30. By Richard G. Miller.
The Kimmeridge Clay Formation is a Late Jurassic/Early Cretaceous clastic source rock which extends from offshore Norway to offshore Canada and the English Channel. It is the principal source of the North Sea oils. The base is diachronous but the top is synchronous over the North Sea. In the North Sea it is typically 150 m thick with TOC = 4-5% and HI = 350 to 450; accumulation rate was about 15 m/Ma. Deposition apparently occurred in a stratified sea. An upper layer flowed southward from the polar Boreal Ocean to Tethys at perhaps 1 km day-1, over a warm saline bottom water (WSBW). Much evidence exists for a negative water balance, but none for unusual organic productivity. Deposition of the organic-rich facies probably ceased following a slight climatic change; this produced a basin overturn, and consequently a cool, oxygenated bottom current flowing southward.
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Monk , D. 1989. Caring for the environment worldwide. Petroleum Review, vol. 43, no. 508, May 1989 pp. 248-250.
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Morgans-Bell , H.S., Coe, A.L., Hesselbo, S.P., Jenkyns, H.C., Weedon, G.P., Marshall, J.E.A., Tyson, R.V. and Williams, C.J. 2001. Integrated stratigraphy of the Kimmeridge Clay Formation (Upper Jurassic) based on exposures and boreholes in south Dorset. Geological Magazine, 138, 511-539. Abstract: For the purposes of a high-resolution multi-disciplinary study of the Upper Jurassic Kimmeridge Clay Formation, two boreholes were drilled at Swanworth Quarry and one at Metherhills, south Dorset, UK. Together, the cores represent the first complete section through the entire formation close to the type section. We present graphic logs that record the stratigraphy of the cores, and outline the complementary geophysical and analytical data sets (gamma ray, magnetic susceptibility, total organic carbon, carbonate, delta 13C org). Of particular note are the new borehole data from the lowermost part of the formation which does not crop out in the type area. Detailed logs are available for download from the Kimmeridge Drilling Project web-site at http://kimmeridge.earth.ox.ac.uk/. Of further interest is a mid-eudoxus Zone positive shift in the delta 13C org record, a feature that is also registered in Tethyan carbonate successions, suggesting that it is a regional event and may therefore be useful for correlation. The lithostratigraphy of the cores has been precisely correlated with the nearby cliff section, which has also been examined and re-described. Magnetic-susceptibility and spectral gamma-ray measurements were made at a regular spacing through the succession, and facilitate core-to-exposure correlation. The strata of the exposure and core have been subdivided into four main mudrock lithological types: (a) medium-dark-grey marl; (b) medium-dark-grey-greenish black shale; (c) dark-grey-olive-black laminated shale; (d) greyish-black-brownish-black mudstone. The sections also contain subordinate amounts of siltstone, limestone and dolostone. Comparison of the type section with the cores reveals slight lithological variation and notable thickness differences between the coeval strata. The proximity of the boreholes and different parts of the type section to the Purbeck - Isle of Wight Disturbance is proposed as a likely control on the thickness changes.
This paper is available on the internet at Integrated stratigraphy of the Kimmeridge Clay Formation (Upper Jurassic) based on exposures and boreholes in south Dorset, UK.
Detailed, large-scale graphic logs of the Swanworth and Metherhill cores and of the cliff section, with geochemical data etc. are available from the British Library Document Supply Centre as Supplementary Publication No. SUP 90490 (51) pages. They can be downloaded from the Kimmeridge Drilling Project web-site . For the coast see: Coe, A.L., Hesselbo, S.P., Jenkyns, H.C., Morgans Bell, H. and Weedon, G.P. 2001. Kimmeridge Clay Formation composite graphic log for coastal exposures, near Kimmeridge, Dorset. Part of Supplementary Publication No. SUP 90490, British Library.
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Morris , K. A. and Shepperd, C.M. 1982. The role of clay minerals in influencing porosity and permeability characteristics in the Bridport Sands of Wytch Farm, Dorset. Clay Minerals, 17, 41-54.


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Morton, A., Hounslow, M.W. and Frei, D. 2013. Heavy-mineral, mineral-chemical and zircon-age constraints on the provenance of Triassic sandstones from the Devon coast, southern Britain. Geologos, vol. 19, (2013), pp. 67-85. By Andrew Morton, Mark W. Hounslow and Dirk Frei. Available free online.
An integrated heavy-mineral, mineral-chemical and zircon-dating study of the Triassic succession exposed on the south Devon coast, in the western part of the Wessex Basin, indicates derivation from a combination of granitic and metasedimentary lithologies of ages of mostly over 550 Ma. These sources were probably located at a relatively proximal location near the southern margin of the basin. Derivation from more distal sources in the Armorican Massif or local Variscan sources to the west appears unlikely in view of the scarcity of Permo-Carboniferous (Variscan-age) zircons. The Budleigh Salterton Pebble Bed Formation was derived from a different combination of source lithologies than the Otter Sandstone Formation, the former including staurolite-grade metasediments that were absent in the catchment area of the Otter Sandstone. The Devon coast succession has provenance characteristics that differ from equivalent sandstones further east in the Wessex Basin, and from sandstones in the East Irish Sea Basin to the north. These differences indicate that sediment supply patterns to the linked Triassic basin systems in southern Britain are complex, involving multiple distinct sub-catchment areas, and that heavy-mineral studies have considerable potential for unravelling these sub-catchment area sources.

Morton, A., Knox, R. and Frei, D. 2016. Heavy mineral and zircon age constraints on provenance of the Sherwood Sandstone Group (Triassic) in the eastern Wessex Basin. Proceedings of the Geologists' Association, vol. 127, pp. 514-516. By Andrew Morton, Robert Knox and Dirk Frei.
Abstract: Heavy mineral and zircon age data demonstrate that in the Sherwood Sandstone Group of the Marchwood-1 and Southampton-1 boreholes on the eastern margin of the Wessex Basin, sediment was supplied from both the south (Variscan Highlands) and the east (recycled Old Red Sandstone). Interplay of these two sources led to a well-defined heavy mineral stratigraphy in the area. However, the Sherwood Sandstone Group in the Wytch Farm oilfield in the centre of the Wessex Basin, contains only sandstones derived from the Wessex highlands to the south and lacks significant amounts of recycles Old Red Sandstone detritus. The equivalent sandstones (Otter Sandstone Formation) on the western margin of the Wessex Basin have a different provenance to both the central and eastern parts of the basin, since they lack input from Variscan granitoids. Heavy mineral and zircon provenance data therefore demonstrate sediment input from a number of discrete source areas into the Wessex Basin during the Early and Middle Triassic, and that the "Budleighensis River" system may not have been a single river, at least in the southern Wessex Basin area. It is also evident that provenance-based correlation schemes sucha as heavy mineral analysis or whole rock geochemistry should be used with caution over long distances and require careful evaluation of lateral changes in provenance. [Keywords: Provenance, Correlation, Trias, Triassic, Wessex Basin, Zircon, Budleigh Salterton, Sherwood Sandstone, Wytch Farm Oilfield, Southampton].


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Mortimore , R. and Pomerol, B. 1997. Upper Cretaceous tectonic phases and end Cretaceous inversion in the Chalk of the Anglo-Paris Basin. Proceedings of the Geologists' Association, 108, 231-255. Abstract: Three intra-Upper Crataceous tectonic phases, Stille's Ilsede (Late Turonian-Early Coniacian), Wernigerode (Late Santonian-Early Campanian) and Riedel's Peine (latest Lower Campanian) are investigated in the Anglo-Paris Basin. Criteria for recognizing these events include field evidence of slumping, allochthonous chalks; lateral changes in thickness and lithology; seismic evidence for slump horizons; and lacunae closely related to tectonic axes. Further evidence from seismic sections indicates large-scale channel development during these phases but the spatial relationship with tectonic lineaments is more difficult to determine. Each phase rejuvenates the tectonic topography which is subsequently buried by post-tectonic facies changes, for example from Lewes to Seaford Chalk following the Ilsede tectonic phase and Culver to Portsdown Chalk, following the Peine tectonic phase. The tectonic phases are recognized along local tectonic lineaments in contrast to more widespread sea-level fluctuations. New information on the end Cretaceous inversion in the London and Anglo-Paris basins supports the recognition of a London axis of uplift where the chalk at subcrop was more deeply eroded than at outcrop. Maximum inversion in the Weald-Wessex area occurred in East Sussex along the southern margin of the Weald where the thickest chalks had previously been deposited.
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Myers , K. and Wignall, P. 1987. Understanding Jurassic organic-rich mudrocks: new concepts using gamma-ray spectrometry and palaeoecology; examples from the Kimmeridge Clay of Dorset and the Jet Rock of Yorkshire. In: Leggett, J.K. and Zuffa, G.G. (eds). 1987. Marine Clastic Sedimentology: Concepts and Case Studies. Graham and Trotman, London, 172-189.

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Navitus Bay. 2013. Proposed Navitus Bay Wind Park [Offshore Windfarm]. Phase 3 Community Consultation. February 2013. 49pp. [Inserted comments, 4th November 2016. At a later date, about 2015, the Navitus Bay Wind Park scheme was abandoned. The adverse effect that this huge scheme would have had on the view from "Jurassic Coast" as at Swanage was probably a factor. The topic was originally mentioned here mainly because the chosen site overlaped the oil and gas generation area, the central part of the Portland - Isle of Wight Basin (offshore). The originally- chosen location for northern part of the once-proposed wind farm was to be located directly over thermally mature Lower Jurassic (Lias), bituminous shales, i.e. a potentially major oilfield. Had the structures been build the windmills might have been subjected to small changes in sea-bed level and possibly minor earthquakes. This could have happened if the rich oil shale between the Isle of Wight and Durlston Head, Swanage was drilled into and then, perhaps, subjected to hydraulic fracturing (fracking). This has not happened yet (in 2016) but is expected sooner or later. Probably, many of the public would rather have the invisible fracking than a huge, ugly windfarm. They do not complain about the Wytch Farm Oilfield that has been fracking the Sherwood Reservoir south of the western part of Bournemouth for many years. There may be people in the area who are not even aware of the development and extension of the oilfield. Although it is not going to happen now, some brief information and links ren the once-proposed Navitus Windfarm is given below.]
Go to:
Petroleum-South-Portland-Wight-Basin - Navitus Wind Park Location .

The Navitus Offshore Wind Park, English Channel, Community Consultation Document for Phase 3

[p.3] "About the Project.
The proposed Nativus Bay Wind Park is an exciting 50-50 joint venture between Eneco Wind UK Ltd (Eneco)[a wind farm company, with a wind farm at Tullo, Aberdeenshire and planning another one in Scotland] and EDF Energy [a gas and electricity supplier]. At the moment, we are developing plans to build and operate an offshore wind park off the Dorset and Hampshire coasts to the west of the Isle of Wight.
Navitus Bay could produce enough clean, safe energy to power over 790,000 homes ever year, that is about nine times the number of homes in Bournemouth or 13 times the number of homes on the Isle of Wight. The the wind park could also lower harmful carbon dioxide (CO2) emissions by 1,150,000 tonnes a year.
All proposed works described in this document are subject to development consent being granted by the Secretary of State for Energy and Climate Change. The purpose of this document is to provide details of the proposed project we intend to seek development consent for and to seek feedback from the local community prior to the submission of an application for development consent. ...."[continues with "Community Consultation - Phase 3, running from 1st Feb. 2013 to 5th April 2013, and thus this part of the programme is completed.][The report discusses bats, dormice and archaeology etc, but not geology. It says nothing about the shale gas potential under at least part of the area, in spite of the fact that one of the two companies is a gas supplier. ]

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Newell, A. J. 2001. Bounding surfaces in a mixed aeolian-fluvial system. Marine and Petroleum Geology, vol. 18, no. 3, pp. 339-347.
The Dawlish Sandstone Formation is a Late Permian succession of mixed aeolian and fluvial deposits in the Wessex Basin (SW England). It is used to illustrate two contrasting types of fluvial/aeolian bounding surface (planar and incised). Planar bounding surfaces separate tabular bodies of fluvial conglomerate and aeolian dune sandstone. They were produced primarily by wind scour to groundwater table, with the later emplacement of conglomerates resulting in local fluvial erosion of cemented aeolian dune sandstones. Incised bounding surfaces were produced by fluvial downcutting. The erosive relief was infilled with mixed aeolian/fluvial deposits. The Dawlish Sandstone Formation may provide the first outcrop example of these incised valley fills, which have recently been identified as a major component of the subsurface Rotliegend in the Southern North Sea Basin. The potential variability of aeolian/fluvial sedimentary architecture has important implications for well-to-well correlation and reservoir modelling.

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Newell, A. J. 2001. Construction of a tide-dominated shelf: influence of Top Chalk topography and sediment supply. Journal of the Geological Society, vol. 158, pp. 379-390.
Abstract: Paleogene siliclastic sediments (Reading and London Clay Formations) in the Wessex Basin record and upward change through four tidally influenced depositional systems. The lowest (Reading Formation) was deposited in estuarine and coastal plain environments. The overlying London Clay records discrete upward changes from deltaic, to mixed tidal flat sandsheets ('Bagshot Sands'). Erosional topography on the top Chalk surface had an important control on deposition: (1) topographic lows controlled the initial sites of marine flooding and sedimentation; (2) lows would have acted as conduits for sediment delivery; (3) lows created additional accomodation by the compaction of thick mud fills; (4) lows may have formed preferential sites for delta growth. As topography as reduced by sediment infill, depositional units tended towards more sheet-like geometries. Heavy minerals reveal that an upward progradational/aggradational trend and the development of more sand-rich facies are related to a change in provenance towards sand-rich Cornubian sources.
[This paper contains Tertiary data from various boreholes including Christchurch Bay, Shamblehurst, Bunkers Hill, Hoe 1, Bransgore, Blashford, Christchurch, Wareham, Wilmington, Bottom Copse, etc.]

Newell , A.J. and Evans, D.J. 2011. Timing of basin inversion on the Isle of Wight: new evidence from geophysical log correlation, seismic sections and lateral facies change in the Headon Hill Formation. Proceedings of the Geologists' Association, London. Vol. 122, Issue 5, pp. 868-882. [a key paper]
By Andrew J. Newell. and David J. Evans, of the British Geological Survey, Keyworth, Nottingham.
Abstract:
Paleogene thickness patterns across the Bouldnor Syncline and Porchfield Anticline in the northwestern Isle of Wight have been deduced using outcrop information, borehole correlation, gamma-ray logs and seismic reflection data. The thickness patterns provide evidence for an early phase of basin inversion at around the Bartonian–Priabonian boundary (Late Eocene) in the Isle of Wight. Paleogene strata older than the Becton Sand Formation show little evidence for significant lateral changes in thickness, even though the boreholes are located at various structural positions around the Bouldnor Syncline and Porchfield Anticline. In contrast, both seismic reflection and borehole data provide evidence for marked thinning of Paleogene strata onto the Porchfield Anticline at around the level of the Becton Sand Formation and basal Headon Hill Formation (Totland Bay Member) which probably results from an episode of basin inversion and growth folding. The inversion event was relatively minor and short-lived and continues to point toward the main phase of the basin inversion being late Oligocene or younger. However, it still has important implications for understanding structural control on sedimentation patterns in the Headon Hill Formation, with the migration of sandy channelised depositional systems into the axis of the Bouldnor Syncline, and the sequence stratigraphic significance of the important Bartonian-Priabonian regression event, which may related to tectonics rather than global sea-level change.

Paper Outline
1. Introduction. 2. Structural framework of the IOW. 3. Existing interpretations on the timing of basin inversion. 4. Data sources. 5. Gamma-ray log; stratigraphy and evidence for thickness change in Paleogene strata. 6. Reading Formation. 7. The London Clay (lower clay-rich part). 8. London Clay (upper sand-rich part) to base Marsh Farm Formation. 9. Marsh Farm Formation. 10. Selsey Sand Formation. 11. Barton Clay Formation. 12. Becton Sand Formation. 13. Headon Hill Formation. 14. Bembridge Limestone. 15. Seismic stratigraphy and evidence for thickness change in Paleogene strata. 16. Paleogene thickness change and timing of basin inversion. 17. Conclusion. Acknowledgements. References.


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North Sea Sun Oil Company Ltd. 1983. Proposals for drilling an exploratory borehole at Bottom Copse, in the vicinity of Medina Wharf, Cowes, Isle of Wight. North Sea Sun Oil Company Ltd., John R. Lawrence Partners Ltd. 1983.

North Sea Sun Oil Company Ltd. 1984. Composite Log. Well - Lee-on-Solent, 18th March 1984. [Borehole to 6840 feet in Devonian Sandstone.]

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Norwest Energy (with subsidiary Mirrabooka) [Report of Proactive Investors (Australia)]. Go to:
Norwest Energy - main website.

Example extract:

"Exploration Strategy:
Norwest has a lean and tightly focused structure; highly prospective acreage in overlooked areas; good relationships with joint venture partners and contractors; the ability to use survey technology effectively and at relatively low cost; and a busy but achievable exploration program.
Norwest's core regions of operation - the northern Perth Basin and onshore southern England's Wessex Basin - are known petroleum provinces but are underexplored. They offer relatively low entry costs but have significant potential. The Company's regional specialisation has enabled it to build a significant body of knowledge about these basins. Information gleaned from work in one permit tends to be relevant to the Company's other permits in the same basin and operational synergies can be achieved.
Norwest has also built expertise with an underused and cost-effective exploration technology - full-tensor gravity gradiometry imaging (FTG). This technology helps deliver more geological information at a lower cost and is covered in more detail in another part of this website."

Norwest Energy gains 5 oil and gas exploration licenses in English Channel, January 04, 2012.
"Norwest Energy (ASX:NWE) has been awarded exploration licenses located in the Wessex Basin, south east of Wytch Farm oil field, previously owned by BP (NYSE: BP). Wytch Farm is reported as the largest onshore oil field in Western Europe with 500 million barrels of oil reserves and at the height of production, produced 110,000 barrels of oil per day. It still produces a handy 15,000 barrels per day. BP sold its 68% interest in Wytch Farm field in 2011 to Perenco and Premier Oil (LSE: PMO) for $610 million.
The five exploration licenses were awarded to a Norwest subsidiary (Mirrabooka) in a round of oil and gas licensing by U.K. Energy Minister Charles Hendry in late December. The blocks are located in the English Channel adjacent to Mirrabooka's two onshore licenses PEDL 238 and PEDL 239. Mirrabooka targeted these licenses based on an extensive regional study. Mirrabooka has already identified six structural leads with the geological probability of their success ranging from 15% to 32%. Geological and geophysical studies will use Mirrabooka's extensive database as well as acquiring new 2 - D seismic data. The aim is to bring these leads to drillable prospects.
Mirrabooka holds 65 percent of all five licenses and will be the operator, with Wessex Exploration Plc holding the balance..." [continues]

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Osborn, S., Vengosh, A., Warner, N.R. and Jackson, R.B. 2011. Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing. PNAS, Proceedings of the National Academy of Sciences of the United States of America. vol. 108, no. 20, pp. 8172-8176.
Directional drilling and hydraulic-fracturing technologies are dramatically increasing natural-gas extraction. In aquifers overlying the Marcellus and Utica shale formations of northeastern Pennsylvania and upstate New York, we document systematic evidence for methane contamination of drinking water associated with shale-gas extraction. In active gas-extraction areas (one or more gas wells within 1 km), average and maximum methane concentrations in drinking water wells increased in proximity to the nearest gas well and were 19.2 and 64 mg CH4 per litre (n=26), a potential explosion hazard; in contrast dissolved methane in neighbouring non-extraction sites (no gas wells within 1 km) within similar geologic formations and hydrogeologic regimes averaged only 1.1 mg per litre (P< 0.05; n = 34). Average delta 13C-CH4 values of dissolved methane in shallow groundwater were significantly less negative for active than for non-active sites (-37 plus or minus 7 per mille and -54 plus or minus 11 per mille, respectively; P < 0.0001). These delta C13 - CH4 data, coupled with the ratios of methane-to-higher chain hydrocarbons, and delta 2H - CH4 values, are consistent with deeper thermogenic methane sources such as the Marcellus and Utica shales at the active sites and matched gas geochemistry from gas wells nearby. In contrast, lower concentration samples from shallow groundwater at nonactive sites had isotopic signatures reflecting a more biogenic or mixed biogenic/thermogenic methane source. We found no evidence for contamination of drinking water samples with deep saline brines or fracturing fluids [i.e. fracking fluids]. We conclude that greater stewardship, data and - possibly - regulation are needed to ensure the future of shale-gas extraction and to improve public confidence in its use. [end of abstract]

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Pancost , R.D., Van Dongen, B.E., Esser, A., Morgans-Bell, H.S., Jenkyns, H.C. and Sinninghe Damste, J.S. 2004. Variation in organic matter composition and its impact on organic-carbon preservation in the Kimmeridge Clay Formation (Upper Jurassic, Dorset, southern England). In: Harris, N. (ed.), The Deposition of Organic Carbon-rich Sediments: Models. Mechanisms and Consequences. Special Publication of the Society of Sedimentary Geology (SEPM).
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Parfitt, M.A. and Farrimond, P. 1998. The Mupe Bay oil seep: a detailed organic geochemical study of a controversial outcrop. In: Underhill, J.R. (editor), Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publications, vol. 133, pp. 387-397.
Abstract: The oil seep in an intraformational conglomerate at Mupe Bay has attracted much interest as providing possible evidence of oil generation in the Wessex Basinby the early Cretaceous (Wealden). Previous organic geochemical studies investigating whether oils of different maturity exist in the clasts and matrix of the conglomerate have been complicated by the effects of heavy biodegradation of the oil. In this work we present detailed molecular organic geochemical data from a significantly larger suite of samples tha has been previously studied. These have been screened using a multivariate statistical approach to identify those samples which have been least influenced by biodegradation. Conventional molecular maturity parameters applied to the subset of samples which have suffered no detectable modification to their biological marker (hopane and sterane) distributions indicate that the oil in the clasts is of exactly the same maturity as that in the matrix. However, this observation does not preclude two phases of staining, although it remains to be proven that the clasts contained oil at the time of deposition.
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Parker , A. 1972. Jarosite in Wealden oil-sand from Lulworth Cove. Journal of the Geological Society, London. 128, part 3, pp. 289-290.

Parker , J.R. 1993. Petroleum Geology of Northwest Europe. Proceedings of the 4th Conference. (2 vols). Geological Society Publishing House, Bath. 1600 pp. In slipcase 9.5 cm thick. 350 authors. ISBN 0-903317-85-0.
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Pearson, R. 1903. The discovery of natural gas in Sussex: Heathfield district. Transactions of the Institute of Mining Engineers, vol. 66, (26), 494-507.[Weald area, see recent paper re possibility of gas from deep, pre-Triassic source].
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Penn , I.E., Chadwick, R.A., Holloway, S., Roberts, G., Pharaoh, T.C., Allsop, J.M., Hulbert, A.G. and Burns, I.M. 1987. Principal features of the hydrocarbon prospectivity of the Wessex-Channel Basin, UK. Pp. 109-118 in Brooks, J. and Glennie, K., Petroleum Geology of North West Europe, Graham and Trotman, London. vol. 1, 598p + xxiii,

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PERENCO UK (RE WYTCH FARM OILFIELD)

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Perenco UK. 2013. Perenco United Kingdom.
Go to their website: Perenco United Kingdom. In particular see the webpage: Wytch Farm.
(For older information about Wytch Farm see BP documents.)
Wytch Farm is Europe's largest known onshore oilfield in one of the most environmentally sensitive areas of the UK. Its operations are on the southern shores of Poole Harbour, Furzey Island, Wareham and at Kimmeridge Bay. In 1995, it won The Queens Award for Environmental Achievement. It is currently producing 16,000 barrels of oil equivalent per day (crude oil, liquid petroleum gas and gas) and employs 100 staff and 250 contractors. It is a conventional oilfield extracting oil (with some associated gas) from sandstone and limestone oil reservoirs. There is no know shale gas or coalbed methane in Perenco's licence blocks in Dorset (shown in orange) nor are there any plans to seek any such opportunities. Perenco UK Limited took over the operation of the oilfield in December 2011.

In September 2012, Perenco UK Limited applied to Dorset County Council (DCC) to extend the duration of 39 existing planning permissions for the Wytch Farm, Wareham and Kimmeridge oilfields to 2037. [This has now been approved]
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Perenco UK. 2016. Data on Wytch Farm Oil.
Go to Wytch Farm - Perenco.
[Extract]
API Gravity - 40.6.
Density - 15 degrees, kg/l
Sulphur - Wt. percent - 0.1
Nitrogen - ppm - 520
RVP kPa - 56.5
Pour point -12
TAN mgKOH/g 0.05
Viscosity 40 cSt - 7.4
Viscosity 50 cSt - 5.8
Vanadium ppm. 0.2
Nickel ppm. 0.7

CRUDE OIL CHARACTERISTICS. General Wytch Farm is a light ultra low sulfur paraffinic Crude Oil, that yields 18 % Naphtha for reforming and Mid-Distillates with good cold properties and excellent cetane index. Naphtha 29 % yield is interesting as isomerization and Reforming unit feedstock. Kerosene Good cold properties, high smoke and aniline point makes our kerosene excellent for hydro treating to produce jet fuel. Gasoil Remarkable cold properties and excellent cetane Index. VGO Wytch farm VGO can be used as fuel due to his high Heating value and remarkably low Sulfur, or as thermal fluid. Residue can be dewaxed to produce high quality Wax or can be used as Asphalt base.

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Petrowiki. 2013. Waterflood Design. A very readible webpage. Go to: Waterflood Design - Petrowiki. (deals with water injection)
Example extract:
"Waterflood design
The design of a waterflood has many phases. First, simple engineering evaluation techniques are used to determine whether the reservoir meets the minimum technical and economic criteria for a successful waterflood. If so, then more-detailed technical calculations are made. These include the full range of engineering and geoscience studies.
The geologists must develop as complete an understanding as possible of the internal character of the pay intervals and of the continuity of nonpay intervals. This preflood understanding often is limited because the injector/producer wells connectivity has not been determined quantitatively. Interference testing can provide insight into connectivity when its cost is justifiable. Data gathered from smart wells can be particularly helpful in determining connectivity in high-cost environments where there is a limited number of wellbores. Analogs also can prove useful. Otherwise, little definitive data will be available until after there has been significant fluid movement from the injectors toward the producers ..." [continues]
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Power, T.O. 1978. Gas Seepages off Anvil Point, Swanage. Triton [a diving magazine], February, 1978, No. 57. [gas bubbling up from the sea-floor off Anvil Point, Swanage, Isle of Purbeck, Dorset. This is near Durlston Head, Dorset. Note this in relationship to proposed California Quarry well of Infrastrata (opposed by the Green Party). This borehole has not been drilled by 2016. A previous borehole in the area by BP was abandoned because of loss of drilling fluid. Note also a gas seep at Lulworth Banks. This is said to be a gas seep in sea near the centre of Durlston Bay but this unconfirmed][keywords: gas, seafloor seepage, seep, Swanage, Dorset, Durlston, Anvil, borehole, oil, InfraStrata, Infrastrata].
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Providence [Oil Company]. 2006. Providence Successfully Boosts Singleton Oil Production. See: Providence Succcessfuly Boosts Single Oil Production, pdf file.
- Production exceeds original expectations.
- Consistent with Providence's stated strategy of increasing daily oil production.
Providence Resources Plc is today pleased to announce that its new X-8x production well has successfully been brought on stream in the Singleton oilfield, onshore UK. This is additional to the X-9 well, which was successfully brought on stream in December 2005. The field, in which Providence holds a 20% equity interest, is operated by Star Energy Plc and is located within the Weald Basin in the South of England. These new horizontal wells were designed to develop reserves not presently accessed by the existing revenue generating production wells. The pre-drill production objectives have now been achieved, with the average daily field production now increased by circa 200 BOPD from circa 440 BOPD to circa 640 BOPD. Whilst the two new wells were only drilled to half their planned length, they have already added approximately 50% of incremental daily oil production to the field. In addition, the Singleton Field partners are presently assessing a number of well intervention options which should further improve the performance of these new wells... [continues.] Tuesday, March 7th, 2006.

Providence [Oil Company]. 2007. Providence agrees to acquire majority stake in Singleton oil field and agrees strategic initiative for gas storage in Ireland. pdf file of this document.
"Providence, the AIM (London) and IEX (Dublin) listed oil and gas exploration and production company, today announced that it has reached conditional agreement with Star Energy Group PLC (STAR) to acquire its 79.125% share in the producing Singleton Oil Field [north of Chichester], onshore UK. Subject to regulatory approval and contract, Providence's interest in the Singleton Oil Field will therefore increase from 20% to 99.125 percent. The remaining 0.875 percent of the field is owned by Noble Resources. The principal terms of the proposed transaction are as follows:
A total cash consideration of 22 million US dollars.
Star and Providence agree a 50:50 JV on a proposed CNG (Compressed Natural Gas) Project at the Singleton site to capture the economic value of associated gas production.
Star to be given a first option to utilise the Singleton Oil Field for Gas Storage purposes in the future, working with Providence on a 50:50 basis.
Providence and Star agree to work together on future gas storage opportunities in the Republic of Ireland, again on a 50:50 basis.
Commenting on the proposed transaction, Tony O'Reilly Jnr., Chief Executive of Providence Resources P.l.c., said: "This is a pivotal transaction for Providence as it allows us the opportunity to substantially increase our daily oil production to approximately 600 BOPD (circa. 219,000 barrels per annum). This will ensure a solid operating cash flow on which to build our operations. Having owned 20% of Singleton for over 15 years, we are very comfortable with its operational parameters as well as its geological opportunities and we see upside in both these areas going forward. "We are also very pleased to continue working with Star Energy, both on the CNG Project at Singleton as well as agreeing to work together on gas storage opportunities in Ireland."

Providence. October, 2007. Singleton oil field acquisition effective. (pdf file). Providence daily production increases six fold onshore UK purchase to see Providence production hit 720 boepd. Further exploration and development potential at Singleton.
Providence Resources Plc, the AIM and IEX listed company, today confirms that it has exchanged contracts with Star Energy Group Plc for the purchase of Star's 79.125% interest in the Singleton oil field, onshore UK. As a result, Providence's beneficial interest in the Singleton Oil Field increases from 20% to 99.125%, with a corresponding increase in daily production from approx. 120 BOEPD to 600 BOEPD.....
On 2 April 2007, Providence and Star announced that they had reached conditional agreement on the deal at the Singleton Oil Field, subject to regulatory approval and contract. Providence and Star also agreed a 50:50 JV on a proposed CNG (Compressed Natural Gas) Project at the Singleton site to capture the economic value of associated gas production. Star was given a first right of refusal to use the Singleton Oil Field for Gas Storage purposes in the future, working with Providence on a 50:50 basis..
"About Singleton: The Singleton Field is located 7 km north of Chichester in the onshore licence PL 240 in the Weald Basin in the south of England. The field consists of two east west trending elongate horst blocks divided by a narrow graben. The wells produce from the Great Oolite formation, consisting predominantly of oolitic lime grainstones deposited during transgressive/regressive episodes and has been sub-divided into three members. The field has been producing since 1986. Oil is currently produced from 6 wells. Estimates of STOIIP in the Great Oolite reservoir are approximately 70 MMSTB. Cumulative recovery to 31 December 2006 was 3.37MMSTB, representing a recovery factor of 4.8%. Produced oil, at 37 API, is trucked to the Holybourne Rail terminal for sale..." [continues, with a map showing the oil wells generally trending for two or three kilometres to the south, the southeast and southwest from the well site]

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Redman , P.J. 1986. Drilling environmentally sensitive wells in Southern England. European Petroleum Conference (London), 1986, 1020, England. 457-465


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Reeves, J.W. 1948. Surface problems in the search for oil in Sussex. Proceedings of the Geologists Association, 59, 234-269. By the Reverend J. W. Reeves. [oil seepage, Weald area, example extract follows:]
I. Introduction:
A search for oil resolves itself ultimately into a geological survey, but one where the controlling factor is of commercial rather than academic interest. This gives to it a difference, not so much of method or design, but rather of emphasis. The predominant concern of the oil geologist is a successfully producing oil well, the drilling of which is noted by his Company in "cost per foot." It is upon results in drilling that he will be judged and his value assessed. He tends to think, therefore, in three dimensions rather than in two, and measurements, in structure and thickness, assume a greater significance than is usual. His search is for facts, rather than opinions, and for detailed measurements on which he can base reasonably accurate forecasts. The drawing of sections enters largely into his scheme of things, for they will be the principal aid to the drilling department. From them he tries to indicate the presence of water, oil or gas shows, the occurrence of soft beds which may cause caving and, more particularly, the position of beds hard enough and thick enough to " carry strings of casing." Generally it is on such matters that his advice will be needed and consequently it is on them that his mind is directed in the field, although, naturally, he will find much of academic interest.
In December, 1935, prospecting licences, under the Board of Trade (Petroleum Production Act, 1934) were issued to the D'Arcy Exploration Co. Ltd. over an area of some 2,200 square miles in Southern England. Special areas were selected for study and a geological survey on a 6in.-to-the-mile scale carried out by the writer. The Company has generously allowed the publication of the results, and while my grateful thanks are due to the Directors, it is important to record at the outset that its geologists do not - necessarily agree with all the opinions expressed.
In the work itself and in the assessment of the value of the areas surveyed from the point of view of commercial oil prospects, two important considerations were always kept in mind:
(1) Are there any direct indications of oil? .
(2) Are there structures of sufficient magnitude for retaining such oil in commercial quantities?

2. General Problems:
(1) Oil Indications.
Such indications are comprised in :-(i) Seepages, (ii) Asphalt, (iii) Evolutions of gas, (iv) Bituminous shales, (v) Manjak or Ozokerite, and can be divided naturally into two divisions: (A) Surface, (B) Subsurface.
(A) Surface. (i) Seepages. In Sussex itself the surface evidence for oil rests mainly on an exposure which cannot, strictly speaking, be termed a seepage. It is an outcrop of richly impregnated oilsand which outcrops at Chilley (6370601), five miles NNE. of Eastbourne. Stratigraphically it occurs at about the middle of the Tunbridge Wells Sands and was recorded as early as 1833 by Mantell [14*, p. 172-3]. The black sandy mass on analysis-by extraction with benzine - yields 12 per cent by weight and 25 per cent by volume of a black viscous oil which has a specific gravity of 0.995. Outcrops of a similar sand, though less rich in oil content, were found by geologists of the D' Arcy Exploration Company in the Hailsham district [11, p. 166].
A very small seepage, the actual point of issue was not traced, was discovered by the writer in a stream course one mile NNE. of Mark Cross (587330). This showed itself as thin films on the small pools in the stream, but gave no opportunity of collection. It occurs in the Wadhurst Clay.
(ii-v) None recorded.

(B) Subsurface or Borehole Indications.
These, which are more numerous than those at the surface, can be outlined as follows:
(i) Seepages. In the year 1874 the" First Sub-Wealden Boring" was drilled about three-quarters of a mile SW. of Mountfield Church (727197). At a depth of 602ft. and in all probability in the Kimmeridge Clay, a " hard light coloured bed, very rich in petrolleum," was passed through [6, p. 155]. From a boring put down in Worth Forest, SE. ofCrawley, about 1932, some slight" oil shows" were reported. The records of this well are still confidential.
(ii) Asphalt. None.
(iii) Evolutions of Gas. The most important" gas shows" are found in the neighbourhood of Heathfield. In the years 1894-6 wells put down in search of water encountered gas in fairly large quantities at a pressure of 150-200 lbs. per square inch. The very local nature of this gas was shown when many other borings, put down to exploit this" gas field," proved failures. The beds from which the gas was obtained are either basal Ashdown [5] or top of the Purbeck [18]. Several analyses have been recorded of which two are appended [second in brackets][27, pp. 112-13] :
Methane 93.16 (91.9)
Ethane 2.94 (-)
Nitrogen 2.90 (0.9)
Hydrogen - (7.2)
Carbon Monoxide 1.00 (-)
Such analyses, with their overwhelming percentage of methane, show it to be a " dry" gas - as distinct from a " wet" one which contains definite amounts of the higher hydrocarbons of the paraffin or kindred series-and therefore not exceptionally good as an indication of an oil reservoir at a greater depth.
The records of a boring for water at Cuckfield Workhouse (334247) give" At a depth of 195 and a half ft. a lot of gas bubbled up" and "Very hard sandrock, a lot of gas met with after passing through this, 219-223ft.'" [6, p. 82). It is not easy to decide exactly the stratigraphical position of these beds, but in all probability they belong to the Wadhurst Clay. No analyses have been recorded.
(iv) Bituminous Shales. According to Milner [18,p. 148] there is one recognisable bituminous shale bed in the well at Heathfield Station, in the Purbeck, and he also states: " At Mountfield there is some 1,200ft. of Kimmeridge Clay which contains several marked bituminous shale horizons."
(v) Manjak or Ozokerite. None. Normally one would be inclined to be pessimistic about the possibilities of any commercial venture for oil in Sussex on the indications outlined above; but if one goes outside the area stronger support is to be found. The evidence from Dorset [11], only 80 miles to the west of Sussex, shows a series of rocks from the Lower Cretaceous to the Lias, which give abundant indications of being petroliferous. To the east at Heathfield, Mountfield and Pevensey there are good, though not exceptional, indications. If between these two areas the Lower Cretaceous and Jurassic rocks were sufficiently porous, there was, at the time when the investigation began, an even chance that some of the structures might yield oil in commercial quantities. Only the drill could prove this... [continues with "Structures", including various structure contour maps and isopachyte maps].
[Oil seepages are recorded at: Chilley, (636061), Down Ash (600078), Near Hailsham Cemetary (586086), Rickney No. 4 (6222066), Near The Horns (619063).]

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Restuccia, F., Ptak, N. and Rein, G. 2017. Self-heating behavior and ignition of shale rock [re Kimmeridge oil shale]. By Francesco Restuccia, Nicolas Ptak, and Guillermo Rein, http://dx.doi.org/10.1016/j.combustflame.2016.09.025. Combustion and Flame (Journal), vol. 176, February 2017, pp. 213-219.
Open Access funded by Engineering and Physical Sciences Research Council Under a Creative Commons license.
[This paper is difficult to understand because it states that shale is a "porous sedimentary rock" and involved sampling west of the car park in Kimmeridge Bay, not at the classic Kimmeridge Blackstone or Oil Shale site, which is much further east, near Rope Lake Head. The paper does not clarify how and why oil shale was obtained in Kimmeridge Bay near the car park. There may be some explanation of how and why sampling took place here, but the matter is not discussed in the paper. It seems to indicate that there is either some error, or the paper is not explaining something to the reader. There is no detailed data given on specific bed or beds studied.]
Abstract:
The combustion of shale, a porous sedimentary rock, has been reported at times in outcrop deposits and mining piles. However, the initiating event of most of these fires is unknown. It could be that, under the right conditions, shale rock undergoes spontaneous exothermic reactions in the presence of oxygen. This work studies experimentally and for the first time the self-heating behavior of shale rock. Because shale has high inert content, novel diagnostics such as mass loss measurements and visual observation of charring are introduced to detect self-heating ignition in respect to other self-heating materials with lower inter content. Using field samples collected from the outcrop at Kimmeridge Bay (UK) and the Frank-Kamenetskii theory of ignition, we determine the effective kinetic parameters for two particle-size distributions of shale. These parameters are then used to upscale the results to geological deposits and mining piles of different thicknesses. We show that for fine particles, with diameter below 2 mm, spontaneous ignition is possible for deposits of thickness between 10.7 m and 607 m at ambient temperatures between -20 degree C and 44 degrees C. For the same ambient temperature range, the critical thickness is in excess of 30 km for deposits made of coarse particles with diameter below 17 mm. Our results indicate that shale rock is reactive, with reactivity highly dependent on particle diameter, and that self-ignition is possible for small particles in outcrops, piles or geological deposits accidentally exposed to oxygen.

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Rhys, G.H., Lott, G.K. and Calver, M.A. (Editors). 1982. The Winterborne Kingstone Borehole, Dorset, England. Institute of Geological Sciences [now British Geological Survey], Natural Environment Research Council, London, Her Majesty's Stationery Office. 196pp. with logs in pocket at the back. Includes 21 papers and a Foreword.

"Introduction:
The Winterborne Kingston borehole is situated on the southern margin of the North Dorset Downs, 19km (11.8 miles) east-north-east of Dorchester and 9.5km (5.9 miles) south-south-west of Blandford Forum (Fig.1). The National Grid reference for the borehole is [SY 8470 9796]. ... The ground elevation at the borehole site is 61m (200ft) above OD and the Rotary Table Elevation (RTE) above ground level is 4.1m (13.5ft). All depths quoted are below RTE. .. The borehole was funded by the Department of Energy (DEn) and drilled for the Institute of Geological Science [i.e. BGS] by Kenting (UK) Ltd. The borehole was drilled as a stratigraphic test and as part of DEn's programme of geothermal investigations in southern England. Drilling commenced on 30th November 1976 in Upper Cretaceous Chalk sediments beneath which were proved Lower Cretaceous, Jurassic, Triassic and a possible Permian sequence to a total depth of 3034.30m. (9982ft) below RTE.

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Roberts , D.G. 1989. Basin inversion in and around the British Isles. In: Cooper, M.A. & Williams, G.D. (eds) Inversion Tectonics . Geological Society Special Publication 44, 131-150.

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ROYAL SOCIETY :

ROYAL SOCIETY AND ROYAL ACADEMY OF ENGINEERING. 2012.
SHALE GAS EXTRACTION IN THE UK: A REVIEW OF HYDRAULIC FRACTURING ["FRACKING"].

June 2012. 75pp document, available free online as a pdf file.
Royal Society - Shale Gas Extraction in the UK: a review of hydraulic fracturing [fracking]
[This is a key publication, that provides an excellent explanation of "fracking" and how to control it and keep it in safe conditions; it is explained in plain, simple, non-technical language and has clear diagrams and is very easy to read. It is strongly recommended that the full account be read, not just the summary.]

Example extract - Summary only (p.4).

The health, safety and environmental risks associated with hydraulic fracturing (often termed "fracking") as a means to extract shale gas can be managed effectively in the UK as long as operational best practices are implemented and enforced through regulation. Hydraulic fracturing is an established technology that has been used in the oil and gas industries for many decades. The UK has 60 years experience of regulating onshore and offshore oil and gas industries. Concerns have been raised about the risk of fractures propagating from shale formations to reach overlying aquifers. The available evidence indicates that this risk is very low provided that shale gas extraction takes place at depths of many hundreds of metres or several kilometres. Geological mechanisms constrain the distances that fractures may propagate vertically. Even if communication with overlying aquifers were possible, suitable pressure conditions would still be necessary for contaminants to flow through fractures. More likely causes of possible environmental contamination include faulty wells, and leaks and spills associated with surface operations. Neither cause is unique to shale gas. Both are common to all oil and gas wells and extractive activities. Ensuring well integrity must remain the highest priority to prevent contamination. The probability of well failure is low for a single well if it is designed, constructed and abandoned according to best practice. The UK's well examination scheme was set up so that the design of offshore wells could be reviewed by independent, specialist experts. This scheme must be made fit for purpose for onshore activities. Effects of unforeseen leaks or spills can be mitigated by proper site construction and impermeable lining. Disclosure of the constituents of fracturing fluid is already mandatory in the UK. Ensuring, where possible, that chemical additives are non-hazardous would help to mitigate the impact of any leak or spill.
Concerns have also been raised about seismicity induced by hydraulic fracturing. Natural seismicity in the UK is low by world standards. On average, the UK experiences seismicity of magnitude 5 ML (felt by everyone nearby) every twenty years, and of magnitude 4 M (felt by many people) every three to four years. The UK has lived with seismicity induced by coal mining activities or the settlement of abandoned mines for a long time. British Geological Survey records indicate that coal mining-related seismicity is generally of smaller magnitude than natural seismicity and no larger than 4 ML. Seismicity induced by hydraulic fracturing is likely to be of even smaller magnitude. There is an emerging consensus that the magnitude of seismicity induced by hydraulic fracturing would be no greater than 3 ML (felt by few people and resulting in negligible, if any, surface impacts). Recent seismicity induced by hydraulic fracturing in the UK was of magnitude 2.3 M and 1.5 M (unlikely to be felt by anyone). The risk of seismicity induced by hydraulic fracturing can be reduced by traffic light monitoring systems that use real-time seismic monitoring so that operators can respond promptly. Monitoring should be carried out before, during and after shale gas operations to inform risk assessments. Methane and other contaminants in groundwater should be monitored, as well as potential leakages of methane and other gases into the atmosphere. The geology of sites should be characterised and faults identified. Monitoring data should be submitted to the UK’s regulators to manage potential hazards, inform local planning processes and address wider concerns. Monitoring of any potential leaks of methane would provide data to assess the carbon footprint of shale gas extraction.

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Ruffell, A. 1992. Early to mid-Cretaceous tectonics and unconformities of the Wessex Basin (southern England). Journal of the Geologicla Society, vol. 149, pp. 443-454.

Ruffell , A. and Shelton, R. 1999. The control of sedimentary facies by climate during phases of crustal extension: examples from the Triassic of onshore and offshore England and Northern Ireland. Journal of the Geological Society of London, 156, 779-789. [The Mercia Mudstone Group is a syn-rift phase of deposition with the fine-grained nature of the sedimentary record at this time controlled by the prevailing arid climate. The underlying Sherwood Sandstone Group is the result of fluvial deposition in conditions that were at times somewhat more humid. The Sherwood Sandstone is not syn-rift but post-rift, i.e. after a major phase of rift development, while only minor rift changes were taking place.]

Ruffell, A.H. and Wignall, P.B. 1990. Depositional trends in the Upper Jurassic - Lower Cretaceous of the southern margin of the Wessex Basin. Proceedings of the Geologists' Association, vol. 101, pp. 279-289.

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Scotchman , I.C. 1987. Relationship between clay diagenesis and organic maturation in the Kimmeridge Clay Formation, Onshore UK. In: Petroleum Geology of North West Europe (ed. by K. Brooks and J.W. Glennie), pp. 251-262.

Scotchman, I.C. 1989. Diagenesis of the Kimmeridge Clay Formation, Onshore UK. Journal of the Geological Society, London, 146, 285-303. By I.C. Scotchman, then at Department of Geology, University of Sheffield, and subsequently at Amoco (UK) Exploration Co., London.
Abstract: Study of sedimentology, carbonate geochemistry and clay mineralogy of four laterally continuous beds from the outcrop of the Kimmeridge Clay Formation indicates strong lateral variations in the depositional and early diagenetic processes, reflecting the basin and swell topography of the depositional basin. The mudstones from the swell environment with low sedimentation and subsidence rates are shelly and carbonate-rich with thin, poorly developed oil shales. They were deposited under dysaerobic conditions with consequent poor organic-matter preservation. Early diagenetic processes were limited to the sulphate reduction and methanogenesis zones with the formation of discrete horizons of concretions. The shallow burial depths attained are reflected by the immaturity of the organic matter in the mudstones although ordered illite-smectites are present. Sediments from other locations comprise black, organic-rich mudstones, the thick beds and good organic-matter preservation indicating deposition under high sedimentation and subsidence rates with anoxic bottom waters in a basinal environment. These indurated mudstones contain a few shell fragments and much pyrite, indicating intense reaction in the sulphate reduction zone. Carbonates were precipitated in the methanogenesis and decarboxylation zones as ferroan calcites and dolomites. The much greater burial depths are indicated by the higher maturity of the organic matter and by the ordered nature of the illite-smectites and the loss of kaolinite.

Scotchman, I.C. 1991. The geochemistry of concretions from the Kimmeridge Clay Formation of southern and eastern England. Sedimentology, vol. 38, pp. 79-106. [Three types of nodules - calcareous concretions, septarian calcareous concretions and pyrite/calcite concretions. Septarian - long history - early initiation, several phases of burial. Non-septarian concretions began growth in sulphate reduction zone. Pyrite/calcite concrets formed in sulphate-reduction to methanogenesis transition zone. Calcareous concretions form in swell areas and also in basin during low sedimentation rate. Pyrite/calcite concretions occur in organic rich mudstones deposited in basin under high sedimentation rates. Ferroan dolomite nodules grew under very high sedimentation rates. Curtis zones. Sulphate reduction known as SR zone, Methanogenesis is Me zone, decarboxylation zone is D zone. Due to lack of sulphate in the Me and D zone porewater carbonates are predominantly dolomitic. Nodule locations can be controlled by high organic matter horizons or biogenic carbonate. In fractures early brown cement and later white cement. Fibrous outer calcite is synchronous with septarian fracture infills. Burial history curves. Useful isotope data.]

Scotchman, I.C. 1991a. Kerogen facies and maturity of the Kimmeridge Clay in southern and eastern England. Marine and Petroleum Geology, 8, 278-295.

Scotchman, I.C. 1994. Maturity and burial history of the Kimmeridge Clay Formation, onshore UK; a biomarker study. First Break, 12, 193-202.

Scotchman, I.C. 2001. Petroleum geochemistry of the Lower and Middle Jurassic in Atlantic margin basins of Ireland and the UK. Geological Society, London, Special Publications; 2001; vol 188; p. 31-60. By Iain C. Scotchman, Statoil (UK) Ltd., Statoil House, 11a, Regent Street, London.
[Abstract]
Potential hydrocarbon source rocks of Lower and Middle Jurassic age have been reported from outcrop, shallow boreholes and exploration wells in Atlantic margin basins of the UK (Hebrides, West of Shetlands and flanking the NE Rockall Trough) and, recently, in the continuation of this trend offshore Ireland (Slyne, Erris and Porcupine basins). Previously these organic-rich mudrocks were considered to be of little economic importance, due largely to their perceived limited areal distribution and low maturity. However, recent geochemical studies of oils and shales from exploration drilling of these basins shows the Lower and Middle Jurassic to have considerable potential as effective hydrocarbon source rocks, supplanting the Late Jurassic-Early Cretaceous Kimmeridge Clay Formation equivalents as the only viable oil source rock in the region. Flanking the Atlantic margin in the Irish and UK sectors, rich oil source potential occurs in two transgressive mudrock cycles of Lower Jurassic age. These are the Sinemurian-Pliensbachian interval and the overlying Toarcian section, present in basins such as the Solan, Minch, Hebrides, Slyne, North Celtic Sea, St George's Channel and Central English Channel. The Middle Jurassic source rocks have a more limited areal distribution and occur in the Faroe-Shetland, Solan, West Lewis, West Flannan, Hebrides, Slyne and North Porcupine basins with oil source potential in regressive marginal marine to lacustrine facies mudrocks. Geochemical studies were undertaken on mudrocks from the Lower and Middle Jurassic sections in Atlantic margin basins (outcrop, shallow borehole core and exploration well cores and cuttings samples) and on oils from drill stem test and shows (core and cuttings extracts). Detailed analyses using GC, GC-MS and carbon isotopes allowed both characterization of the source rocks and oil-to-source correlation. Biomarker and carbon isotope studies of oils from the Faroe-Shetland Basin (Foinaven and Schiehallion fields), the Porcupine Basin (Connemara accumulation), the Wessex Basin (Wytch Farm and Kimmeridge oil fields) and wells in the Slyne Basin show strong correlations to the various source rock developments in the Lower and Middle Jurassic. The mixed biodegraded Foinaven and Schiehallion oils have a major waxy component and correlate with lacustrine Middle Jurassic source rocks in the Solan and West Lewis/West Flannan basins. Middle Jurassic sourcing of the Connemara oils is also suggested, while oils in the Slyne Basin appear to have been largely sourced by the Lower Jurassic Pabba Shale Formation. Oils in the Wessex Basin (Wytch Farm and Kimmeridge) appear to have been sourced by Hettangian-Sinemurian mudrocks and those in the North Celtic Sea Basin by Toarcian source rocks. The results from this study, in combination with previously published data, show that rich, effective oil-prone source rocks occur in both the Lower and Middle Jurassic of the Atlantic margin basins offshore Ireland and the UK. These source rocks can be correlated with indigenous oils, indicating the existence of a previously under-evaluated petroleum system.

Scotchman, I.C., Carr, A.D., Astin, T.R. and Kelly, J. 2002. Pore fluid evolution in the Kimmeridge Clay Formation of the UK Outer Moray Firth: implications for sandstone diagenesis. Marine and Petroleum Geology, 19, (3), 247-273. Abstract: Carbonate concretions in Upper Jurassic Kimmeridge Clay Formation from three overpressured wells provide a detailed record of pore fluid evolution in the Outer Moray Firth/Northern Central Graben. The concretions contain multiple generations of septarian cements, with morphologies ranging from simple cracks to complex fractures. Discrepancy exists between diagenetic studies, which indicate these concretions formed during the initial 1¯1.5 km of burial and palaeotemperature predictions, based on a thermal history calibrated from the vitrinite reflectance kinetic model, which indicate formation at much greater depths of between 1.5 and 2.5 km. Modelling undertaken for this study indicate that the concretions formed during the initial stages of burial under high heat flows, fitting the early diagenetic model for their formation. These conclusions have important implications for understanding the cementation of adjacent sandstone reservoirs where cement sequences have similar mineralogy and isotopic compositions, with precipitation in the same temperature range from mudrock derived pore fluids. Early cementation of these sandstones is implied by analogy with the mudrock concretions. [A diagram shows the isotopic data on the Kimmeridge dolomites of Dorset in relation to the new Kimmeridge North Sea data. ]. The paper is available in full on the Internet at Science Direct, but an id and password may be needed.
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Scott, J. and Colter, V.S. 1987. Geological aspects of current onshore Great Britain exploration plays. Pp. 95-107 in Brooks, J. and Glennie, K. (eds.), Petroleum Geology of North West Europe, Graham and Trotman, London.

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SELLEY


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Selley, R.C. 2012. UK shale gas: The story so far. By Richard C. Selley, Department of Earth Science and Engineering, Imperial College, London SW7 2AZ, UK. Marine and Petroleum Geology, vol. 31, (2012), pp. 100-109.
Available online:
Selley, R.C. 2012. UK Shale Gas: The Story So Far.
Abstract:
The UK's first well to encounter shale gas was drilled into the Upper Jurassic Kimmeridge Clay in 1875, but its significance was not realised at the time. 25 years ago research at Imperial College applied the US shale gas paradigm to evaluate the UK's shale gas potential. Shale sequences with potential for gas production were identified in Carboniferous strata in the Midlands, and in Jurassic strata, particularly in the Weald. Without encouragement from Her Majesty's Government no exploration resulted from this initial research. Publication of the results of the project was rejected by many UK journals. It was finally published in the USA in 1987. Subsequent evaluations of UK petroleum resources by the Department of Energy and its descendants published in 2001 and 2003 omitted any mention of shale gas resources. Recent timely re-evaluations of the UK's shale gas potential have been carried out by the British Geological Survey and the Department for Energy & Climate Change. In 2008 the 13th Round of Onshore Licensing resulted in the award of several blocks for shale gas exploration, though bids were often based on a quest for both shale gas and conventional prospects. Cuadrilla Resource's Preese Hall No. 1 well drilled in 2010 was the first well drilled to specifically test for UK shale gas. The same drilling and fracturing techniques that led to the shale gas renaissance in the USA are now being applied to extracting oil from organic-rich shales that are currently in the oil window. It is interesting to speculate that oil may be produced by such techniques from the thermally mature Jurassic shales in the Wessex and Weald basins in the southern UK.


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Selley, R.C. and Stoneley, R. 1987. Petroleum habitat in south Dorset. Pp. 139-148 in: Brooks, J. and Glennie, K. (eds.), Petroleum Geology of North West Europe. Graham and Trotman. Abstract: An analysis of the surface geology and of surface and subsurface petroleum occurrences is used to unravel the complex history of the generation, migration and entrapment of oil in south Dorset. Early basin subsidence lead to growthfaults downthrown to the south. Field evidence suggests that the Purbeck - Isle of Wight disturbance controlled the deformation of the Broken Beds of the Purbeck Beds, and that these brecciated down the northern limb of a rollover anticline. This fault also appears to have controlled sedimentation in a Wealden palaeovalley. Liassic shales began to generate oil in the Early Cretaceous. Some oil escaped up faults to the surface, generating the Mupe Bay palaeoseep, but much was trapped in the Briport Sands. By the end of the Cretaceous, oil was migrating north across the Purbeck - Isle of Wight flexure. Inversion through the Tertiary sealed the faults, trapping petroleum in Wytch Farm and adjacent traps. Palaeogene uplift and cooling allowed the development of the fault-sealed Kimmeridge Bay underpressured system. Adjacent fault blocks to the north and south may still be petroliferous at deeper levels.
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Selley , R.C. and Stoneley, R. 1983. A Field Guide to the Petroleum Geology of the Wessex Basin. Post-Congress Tour C, 3-9th September, 1983. The World Petroleum Jubilee Congress, 1983. 27 pp.

Selley, R.C. and Stoneley, R. 1987. Petroleum habitat in south Dorset. Pp. 139-148 in: Brooks, J. and Glennie, K. (eds.), Petroleum Geology of North West Europe. Graham and Trotman. Abstract: An analysis of the surface geology and of surface and subsurface petroleum occurrences is used to unravel the complex history of the generation, migration and entrapment of oil in south Dorset. Early basin subsidence led to growth faults downthrown to the south. Field evidence suggests that the Purbeck - Isle of Wight disturbance controlled the deformation of the Broken Beds of the Purbeck Beds, and that these brecciated limestones slid northwards towards the fault down the northern limb of a rollover anticline. This fault also appears to have controlled sedimentation in a Wealden palaeovalley. Liassic shales began to generate oil in the Early Cretaceous. Some oil escaped up faults to the surface, generating the Mupe Bay palaeoseep, but much was trapped in the Briport Sands. By the end of the Cretaceous, oil was migrating north across the Purbeck - Isle of Wight flexure. Inversion through the Tertiary sealed the faults, trapping petroleum in Wytch Farm and adjacent traps. Palaeogene uplift and cooling allowed the development of the fault-sealed Kimmeridge Bay underpressured system. Adjacent fault blocks to the north and south may still be petroliferous at deeper levels.

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Selley, R. C. 2012. UK shale gas: The story so far. Marine and Petroleum Geology, vol. 31, Issue 1, March 2012, pp. 100-109. Insights into Shale Gas Exploration and Exploitation. By Richard C. Selley, Department of Earth Science & Engineering, Imperial College, London SW7 2AZ, UK.
Abstract:
The UK's first well to encounter shale gas was drilled into the Upper Jurassic Kimmeridge Clay in 1875, but its significance was not realised at the time. 25 years ago research at Imperial College applied the US shale gas paradigm to evaluate the UK's shale gas potential. Shale sequences with potential for gas production were identified in Carboniferous strata in the Midlands, and in Jurassic strata, particularly in the Weald. Without encouragement from Her Majesty' s Government no exploration resulted from this initial research. Publication of the results of the project was rejected by many UK journals. It was finally published in the USA in 1987. Subsequent evaluations of UK petroleum resources by the Department of Energy and its descendants published in 2001 and 2003 omitted any mention of shale gas resources. Recent timely re-evaluations of the UK's shale gas potential have been carried out by the British Geological Survey and the Department for Energy and Climate Change. In 2008 the 13th Round of Onshore Licensing resulted in the award of several blocks for shale gas exploration, though bids were often based on a quest for both shale gas and conventional prospects. Cuadrilla Resource' s Preese Hall No. 1 well drilled in 2010 was the first well drilled to specifically test for UK shale gas. The same drilling and fracturing techniques that led to the shale gas renaissance in the USA are now being applied to extracting oil from organic-rich shales that are currently in the oil window. It is interesting to speculate that oil may be produced by such techniques from the thermally mature Jurassic shales in the Wessex and Weald basins in the southern UK.
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SELLWOOD

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The late Professor Bruce W. Sellwood, of the former Department of Geology, and then Postgraduate Institute for Sedimentology, Reading University; specialist on petroleum sedimentology of the Great Oolite, Middle Jurassic, and other sedimentological topics.

Sellwood, B.W. The late Professor Bruce Sellwood of the Postgraduate Institute for Sedimentology, Reading University, Berkshire, England. Jurassic sedimentologist and petroleum geologist.

Sellwood, B.W., Scott, J., Mikkelsen, P. and Akroyd, P. 1985. Stratigraphy and sedimentology of the Great Oolite Group in the Humbly Grove Oilfield, Hampshire. Marine and Petroleum Geology, vol. 2, February, 1985, pp. 44-55.
Abstract:
The main reservoir of the Humbly Grove Oilfield comprises variably dolomitic grainstones and packstones representing the Bathonian Great Oolite Group. The Bathonian sequence commences in Lower Fuller's Earth claystones which coarsen upwards into oncolitic claystones and skeletal packstones probably equivalent to the Fuller's Earth Rock. Above is a variable succession of wackestones and thin packstones which have a distinctive sandstone at their base. This sequence is named here the Hester's Copse Formation. The succeeding Great Oolite Limestone is predominantly oolitic and cross-bedded on a variety of scales. It exhibits both coarsening and fining sequences which have locally well-developed capping hardgrounds and burrowed horizons. The Great Oolite Limestone is subdivided into three Members: the lowest (the Humbly Grove Member). and the highest (the Herriard Member) begin with massive shoal oolite deposition, but each then pass upward into more interbedded sequences representing a more transgressive environment. The middle member (the Hoddington) IS a thin but widely correlatable wackestone. The overlying Forest Marble commences abruptly in claystones, but there is an upward increase in both the incidence and thickness of discrete oolitic limestones. Both the Great Oolite Limestone and Forest Marble were affected by early fresh-water dissolution and cementation in addition to the localized development of submarine cements. The top of the Great Oolite Group is represented by the Cornbrash. The Lower Cornbrash is a thin micritic limestone while the Upper Cornbrash is a calcareous claystone which passes upwards into the Kellaways Clay. The Bathonian sequence overlies the dolomitic limestones of the Inferior Oolite, the Lower Fuller's Earth claystones being interpreted as a basinal marine mudstone sequence, marking a substantial deepening and transgressive phase at the opening of the Bathonian. These mudstones shoal upwards into the quiet, but photic, water deposits of the Fuller's Earth Rock. The Hester's Copse Formation represents the temporary development of wave-dominated terrigenous shoreface and lagoonal conditions. Renewed transgression established a high-energy, tide-dominated, carbonate shelf upon which the Great Oolite Limestone was deposited as a series of shoal oolites, channels, tidal deltas and splll-overs. Periodic exposure of the carbonate sand-bodies led to the production of early dissolutional and cementation fabrics that post-date (and largely obliterate) submarine cements. The Forest Marble opened with a further phase of deepening, and the temporary establishment of muddy facies. Subsequently discrete tide-dominated ridges and linear channelized oolitic sands prograded into the area. The latest Bathonian is marked by subsidence of the carbonate ramp to the south of the London Platform, the Cornbrash-Kellaways Clay sequence accumulating under progressively deepening waters.

Sellwood, B.W., Scott, J., James, B., Evans, R. and Marshall, J. 1987. Regional significance of "dedolomitization" [or dedolomitisation] in Great Oolite reservoir facies of Southern England. In: Brooks, J. and Glennie, K. Petroleum Geology of North West Europe. Graham and Trotman, London, p.598 + viii, pp. 129-137.
Abstract:
The Great Oolite in the subsurface is often extensively dolomitized. Dolomite occurs in two forms: (1) as finely crystalline rhombs replacing original micrite; and (2) as weakly ferroan saddle (or 'baroque' dolomite).
Saddle dolomite occurs within primary pores, secondary inter- and intragranulare pores, as intergranular displacive crystals, within fractures and locally replacing ooids and ferroan calcite cements. Microrhombic dolomite represents an early phase of mixing zone dolomitization. Saddle dolomite was emplaced at a late stage during deeper burial and at temperatures well in excess of 55 degrees centigrade. Saddle dolomite precipitated from ferroan waters derived from compacting shales within deeper parts of the basins. Saddle dolomite is frequently replaced (both partially and wholly) by mildly ferroan calcite ('dedolomitization'). Relics of saddle dolomiteare concentrated along stylolites protected by films of bitumen from calcitization. Calcitization of dolomite could have been triggered by meteoric recharge in the Great Oolite leading to a deep-seated water-drive.
After deposition and early diagenesis the Great Oolite was onlapped by a later Jurassic sequence dominated by shales. The Great Oolite is not likely to have acted as an aquifer until the Early Cretaceous when it was re-exposed along the southern flanks of the London-Brabant Massif, and in the Cotswolds. It was subsequently onlapped during the later Cretaceous only being re-exhumed along the Cotswold belt during the Mid-Cenozoic.
[The data base for this study was a large number of wells by Carless Exploration Limited and from older released wells. For confidentiallity reasons well location are not given.

Sellwood, B.W., Scott, J. and Lung, 1986. Mesozoic basin evolution in southern Britain. Proceedings of the Geologists' Association, vol. 97, pp. 259-289.
Sellwood, B.W., Scott, J. and Lunn, G. Mesozoic basin evolution in Southern England. Proceedings of the Geologists' Association, vol. 97, part 3, pp. 259-289. By Professor Bruce Sellwood and others. Basin evolution is illustrated as a series of structural contour maps, isopachyte maps and cross-sections based upon data from more than 80 boreholes. The maps illustrate the basinal geometry for individual rock units and thus compliment existing accounts that are largely based on time-stratigraphic units.
Note: For those interested in, say, Great Oolite thicknesses in Sussex, or Sherwood Sandstone thicknesses for example this provides reasonably good overall views. Some boreholes in the western Weald, however, had not been drilled by this date, so rather greater thicknesses than would now be expected may be present for some areas. This is mainly just a matter of detail though.

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Shabesteri, G. M., Worden, R.H and Marshall, J.D. 2009. Source of cement in the Great Oolite Reservoir, Storrington Oil Field, [Sussex] Weald Basin, South of England. Journal of Sciences, Islamic Republic of Iran, vol. 20 (part 1), pp. 41-53, 2009. First author - G. Mirab Shabestari, Department of Geology, Faculty of Sciences, University of Birjand, Birjand, Islamic Republic of Iran. [thanks to Professor John Marshall, Southampton University for copy of this paper.]
Abstract: The source of cement in oilfields is critical to the prediction of the distribution of cements in the reservoirs and also prediction of reservoir quality. The source of mineral forming cements has been determined for the Storrington oolitic carbonate reservoir (Middle Jurassic Great Oolite Formation, Weald Basin, onshore UK) using a combination of petrography, electron microscopy, fluid inclusion analysis, atomic absorption spectrometry and stable isotopes analysis techniques. Petrographic interpretations revealed that the ferroan calcite cement is the most significant diagenetic mineral and has a major control on reservoir quality. The preferred conclusion from this study is that the Great Oolite reservoir has acted as a closed system during early diagenesis and has performed as an open system during burial diagenesis. Also, elements for burial diagenetic cements have been sourced from neighbouring formations. Finally, stable isotopes analysis demonstrated that the dominant source of carbon in the Great Oolite reservoir is marine and derived from the rock itself.
[I have a copy of the full paper. It may relevant as a rough guide to other Great Oolite borehole locations, such as Markwells Wood, Sussex (a subject of discussion in 2017) where acidization might take place.].
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Shaw, D.T. and Roberts, J.D.M. 2009. An Independent Assessment of Wessex Exploration plc. Woodfall Consulting Ltd. and D'Orange Ltd., pp. 5-10.


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Shephard-Thorn, E.R. [British Geological Survey] 1998. Geology of the Country around Ramsgate and Dover. Memoir for the 1:50,000 geological sheets 274 and 290 (England and Wales). British Geological Survey, London, Her Majesty's Stationery Office. 49 pp. Contributors: Bisson, G., Harding, P.E., Warren, S., Hughes, M.J., Mitchell, M., Wood, C.J., Dangerfield, J., Strong, G.E., Wheatley, C.W. and Howells, E.A.
This memoir is relevant to petroleum geology, because it shows and discusses the subcrop of the Coal Measures of the Kent Coalfield. This old coalfield might yield coal mine methane, coal bed methane and provide targets for hydraulic fracturing ("fracking"). Beneath the Coal Measures the Dinantian Carboniferous Limestone has been proved in several borehole. It is of interest that some limestone have small drusy cavities lined by sparry calcite, with apparently oily inclusions. Note that there are many oilfields and some gas fields in the Westphalian (Coal Measures) of the East Midlands on the north side of the London-Brabant Massif. Welton Oilfield is the third largest oilfield onshore in the UK, after Wytch Farm, the largest, and Stockbridge, the second largest. By analogy, some oil in addition to gas might be discovered in the Kent coalfield.
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Shell U.K. Ltd. 1982. Lyndhurst - Denny Lodge Borehole etc. Unpublished Xerox copies of maps and structures. [New Forest, Hampshire].


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Smith A.J. and Curry, D. 1975. The structure and evolution of the English Channel. Philosophical Transactions of the Royal Society of London, A279, pp. 3-20. Geology Department, University College London, Gower St., Londow WC1E 6BT. By A.J. Smith and Professor Dennis Curry.
The Channel consists of three distinct provinces each characterised by its own geological style. The Western Province has rocks ranging in age from Lower Palaeozoic to Miocene with marked unconformities beneath the Upper Cretaceous and the Eocene strata. A major tectonic feature is a line of faults extending east-northeast up Channel. The Central Province is dominated by three fault or monoclinal structures and has rocks ranging from Jurassic to Eocene age. The Eastern Province is a relatively stable area dominated by a Tertiary syncline and a continuation of the Wealden anticline. Events related to the development of Ocean crust in Permian times are believed to have caused basic igneous activity, rifting and crustal thinning in the Western Channel and these factors and the subsequent opening of the Atlantic exerted a control over the develment of the Channel. Alpine tectonism led to renewned movement on some structures. Folds are thought to be surface expression of movement on old fault planes. The importance of a tectonic line between the Isle of Wight and nothern France is emphasised.
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Smith, C. and Hatton, I.R. 1998. Inversion tectonics in the Lyme Bay - West Dorset are of the Wessex Basin. In Underhil, J.R. (editor). Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publication, vol. 133, pp. 267-281. By C. Smith, Imperial College, London and I.R. Hatton, Kerr-McGee Oil (UK), London.
Abstract:
Inversion in Lyme Bay and West Dorset was characterised by the reversal of motion on major Jurassic faults, and regional uplift which resulted in the widespread loss of the mid-Cretaceous to Tertiary post-rift cover throughout the area. North-south contraction during the Tertiary resulted in the development of a major anticline in the hanging wall of the Lyme - Portland faults, which was accompanied by widespread folding within the footwall of these faults. Northeast-southwest sinistral and northwest-southeast dextral strike-slip faults were also developed throughout the Lyme Bay - West Dorset area and accomodated much of the north-south contraction. These features are considered to be a consequence of the mechanical effects of an extensive salt interval within the Triassic Mercia Mudstone Group of this area. Major Early Jurassic faults appear to have been directly linked with basement through the salt interval, although smaller faults within the footwall completely detached on this horizon. The major faults were inverted in a complex manner during the Tertiary, commencing with simple reversal of motion on these faults, followed by the detachment of the post-salt carapace as the footwall and hanging wall salt layers were brought into close proximity, thereby resulting in the widespread deformation observed in the footwall of these faults.


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Smith , G.S. and Hogg, A.J.C. 1997. Integrating static and dynamic data to enhance extended reach well design. Congress on reservoir engineering : San Antonio TX, 5-8 October 1997, SPE annual technical conference, San Antonio TX , USA, 1997, pp. 347-358. (Smith and Hogg, from BP Exploration Operating Company Ltd.)
Abstract:
Development of the offshore extension of the 700 mmSTB Sherwood reservoir, Wytch Farm Field, Dorset, UK, commenced in 1993 with 4 to 6 km extended reach (ERD) wells drilled from an onshore site. Initial focus was on reserves from the Central Horst where oil columns of 70 to 100 m thickness were anticipated. Ability to reach 8 km departure was soon demonstrated, giving access to the eastern rim. However this required wells to be aimed at targets often less than 50 m thick in the more layered Upper Sherwood. Reservoir sections of up to 2.3 km have been drilled, often developing two geological targets via one wellbore. Optimal trajectory design must consider reach, directional control, cross-cutting of different producing layers and later well interventions. RFT measurements have been made at 250 locations in 10 wells at departures up to 7400 m, and production logs have been acquired in two wells. These dynamic data, together with 21 km of formation evaluation logs obtained whilst drilling, reveal that although the reservoir is layered and faulted, it is not compartmentalised. This aids oil recovery, but also presents a threat of water ingress by upwards movement of the oil-water contact and along open fault planes. Such understanding of fluid flow and recovery mechanisms has been used to refine trajectory and completion design in the Upper Sherwood. Combined with uncertainty analysis of reservoir structure and quality, a simple tool has been developed to evaluate reserves associated with a given trajectory, and convey reservoir risk across disciplines. The result has been a clear demonstration of the value of surveillance data, and a strategy aimed at maximising length of productive wellbore whilst minimising trajectory complexity.

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Smythe, D. 2013. Critiques of Cuadrilla's Plans and Proposals for Drilling near Balcombe, West Sussex. Original Version. PDF file by Professor David Smythe, Emeritus Professor of Geophysics, University of Glasgow, August 2013. To find the file search for: "Cuadrilla Smythe Balcombe". You will then obtain a reference from Google from which you can download the file (cuadrilla sussex critique.pdf).

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Smythe, D. 2014. Critique of Cuadrilla's Plans and Proposals for Drilling near Balcombe, West Sussex. 19th July 2014 Update, Version 2. This is a PDF slideshow, 15pp including the title page, previously used for a lecture at Lewes and since updated. It can be downloaded from the Website given below:
David Smythe - Fracking and Faulting: the Weald .

Example extract from the webpage:

"Introduction
A number of small oil and gas fields were found around the fringes of the Weald basin in the 1980s. Following a fallow period of some 25 years in which there was little interest, the Weald has again become the target of licence applications and exploration, since about 2009. This renewed interest is undoubtedly due to the possibility of exploitation of unconventional hydrocarbon resources in the central, geologically low part of the basin. There are two small companies currently active in this part of the Weald, Cuadrilla Resources and Celtique Energie.

The Weald
Cuadrilla Resources Limited
In August 2013 I prepared a pdf slideshow, since revised in the light of the completion of Cuadrilla's drilling at Balcombe in September 2013, discussing the technical problems. The company appears to have considerably altered its plans as to what rock type it is targeting, and whether or not fracking will be employed.
Celtique Energie
In 2013 Celtique Energie applied to drill two wells in the Weald, one in each of its licences PEDL231 and PEDL234. Although the wells are claimed to be in pursuit of conventional resources that it has recognised, the letter from Celtique to DECC, dated 15 December 2011 and obtained under Freedom of Information, proves otherwise.
I submitted a revised technical objection in June 2014 to Celtique's application to drill at Wisborough Green in PEDL234. It replaces a version submitted in October 2013. Related to this, I prepared a very short slideshow for the West Sussex County Council (WSCC) planning committee meeting on 22 July 2014." .... continues.

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Sniffer - Scotland and Northern Island Forum for Environmental Research. 2004. Phase I Identification and assessment of alternative disposal options for radioactive oilfield wastes [NORM]. September 2004. [may be out-of-date]
Example extract regarding NORM [Naturally Occurring Radioactive Materials, in oilwells]:
"The low level radioactivity present in oilfield wastes (and subject to regulation) is due to the presence of naturally occurring radionuclides. These are derived from decay of Uranium and Thorium isotopes (238U and 232Th) present throughout the earths crust. These have long half-lives and have been present since the formation of the earth (primordial nuclides). Although the 238U and 232Th are relatively immobile and remain in the subsurface their daughter nuclides are more mobile and are unavoidably extracted from the reservoir with produced hydrocarbons and water. They are subsequently deposited in oil and gas production and processing facilities from where they have to be removed either by onshore decontamination or discharge to sea as scale, sludge and in produced water."
[extract from Sniffer (2004) re the NORM - naturally occurring radioactive materials, well-known to be present in the Wytch Farm Oilfield, Dorset and contaminating pipes and pumps. , The NORM is radioactive minerals occurring mainly in the Triassic strata, the Sherwood Sandstone Reservoir, the main reservoir. Note also that uranium nodules are present at the surface and can be seen and investigated in Triassic strata at Littleham Cove, Budleigh Salterton, Devon - see the appropriate, associated webpage - Budleigh Salterton. There are also some radioactive minerals in certain deep boreholes into the Permo-Trias in southeast England]
[Extract: "A well-known exception to this is the NORM found at Wytch Farm [Dorset] onshore oil field where the predominant NORM type is thin metallic coatings of 210Pb [lead] and 210Po [polonium][Polonium was discovered in 1898 by Marie and Pierre Curie - polonium's intense radioactivity makes it dangerously toxic, but it has a short half life; it is associated with uranium ores - Wikipedia; uranium nodules occur in the Trias of Devon and probably in Triassic strata elsewhere. The Wytch Farm [Dorset] oilfield has a main reservoir in the Triassic Sherwood Sandstone]. Very little radium isotope containing scale is found although there is plenty of produced water. Worden et al. (2000) reports that the formation water from the reservoir has a high 238U content, up to 70 ppm. and is therefore rich in 238U daughters. It also has high sulphate levels and very low barium content so that any 226 Radium will precipitate out as barite with radium sulphate and not remain in the produced water. However, the waters are undersaturated with respect to PbS. Therefore 210Pb will remain in solution in the produced water and be deposited in downhole and processing equipment. Some high activity values (1000 Bq/g) are recorded from these tubulars."
[p.44,] - 4.8.1 Wytch Farm Gathering Station.
Wytch Farm in Dorset, operated by BP [but now by Perenco UK], is the only major onshore field in the UK and well known and documented NORM. It is the only field to produce the thin metallic 210Pb and 210Po [polonium] containing deposits that are more normally associated with gas condensate production. It is the only onshore field with reported NORM disposals. Until recently NORM was disposed of under authorisation by re-injection on site. NORM disposal is now onshore from a cleaning facility at Winfrith. Waste is to be supercompacted and sent to Drigg with a small amount (2 percent) disposed of to sea via the existing Winfrith sea outfall. [In 1959, a six mile dual core pipeland was laid across the Dorset countryside, from the newly constructed Atomic Energy Authority site on Winfrith Heath to a point two miles out at sea off Arish Mell. The core of the pipe was used to discharge radioactive effluent from Winfrith AEA to sea. It is not known to the writer whether this pipe still exists; it may or may not. ]
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Spencer , A.M. 1991. Generation, Accumulation and Production of Europe's Hydrocarbons. Special Publication of the European Association of Petroleum Geoscientists. Oxford University Press. 476p.
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StarEnergy. 2011. See the StarEnergy Website - Humbly Grove. Text with photographs.
"We have already built a successful 10-billion cubic feet gas storage facility at our Humbly Grove oilfield near Alton in Hampshire. The store operates by taking natural gas from the national transmission system (NTS), operated by National Grid Gas plc, at Barton Stacey through a 17-mile pipeline to the Humbly Grove oilfield. The gas is then pumped into the reservoir for storage. During periods of high demand, the gas is returned to the NTS after processing.
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Stockopedia. 2011. Northern Petroleum and Egdon Resources boosted by Markwells Wood oil success. www.stockopedia.co.uk/content/northern petroleum and egdon....
Online at: Stockopedia - Northern Petroleum and Egdon Resources boosted by Markwells Wood oil success.
"The presence of live oil was observed when the 30 feet of core was extracted from the well. Initial analysis of the logs indicates the well, which was deviated at an an inclination of approximately 56 degrees through the Great Oolite penetrated a gross hydrocarbon bearing interval of 275 feet with a calculated net reservoir of 192 feet with an average porosity of 13 - 14 percent, a typical porosity value for this reservoir in the nearby fields in the same formation. The top of the Great Oolite was encountered 51 feet low to prognosis and the Great Oolite vertical thickness was 146 feet compared to a prognosis of 240 feet."
[Notes: Drilling logs had confirmed that the entire Great Oolite drilled reservoir sequence in the well is oil-bearing. Nine metres (30ft) of core was extracted. The gross hydrocarbon-bearing interval in the well was 83.8 metres (275 ft) but the well was deviated at approximately 56 degrees. Net reservoir was 58 m (192 ft), but remember that this is in the very deviated well. Of broader significance it should be noted that the vertical thickness of the Great Oolite was found to be 44.5 m (146 ft), compared to a prognosis of 73 m (240 ft). This is low for the area. See the Great Oolite isopach map in Sellwood et al., 1985. The average porosity was found to be 12 to 13 percent which is typical for this reservoir in the nearby fields in the same formation. Expected production rates will be determined in a future test programme.]
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Stoneley , R.C. 1982. The structural development of the Wessex Basin. Journal of the Geological Society, London vol. 139, pp. 545-552. With Discussion, pp. 552-554. By Professor Robert Stonely, 10th April 1981, Department of Geology, Imperial College of Science and Technology, Prince Consort Road, London, SW7 2BP.
The Mesozoic and Cenozoic structures of southern England form part of a system of disturbances which extend across the Channel inot northern France. They are reviewed in the light of published data from south Dorset. Basin development started with Permo-Triassic rifting and is believed to have continued throughout the Jurassic and early Cretaceous with intermittant growth on deep-seated listric normal faults, probably associated with roll-over anticlines. The regime had ceased by the Aptian and the basin passed througha period of relative stability in the late Cretaceous, followed by tectonic inversion, and in the Miocene, by northwards compressive movement along the former normal faults. This partially restored the earlier separative displacement at depth, and probably accentuated pre-existing roll-over anticlines; it was expressed in the surficial Upper Cretaceous-Palaeogene sequence as monoclinal flexuring. The early rifting and the change from overall N-S crustal stretching to compression may reflect plate tectonic events in the North Atlantic region

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Strahan , A. 1898. The Geology of the Isle of Purbeck and Weymouth. Memoirs of the Geological Survey, England and Wales, 278pp.

Strahan, A. 1918. Special Reports on the Mineral Resources of Great Britain. Vol. VII, - Lignites, Jets, Kimmeridge Oil Shale, Mineral Oil, Cannel Coals, Natural Gas; Part 1. England and Wales. By A. Strahan, Sc.D., LL.D., F.R.S., with a contribution by J. Pringle. 69pp. with one fold-out diagram (Pits and Borings in the Bovey Basin). London, His Majesty's Stationery Office.

"Preface:
The urgency of the demand for Mineral Oil and prevalence of rumours, more or less ill-founded, as to the presence of copious, but untapped resources in Britain, have led to the publication of this volume at the present juncture..."

p. 27 - Uses and Values:
"Methods of utilising the oil in the bituminous bands [Kimmeridge Oil Shale] of the Kimmeridge Clay have been under consideration for many years. In 1848 the Bituminous Shale Company erected works at Weymouth and produced varnish, lubricating grease, naphtha, pitch and paraffin wax. .....
p. 28 -
"The [Kimmeridge] Blackstone contains a very large amount of sulphur. This not only makes the operation of distillation very offensive, but the presence of sulphur in the retort leads to the complete destruction of the paraffin hydrocarbons, so that the crude oil contains no paraffin, and is therefore valueless to the refiner. ..
"The revision made in 1912 of the Admiralty Specification for Oil Fuel, whereby the proportion of sulphur permissable was raised from 0.75 per cent to 3 per cent. has been effected only by mixing in other material of low sulphur content. The oil obtained by retorting Kimmeridge Shales contain from 6 per cent to 7 per cent of sulphur."
[See Chapter 5, p. 59, for old information on natural gas in Sussex, including exploration by the company - The Natural Gas Fields of England, Ltd. in 1902, around Heathfield and Mayfield.]

Strahan, A. 1920. Mineral oil, Kimmeridge oil-shale, lignites, jets, cannel coals, natural gas. Special Reports on Mineral Resources of Great Britain, vol. 7, 69pp. with 1 plate and 3 text figures (see pp. 18-40). Part 1: England and Wales. By Sir Aubrey Strahan, Director of the Geological Survey of England and Wales. Originally published, first edition, in 1918 at the price of 2 shillings and six pence; second edition, 1920.
[Aubrey Strahan graduated from Cambridge in 1875 and immediately joined the Geological Survey. During the First World War he worked on mineral resources and this publication is a result of that study.]

A old review, probably from the Geological Magazine, is provided below to indicate the contents:

During the last four years there has been a vast amount of irresponsible talking and writing about the possibility of the discovery of workable sources of oil and other natural fuels, other than coal, in the British Isles. It is, therefore, highly satisfactory to find that the Geological Survey has collated all known information on the subject, examining the records of past operations so far as available, and in the case of present explorations, carrying out independent investigations on the spot. The scope of the Memoir is sufficiently indicated by its title. The most important sections deal with the lignites of Bovey Tracey, the explorations made in them by Germans and others, and the uses to which they have been put; the distribution of Kimmeridge Oil-shale throughout the country; the principal known occurrences of mineral oil, cannel coal, and natural gas. It may be said at once in general terms that a careful perusal of this volume does not lend any notable amount of support to the highly optimistic views set forth in the daily papers during the last year or two.
A very full description is given of the well-known lignite and clay deposits of Bovey Tracey, and of the somewhat obscure operations of the German company, which mysteriously vanished two days before the declaration of war [1914-18 First World War]. It appears that the products of their industry were not of satisfactory quality, owing to the fact that the lignite consists mostly of highly resinous Sequoia wood, which seems to be unsuitable for the manufacture of paraffin wax and similar materials; the chief product of distillation being an evil-smelling yellow tar, a wholly unsaleable substance. Detailed sections are given of several borings put down in this area; these show the presence of a large amount of lignite, which is apparently only of poor quality and much mixed with clay. It is also shown that lignite has a wide distribution in Tertiary, Cretaceous, and Jurassic rocks, but nowhere in workable quantities.

A brief account is given of the almost extinct Whitby jet industry.

A chapter of seventeen pages is devoted to a consideration of the Oil-shales of the Kimmeridge series, which have lately been the subject of much discussion. The observations here recorded are largely founded on the results of borings made by the Department for the Development of Mineral Resources. The possible oil-yielding bed, locally known as the "Blackstone", forms part of the upper division of the Kimmeridge, and was probably never laid down over much of the distance between Dorset and Cambridgeshire, coming in again as bituminous shales in Lincolnshire and Yorkshire. Numerous analyses are given of samples from Kimmeridge and Corton [near Portesham], in Dorset, and from Donnington-on-Bain, in Lincolnshire. The yield of oil varies from 13 to 39 gallons per ton, and of sulphate of ammonia from 11 to 32lb. per ton in Dorset, the figures for Lincolnshire being much lower.
The well-known occurrence of natural gas at Heathfield, in Sussex, is described, as well as other instances met with in borings at Calvert, in Bucks, and near Middlesbrough, which appear to be unimportant. From a statement in the preface it appears that this memoir is to be regarded as an instalment, and that a further publication on the subject of mineral oil in Britain is in contemplation. R.H.R.

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Strong, G.E. and Milodowski, A.E. 1987. Aspects of the diagenesis of the Sherwood Sandstones of the Wessex Basin and their influence on reservoir characteristics. Special Publications of the Geological Society, London, vol. 36, pp. 325-337.
Abstract:
The Sherwood Sandstone Group sandstones of the Wessex Basin are important potential reservoirs for both hydrocarbons and geothermal brines. Analyses of conglomerate, sandstone and siltstone samples from outcrop and deep boreholes indicate a complex diagenetic history that has had important positive and negative effects on the reservoir properties. Over most of the basin, early diagenesis (eodiagenesis) is dominated by calcrete development but, towards the basin centre, non-ferroan dolomite associated with early evaporitic sulphate cements that appear to have been deposited in an inland sabkha or playa environment are important. Later diagenesis (mesodiagenesis) is characterized by selective framework grain dissolution of feldspars, and anhydrite cementation and subsequent dissolution-processes that have locally yielded significant secondary porosity. However, in some cases this secondary porosity has been destroyed by the precipitation of late manganiferous ferroan calcite and ferroan dolomite. Quartz cements are locally important. Rocks near the present-day outcrop have been affected by weathering processes (telodiagenesis) that have resulted in decalcification, and the precipitation of kaolinite, illite and iron hydroxides. The key factors determining the permeability of the sandstones are the original grain size and degree of sorting, the precipitation and subsequent removal of anhydrite, and the extent of early and late carbonate cementation, framework grain dissolution and overgrowth.


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Summers , S.T., Larsen, H.A. and Gardiner, H. 1995. Use of coiled tubing during the Wytch Farm extended-reach Drilling Project. Journal of Petroleum Technology, vol. 47, p. 414.
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Sun, S.Q. 1990. Sedimentation, diagenesis and reservoir evaluation of the Corallian (Upper Jurassic) Group, southern England. Unpublished Ph.D. Thesis, University of Reading.

Sun, S.Q. and Wright, P.V. 1998. Controls on Reservoir Quality of an Upper Jurassic Reef Mound in the Palmers Wood Field Area, Weald Basin, Southern England. By S. Qing Sun and V. Paul Wright. AAPG Bulletin, V. 82 (1998), No. 3 (March 1998), P. 497-515.
Abstract:
An Upper Jurassic (Oxfordian) reef mound in the Palmers Wood field area of the Weald basin, southern England, clearly shows the relationship of facies, diagenesis, and porosity development to relative sea level changes. The coral-microbial reef mound was initiated over a drowned oolite shoal during a third-order marine transgression and exhibits changes in coral morphology from base to top as the reef mound caught up with sea level during the subsequent highstand. During the highstand, extensive encrustation of the reef mound took place by microbial, stromatolitic cements, with subsequent porosity loss. During the following lowstand of relative sea level, extensive leaching of the aragonitic corals took place, and a lowstand wedge accumulated down-ramp. Porosity was lost during burial-related cementation and compaction. Coral-microbial reef mounds of this type have moderate potential for porosity formation, unlike tighter, deeper ramp reefs in the Jurassic, which are less prone to subaerial leaching and have less potential for secondary porosity development because they are less rich in aragonitic components. Although the Upper Jurassic reef mound is only a minor contributor to reservoirs in the Palmers Wood field, it may provide a model for other Upper Jurassic reef plays.

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Taitt, A. H. and Kent, P.E. 1939. Note on an examination of the Poxwell Anticline, Dorset. Geological Magazine, vol. 76, pp. 173-181.

The discovery of an active oil seepage in Corallian sandstones at Osmington Mills, near Weymouth, led in 1937 to an examination of the adjacent Poxwell or Moigns Anticline by geologists of the D'Arcy Exploration Company, a subsidiary of the Anglo-Iranian Oil Company, Ltd. [now well-known under its modern name - "BP"]. The investigations, carried out by Dr. C.T. Barber in the earliest stages, and subsequently by the junior author, consisted of surface mapping assisted by pits, trenches, auger holes, and shallow bore-holes, and culminated in the drilling of a test well in the crestal area of the anticline. This note summarises the more important information obtained with regard to stratigraphy and tectonics.
The general form of the Poxwell Anticline, which was ably described by Strahan (1898), is a dome, greatly elongated in an east-west direction, separated in the west by a small saddle from the larger Sutton-Poyntz anticline. In order to locate a bore-borehole to test the oil-producing possibilities of the Corallian it was, however, necessary to obtain informtion concerning the Ridgeway fault, which separates the the Jurassic and Cretaceous rocks on the northern flank of the structure.
Three shallow bore-holes were drilled along a north-south line across the presumed trace of the fault near Poxwell village. The most northerly borehole (lat. 50 degrees, 39 minutes, 14.3 seconds N, long. 2 degrees, 21 minutes, 52 seconds W.) penetrated 120 feet of Chalk, of which the lowest 22 feet was of the Micraster cortestudinarium Zone. A bore-hole 120 feet south of this, 40 feet deep, drilled through 20 feet of Chalk and Purbeck Limestone debris before encountering solid Chalk of the Rhynchonella cuvieri Zone. No. 3 bore-hole, 166 feet farther south, started in Purbeck and entered the Portland Sand at 171 feet, and at 230 feet the Upper Greensand, in which formation the well was completed at a depth of 432 feet (Fig. 2).
The true thicknesses, allowing for dip of the formations encountered in No. 3 borehole were Purbeck [but not complete Purbeck sequence] 80 feet [24 metres], Portland Stone 40 feet [12 metres], Portland Sand 42 feet [13 m.], and Upper Greensand c. 100 feet [c. 30m.].
The thickness of the Portland Stone, obtained by allowing for the dip of 42 degrees, shown in the cores of the Purbeck, proved to be less than anticipated. Dr. Arkell suggested that the apparent attenuation might be the result of normal faulting, but augering over the mapped Portland Stone outcrop on both flanks of the anticline showed that the recorded outcrop was too wide. The amended boundaries agreed with an approximate thickness of 40 feet for the Portland Stone.
In the light of the evidence obtained in the three shallow boreholes a location was chosen (lat. 50 degrees, 39 minutes, 4.7 seconds N., long. 2 degrees, 21 minutes, 23 seconds W.), with the object of penetrating the Corallian in the crestal area of the anticline and on the upthrow side of the Ridgeway Fault. Drilling was commenced on 24th May 1937, and completed at a depth of 1,666 feet [508 m.] two months later.

The following is a brief account of the formations penetrated in the Poxwell deep borehole.

-- Portland Beds: True thickness: 162 feet [49m.] in the borehole, 152 ft [46m.] true thickness.

-- Portland Stone. Soft buff limestone with rare chert bands. 0 to 28ft [8.5m] in borehole [not normal to the strata].

-- Portland Sand. Dark grey sandy clay and argillaceous sandstone. 28 - 160 ft in borehole.

-- Kimmeridge Clay:

842 ft in borehole [247m]. True thickness: 700 ft [213m.] [conversion: 0.83]
Dark calcareous clays, rather silty in the upper part. 160 - 485 feet [325 feet, 99m.] in borehole, not at right-angles to the strata. [true thickness conversion: 82m. thick].
Oil shale with Saccomoma [Kimmeridge Blackstone] - depth in the borehole (oblique to bedding) 485-490 ft. [Thickness along borehole 5 ft or 1.5m, corrected to true thickness 1.26m. This is probably too thick for the Blackstone itself, about 60cm at Kimmeridge in the basin, and may include adjacent oil shale.]
Dark grey calcareous clays; abundant Aulacostephanus [Lower Kimmeridge Clay ammonite] in cores between 590 [180m] and 600 feet 183m.] in the borehole; Aulacostephanus with Amoeboceras and Aptychi between 750 [229m.] and 770 ft [235m.] in the borehole; Rasenia [ammonite from near the base of the Kimmeridge Clay] at 890 ft. [271m.] in the borehole, and Ostrea fragments [presumably the flat oyster Liostrea delta of the basal Kimmeridge Clay] below 965 ft [294m.]. Depths 490 - 1002 ft [149m - 305m in borehole, [apparent thickness in borehole - 185m, converted to vertical thickness 151m.]

-- Corallian Beds. 305 ft drilled. True thickness: 245 feet [75m.]

Ringstead and Sandsfoot Beds.

Brown and dark green sandy clay with scattered ironshot ooliths. 1002-1067 ft in the borehole. [not corrected for angular difference]
Rich oolitic ironstone [like the Abbotsbury Ironstone] with Chlamys midas. 1067 - 1075 ft in borehole. i.e. 8 ft in the borehole. Corrected - 6.4 ft = 1.95 m. [almost 2m of oolitic iron ore, an unusual feature, not seen on the coast at Ringstead].
Oolite of calcareous ooliths in a dark green matrix. 1075-1090 feet in borehole.

Trigonia clavellata Beds.

Hard grey crystalline limestone with abundant Trigonia and bands of marl and sandstone. 1090-1101 ft in the borehole. 1090-1101 ft in borehole.

Osmington Oolite Series.
Pale nodular limestone and dark clay ("Nodular rubble" [sponge spicule beds]). 1101-1117 in borehole.
Nodular oolitic limestone and marl. 1119-1142 ft in bh.
Light oolitic limestone. 1142-1152 ft in bh.
Dark grey oolitic marl with oolitic limestone nodules and pisolite. 1152-1176 ft in bh.

Bencliff Grit.

Soft grey sandstone and marly sandstone [notice not yellow underground and unoxidised]. 1176 - 1200 in bh. 24 ft in bh = 7.3m. Corrected 5.8m. vertical thickness approx.

Nothe Clay.

Dark grey silty clay with Trigonia hudlestoni. 1200 - 1238 ft in bh.

Trigonia hudlestoni Bed

Oolitic limestone with abundant Chlamys fibrosa, Pleuromya sp. and Gryphaea sp. 1238-1256 ft in bh.

Nothe Grit.

Calcareous sandstones and sandy limestones with large Gryphaea sp. and Cercomya undulata. 1256-1307 ft. in bh.

-- Oxford Clay.

223 ft in borehole. True thickness 185 ft [56m.]
Dull grey silty clay with Cardioceras sp. at 1320 ft. and again at 1445 ft.

-- Great Oolite Series - 136ft drilled.

-- Forest Marble - 74 ft. drilled.

Hard light grey raggy limestone with Chlamys sp. 1530-1535.5 ft. in bh.
Hard grey-green marl with conchoidal fracture. Rare small Rhynchonella sp. in the lower part. 1535.5 - 1602.5 ft in bh.
Hard grey green marl with conchoidal fracture. Rare small Rhynchonella sp. in the lower part. 1535.5 - 1602.5 ft in bh.
Grey marl and limestone with abundant Goniorhynchia boueti, Ornithella cf. digona and Chlamys sp.

-- Fuller's Earth. 62 ft [18.9m.] drilled.

Hard light grey marl with limestone nodules. 1604-1612 ft in bh.
Hard light grey marl with conchoidal fracture, with scattered plant fragments and Oppelia fusca at 1646ft. 1612-1666. [end of borehole log]

[---- Notes: This is interesting in showing a very well-developed oolitic facies in the upper part. There is a rich oolitic iron ore with Chlamys midas in the Ringstead and Sandsfoot Beds. This is of Abbotsbury Ironstone facies, but within the Corallian not the Kimmeridge Clay. Another interesting aspect is the presence of green material, probably berthierine in the iron-rich Ringstea and Sandsfoot Beds. All this is suprising in view of the proximity to the coast section at Osmington Mills.]
[The subdivisions of the Corallian sequence are given as top and bottom depths in a borehole that is inclined in relation to bedding, and the figures are in feet. Therefore they need conversion before they become useful in comparision with the Osmington Mills coast section.]
[The paper continues for three more pages of text and one diagram. These further details are not reproduced here, but the short paper is in a well-known journal and probably very easily obtainable.]
[Of interest is mention of the early recognition by Lees and Cox of the thick Triassic salt sequence beneath the Poxwell area. This was understood even though it was not penetrated in the borehole. Here is a short extract from p. 180.]

There are a number of points of interest about this succession. The Kimmeridge Clay shows marked attenuation as compared with the standard succession at Kimmeridge, so that the Gravesia and Subplanites zones [i.e. Pectinatites Zones](from the "Blackstone" oil shale to the highest Aulacostephanus) measure less than 100 ft [30m.], as compared to 210 ft. [64m.] in the type section.

The unexpected development of Oolite and Oolitic Ironstone in the upper part of the Corallian is comparable with the facies at Abbotsbury, but the Ironstone here occurs at a lower horizon. The remainder of the Corallian is, as would be expected, closely similar to the outcropping beds at the well-known Osmington Mills sectin, 1 and a half miles distant. The Nothe Beds yielded a specimen of the lamellibranch Cercomya undulata, which was interesting in showing punctation, a feature usual in France, but previously unrecorded in England.

The beds below the Corallian were greatly reduced in thickness or absent. [continues]

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Taitt , A.H. and Kent, P.E. 1958. Deep boreholes at Portsdown (Hants) and Henfield (Sussex). Technical Publications of the British Petroleum Company Ltd., London, 41pp.
[Example extract]
Introduction:
The pages which follow give an account of the strata penetrated in the Portsdown and Henfield boreholes drilled by the D'Arcy Exploration Company in 1936-37. These wells commenced in Cretaceous rocks and reached Trias and Carboniferous respectively, proving a very full and thick development of the Jurassic in what might be described as a new province. A short summary of the formations penetrated has already been published (Lees and Cox, 1937), and in the present paper the evidence for the classification of the beds will be discussed in detail. Since the publication of that paper identification of a more complete series of fossils has led to minor revisions in the position of certain formation boundaries.
All the fossils recorded, with many more of lesser diagnostic value, are deposited in the collections of the Geological Survey in London.
[Map - The Portsdown and Henfield Borings in Relation to the Jurassic Basin]
The reasons for choosing Portsdown and Henfield as localities for testing were dealt with by G. M Lees and P. T. Cox in 1937. The Portsdown well was located on the anticline of that name which produces an inlier of chalk a few miles north of Portsmouth (Lat. 50 degrees, 51, I5 Long. 1, 5, 32) and the Henfield borehole commencing in the Wealden clay was sited in the axial region of the Henfield anticline on the southern side of the Weald (Lat. 50 dgrees, 55, 6, Long. 0, 19, 20). Elevations of the rotary tables (datum for measurements) were 222.4 ft. and 34.75 ft. respectively above sea level.
In the following pages formations are described at the two localities together, so that the points of similarity and difference can be more conveniently appreciated and the stratigraphy regarded as pertaining to a region rather than to two isolated sections.
In the interests of speed and economy modern practice of deep drilling reduces the taking of cores of formations as far as is possible, and at each place a considerable part of the succession is reconstructed from the evidence of cuttings of rock which are flushed continuously from the bottom of the hole by circulating mud. Although this procedure prevents the recovery and recognition of macro-fossils from a proportion of the sequence drilled, it is nevertheless possible with proper mud control to recognise changes of formation with a high degree of accuracy, and to obtain a limited amount of palreontological information from fragmentary and microscopic fossils.
The sequence penetrated may be summarised as follows (thicknesses throughout this account are in feet):
[Table of borehole log, down to Trias at Portsdown and to the Carboniferous at Henfield. TDs - Portsdown 6556ft., Henfield - 5105ft.]
[Full page, diagrammatic logs are then given for each formation, with depths in feet - an example is given below]
Great Oolite log from Taitt and Kent, Portsdown and Henfield Boreholes


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Taylor , C. 1986. Some small, but commercial onshore oilfields will probably be found. Petroleum Review, May 1986.

Taylor, J.C.M. 1986. Gas prospects in the Variscan Thrust Province of southern England. In Brooks, J., Goff, J.C. and Hoorne B. van, Habitat of Palaeozoic gas in NW Europe. Special Publications of the Geological Society, London, No. 23, 37-53.

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Taylor, S.P. and Sellwood, B.W. 2002. The context of lowstand events in the Kimmeridgian (Late Jurassic) sequence stratigraphic evolution of the Wessex-Weald Basin, Southern England. Sedimentary Geology, 151, 89-106.
A depositional sequence stratigraphic framework for the Kimmeridgian Stage of the Wessex-Weald Basin, southern England, is applied in the investigation of the sedimentary and erosional response to proposed lowstand events. This framework recognises 13 sequence boundaries (Km1-Km13) and is based on the integrated assessment of geophysical, sedimentological, palaeontological and geochemical data. Changes in the nature and continuity of Kimmeridgian unconformity surfaces record the effect of the reorganisation of the onshore basins in response to eustasy and tectonic movements. During the Earliest Kimmeridgian, the basin geometry was such that falls in relative sea level generated widespread unconformities. Associated lowstand events are recorded in marginal areas by a number of sand units, derived from a variety of local sources. A tectonically enhanced deepening event during the late Early Kimmeridgian (Eudoxus Zone) led to unconformities being confined in their distribution, to the basin margins. As sea level fell during the Latest Kimmeridgian, a progressive reduction in the depositional area led to an amplification of the effects of lowstand processes at the basin margins where unconformity surfaces are amalgamated. On the most positive areas these surfaces are overprinted by a major interregional hiatus, the 'Late Cimmerian Unconformity'. The timing and effects of Kimmeridgian lowstand events were intimately linked to the tectonic evolution of the Wessex-Weald Basin. Thus at times when rates and amounts of eustatic change are small (i.e. during 'greenhouse times') the tectonic signature of a basin will be the primary signal recorded in sedimentary successions.

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Taylor, S.P., Sellwood, B.W., Gallois, R.M. and Chamber, M. 2001. A sequence stratigraphy of the Kimmeridgian and Bolonian stages (late Jurassic): Wessex–Weald Basin, southern England. Journal of the Geological Society, London. Vol. 158, 2001, pp. 179-192. By Steve P. Taylor, Bruce W. Sellwood, Ramues W. Gallois and Martin, H. Chambers.
A sequence stratigraphic framework for the late Jurassic Kimmeridgian and Bolonian stages of the Wessex-Weald Basin, southern England is proposed, based on the integration of sedimentological, geophysical and geochemical data. The NERC-funded Rapid Global Geological Events (RGGE) boreholes of Swanworth Quarry 1 and 2, and Metherhills 1, are used as reference sections. Eleven complete depositional sequences and their component systems tracts are recognized within the Kimmeridge Clay Formation, bounded by 12 sequence boundaries (Km1-12). Seventy-four boreholes have been used in this study. During the Kimmeridgian, a major transgression, associated with tectonic movements, led to a marked change in basin geometry. Major deepening of the sea during the late Kimmeridgian (Eudoxus Zone) led to a change from unconformities of basinwide extent to those confined to the basin margins. The progressive deepening of the basin towards a highstand in the mid-Bolonian (Wheatleyensis to Pectinatus zones) was associated with a broad-scale change in sedimentary, faunal and geochemical characters. The 'layer-cake' basin architecture and thickening of the Kimmeridge Clay Formation towards the basin centre suggests a dominantly aggradational system. The partially enclosed nature of the Kimmeridgian and Bolonian seas generated basin dynamics more analogous to those of modern day meromictic lakes [a meromictic lake, unlike a holomictic lake, has waters that do not intermix]. Consequently, sequence stratigraphic approaches derived from continental shelf-margins are inappropriate in epicontinental basins of this type.
[although not the objective of the paper, the borehole records for the Kimmeridge Clay of the Weald area are of relevance to Cuadrilla drilling at Balcombe, and the local dispute about hydraulic fracturing or "fracking" if it ever takes place here.]

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Terris , A.O. and Bullerwell, W. 1965. Investigations into the underground structure of southern England. Advancement of Science, Aug. 1965, 232-252.
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Thomas , J. and Ensom, P. 1989. Bibliography and Index of Dorset Geology. Dorset Natural History and Archaeological Society, Dorchester, Dorset, 102p. [most earlier Dorset oil references listed]
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Thomas , L.P. and Holliday, D.W. 1982. Southampton No. 1 (Western Esplanade) Geothermal Well: Geological Well Completion Report. Institute of Geological Sciences, Environmental and Deep Geology Division. By Thomas, L.P. and Holliday, D.W., with contributions by Kirby, G.A., Kubala, M., Lamb, R., Bird, M.J. and Freshney, E.C. Deep Geology Report No. 82/3. Extract: Southampton No 1 (Western Esplanade) was drilled as a geothermal development well, on behalf of the Department of Energy in association with Southampton City Council, following the successful testing of Marchwood No 1 Borehole and studies of the geothermal potential of the Wessex Basin area by the Institute of Geological Sciences. The site was selected near Southampton city centre, with the aim of providing space heating for the proposed Western Esplanade development area. The nearby Marchwood No 1 Borehole is situated 1.8 km to the south-west, and the south-east part of NERC 81-1 seismic line is adjacent to the site (Figure 1.2). Southampton No 1 is situated in an area of negative gravity anomaly as indicated on the regional Bouguer anomaly map (Figure 1.4). The primary objective was to drill to the known aquifer, the Triassic Sherwood Sandstone, and to carry out hydrogeological and geothermal tests. The whole of the Sherwood Sandstone was cored for geological and hydro-geological analysis. Samples additional to those required by IGS for stratigraphical purposes, were collected for thermal conductivity determinations and for organic geochemical studies on the Jurassic part of the sequence. [See also Institute of Geological Sciences for more on the Southampton geothermal well and nearby Marchwood Borehole.]

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Tootill, A. 2013. Fracking the UK; The Storm Gathering over Our Countryside. 234pp. A low-cost, paperback book by Alan Tootill. (www.alantootill.com). This is a very readible book, not technical but giving a critical and fairly detailed account of hyraulic fracturing or fracking activities in the UK, with reference to American experiences. The book is openly partisan and anti-fracking [please note, though, that this present website is neutral]. In amongst the detailed and journalistic-type accounts of fracking activities in the north of England and at Balcombe, it provides some technical details scattered through the text. There are for instance the following comments (p. 108) regarding a Balcombe Parish Council Report of 2012, which is unlikely to be generally read by geologists:
"The report is largely intended to provide information on the fracking process. There are a couple of statements of interest. The first, in discussing Cuadrilla's fracking fluid cocktail:
"Both polyacrylamide [slicks the water to reduce friction] and biocides [biocides are to eliminate bacteria that may produce corrosive biproducts] contain toxins that are hazardous. In concentrated form these materials require special handling."
The working party clearly wouldn't agree wholeheartedly with Cuadrilla's claim that "What we are putting into the ground is non-hazardous".
And in dealing with flowback fracking waste, the report says:
"At present Cuadrilla's plans are not sufficiently advanced for it to identify its proposed method of processing the flowback at the Lower Stumble site." - yet another reference to the fact that Cuadrilla can not even in a testing phase tell how their waste is to be disposed of."
The above extract shows the style of the book and the type of content.

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Tree , I. 1989. Defining Dorset's gold. Geographical Magazine, 1989. v 61(1) pp 1822.

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Tribovillard , N., Bialkowski, A., Tyson, R.V., Lallier-Verges, E. and Deconinck, J-F. 2001. Marine and Petroleum Geology, 18, (3), pp. 371-389. Abstract: Recent studies of the upper Kimmeridgian of the Boulonnais area (northernmost France) have provided a sequence-stratigraphical framework that is here used to help interpret variations in sedimentary organic matter (OM) content and composition in response to fluctuations in relative sea-level. The organic facies are characterised using a combination of palynofacies, bulk organic geochemistry (TOC, Rock Eval pyrolysis, and sulphur data), and the particle-size distribution of the total palynological residues. The organic facies show a good correlation with the sequence stratigraphy, exhibiting peak TOC, HI, total S and Sorg values in the lithofacies deposited around the two MFS. The palynofacies in these intervals is characterised by a high content of fluorescent, orange, marine AOM. There is a strong correlation between the orange AOM and the total and organic sulphur contents. Similar positive correlations between orange AOM and organic sulphur have previously been observed in the distal organic-rich sediments of the Kimmeridge Clay Formation of Dorset (lateral time equivalents of the Boulonnais facies), but there the sulphur contents are lower, indicating that organic sulphur content of orange AOM is not fixed, suggestive of preservation-related parallel but not intrinsically related trends. The S data can be used to estimate an apparent burial efficiency and hence the proportion of the primary productivity preserved; this allows a rough estimate of palaeoproductivity. Model calculations suggest that for a sulphide retention of 30-70 percent and uncompacted sedimentation rate estimates in the range 5-10cm/ka, the mean palaeoproductivity was in the range 52-175gC/m2/a (up to 6 percent of which was preserved). Thus, if the preservation is high, as is the case for MFS, the palaeoproductivity does not need to be above average for shelf waters to produce a given TOC.

Tribovillard, N., Trentesaux, A., Ramdani, A., Baudin, F., Riboulleau, A. 2004. Controls on organic accumulation in late Jurassic shales of northwestern Europe as inferred from trace-metal geochemistry. Bulletin de la Societe Geologique de France, 175 (5), pp. 491-506.
Abstract: In the Kimmeridge Clay Formation of the Wessex-Weald Basin, five organic-matter-rich intervals (or ORIs), dated from Kimmeridgian-Tithonian times, can be correlated from distal depositional environments in Dorset and Yorkshire (UK) to the proximal environments in Boulonnais, northern France. The ORIs are superimposed on a meter-scale cyclic distribution of organic matter (OM), referred to as primary cyclicity, which is commonly interpreted to result from Milankovitch climate forcing. The present work addresses the distribution of redox-sensitive and/or sulfide-forming trace metals and selected major elements (Si, Al and Fe) in Kimmeridge Clay shales from the Cleveland Basin (Yorkshire) and the Boulonnais cliffs with two objectives: 1) to determine whether the ORIs formed in similar paleoenvironments, and 2) to identify the mechanism(s) of OM accumulation. High-resolution geochemical data from primary cycles in the Yorkshire boreholes (Marton and Ebberstone boreholes), were studied and the results are then applied with lower resolution sampling at the ORI scale in the Flixton borehole and Boulonnais cliff. Good correlations are found between total organic carbon (TOC) vs Cu/Al and Ni/Al, but relationships between TOC and Mo/Al, V/Al and U/Al are more complex. Cu and Ni enrichment is interpreted to have resulted from passive accumulation with OM in an oxygen-deficient basinal setting, which prevented the subsequent loss of Cu and Ni from the sediment. Mo and V were significantly enriched only in sediments where considerable amounts of OM (TOC>7%) accumulated, the result of strongly reducing conditions and OM burial. At the scale of the Flixton ORIs, the samples with the highest Mo and V concentrations also show relative Fe enrichment, suggesting pyrite formation in the water column (combination of euxinic conditions and presumably low sedimentation rates). Samples from all ORIs were slightly enriched in Si relative to Al, interpreted as reflecting decreased sediment flux during transgressive and early-highstand systems tracts. The data show that in some ORIs, OM accumulation proceeded while productivity was not particularly high and sediments were not experiencing strong anoxia. In other ORIs, OM accumulation was accompanied by widespread anoxia and possibly euxinic conditions in distal settings. Though somewhat different from each other, the ORIs have all developed during episodes of reduced terrigenous supply (transgressive episodes). The common feature linking these contrasted episodes of enhanced OM storage (ORIs) must be the conjunction of productivity coupled with a decrease in the dilution effect by the land-derived supply, in a depositional environment prone to water stratification and, therefore, favorable to OM preservation and accumulation.
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Trueman, S. 2003. The Humbly Grove, Herriard, Storrington, Singleton, Stockbridge, Goodworth, Horndean, Palmers Wood, Bletchingly and Albury Fields, Hampshire, Surrey and Sussex, UK Onshore. Pp. 924-941 in: Gluyas, J. G. and Hichens, H.M. (eds.) 2003. In: United Kingdom Oil and Gas Fields. Commemorative Millenium Volume, Geological Society of London, Memoir 20. (This large memoir is full of useful data, most of it on the North Sea; however, it is very expensive for the ordinary reader to buy, with a minimum price of about 200 pounds ranging up to about 350 pounds or more. It can be consulted in libraries such at the NOC library of Southampton University, NOC (docks) campus.)
Abstract: The Weald Basin of SE England is a lozenge shaped accumulation of sediments occurring from Southampton and Winchester in the west to Maidstone and Hastings in the east. It is approximately 150km long by 60km wide, covering an area of some 9000 square kilometres. Several commercial oil and gas discoveries have been made, mostly on the flanks of the basin. These fields have been in continuous production since the early 1980s. Field size in terms of recoverable hydrocarbons is small, 0.5 to 6 MMBBL [million barrels]. Hydrocarbons are produced primarily from the Middle Jurassic Bathonian Great Oolite at Humbly Grove, Herriard, Storrington, Singleton, Stockbridge, Goodworth and Horndean field but also from the late Oxfordian - Early Kimmeridgian Corallian Sandstone at Palmers Wood, Portland Sandstone at Brockham and Godley Bridge, Corallian Limestone at Bletchingly; Purbeck Sandstone in Albury and Late Triassic Rhaetic calcarenites in Humbly Grove, Cumulative oil production from the basin is currently 19.1 MMSTB [19.1 Million Stock Tank Barrels - 1 barrel = 35 English gallons, or 42 US gallons].
[This is a very good paper for briefly summarising the data on oil fields of the Weald and especially western Weald (Sussex-Hampshire border)].
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Tyson , R. V. 1985. Palynofacies and sedimentology of some Late Jurassic sediments from the British Isles and northern North Sea. Ph.D. thesis. Open University.

Tyson R. V. 1989. Late Jurassic palynofacies trends, Piper and Kimmeridge Clay Formations, UK onshore and northern North Sea. In: Northwest European Micropalaeontology and Palynology (eds. D. J. Batten and M. C. Keen), pp. 135–172. Ellis Horwood.

Tyson, R.V. 2004. Variation in marine total organic carbon through the type Kimmeridge Clay Formation (Late Jurassic), Dorset, UK. Quarterly Journal of the Geological Society, London, vol. 161, 667-673. By Richard V. Tyson, School of Civil Engineering and Geosciences, Drummond Building. University of Newcastle, Newcastle upon Tyne NE1 7RU, UK.
Abstract: Bulk geochemical data from the NERC Rapid Global Geological Events project are used to appraise the pattern of variation in mean organic content through the cymodoce to rotunda zones of the type Kimmeridge Clay Formation in southern Dorset. There is a symmetrical stratigraphic pattern in mean and modal total organic carbon (TOC) values, which increase from 1-2% at the top and base to a peak of 8-9% in the middle of the formation. To remove distortion caused by the strong positive skewness of the TOC values, the mean TOC per zone was recalculated for the first mode of the TOC distribution only, and combined pragmatically with pyrolysis estimates of the reactive (marine) TOC fraction to derive marine TOC values; these also vary symmetrically from c. 0.5% to peak values of c. 5.0%. The mean TOC is negatively correlated with sedimentation rate, indicating that dilution is a significant controlling variable. Mean palaeoproductivity was assessed using modem marine sediment relationships between carbon burial efficiency, sedimentation rate (derived from RGGE cyc10stratigraphic analyses), the likely dissolved oxygen range, and water depth. Best estimates of palaeoproductivity range from 40 to 150 g C m-2 a-1 [per square metre per annum] (low to moderate by comparison with present-day shelves) and are positively but nonlinearly correlated with mean dell3C TOC values.

Tyson, R.V., Wilson, R.C.L. and Downie, C. 1979. A stratified water column environmental model for the type Kimmeridge Clay. Nature, 277, pp. 377-380.

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UKOG. UK Oil and Gas Investments PLC. 2016. Markwells Wood. Licence No. PEDL126. UKOG interest 100%.
Go to website: Markwells Wood.
The Markwells Wood-1 discovery well was drilled in 2010. It is operated by UKOG's fully-owned subsidiary UKOG (GB) Limited. The discovery is a conventional Jurassic Great Oolite limestone reservoir, the same as in the Horndean producing oil field (UKOG 10%), which is located 3 km to the west. The well was tested over a 6-month period in 2011-12, producing 3,931 bbl of oil. UKOG has applied to extend the Markwells Wood planning permission to 30 September 2016. Approval is expected shortly [but was not necessarily given]. [continues - go to UKOG webpage]
[This brief but informative webpage includes a colour map of the top Cornbrash, showing the structure, the traps and the faults. The production estimates and the intended locations of development wells are shown. The webpage is very open and informative. It is has similarity to the nearby Horndean field, except for the suggested horizontal wells at Markwells Wood.]
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UK Onshore Geophysical Library. [major source of seismic data] .

This is the major source of onshore seismic data for the UK, including that of the Wessex Coast area, suc as Devon, Dorset, Hampshire and the Isle of Wight. This is primarily of use to the oil industry, but can be used by others with geophysical interests.

"With over 75,000 km of available seismic survey data as acquired by the onshore exploration industry, the Library strives to locate all available data items pertaining to each seismic profile, with the aim of providing a fully reconciled archive of:
Original pre-stack field records de-multiplexed to SEG-Y.
Supporting scanned observers reports and associated acquisition documents.
Line location data in UKOOA format.
Processed post-stack and migrated data in SEG-Y.
Hardcopy and scanned seismic sections."

A school project is given at:
Seismic Aquisition Onshore - School Project.

Example regarding the Weymouth Anticline

Weymouth Relief Road, Dorset

Shown here is a north-south seismic section across the Weymouth Anticline, modified and with some notes added. See the original seismic section by going to the website:

UK Onshore Geophysical Library.

By agreement with the DECC and HMSO, the Library operates as a registered charity, funded by revenues raised from data sales and donations, with the long term objective of bringing all available UK onshore seismic data into secure archival storage, whilst providing efficient access to all interested parties:

* Oil and Gas Exploration
* Gas Storage, Mining, Coal Bed Methane Extraction
* Water Resources and Environmental Issues
* Planning and Engineering
* Academic Studies and Teaching Resources

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UK Onshore Operators Group, 2006. OOG News and Press Releases. Re Hurst Castle Prospect.
"Offshore Licence P1153.

P1153, located in the Wessex-Channel Basin also contains the Hurst Castle prospect which straddles the Hampshire coastline. The main reservoir objective is the Sherwood Sandstone with secondary potential in the Bridport Sandstone.
The offshore well 98/7-2 driilled by BP in 1987 is of particular significance regarding the prospectivity of this licence. 98/7-2 is situated approximately six kilometres from the southwest corner of Licence P1153 and encountered oil in the upper section of the Triassic Sherwood Sandstone. This well tested 1095 bopd of 43 degree API oil from the Sherwood Sandstone interval, the same reservoir as in the Wytch Farm field. This oil is lighter gravity than that at the Wytch Farm field which is 36 degree API.
The significance of this well is that it indicates that oil has migrated and is preserved east of the main hydrocarbon trap at Wytch Farm. This is believed to be the result of the basin configuration at the time of oil migration. Early formed structures of pre-Upper Cretaceous age such as that at Hurst Castle are potential traps for migrating oil."


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Underhill , J.R. and Stoneley, R. 1998. Introduction to the development, evolution and petroleum geology of the Wessex Basin. In: Underhill, J.R. (Ed.) Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society, London, Special Publications, 133, pp. 1-18. (Key paper for a summary re the area)
Despite containing the largest known onshore oilfield in western Europe, the Wessex Basin hydrocarbon province appears to be extremely limited spacially and it currently [in 1998] only consists of three producing oilfields: Wytch Farm, Wareham and Kimmeridge. The main factor which controls hydrocarbon prospectivity in the area appears to be preservation of oil accumulations originally sited in Mesozoic tilted fault blocks. The extensional palaeostrutures of Wytch Farm and Weymouth are interpreted to have been charged by upwards migration of oil from mature Liassic source rocks situated across the Purbeck - Isle of Wight fault system in the Channel (Portland-Wight) sub-basin prior to and unaffected by, either significant effects of intra-Cretaceous (Aptian-Albian) easterly tilting or by Tertiary tectonic inversion. To date, only the small Kimmeridge oilfield which is situated in the core of a periclinal fold created in response to structural inversion, suggests that any hydrocarbon remigration into younger structural inversion structures has taken place.

Underhill, J.R. and Patterson, S. 1998. Genesis of tectonic inversion structures: seismic evidence for the development of key structures along the Purbeck - Isle of Wight Disturbance. Journal of the Geological Society, London, vol. 155, pp. 975-992. By John R. Underhill and Susan Patterson.
Underhill and Paterson Paper - Lyell Collection, Geological Society of London.
The interpretation of a densely spaced and well-calibrated seismic grid sheds new light on the development and evolution of key regional and local structures in the Wessex Basin. The results help to resolve long-standing controversies concerning the tectonic significance of apparently anomalous outcrop patterns and the role of important, local ancillary structures with respect to the major monoclinal folds with which they are associated. Although the structures are entirely consistent with the effects of contractional reactivation (tectonic inversion) of normal faults, the subsurface data demonstrate the role that original extensional fault segmentation and associated relay ramps had on original depositional patterns, subsequent inversion geometries and resultant outcrop patterns. As well as illustrating regional controls on the formation of structures, the new seismic-based interpretations enable a reassessment of the Lulworth Crumple and the Ballard Down Fault. The Lulworth Crumple is interpreted as a parasitic fold complex generated by internal folding of the inverted, incompetent syn-rift fill in the immediate hanging wall to the Purbeck Fault, a reactivated major normal fault. The Ballard Down Fault's origin is interpreted to result from the formation of a local, late-stage 'out of the syncline' reverse fault which propagated southwards and upwards through a Chalk succession. As the Chalk had already been rotated to form the northward-dipping steep limb of the Purbeck Monocline at Ballard Down, the structure cuts down stratigraphically. The results stress the importance of understanding the nature of original extensional fault geometries and the competence of the sedimentary units incorporated in folds in gaining a full understanding of the genesis and evolution of structural styles in inverted basins.
[this is a key paper on south Dorset structures!]

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Underhill, J.R. - reported by Harrabin. 2017.
Harrabin, R. [Roger Harrabin, BBC Environment Analyst]. FRACKING: Shale rock professor says UK gas reserves 'hyped'.

1.1 INTRODUCTION - AN OVERVIEW FROM PROFESSOR UNDERHILL, AUGUST 2017 - REPORTED IN BBC NEWS (BY ROGER HARRABIN)
Reference: Harrabin, R. 2017. BBC NEWS ARTICLE - Business section. Available online:

[For more information see the Reference by Harrabin to Underhill in the Oil South Bibliography.]
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Van Kaam-Peters, H.M.E., Schouten, S., Koster, J. and Damste, J.S.S. 1998. Controls on the molecular and carbon isotopic composition of organic matter deposited in a Kimmeridgian euxinic shelf sea: Evidence for preservation of carbohydrates through sulfurisation. Geochimica et Cosmochimica Acta, 62, (19-20) pp. 3259-3283, Oct 1998. Abstract: Thirteen samples from the Kimmeridge Clay Formation (KCF) in Dorset, covering all different lithologies, were studied using bulk and molecular geochemical and microscopical techniques. Our data show that the positive correlation between TOC and delta(13)C(TOC) reported for shales (Huc et al., 1992) also holds for other lithologies (e.g., limestones) if we correct for dilution by carbonate (TOC). Despite the wide range of delta(13)C(TOC) values (-26.7 to -20.7 parts per thousand), the delta(13)C values of individual biomarkers of algal and green sulfur bacterial origin and of kerogen pyrolysis products (i.e., n-alkanes) show in general only small changes (less than 2 parts per thousand). This indicates that changes in the concentration of dissolved inorganic carbon (DIC) or delta(13)C of DIC (delta(13)C(DIC)) in the palaeowater column cannot account for the 6 parts per thousand difference in delta(13)C(TOC).-- Kerogen pyrolysates indicated that with increasing TOC*, and thus increasing delta(13)C(TOC), carbon isotopically heavy C-1-C-3 alkylated thiophenes with a linear carbon skeleton become increasingly abundant; in the case of the Blackstone Band kerogen (TOC = 63 percent) they dominate the pyrolysate. These thiophenes are probably derived from sulfur-bound carbohydrates in the kerogen. Algal carbohydrates are typically 5-10 parts per thousand heavier than algal lipids and differences in preservation of labile carbohydrate carbon through sulfurisation may thus explain the range in delta(13)C(TOC) values without the need to invoke any change in water column conditions. The increasing dominance of thiophenes in the kerogen pyrolysate with increasing TOC* is consistent with the increasing Sulfur Index (mg S org/g TOC), the decreasing S-PYRITE/S-TOT ratio, and the increasing dominance of orange amorphous organic matter produced by natural sulfurisation. -- The organic matter of all sediments was deposited under euxinic conditions as revealed by the occurrence of isorenieratene derivatives indicating (periodic) photic zone euxinia. At times of reduced run-off from the hinterland, represented by so-called condensed sections, the flux of reactive iron was relatively small compared to the flux of reactive organic matter, which resulted in the formation of relatively small amounts of pyrite and an excess of hydrogen sulfide capable of reacting with fresh organic matter. Within the condensed sections, variations in the degree of sulfurisation of organic matter are probably due to both differences in primary production and differences in the supply of reactive iron. These findings demonstrate that climatic changes, probably driven by Milankovitch cycles, can have a large impact on the molecular and carbon isotopic compositions of the sedimentary organic matter in an otherwise relatively stable stratified basin. They also show that large amounts of labile carbohydrate carbon may be preserved through sulfurisation.
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von Hoffman , A. W. 1857. [Production of gas from Kimmeridge oil shale]. Journal of Gas Lighting , vol ?. Historic paper.

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Wahidiyat, E. 2010. Update on ESP Operation at BP Wytch Farm Oilfield. Presented at the European Artificial Lift Forum, 17th-18th February, 2010. BP. 18 pp. including diagrams. By Erwin Wahididiyat. Available online as a pdf file: Update on ESP Operation at BP Wytch Farm Oilfield.
This presentation is on the experiences with high horse-power-motor, electrical submersible pumps in the Sherwood Sandstone Reservoir, particularly offshore in Poole Bay. From October 1997 to February 2010, a total of 47 high HP ESP systems were installed, of which there were 27 failures. The largest HP ESP system operates at 1,400 HP (2 x 700 HP motors). Wahidiyat also gives useful summary data on the Sherwood Reservoir of the Wytch Farm Oilfield:
Triassic sandstone reservoir, with top reservoir at ca. 1585 metres TVDS (true vertical depth subsea) with a maximum 110 metre column of oil-bearing sand above the oil-water contact.
Divided into zones numbered down. Zones 30, 50 and 70 are the main oil bearing zones. Zones 20, 40 and 60 are muddier intervals acting as barriers. Thus there are effectively three reservoirs within the Sherwood Sandstone reservoir. However, the upper of these has lower permeability, and less net-to-gross oil.
The western part of the reservoir lies beneath Poole Harbour and adjacent area, while the eastern part is under Poole Bay. More than half of the Sherwood reserves lie in the offshore area (Poole Bay). This caused the drilling of ERD, Extended Reach Drilling wells, beginning in 1993.
Production from the Sherwood Reservoir accounts for 85% of the total Wytch Farm production.
NORM, Normally Occurring Radioactive Material is present within the produced fluids (oil and water) and causes complications in handling retrieved (radioactive) pumps during teardown (dismantling).

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Warren, G. 2014. Comments relating to the water resource and environmental quality implications of the application by Cuadrilla for temporary planning permission for flow testing at the Lower Stumble Borehole, Balcombe, No. WSCC/005/14/BA. Graham Warren Water Report Balcombe.pdf, 245kb. 3 printed pages, including a sketch diagram. [attached to FFBRA nl. 26]. By Graham Warren, B.Sc., M.Sc. DIC Eng., F.G.S., MICE, Ch. Eng. etc, Retired Water Resources Manager, Kent Area Environment Agency.
[My summary: Discussion about two old boreholes (c. 1888, 1898) at Balcombe pumping station, approximately 800m. west of the village seem to have gone through the Wadhurst Clay into the uppermost Ashdown Beds.In 1947 there was no reference to methane. However, the WSCC, West Sussex County Council's Technical Officer refers to "naturally high levels of methane" in the Ashdown Beds at the Lower Stumble, Balcombe, oil-well site. It is suggested that the methane is not natural, but originates from penetration of Kimmeridge Micrite unit at Lower Stumble. There is further discussion about risk to the Balcombe pumping station and to the River Ouse. The Wadhurst Clay is not a "natural barrier" but has mixed lithologies, including carbonates, which will be subject to attack by the acid flush process, and this will create new pathways for the flow of contaminants. "And contrary to the Environment Agency's conclusion, quoted in Para. 9.62, the saline product of HCl flushing could therefore constitute a risk to groundwater. Incidently, this articles also notes that the acid flushing process involves high pressure injection over a period of 7 days, followed by 60 days of pressure monitoring.]

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Watts, G. 2000. Old Harry Review: Review of results from Exploration Well L98/06-M18 and L98/06-M18Z in 98/11. By Giles Watts, June 2000. Internal Report of BP? This is on an Extended Reach Borehole from Wytch Farm Wellsite M (Goathorn Peninsula) to a prospect, Old Harry - 1, to the east of Harry Rocks, near Studland. See also DECC report on Reliquishment. The topic is discussed in the Petroleum Geology, South of England. webpage.

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Wessex Exploration PLC.

[A major oil exploration company in southern England dealing with the Isle of Wight, and elsewhere]

Go to: Wessex Exploration PLC, the main web site, for a listing of their many webpages.

"Wessex Exploration PLC (Wessex) was formed to explore the Wessex and Weald Basins of southern England at a time when the prolific Sherwood Sandstone reservoir had just been discovered in the giant Wytch Farm oil field and smaller oil and gas discoveries were being made in the Weald Basin. Wessex completed a regional geological study of these basins and concluded that the complexity of the stratigraphy, structure and geological history of the basins required a careful, disciplined and highly technical approach to hydrocarbon exploration and that additional significant hydrocarbon potential remained in place."

[Wessex Exploration PLC. holds three licences in southern United Kingdom - PEDL 238: 50%; PEDL 239: 25%; P1928: 35% - alongside its partner and operator, NWE Mirrabooka (UK) Pty. Ltd (a fully owned subsidiary of ASX listed Norwest Energy NL).]

Wessex Exploration Limited. 2007?. [older web page] Wessex Exploration Ltd. PEDL 089 and P1153. pdf file that was available online.
[This concerns: Lymington and New Milton, Hampshire - Petroleum Exploration License - PDL089 - Wessex Exploration Ltd.
Part of the New Forest region near Lymington has been under investigation for petroleum resources by Wessex Exploration Ltd. Details were given on their website at: Wessex Exploration Limited (not necessarily available now). Here is a small extract from the start of the webpage to draw attention to their work. Particularly see the good maps. Note the information on the Hurst Castle Prospect.
"Wessex Exploration Limited, bidding on its own in the 9th Landward Bid Round was awarded Petroleum Exploration and Development License (PEDL) 089 on 4 September, 2000. PEDL 089 is located in southern Hampshire near the towns of Lymington and New Milton, on the mainland opposite the western end of the Isle of Wight. The work obligation for the initial term of the PEDL was met when Northern Petroleum drilled the Bouldnor Copse 1 well, and fifty percent of the PEDL was relinquished in September, 2006. The PEDL is now in its second exploration period. Wessex on 11 September, 2002 made an "Out of Round" application for a Petroleum Production License over the area immediately offshore from and adjacent to PEDL 089. Wessex was awarded License P1153 over this offshore area, effective 3 October, 2003. The primary term of this license expired in October, 2007, but was renewed by DBERR into a second exploration period. A preliminary structural map of the Hurst Castle Prospect at the Sherwood Sandstone level is shown. Estimated P10 oil-in-place is of the order of 190 million barrels for the Sherwood reservoir alone, with possible recoverable reserve of 36 million barrels. A separate structural map shows four-way dip closure offshore, with possible P50 recoverable reserves in the 16 million barrel range." ...] [continues]
See further details of the Hurst Castle Prospect.
They report that the Hurst Castle Prospect has potential recoverable reserves of the order of 36 million barrels from the Sherwood reservoir, in a Wytch Farm type fault-block feature. The primary reservoir is the Triassic Sherwood Sandstone. The Bridport Sands is a secondary objective as is the Frome Limestone (Great Oolite). In the same region an exploratory well was drilled at Boulder Copse across the West Solent on the Isle of Wight. The results were negative but Wessex Petroleum did not consider that this impacts on the prospectivity of the Hurst Castle objective.

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Wessex Exploration PLC. 2012. Southern England Update.
Wessex Exploration notes the ASX announcement of Norwest Energy NL ("Norwest") made today in respect of PEDL 239 in Southern England, in which Wessex Petroleum holds a 25% interest.
Norwest Energy (ASX:NWE)through its wholly owned subsidiary NWE Mirrabooka (UK) Pty Ltd ( NWE Mirrabooka ), has commenced the acquisition of a 50km 2D seismic survey. The survey is being undertaken at onshore UK, Isle of Wight PEDL 239 and is designed to detail the Razorback prospect. The Razorback prospect is located centrally on the Isle of Wight, is Norwest’s highest ranked prospect in PEDL 239 and is estimated to contain 43 MMbls oil in place (P50). The primary target is the Triassic Sherwood Sandstone and the secondary target is the Jurassic Oolite reservoir. The Razorback prospect is located to the east of and relatively close to the giant Wytch Farm field. The identification of the Razorback prospect is the culmination of over 3 years of extensive technical work mapping the migration pathways, reservoir distribution, seal quality and structural history of PEDL 239 and surrounding regions. Razorback appears to be favorably located, however the prospect is defined by a coarse 2D seismic grid. The current survey will infill this coarse grid and should provide ufficient detail to confidently demonstrate the prospects structural integrity. ....... The joint venture partners in PEDL 239 are: NWE Mirrabooka (UK) Pty Ltd 75%, Wessex Exploration 25%. NWE Mirrabooka (Norwest) and its partner Wessex Exploration now have a large footprint in the Wessex Basin both onshore and offshore. Evaluating the Razorback prospect is an important component in the plan to explore and maximize the value of this acreage...
[continues, go to the original webpage for the full account]

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West , I.M. 1975. Evaporites and associated sediments of the basal Purbeck Formation (Upper Jurassic) of Dorset. Proceedings of the Geologists' Association, London, 86, 205-225. (Relationship of Mupe Bay structures to Purbeck evaporite distribution. Growth faults etc.)

West, I.M. 1993. Natural hydrocarbon seepages and surface oil impregnations of the Wessex Basin: A review. Unpublished report of the Geology Department, Southampton University. [This briefly reviewed the Dorset oil and gas seepages from east to west, mostly from the literature.]


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Williams, P.F.V. 1986. Petroleum geochemistry of the Kimmeridge Clay of onshore southern and eastern England. Marine and Petroleum Geology, vol. 3, pp. 258-281.


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Whaley, J. 2016. [ WHALEY] The 'Gatwick Gusher' [Horse Hill Well, Weald] Fact or Fiction.
[Important Paper summarising the Horse Hill field.]
GeoExPro, vol. 123, No. 5, 2016, pp. 26-29. Magazine article on the Horse Hill Oil Field, Sussex, by Jane Walley, Editor in Chief of the magazine Geoexploration. It contains information from geologist Chris Pullen, a consultant with Magallan Petroleum. [A short but very informative article, with maps and diagrams.]
[Extracts] The 'Gatwick Gusher' Fact or Fiction. "More than 70 percent of the wells in the Weald Basin, which were drilled between 1960 and early 1980s have encountered hydrocarbon shows" says Chris Pullen, a consultant with Magellan Petroleum. "There was evidence of hydrocarbons at several levels, so why were they not followed up properly until now? There could be several reasons including the fact that drilling in the very populated and protected southeast of England, a mere 60 kilometres or so south of London, is practically quite difficult - but mostly, I think we just did not look hard enough at the results. Interest in the Weald's potential has been increasing in recent years, but the area really hit the headlines late in 2014 when preliminary resultss from Horse Hill - 1, drilled on PEDL (Petroleum Exploration and Development Licence) 137 on the northern flank of the Weald Basin, suggested that the total in-place resource for the area could be considerably larger than previously estimated. Further positive analysis and testing of the well led to news reports suggesting the discovery - nicknamed the 'Gatwick Gusher' - may be 'a world-class resource with millions of barrels of oil', which could play a 'key role in transforming the UK's energy balance'.
Less positive press exposure to the hydrocarbon potential of the area had occurred in 2013 and 2014, when Cuadrilla Resources proposed a test well near the village of Balcombe in the centre of the Weald Basin. There was considerable public concern and anti-fracking protests over the proposed well, although no application to use hydraulic fracturing had been made.
Early Gas Use. The occurrence of hydrocarbons has been recorded in southern England for over 150 years, with gas being reported in water wells as long ago as 1836, as well as natural oil seeps being noted. In fact the first UK discovery and production of onshore gas was in the Weald Basin, when gas was found in water wells during the construction of Heathfield railway station, subsequently used to power the lights for the station.
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Also in the 1970s, improvements in seismic acquisition techniques enabled exploration of prospective plays which were previously hidden below unconformities. These included the Humbley Grove, Herriard, Horndean and Singleton oil fields in the western part of the basin, reservoired in the Middle Jurassic Great Oolite Formation. Fields found in the Upper Jurassic sandstones and limestones in the northern and central part of the basin at this time included the Palmers Wood and Brockham oil fields and Albury and Godley Bridge gas fields.
After oil prices crashed in the late 1980s there was little interest in the area for nearly two decades. At the moment there are 13 producing sites in the Weald Basin, but some are almost 30 years old and many reservoirs are declining. However, the last decade has seen a considerable resurgence of the interest in the area, with some very interesting well results.
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Magellan Petroleum first got into the Weald Basin during the 9th UK Onshore Round back in 2000. We knew there was a potential, but had a lot of questions. For example, what was the source of oil in the younger formations - could it be the same Lower Jurassic shales as at the Wytch Farm field, evne though their quality in the Weald Basin was fair at best? Or was it sourced from a higher level, such as Oxford or Kimmeridge Clays? What about the possibility of a deeper gas play? How deformed was the centre of the basin? We methodically set about preparing a regional study to find answers to these questions........
------------------- .... The plays traditionally chased in the area are the Upper Jurassic Portland and Corallian Sandstones, ..... all sealed by Upper Jurassic Kimmeridge Clay shales and Purbeck anhydrites.
Magellan's regional re-evaluation ..... suggested that the oil could be coming from the Upper Jurassic Oxford Clay and in some cases from the Kimmeridge Clay. Furthermore the source of the gas in the area was unlikely to be Jurassic and probably came from a deeper level, possibly Palaeozoic.
"This was a very exciting realisation, as it suggests that in addition to sourcing gas in higher levels, deeper Triassic reservoirs could also be charged from this source." Chris explains. .....
[continues - an interesting paper - see the original!]
[Particular Points re Kimmeridge Clay!!}
"The potential of the Kimmeridge is particularly exciting: we don't have any good core from the section, as previously we just drilled through it to look at the deeper horizons."
"Also the conventional Triassic gas play could be very significant, but needs a lot more data, work and analysis."
[Very good publication - see the original in GeoExPro!]

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White , P.H.N. 1949. Gravity data obtained in Great Britain by the Anglo-American Oil Co. Ltd. Quarterly Journal of the Geological Society, London, vol. 104, pp. 339-364. [Of historic interest.]
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Woodfall Consulting Ltd. An Independent Assessment of Wessex Exploration Plc. Prepared for Wessex Exploration plc and Westhouse Securities Ltd. By Daniel T Shaw of D'Orange Ltd. and J David M Roberts of Woodfall Consulting Ltd. 30 November 2009. Preface
Example extract:
"Wessex Exploration Ltd. was formed in the mid-1980s to explore the hydrocarbon potential of the Wessex and Weald Basins of southern United Kingdom. As a private limited oil and gas exploration company, it has acquired licences in other parts of the world. In October 2009, Wessex Exploration Ltd. raised circa 1.1 million pounds after costs from private shareholders to fund advancement of its assets. In November 2009, Wessex Exploration Ltd. converted to a public limited company, changing name to Wessex Exploration plc." [......continues].
Wessex Exploration plc currently [2009] has interests in three licences in the southern UK:
PEDL 238 - A large onshore block covering most of Bournemouth and much of eastern Poole. It includes much of the Bournemouth and Boscombe sea front, but not Sandbanks. It includes Christchurch, Mudeford, and Friars Cliff.
PEDL 089 - This includes Highcliffe, Barton and Milford, onshore. It does not extend far inland.
PEDL 239 western part - This includes the onshore, western part of the Isle of Wight. Yarmouth, Freshwater and Compton Bay are within this licence block.
PEDL 239 southeastern part - This includes the onshore southeastern part of the Isle of Wight, including Blackgang Chine, St. Catherine Point, Ventnor, Shanklin, and reaches Sandown.


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Worden, R.H., Manning, D.A.C. and Bottrell, S.H. 2006. Multiple generations of high salinity formation water in the Triassic Sherwood Sandstone: Wytch Farm oilfield, onshore UK. Applied Geochemistry, vol. 21, issue 3, March 2006, 455-475.
Abstract: The origin and heterogeneity of oilfield formation water in the Lower Triassic Sherwood Sandstone at Wytch Farm in the Wessex Basin, UK, have been investigated using production data, detailed water geochemistry and O, S and H stable isotope data. The formation waters are highly saline, NaCl-type brines with TDS values of up to 230,000 mg/L. There is a general decrease in salinity from the flanks of the field to the crest with Cl- decreasing from about 136,000 to 109,000 mg/L. The Cl/Br ratio of the water shows that salinity was largely derived from the dissolution of Upper Triassic continental evaporites found off-structure to the west and north of the field. The water in the field had a meteoric source although variation in d2H values suggests that there may be meteoric waters of different ages in the oilfield, reflecting recharge under different palaeoclimatic conditions. At the crest of the field, aqueous resulted from dissolution of anhydrite in the reservoir. In contrast, in other parts of the field there is an indication that some of the dissolved was derived from oxidation of pyrite at some point on the recharge path of meteoric water to the field. There were two meteoric influx events bringing different Cl- concentrations and different d2H values. The first was probably before the Eocene oil influx and could have occurred in the Lower Cretaceous or early Tertiary. The second meteoric influx event probably occurred after or during oil migration into the Wytch Farm structure since the second meteoric water is found at the flanks of the field adjacent to the regions where salt is found in the stratigraphy. The preservation of heterogeneities in oilfield formation water compositions suggests that there has been little aqueous fluid movement or diffusive flux for over 40 million years. Mass flux has been restricted by density stratification within the aquifer and the very low effective permeability for the aqueous phase in the oil-filled reservoir.

Worden, R.H., Manning, D.A.C. and Lythgoe, P.R. 2000. The origin and production geochemistry of radioactive lead (210Pb) in NORM-contaminated formation waters. Journal of Geochemical Exploration, vols. 69-70, June 2000, pp. 695-699.
Abstract:
Radioactive produced formation waters in Wytch Farm, a Triassic fluvial reservoir, onshore southern UK, are unusual in that they are enriched in NORM (naturally occurring radioactive material: in this case 210Pb). 210Pb belongs to the 238U decay chain. Key issues include the origin and distribution of radiogenic lead in sub-surface waters and the absence of the more common type of NORM (226Ra). The sandstones are unusually enriched in uranium with concentrations of 0-70 ppm; 210Pb was thus probably sourced internally within the reservoir. Stratigraphic and aerial distribution of high levels of subsurface uranium correlates well with the highest level of NORM-contamination in produced waters. Triassic formation waters have very high sulphate and very low barium concentrations and are at saturation with respect to barite. Radium is not a NORM problem presumably because its concentration is limited by coprecipitation with barite. While the sulphate concentration is very high, the sulphide concentration is below routine detection limits. Geochemical modelling indicates that Triassic formation waters are undersaturated with respect to PbS (galena) thus allowing radiogenic lead to remain in aqueous solution.

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Dr Ian West, author of these webpages

Webpage - written and produced by:


Ian West, M.Sc. Ph.D. F.G.S.

at his private address, Romsey, Hampshire, kindly supported by Southampton University,and web-hosted by courtesy of iSolutions of Southampton University. The website does not necessarily represent the views of Southampton University. The website is written privately from home in Romsey, unfunded and with no staff other than the author, but generously and freely published by Southampton University. Field trips shown in photographs do not necessarily have any connection with Southampton University and may have been private or have been run by various organisations.