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The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Research project: Impact of seabed properties on the ampacity and reliability of cables

Currently Active: 
Yes

HV cables are frequently laid in trenches at the seabed and buried within local seabed sediments, with little thought about the thermal regime they will either enter or generate.

Background

The sediment thermal regime is dependent on the ability of the sediment to balance the cable heat generation (from electrical losses) with transfer to the surrounding sediment. The ability to transfer and balance the generated heat is strongly dependent on the sediment physical and thermal properties.

The sediment thermal regime will generate significant impacts on the cable performance and stability, such as reduction of bed shear stresses and hence seabed erodibility as well as de-rating and early failure of sub-marine cables links due to excessive sediment temperature, which distorts HVDC cable electric field, prematurely damage insulation and other components.

Figure 1
Figure 1

Aims:

  1. Synthesize previous thermal properties measurements of marine sediments.
  2. Investigate the impact of varying rock and fluid properties on thermal properties of marine sediment using lab experiments.
  3. Acquire, process and interpret new and existing field (pre/post-installation) data such as high resolution seismic data (swath sonar and sub-bottom); geotechnical core logs; CPT and direct time series of thermal measurements.
  4. Develop a new approach using high resolution seismic constrained with geotechnical data to adequately quantify and fully understand the spatial and temporal variability of the thermal regime experienced by buried cables along cable routes on the UK shelf.

Data and Methods

New and existing pre/post-installation field data acquired across HV cable routes (e.g. West-Link, East-Link and Brit-Ned) of the UK shelf are being processed and interpreted (AVO, Inversion, rock physics and thermal modelling) using high resolution seismic data to generate key physical and thermal sediment properties. The result will be ground-truthed using geotechnical core logs, CPT and in-situ thermal measurements analysis.

Figure 2
Figure 2

The synthesis results (fig. 2) of various published researches carried out on shallow marine sediments, shows a very vague relationship between thermal diffusivity/conductivity with lithology, grain size, porosity and water content etc. Hence, this PhD project, is particularly aimed to develop a new approach that adequately quantify and fully understand the sub-seabed thermal regime experienced by a buried cable.

Key Contacts

Mr. John Emeana (PhD Student)

Dr. Justin Dix (Supervisor)

Prof. Tim Henstock (Supervisor)

Dr. Charlie Thompson (Supervisor)

Dr. Thomas Gernon (Supervisor)

Dr. James Pilgrim (Supervisor)

PhDs and Other Opportunities

Visit GSNOCS

Related research groups

Geology and Geophysics
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