The application of Distributed Acoustic Sensing technology for subsea monitoring Seminar

Fibre optic –based Distributed Acoustic Sensing (DAS) technology makes it possible to observe the sound at every point along a length of a standard fibre optic cable. The application of this technology to subsea tie-backs can enable several capabilities, including leak detection, equipment condition monitoring, flow assurance sensing, and structural condition monitoring. Recently, wet trials have been conducted to examine the way in which DAS can be applied for subsea monitoring. This talk will focus on an experiment conducted in a dry-dock in Blythe, UK in Autumn 2013. During this experiment, a 70m pipeline was temporarily built within the dry dock. Controlled leaks were welded along the pipeline. Gas leaks were activated, and the acoustic signal was monitored. It was seen that a detection algorithm could be used to differentiate between the gas leaks and other background noise. DAS was also used to monitor the speed of sound within the pipe, hence providing detail concerning the fluid within the pipe. Further testing was conducted by outfitting a subsea annulus top-up pump with fibre optic cable, and deploying this instrumented pump within the tank. Basic machine condition monitoring was then performed using the acoustic emissions from the pump. In addition to the experimental results, the seminar will be used to consider some of the practical challenges presented by the deployment of such a monitoring system along operational tie-backs.