The top image shows the iDAS acoustic response over 1200m of fibre cable. A leak appears at 620m after 6 seconds. The second image shows the acoustic response at 620m on the same time axis. The two images at the bottom compare the frequency response at 620m before and during the leak.
Silixa offers two complementary techniques to address the challenge of detecting and accurately locating a subsea leak within a flow network.
Utilising either Silixa’s range of Distributed Temperature Sensors (DTS) or our iDAS™, intelligent Distributed Acoustic Sensor, we can provide the operator with a rapid alert of a leak and locate the leak with sub-metre precision. The techniques are complimentary and can be deployed individually or in partnership within a single fibre optic cable. Both techniques rely on detecting tiny changes in the behaviour within an optical fibre due to experiencing an external effect such as temperature change or an acoustic signal.
By interrogating an optical fibre placed on or in the asset and using a DTS located within the control room an accurate picture of the temperature profile along the asset can be obtained. A subsea leak of fluid or gas within a riser or umbilical will give rise to a localised change of temperature in the fibre optic cable closest to the leak. By detecting this localised anomaly, Silixa can deliver automated alarms based on user-configurable criteria, such as max/min temperature and provide an accurate location of the leak.
Where there is sufficient pressure, sound will also be produced by the escape of fluid, either by flow into the asset or due to the formation of bubbles caused by the leak. This sound can be detected and captured by the iDAS. Sophisticated signal processing identifies this as a subsea leak rather than as some other noise source and immediately alerts the operator in with both the nature of the event and its position.