A ten channel fibre-optic device for distributed sensing of underground hydrocarbon leakage

With millions of fuel storage tanks and oil pipelines installed around the world, there is inevitably frequent leakage of potentially hazardous hydroc arbons. As many of these installations are below ground, it can often be ma ny years before the extent of the leak is discovered. We have previously re ported the development of a sensor for the detection of such subterranean l eaks, using infrared reflectometry to interrogate a hydrocarbon sensitive m embrane. However, a single sensor cannot provide any information about the flow rate or direction of the leak. This paper describes the extension of t he technology to a multi-channel distributed sensing system, using optical fibres capable of distributing the sensors over large subterranean areas. R esults are reported from the evaluation of the device, which consisted of m onitoring the movement of different hydrocarbons (gasoline, diesel and insu lating oil) through a vertical sand-filled vessel.