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Many variants of pipeline line leak detection systems are in operation today on liquid or gas pipelines. These often rely upon a single leak detection methodology. This could include; CPM, Mass Balance, Acoustic, Flow or Temperature Monitoring. Latest developments in fibre optic technology now mean that a number of these methods can be combined in a single system. Fibre Optic Distributed Acoustic Sensing (DAS) is able to use the following measurands to detect within leaks seconds with a location accuracy of 10 meters. DAS detects the following signatures of a leak; Acoustic Anomaly; Temperature Gradient, External Ground changes and Negative Pressure Pulse. By fusing these signatures together DAS is able to provide a sensitive yet robust and reliable leak detection solution. Added benefits of the system are also the traditional security aspects that help prevent as opposed to detect pipeline damage as well as Inline Inspection Gauge Tracking through the same hardware set. This paper examines the methodologies used to detect leaks in all phases of products. Discusses the industry led tests conducted so far and provides real life evidence of leaks detected in the field.

Fiber Optic (FO) sensing technology is an exciting and novel technique offering many advantages over traditional wellbore surveillance methods 1-3 . Multiple FO cables can be installed that can be designed for sensitivity to a wide variety of signals such as temperature, pressure 4-5 , strain 6-7 , sound 8 , and the presence of specific chemical compounds. Permanently installed FO cables enable a cost effective surveillance policy where data acquisition surveys can be conducted without well interventions, in real-time, at any time, and continuous along the entire well bore. The avoidance of well intervention eliminates production deferment and operational risks of conventional surveys. Frequent, time-lapse FO based surveys can provide critical reservoir surveillance data for production and recovery optimization.One instance of fiber-optic surveillance is Distributed Sensing, which uses the entire fiber as a sensing element. Recently, very good progress has been made in Distributed Acoustic Sensing (DAS) for hydraulic fracturing monitoring 9 , production profiling for commingled oil and gas producers, injection profiling for water injectors 10 , gas lift monitoring and the acquisition of wellbore seismic data such as Vertical Seismic Profile (VSP) surveys 11-12 . These applications are also seen to benefit from integration with other methods such as Distributed Temperature Sensing (DTS) and Distributed Pressure Sensing (DPS). In terms of wellbore surveillance, the possibility to monitor flow along the entire wellbore from FO sensing provides useful insights in the complex flow behavior in a well which can be used to optimize well performance.There are also many improvements to be made in the enabling Distributed Sensing infrastructure such as the handling and evaluation of very large data volumes and seamless FO data transfer, the robustness & cost of the FO system installation, and the overall integration of FO surveillance into the full workflows. It will take some time before all these issues are addressed but it is clear that FO based applications will play a key role in future well and reservoir surveillance.In this paper some examples of using DAS for Production Allocation are discussed. TX 75083-3836, U.S.A., fax +1-972-952-9435

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This paper describes the testing of a novel ground condition and slope stability monitoring system based on Distributed Rayleigh Sensing (DRS) on a landslide observatory operated by the British Geological Survey (BGS). The DRS system uses the backscattered light from buried fiber optic cables to determine the strain and temperature at any point along the fiber up to distances of over 50 km and has been shown to respond to ground movement, moisture content changes and temperature variations. The output of the fiber is compared to that expected based on the known geology of the slope and other instruments such as tiltmeters and moisture content sensors. In addition to long-term strain and temperature measurements, the system can also sense acoustic vibrations and can be used to make active and passive seismic surveys to give a comprehensive 3d picture of the subsurface state. The results show that the DRS system can provide improved spatial and time resolution and sensitivity to give a more comprehensive and detailed picture of slope behavior than would otherwise be possible. Such detail allows improved landslide prediction methods and early warning systems to be developed.