ABSTRACT:

Exploration and production of offshore oil&gas fields is extending to increasingly deep waters and environmental sensitive remote areas. Current plans and projects aim to install and operate platforms with a water depth between 1500 and 3000 m. This puts high demands on platforms, pipelines and risers, in particular in term of design limits and integrity of these structures due to extreme variability of environmental conditions. It is therefore beneficial to rely on a permanent and real time monitoring system, able to give information on static and dynamic structural loads by direct measures of strain levels experienced by critical components during its whole lifetime. Capability to detect and locate leakages in pipelines is another major issue, for the environmental and economic consequences associated to an oil/gas spill at sea. Accurate and continuous temperature monitoring over risers and pipelines may also give important indications for flow assurance purposes. Fiber optic sensors are one of the most promising solutions for the continuous monitoring of structural loads, leakages and temperature on new and existing structures during the whole lifetime. This technology is well known and has many applications in onshore activities like civil engineering (dams, bridges, galleries, buildings), nuclear and industrial plants, aerospace. Transfer to the offshore oil&gas facilities is ongoing, but specific efforts are required for the development of engineered and qualified solutions, capable to meet the demanding requirements of the offshore and deepwater applications (aggressive environment, pressure, installation constraints, capability to operate for lifetime in the order of tens of years). This paper gives an overview of the status and perspectives of fiber optic monitoring in offshore oil&gas applications, including a description of the main results of past and ongoing Eni E&P research projects in this field, that included a field test of a riser strain monitoring system in shallow water, the qualification of a FO strain sensor for deep water applications (3000 mwd) and the design and qualification of fiber optic sensors for pipeline leak detection and temperature profile measurement on long pipelines and sealines

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