This paper summarizes leak detection technologies available for use on subseapipelines and the potential role of fiber optic cable (FOC) integritymonitoring systems to improve leak detection capabilities. Available systemswhich monitor offshore pipelines for potential leaks based on internalflowrates and pressures are described along with their limitations for rapidlydetecting small leaks. Alternative pipeline leak detection technologies whichhave been used on some specialized subsea pipeline projects to supplement thecapabilities of these flow-based systems are also described along with theirlimitations. The potential for modern FOC distributed sensing technologies tofill the remaining leak detection capability gaps is then addressed.
There is increased interest in improving leak detection system capabilitiesthroughout the pipeline industry. However, the primary application of thispaper is for offshore pipeline projects which may not be adequately covered byconventional flow-based leak detection systems and supplemental monitoring forpotential oil sheens visible on the sea surface. These applications includedeep water pipelines, where potential oil leaks may not reach the surface untilmiles away from the source, and subsea arctic pipelines, which could slowlylose significant oil volumes under the cover of winter sea ice. Other potentialapplications include subsea field developments and pipelines installed inunusually sensitive marine environments.
Distributed FOC sensor systems can monitor real-time temperature, acousticnoise/vibration and strain along many miles of pipeline. Changes in any one ofthese monitored parameters can indicate a leak event or other potentialintegrity threats to a pipeline. An overview of FOC systems already installedon offshore pipeline projects and the current testing status of FOC systems forpipeline leak detection are provided. Recommendations for installation andimplementation of the available FOC technologies for subsea pipeline leakdetection are summarized.
The limited applications of distributed fiber optic cable (FOC) monitoringsystems on subsea pipelines have not yet been used specifically for leakdetection purposes. The leak detection thresholds defined for FOC systems andthe procedures for design, installation and system repair will facilitate theuse of FOC systems to help ensure leak free pipeline operations.