Chronic pipeline leak detection survey: A description of various case studies

A pipeline leak detection survey for the oil and gas sector is investigated with aim of determining accuracy, resource level requirements and risk of installation and operation for various technologies. Medium to large scale leaks between 3 to 10mm could be detected using dynamic pressure wave monitoring for single phase flow whereas sequential probability ratio testing (SPRT) using real time transient monitoring (RTTM) can be used to monitor leaks for multiphase flows even in offshore shallow water conditions and along elevated pipeline networks. Chronic leaks could be measured based on accuracy of hydrocarbon and pressure monitoring devices installed in a vacuum annulus pipe-in-pipe arrangement however the pipeline length is restricted due to weight and difficulty of pipeline installation. Distributed temperature sensing and distributed acoustic sensing leak detection using fiber optic cable (FOC) were found to be resource intensive and have higher installation and operation risks due to unknown equipment reliability and location or sealing of the FOC on the pipeline structure. RTTM and SPRT have comparable accuracy to DTS or DAS leak detection and can be retrofitted to existing pipeline networks. None of the leak detection technologies evaluated had proven capability to predict leaks for pipelines manufactured from reinforced thermoplastic (RTP) materials.