Leak detection in natural gas distribution pipeline using distributed temperature sensing

Water ingress problem caused by gas leaks in distribution gas pipeline is a rather thorny problem, which the gas companies typically encounter. Replacing the existing faulty pipeline is rather costly and troublesome. For gas pipelines, when leak happens, gas escapes from the pipelines into the free space or surrounding environment, and results in cooling of the nearby area due to the Joule-Thomson effect. Commercial distributed temperature sensing (DTS) system with appropriate operation method could be a solution as it can achieve a resolution of 0.05°C. The background knowledge, characteristic and measuring principle of DTS technique is introduced. As one of the principal composition for the natural gas, methane is selected for study and the temperature change during leak has been evaluated. For the pipe's gauge pressure of 2 kPa, when methane leaks through narrow crack, the temperature drops about 0.69°C which could be detected by the DTS system.