Distributed Fiber-Optic Vibration Sensor for Gas Pipeline Leak Detection Using Hybrid Interferometer

In this paper, distributed optical fiber sensing system based on hybrid interferometer to measure and locate leaks for gas-filled pipelines. The phase signal induced by the gas leaky acoustic wave can be detected, and then the leakage position can also be calculated from null frequency of the output spectrum. The measuring principle and the leaky source locatiom method for the hybrid interferometer was analyzed. Localization performance was evaluated. The experiment was designed to evaluate leaks positions detection and location performance. The results show that the fiber optical sensor has good accuracy of the leaky positon, the fiber optic max inspection length is 10 kilometers, leaky hole is 2.5 mm, gas pressure range 0.5-1.5 MPa, the fiber optic sensor system location error is less than 1.68%.