Numerical Model for Small Leakage of Buried Natural Gas Pipeline

The natural gas pipeline small leakage increased rapidly in China recent years. Its overall amount has exceeded 40,000 km and the national-wide gas pipeline network has taken shape. Therefore, safety management of pipeline has gained more and more attention. The signals of sound, pressure drop and vibration, which are produced by buried pipeline small leakage, are always too weak to be captured by SCADA. But if the small leakage last for certain time, it can cause very severe damage. Therefore, this paper researched the diffusion rule of buried pipeline small leakage based on theory of single-phase seepage and high-speed non-Darcy seepage and established a mathematical model of seepage using FVM to solve control equations, and finally verified by experiment. By comparing the results of experiment and numerical computational, we built an empirical formula to determine non-Darcy coefficient and a pressure correction equation which suit to high permeability soil and soil deformation. This model can be used to estimate mass flow of buried pipeline and seepage time to the ground and provide reference to establish management regulation such as natural gas long-distance pipeline’s patrol cycle.