Calculation the Amount of Natural Gas Loss from a Hole in Buried Distribution Gas Pipelines

In this research, the amount of natural gas leakage from a small hole located on the lateral surface of the above-ground or buried distribution gas pipe lines is estimated. The geometry was designed and meshed by GAMBIT software and then numerical calculation is carried out by FLUENT software. The working fluid was considered as compressible ideal gas. The fluid flow was assumed turbulent and soil considered as a porous zone. The results indicate that for small hole diameters, discharge speed reaches to the sound speed and at the so-called, choking occurs at exit position. Also, the volumetric flow rate of leaked gas has a linear relation with pressure of initial point and second order relation with hole diameter. In the case of buried pipes, permeation depth of gas in soil at the small diameter holes, is more than large holes but volumetric rate of leaked gas is lower. Finally, with the goal of making the results applicable for the natural gas industry, two correlations were developed for estimating the amount of leaked gas in aboveground and buried pipelines.