Experimental study of methane diffusion in soil for an underground gas pipe leak

Pipeline leaks can cause large economic losses as well as environmental hazards such as fires and explosions. A full-scale experimental system was developed to simulate low pressure gas leaks from small holes in four different directions from a pipe buried in soil. The methane concentration variations in the soil were measured during the release phase and after the dissipation phase for various mass flow rates and leak directions. The results show that the larger mass flow rate required less time to reach saturation and had larger concentrations at the end of the release phase. The locations near the soil surface had the fastest gas concentration growth rates and shortest times to reach steady state, while the locations below the pipe had slower grow rates but larger concentrations at the end of the release phase. The leak direction significantly influences the concentration distribution above the pipe, while the concentrations below the pipe differ only for upward flow.