Unconventional shale gas provides a potential resource for future energy consumption. However, there are many environmental issues including leakage of shale gas into soil and groundwater. This research is an attempt to understand the micro mechanics of shale gas movement through soils. A 3D pore network can capture both the geometrical information of soil matrix including pore size and throat size distributions with their correlation and the topological information of soil matrix including the distribution of coordination numbers. The geometrical and topological information of soil structure including pore size distribution, throat size distribution, pore center distance, pore size and throat size ratio, coordination number distribution, and spatial correlation of the above parameters can also obtain by analyzing computer generated random packings of equal size spheres. A micromechanical investigation to understand the physics of shale gas migration and subsequent spatial distribution of shale gas at pore scale was also performed by a rule-based dynamic two-phase flow model. This paper summarizes observations from the simulation of shale gas migration and subsequent spatial distribution and discusses its application in shale gas exploration.