Numerical Simulation of Underground Coal Seam Gas Pressure Measurement by Direct Method

To study the influence of original gas pressure of coal seam and permeability and exposure time on measuring pressure, we built the mathematical model of gas flow in coal seam during measurement based on the classical seepage mechanics, and we simulated the measuring pressure procedure through COMSOL Multiphysics. The results show that under certain conditions, the bigger of original gas pressure or permeability in coal seam is, the larger scope of pressure drawdown distribution is, but the time of gas pressure balance will not increase; under certain conditions, the longer of exposure time is, the larger scope of pressure drawdown distribution is and the longer time of gas pressure balance is.