Numerical simulation of gas drainage from boreholes in coal seams

In order to seek the reasonable parameters of drilling drainage,the computational fluid dynamics method is used to establish the model of gas drainage.The Darcy law is applied to simulate the gas seepage flow in coal seams.The effect of drainage pressure and the permeability on the gas flow condition is analyzed.The results show that the effective gas drainage radius is about 2m,the impact of negative pressure on drainage radius is not very obvious.The gas volume increases with the increase of the negative pressure of extracted drainage.The impact of coal seam gas permeability on the gas volume is relatively large.The simulation results agree well with the measurement value,so the simulation result can provide theory guidance for gas drainage.