Numerical Simulation of Coal-Seam Gas Drainage Based on Solid-Gas Coupling Model

Gas drainage is one of the important methods to prevent gas accidents in coal mines. In order to accurately reflect the gas migration law of the gas drainage process in the bedding and determine the reasonable boreholes layout parameters, the gas-solid coupling model of coal gas seepage was established with gas dynamics introduced diffusion coefficient, based on the coupling effect of elastic media with dual-pores and dual-permeability and combined with coal body deformation and permeability evolution. COMSOL Multiphysics was used to simulate gas drainage process in the bedding to explore the influence of different factors on the gas migration. According to the simulation results, the changing trends of coal seam gas pressure and permeability during the gas drainage process were analyzed under the different conditions including drainage time, negative pressure and boreholes diameter.