Numerical Simulation Analysis of Ground Pre-extracted Coalbed Methane

In order to study the influence of different in-situ stress and gas pressure conditions on the effect of ground pre-extracted coalbed methane, according to the example of Jincheng mining area, based on the COMSOL numerical simulation software, with the stress of 5 MPa, 10 MPa, 15 MPa, 20 MPa and reservoir pressure of 1.0 MPa, 1.5 MPa, 2.0 MPa and 2.5 MPa, the effect of coal seam stress and reservoir pressure on the surface pre extraction of coal bed gas is studied. The results show that the increase of ground stress in coal seam makes the porosity of the matrix and the fracture tend to close, resulting in the decrease of permeability, the decrease of the flow rate of gas in the pores and cracks, and the decrease of gas production rate and gas production rate, and the pressure of the reservoir is positively related to the rate of coalbed methane production, and the higher the reservoir pressure is. The higher the production rate and the higher the total output, the higher the extraction time, the higher the permeability of coal seam, and the greater the reservoir pressure is, the more significant the change is.