关键词: 瓦斯抽采, 流固耦合模型, 基质瓦斯渗流, 双渗透率, 数值模拟

Abstract: In order to more accurately reflect the migration process of coal methane in the process of extraction, it was assumed that the coal seam was a kind of elastic medium with dual porosity and dual permeability, and a fluid-solid coupling model considering matrix methane seepage for extraction was built on the basis of considering the action of matrix methane seepage and coupling effects of groundwater and methane adsorption/desorption characteristics, coal rock deformation and permeability evolution. Numerical simulations of coal methane extraction process were carried out, and the influences of migration law and matrix methane seepage were analyzed. The results show that there is a negative correlation between both the pressure of matrix methane and that of fracture methane and time, and the difference between them increases first and then decreases, that under the simulated conditions, the matrix methane seepage only accounts for 0.5% of the amount of methane flowing into fracture, that matrix methane seepage influences both the methane production capacity and the reservoir pressure, and that both methane production and reservoir pressure drop predicted by the dual porosity and dual permeability model considering the matrix methane seepage are less than those by the dual porosity and single permeability model.

Key words: coal methane extraction, low-solid coupling model, matrix methane seepage, dual permeability, numerical simulation