煤岩渗透率各向异性模型及瓦斯抽采模拟研究

Study on model for coal rock permeability anisotropy and simulation of gas extraction

为进一步明晰煤岩渗透率演化特征和基质瓦斯渗流对瓦斯抽采的影响,基于已有的基质瓦斯渗流流固耦合模型,考虑煤岩渗透率的各向异性特征,建立煤岩渗透率各向异性耦合模型;运用COMSOL Multiphysics软件,分析煤岩渗透率各向异性特征和基质瓦斯渗流对瓦斯抽采的影响。研究结果表明:随着渗透率各向异性系数的增大,基质与裂隙渗透率比例系数降低,瓦斯抽采效果明显降低;基质瓦斯渗流量比重最大值随各向异性系数的增大而增大,但在抽采中后期渗流量比重逐渐趋于稳定,且稳定在0. 1%左右;基质瓦斯渗流项在瓦斯抽采中某一特定阶段有促进作用。

In order to further clarify coal rock permeability evolution law and influence of matrix gas seepage on gas extraction,based on the existing fluid-solid coupling model of matrix gas seepage,considering anisotropic characteristics of coal permeability,a permeability anisotropy coupling model of coal rock was built. COMSOL Multiphysics software was used to analyze the anisotropic permeability characteristics of coal rock and the influence of matrix gas seepage on gas extraction. The results show that with the increase of permeability anisotropy coefficient, the ratio coefficient of matrix to fracture permeability decreases,and the effect of gas extraction is obviously reduced,that the peak value of matrix gas seepage rate increases with the increase of anisotropy coefficient,but matrix gas seepage rate in the middle and late stages of gas extraction is gradually stable,and the value is about 0. 1%,and that the matrix gas seepage term plays a promoting part at a certain stage in gas extraction.