The permeability of a coal seam is an important index for coal mine gas control and coalbed methane development, and its magnitude determines the degree of difficulty of gas drainage. To obtain the permeability value, a dimensionless mathematical model for dual-porosity borehole gas-coupled flow in a coal seam was established and adopted using a simulator developed by our group. A new method of inversion was developed to determine the fracture permeability coefficient λ _f and the matrix micro-channel diffusion coefficient K _m by fitting the simulated results with onsite measured data. A range of simulations quantified the effects of different dimensionless parameters on gas migration. The results verified the feasibility of the inversion method based on the high matching degree of the fitted results, and the dimensionless mathematical model was accurate. The desorption and release of adsorbed gas from the center to the surface in coal matrices were heterogeneous, and unsteady states and gas migration times in coal matrices cannot be neglected. The new method can be introduced to analyze the problem of gas migration in different coal reservoirs, simplify the corresponding calculation and computational processes, and provide guidance in determining the permeability of coal seams.

中文翻译：

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双孔耦合井眼瓦斯流动模型：反演煤层渗透率的新方法

煤层的渗透率是控制煤矿瓦斯和开发煤层气的重要指标，其大小决定了瓦斯抽采的难度。为了获得渗透率值，使用我们小组开发的模拟器建立并采用了煤层中双孔隙度钻孔气体耦合流的无量纲数学模型。反转的新方法的开发是为了确定裂缝渗透系数 λ _˚F和基质微通道扩散系数 ķ _米通过将模拟结果与现场测量数据拟合。一系列模拟量化了不同无因次参数对气体迁移的影响。结果表明，基于拟合结果的高匹配度，反演方法是可行的，无因次数学模型是准确的。煤基质中吸附气体从中心到地面的解吸和释放是非均质的，煤基质中的不稳定状态和气体迁移时间不能忽略。可以引入新方法来分析不同煤层中瓦斯运移的问题，简化相应的计算和计算过程，为确定煤层的渗透性提供指导。