In the process of gas mining, the fracture distribution with power law length and the pore structure with adsorption effect have an important influence on the coal seam permeability. In recent years, the research on the internal structure of coal seam and the fluid flow mechanism has attracted a large number of researchers. In this paper, by considering the coal matrix deformation caused by adsorption, a pore-fracture model coupled with the multi-field effects and with power law length distribution of fractures in coal seam is established based on the fractal theory for porous media. In this work, we study the influences of the power law exponent α of fracture length and the ratio r of the minimum to maximum fracture lengths on the permeability of coal seam and the evolution mechanism of permeability with the structural and mechanical parameters of coal seam. It is found that the permeability of coal seam is inversely proportional to α, directly proportional to r, and to Langmuir volume constant and Langmuir volume strain constant. Compared with other factors, the power law component α of fractures has the most significant effect on the coal seam permeability.

中文翻译：

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具有幂律长度分布裂缝的煤层多场耦合渗流模型

在瓦斯开采过程中，具有幂律长度的裂缝分布和具有吸附作用的孔隙结构对煤层渗透率有重要影响。近年来，煤层内部结构及流体流动机理的研究吸引了大量的研究人员。本文在考虑吸附引起的煤基质变形的基础上，基于多孔介质分形理论，建立了结合多场效应和幂律长度分布的煤层孔隙-裂缝模型。在这项工作中，我们研究了幂律指数的影响α断裂长度与比例r煤层渗透率的最小至最大裂缝长度及渗透率随煤层结构和力学参数的演化机制。发现煤层的渗透率与α, 成正比r，以及朗缪尔体积常数和朗缪尔体积应变常数。与其他因素相比，幂律分量α裂缝对煤层渗透率的影响最为显着。