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数值模拟是研究煤层气渗流的重要手段。将煤层气储层视为双孔双渗的多孔介质,同时考虑煤层的变形对瓦斯渗流的影响,建立煤层气藏应力—渗流流固耦合模型。综合考虑了煤层气的吸附与解吸效应、应力与渗流耦合作用等因素对煤层气开采的影响。采用SPH(Smoothed Particles Hydrodynamics)法求解控制方程,编制计算机程序。利用该模型求解并分析了煤层气的解吸—渗流过程以及煤层渗透率的变化情况。结果表明,SPH方法能够应用于煤层气解吸—渗流过程的数值模拟研究中来;煤层基质渗透率与裂缝渗透率与有效应力变化有密切关系,煤层气的渗透过程需要考虑煤层基质与裂隙受到的变形影响;考虑煤层气的吸附与解吸效应更加符合实际的煤层气渗流过程,能够更合理地估算实际采气过程中瓦斯涌出量。
Numerical simulation is an important method to study CBM seepage. The CBM reservoir is considered as a porous medium with dual porosity and permeability. The effect of coal seam deformation on gas seepage is also considered, and the stress-seepage fluid-structure interaction model of CBM reservoir is established. Considering the effects of CBM adsorption and desorption, coupling of stress and seepage on CBM production. Using SPH (Smoothed Particles Hydrodynamics) method to solve the control equations, the preparation of computer programs. The model is used to solve and analyze the process of desorption and seepage of coalbed methane and the change of coalbed permeability. The results show that the SPH method can be used in the numerical simulation of coalbed methane desorption and seepage process. The permeability and fracture permeability of coalbed are closely related to the change of effective stress. The process of coalbed methane permeation needs to consider the influence of the coalbed matrix and fracture It is more reasonable to consider the gas emission in the actual gas production process considering that the adsorption and desorption effects of CBM are more in line with the actual CBM seepage process.