煤层气藏应力—渗流流固耦合模型及SPH求解  

Stress-seepage hydro-mechanical coupling model of coal-bed methane reservoir and its SPH analysis

作　　者：孙超群[1,2] 李术才[2] 李华銮[2] 崔伟[2] 宋曙光[2] 

机构地区：[1]山东交通学院交通土建工程学院,山东济南250357 [2]山东大学岩土与结构工程研究中心,山东济南250061

出　　处：《天然气地球科学》2017年第2期305-312,共8页Natural Gas Geoscience

基　　金：国家重点基础研究发展计划("973")项目(编号:2013CB036000);山东交通学院校级基金项目(编号:Z201612)联合资助

摘　　要：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 a significantly important method for the dynamic analysis of coal-bed methane reservoir and gas production. This paper proposed a stress-seepage hydro-mechanical model for coal-bed methane reservoir that was considered as dual permeability media of matrix pore and fracture.At the same time, the influence of the deformation of coal-bed on the gas seepage field was considered. The model involved the effects of coal-bed methane＇s adsorption and desorption, the coupling of stress-seepage, and other factors on the coal bed methane extraction. SPH （Smoothed Particles Hydrodynamics） method was used to discretize the governing equations,and thus corresponding SPH code was made. A numerical example was presented using the proposed model and field coal bed parameters.The model is used to solve and analyze the process of coal bed methane desorption and the change of permeability.The SPH method can be applied to the study of coalbed methane desorption and seepage process and the dynamic analysis of coalbed gas reservoir. Results show that the matrix permeability and fracture permeability are influenced obviously by effective stress.Considering the adsorption and desorption of coal-bed methane are more real- istic in the process of the coal-bed methane seepage,which is needed in the reasonable estimation of the a- mount of gas emission during the actual gas production process.

关 键 词：煤层气 流固耦合 应力-渗流 解吸 SPH 双重介质 

分 类 号：TE31[石油与天然气工程—油气田开发工程]