各向异性三重孔隙介质应力与多相渗流耦合理论研究

Shale gas because of its wide distribution, clean, is considered to be one of the important alternative energy of conventional energy. Due to shale gas reservoir has extra low porosity, extra low permeability, adsorption desorption and anisotropic properties,in the project shale gas reservoir will be regarded as anisotropic triple porous medium, the whole system is divided into three medium:sub-matrix pore, microfracture and macrofracture.Micro and macro fracture network are viscous Darcy flow dominant, the sub-matrix pore is diffusion and desorption dominant. Establishment of dynamic model of permeability which relate to anisotropic effective stress, sub-matrix pore swelling/shrinkage induced strain and considering slippage effect; both the permeability anisotropy and anisotropy of the solid skeleton are considered in the fully coupled triple-porosity model for multiphase flow in anisotropic formations.Through indoor experiment to determine shale transversely isotropic mechanical parameters by ultrasonic method; Stable and efficient numerical method is used to solve the equations. By using the established fluid-solid coupling model of shale gas reservoir, we will study the multi-scale flow output mechanism and make productivity prediction of shale gas. The study has great theoretical significance and practical value for the development of shale gas reservoirs.

页岩气因其分布广、清洁，被认为是常规能源的重要替代能源之一。由于页岩气藏具有超致密特低孔、特低渗、存在吸附解吸和各向异性等特性，本项目将页岩气藏视为各向异性三重孔隙介质，即整个系统由具有纳达西渗透率的非联通子基质、具有毫达西渗透率的联通微裂隙和宏观裂隙组成，微观和宏观裂隙网络以粘性达西渗流为主导，子基质孔隙以扩散和解吸为主导。建立与各向异性有效应力相关、考虑子基质解吸变形和滑脱效应的渗透率动态模型；建立既考虑渗透率各向异性，又考虑岩石固体骨架力学性质各向异性的三重孔隙介质多相流体流动与固体骨架变形耦合的全耦合理论模型；利用超声波方法通过室内实验确定页岩横观各向同性力学参数；利用高效稳定的数值计算方法进行数值求解。并利用所建立的流固耦合数值模型研究页岩气藏的孔渗结构及多尺度渗流产出机理，进而进行页岩气藏的产能预测和动态分析。该研究对于页岩气藏的有效开发具有重大理论意义和实际工程价值。

页岩气因其分布广、清洁，被认为是常规能源的重要替代能源之一。由于页岩气藏具有超致密特低孔、特低渗、存在吸附解吸和各向异性等特性，本项目将页岩气藏视为各向异性三重孔隙介质，即整个系统由具有纳达西渗透率的非联通子基质、具有毫达西渗透率的联通微裂隙和宏观裂隙组成，微观和宏观裂隙网络以粘性达西渗流为主导，子基质孔隙以扩散和解吸为主导。建立与各向异性有效应力相关、考虑子基质解吸变形和滑脱效应的渗透率动态模型；建立既考虑渗透率各向异性，又考虑岩石固体骨架力学性质各向异性的三重孔隙介质多相流体流动与固体骨架变形耦合的全耦合理论模型；采用三轴压缩试验机对龙马溪组露头页岩岩芯进行三轴抗压岩石力学实验，确定横观各向同性岩石的5个材料参数，从而确定有效应力系数。利用岩石声发射Kaiser 效应测定地应力。利用高效稳定的数值计算方法进行数值求解。并利用所建立的流固耦合数值模型研究页岩气藏的孔渗结构及多尺度渗流产出机理，进而进行页岩气藏的产能预测和动态分析。该研究对于页岩气藏的有效开发具有重大理论意义和实际工程价值。