各向异性双重孔隙介质的应力与油水两相渗流耦合理论模型

FULLY COUPLED DUAL-POROSITY MODEL FOR OIL-WATER TWO-PHASE FLOW IN ANISOTROPIC FORMATIONS

针对天然裂缝性油藏的特性,建立了描述双重孔隙介质中油水两相流体流动特性的流固耦合理论模型。该模型不仅考虑了渗透率的各向异性,而且考虑了岩石固体骨架变形的各向异性。渗流方程是依据双重孔隙的概念建立起来的,而固体骨架变形控制方程则是根据Biot的等温、线性孔隙弹性理论建立起来的。同时,给出了横向各向同性及结构各向异性、固体材料各向同性时的双重孔隙介质的应力与油水两相渗流耦合理论模型。对该模型进行了简化,并将其简化后模型与单相流的各项同性和各向异性双重孔隙介质流固耦合理论模型进行了比较。

A fully-coupled geo-mechanics and two-phase（oil-water） fluid-flow model is developed to analyze pressure transient problems in naturally fractured reservoirs（or stress-sensitive reservoirs） with deformable anisotropic formation.For fractured reservoirs,the rock is actually dual-porosity media of matrix pores and fractures,fractures are the main storage of oil.Fluid flow is modeled within the context of dual-porosity concept and based on three basic principles： mass conservation,Darcy＇s law,and equation of state.While geo-mechanics is modeled following Biot＇s two-phase（fluid and rock）,isothermal,linear poroelastic theory,which has three basic principles： stress equilibrium,strain-displacement,and strain-stress-pressure relations.The development follows along the line of the conventional and existing porous single-phase fluid-flow modeling.The interpretation of the pore volumetric changes of the dual continua,fractures and matrix-blocks,and the associated effective stress law for anisotropic double porous media are the most difficult and critical coupling considerations.The model reduces,in the case of isotropic and anisotropic but single-phase response, to that suggested by Li et.al.and Zhao.et al.