裂缝等效介质模型对裂缝结构和充填介质参数的适应性

摘要

基于裂缝各向异性等效介质模型:定量分析了纵横波速度、弹性刚度张量随裂缝密度、裂缝孔隙纵横比及孔隙充填流体性质的变化规律；考察了Hudson模型、Pade近似和Liu含裂缝介质模型的适用条件和精度；重点分析了裂缝孔隙的结构参数、孔隙度大小及充填流体性质对弹性模量和纵横波速度的影响.基于Hudson模型的Pade近似,明确了它对高裂缝密度和大纵横比的适应性.Hudson模型、Pade近似和Liu含裂缝介质模型的响应模拟表明:在裂缝密度小于0.1时,Liu模型和Hudson二阶近似的响应基本一致,Liu模型和Pade近似均适用于裂缝密度小于等于0.2的裂缝介质；裂缝密度大于0.2时,前者适应性更好些.另外,纵横比对饱水裂缝介质标准化刚度模量的影响较干裂缝介质的影响大.%Based on the anisotropic effective model of fracture medium,the authors analyzed velocities of compressional and shear waves,the variations of elastic stiffness modulus with respect to the fracture density,the fracture aspect ratio and the fluid properties filled in the pore.We also examined the applicability and the accuracy of Hudson model and its Pade approximation and the Liu fracture model,and focused on the effects on elastic modulus and velocities of the compressional and shear waves of the geometric parameters of the fracture pore,fracture porosity and the fluid filled in it.On the basis of the Pade approximation of Hudson fracture model,we proved that Pade approximation is suitable for higher fracture density and larger fracture aspect.The simulation results indicate that when the fracture density is less than 0.1,the Liu fracture model and Hudson second order approximation lead to consistent elastic response; Liu fracture model and Pade approximation are applicable to the cases when fracture density is less than 0.2; for the cases of fracture density larger than 0.2,the Liu model shows more reasonable result.Furthermore,in the water saturated and the dry fracture medium,the fracture aspect presents more significant effects on the the Liu model.