各向异性双重介质垂直裂缝井两相流体渗流

TWO-PHASE FLOW THROUGH ANISOTROPIC DOUBLEPOROSITY MEDIA FOR VERTICALLY FRACTURED WELL

建立了各向异性双重介质中垂直裂缝并两相渗流数学模型，用有限差分法求得了其解， 进行了算例分析．得到了含水饱和度沿径向、最大及最小渗透率方向的分布和水驱油前缘等饱 和度面随时间的变化，分别讨论了各向异性、吸渗作用对这种介质中两相流作渗流的影响．结 果表明：渗透率较大的方向，前缘推进速度较快，油井见水较早；吸渗使前缘推进速度减慢， 使油井见水晚．注水开发这种油藏时，见水前注入率不能太大以充分发挥吸渗作用，存在最佳 注入率．这对于水力压裂垂直裂缝井注水开发碳酸盐岩裂缝性油藏有指导意义．

A mathematical model for two-phase flow through anisotropic double-porosity media with a vertically fractured well working is established. Numerical solution to the model is presented by using finite difference method. An example is given and discussed. Distribution of water saturation in the direction of radius, maximum permeability and minimum permeability and change of iso-saturation surface with time are derived. Influence of permeability anisotropy, imbibition on characteristics of the flow is discussed. Results show that: (1) the iso-saturation surface moves and water breaks through the well faster in the direction of the larger permeability than in that of the smaller; and (2) the imbibition makes velocity of the surface movement become smaller and time of water breakthrough get longer. The injection rate should be controlled below a certain value before water breaks through the well so that the imbibition can play an important role in waterflooding development of double-porosity reservoir. There is an optimum injection rate which can make development indexes become the most effective. The results have much importance in the waterflooding development of fractured reservoir.