裂缝性低渗透油藏流-固耦合理论与数值模拟

根据裂缝性低渗油藏的储层特征,建立适合裂缝性砂岩油藏渗流的等效连续介质模型。将渗流力学与弹塑性力学相结合,建立裂缝性低渗透油藏的流-固耦合渗流数学模型,并给出其数值解.通过数值模拟对一实际井网开发过程中孔隙度、渗透率的变化以及开发指标进行计算,并和刚性模型以及双重介质模型的计算结果进行了分析比较.

THEORY AND SIMULATION OF FLUID-SOLID COUPLING FLOW THROUGH LOW PERMEABILITY FRACTURED OIL RESERVOIR

The fluid-solid interaction in porous media influences the recovery efficiency of low permeability fractured sandstone reservoir strongly. The fractures have a significant effect on the oil exploitation. In this paper we present a theoretical study of the fluid-solid coupling flow in fracturedsandstone reservoir. The main content of this paper include: 1) Based on the characteristic of fractures in the reservoir, an equivalent continuum model to simulate the fluid flow in fractured sandstone reservoir was developed. The equivalent model can reflect the anisotropy character well. 2) The mathematical models of coupling analysis on reservoir multiphase flow and stress are established based on the theories of rock mechanics and mechanics of multiphase flow through porous media. It is assumed that the deformation of reservoir framework has an elasto-plastic behavior in the models, and the fluid flow abides by the Darcy law. The coupled relation between fluid flow and rock masses deformation considers the effect of fractured closure and opening. A new permeability evolution model was derived. 3) Numerical solution of the model was given. The computing method of fluid flow is IMPES (implicit pressure and explicit saturation method). The deformation field is solved by finite element method. The solution of the coupling models is iterative computation. 4) According to the above theories, computer program to simulate fluid-solid coupling flow through fractured reservoir were compiled. Using the program, a factual well pattern was simulated during oil exploitation. The effectiveness and utilities for coupling analysis are verified by the example. The changes of porosity and permeability during water-flood process were studied. By comparing the simulation results of the coupling models with the results of rigid non-coupling models, we studied the difference between coupling models and non-coupling models. The difference shows that the fluid-solid coupling effect in low permeability sandstone oil reservoir should not be neglected in the oil reservoir simulation. The paper can provide development simulation, performance evaluation and forecasting of low permeability fractured oil fields with theoretical basis.