致密油藏有限元数值模拟

Finite Element Numerical Simulation for Tight Reservoirs

目前数值模拟方法均基于达西渗流,无法对致密油藏非达西渗流进行有效模拟。致密油藏内在复杂,为实现致密油藏非达西渗流的科学模拟,建立了油水2相微可压缩非达西流的油藏数值模拟数学模型。同时考虑到致密油藏渗透率低、非均质性强的特点并兼顾模拟精度采用有限单元法进行离散,从而建立了有限元数值模型,形成了新的致密油藏数值模拟方法,最后将该方法进行实例检验,验证了方法的正确性。

The fluid flow is non-Darcy flow in a tight reservoir. A startup pressure gradient is necessary for the flow in the tight reservoir porous media. The numerical simulation technology and software are mostly based on the Darcy seepage and could not effectively simulate the non-Darcy flow for tight reservoirs. In this paper, considering the complexity of the tight reservoir, the non-Darcy flow and the nonlinear characteristics, the oil-water two-phase compressible flow continuity equation, the motion equation, the state equation and the auxiliary equation are derived, to establish the oil-water two-phase non-Darcy flow mathematical model for the reservoir. The startup pressure gradient is considered in this model. The model is discretized for the low permeability and the strong heterogeneity in the tight reservoir with the finite element to be applied to complicated boundaries, high order differential equations, and weak grid orientations, with a high calculation precision. The numerical solution equation for saturation and pressure is obtained. The method is verified by examples.