低渗透复合油藏压力动态有限元理论分析

低渗透油藏非均质性较强，孔渗物性差，往往需要通过油藏增产改造获得工业产能。基于非均质油藏生产开 发实践，以实验测试得到附加阻力梯度与驱替压力梯度和流体流度关系式为基础，建立了低渗透复合油藏附加阻力梯 度渗流模型，并采用有限元解法对该非线性模型进行求解，得到了井底压力动态的数值解。研究结果表明，复合油藏 区域间物性差异对井底压力动态影响显著；附加阻力梯度的存在，使得压力及压力导数曲线在径向流阶段逐步上翘， 但上翘幅度小于传统的拟启动压力梯度模型。

Theoretical Analysis of Low Permeability Composite Reservoir Using#br# Finite Element Method

Low permeability reservoir has strong heterogeneity and poor property，and stimulation is often needed to achieve industrial productivity. Based on the heterogeneous reservoirs development practices and the relationship between added resistance gradient and displacement pressure gradient and mobility，a well test model of added resistance gradient of composite reservoir is established and solved by finite element method. Then the characteristic curves are gained and analyzed. The results show that differences between the composite reservoir area have a significant impact on the dynamic characteristics of the bottom hole pressure. Because of the added resistance gradient，dimensionless pressure and pressure derivative in log-log well test plot goes upward gradually，but the amplitude is lower than that of the traditional pseudo threshold pressure gradient method.