低渗注水层的渗透率和启动压力梯度优化研究

The Studying of Permeability and Start-up Pressure Gradient for Low Permeability Layer

由于取心资料和室内实验的局限,低渗透注水层的启动压力梯度和渗透率的求取已成为油藏工程分析的难点。以低速非达西渗流的半解析法为基础,导出激动边界的一种精确表达式。针对前人在采用试算法求解激动半径过程中的不足,提出并证明了使用二分法对激动边界进行数值求解的可行性。提出利用最优化算法对注水井的试注资料进行拟合的思路,可以计算储层的启动压力梯度和渗透率。从现场注水井的应用效果来看,该方法可操作性强、计算误差小,可以在低渗储层注水井的动态分析中推广应用。

Because of the coring data and indoor experimental limitations, threshold gradient and permeability of low permeability layer have become the difficulty of reservoir engineering analysis. Based on partial analytical solution of low permeability reservoir, an exact expression of the active boundary is derived. Dichotomy to solve the active boundary is proposed herein and its reliability is also proved. The optimization algorithm is put forward, which can calculate permeability and start-up pressure gradient of reservoir using the pressure recorded from water injection well. This method has been used in the actual field, proved to be feasible , and can be applied in calculating similar injection and production wells reservoir parameters.