考虑二次梯度项影响的双渗模型的动态特征

在传统试井模型的非线性偏微分方程中根据弱可压缩液体的假设忽略了二次梯度项,已经知道在试井较长时间忽略二次梯度项将产生误差,故对于双重介质流动系统保留了非线性偏微分方程中的二次梯度项,建立了双渗流动模型.采用Douglas-Jones预估校正法获得了无限大地层定产量生产时和定压生产时双渗模型的数值解,分别讨论了液体压缩系数和双重介质参数变化时压力变化规律,做出了典型压力曲线图版,这些结果可用于实际试井分析.

DYNAMICAL CHARACTERISTICS OF DOUBLE POROSITY/DOUBLE PERMEABILITY MODEL INCLUDING THE EFFECT OF QUADRATIC GRADIENT TERM

Traditional well-test models for flow are not consistent with the material balance equation. According to the assumption of slightly compressible fluid, the quadratic gradient term in the nonlinear partial differential equation is usually neglected. It is known that neglecting the quadratic gradient term results in errors for large time well-test. A method which is consistent with the material balance equation for fractured reservoir with double porosity/double permeability is proposed. All terms in the nonlinear partial differential equation are retained. Double porosity/double permeability models are given. The numerical solutions of double porosity/double permeability models are obtained by the Douglas-Jones predictor-corrector method at a constant rate and the constant-pressure production for an infinitely large system. It also deals with the change rule of pressure while fluid compressibility and double porosity parameters change. Plots of the typical pressure curves are given, and the results can be applied to the well-test analysis.