低渗透双孔介质产量递减曲线动态分析

摘要

A non-Darcy transient flow mathematic model based on Warren-Root model in dual-porosity low permeability media is established with the consideration of threshold pressure gradient and dynamic boundary effects. Production decline formulas are derived according to Duhamel theorem. Pressure diffusion equation is linearized by dimensionless pressure derivative using dependent variable transformation. The impacts of threshold pressure gradient, storage ratio, and inter porosity flow coefficient on production are discussed using Laplace transformation and Stehfest inversion method. The production rate and final recovery for single well can be obtained using the non-Darcy transient model provided the paper.%针对低渗透双孔介质储层,依据Warren-Root模型建立了考虑启动压力梯度和动边界影响的低速非达西双孔介质非稳态渗流模型,并通过Duhamel原理导出了单井产量递减公式及累计产量计算公式.采取一种因变量变换重新定义了无因次压力导数,从而使压力扩散方程线性化,利用Laplace变换结合Stehfest数值反演算法计算了不同启动压力梯度、弹性储容比及窜流系数等主要参数对产量递减曲线的影响,并绘制了图版.利用绘制的非稳态产量递减曲线图版可以预测单井在未来某一时间的产量及最终采收率.