反映动态启动压力梯度的低渗透油藏渗流模型

基于流体边界层理论，建立了一种描述在低渗透油藏流体非线性渗流特征的新模型，获得了动态启动压力梯 度的连续变化函数。应用考虑动态启动压力梯度的非线性渗流模型，建立了一维单相流体流动的数学模型，并应用全 隐式方法对离散方程进行了线性化处理；对比研究了线性渗流模型、拟线性和反映动态启动压力梯度的非线性渗流模 型下地层压力的分布特征及流体非线性渗流系数对动边界扩展的影响。数值结果表明：受动态启动压力梯度的影响 在近井区域地层压力下降幅度更大，在远井区域的地层压力越高，地层压力下降范围更小；非线性系数数值越小，流体 流动的非线性程度越强，动边界的扩展速度越慢。

A Flow Model Reflecting Dynamic Kick-off Pressure Gradient for Low#br# Permeability Reservoirs

Based on the fluid boundary layer theory，this paper presents a new flow model that can be used to describe the non-linear seepage feature in low permeability reservoir to obtain continuous function of the dynamic kick-off pressure gradient. And the nonlinear seepage flow model of dynamic kick-off pressure gradient is considered to establish the mathematical model of one-dimensional single-phase fluid flow，and the discrete equations are linearized with fully implicit method. Besides，the distribution feature of formation pressure and influence of nonlinear seepage flow coefficient on moving boundary expansion are studied comparatively from linear seepage model，quasi linear formation pressure and nonlinear seepage model reflecting dynamic kick-off pressure gradient. Numerical results indicate that with the influence of the dynamic kick-off pressure gradient， the formation pressure of near well region declines more greatly，while formation pressure in the far zone is higher，and formation pressure decline range is narrower. In addition，when nonlinear coefficient numerical value is smaller，the degree of fluid flow nonlinearity is stronger，and expansion velocity of dynamic boundary is lower.