各向异性低渗储层渗流特征分析

各向异性、启动压力梯度和应力敏感现象是低渗油藏最显著的特征。建立了同时考虑以上三因素的低速非达西渗流数学模型，考虑方程强烈的非线性，用近似的解法求出稳定渗流以及不稳定渗流方程的解；根据物质平衡原理，得到了定产量、变产量和定流压生产时动边界的运动规律、地层压力分布特征以及产量变化规律。结果表明，各向异性地层激动区边界以椭圆形式向外拓展，改变了井网合理井排距；启动压力梯度和应力敏感使油井产能降低，边界移动速度变慢，单井控制面积减小，增大了油藏的开采难度。

CHARACTERISTIC OF FLOW THROUGH POROUS MEDIA IN LOW PERMEABILITY RESERVOIR WITH EOLOTROPY

Eolotropy, threshold pressure gradient and stress sensitivity are unique feature of low permeability reservoir. The authors of this paper build mathematical model of low velocity non Darcy flow through porous media, which takes three factors above mentioned into consideration. Because of nonlinear for equations, approximate solution is used to solve steady flow and unsteady flow. Meanwhile, under the condition of fixed production and variable production as well as fixed BHP, movement rule of dynamic boundary, reservoir pressure characteristic and production change rule are solved by means of material balance mechanism. The results show that stimulative region boundary of eolotropy reservoir extends outward in the pattern of ellipse, which changes reasonable well row spacing; the factors of threshold pressure gradient and stress sensitivity make productivity decline, and the speed of boundary movement becomes slower, and single well control size reduces. It becomes more and more difficult to develop this kind of reservoir.