裂缝性低渗透油气藏压裂井压力动态特征

Pressure behavior of fractured wells in low-permeability fractured reservoirs

裂缝性低渗透油气藏往往存在明显的应力敏感性,利用椭圆流动模型和平均质量守恒方法,建立考虑介质变形影响的双重介质油气藏有限导流垂直裂缝井不稳定渗流的数学模型,给出数学模型的试探解,绘制并分析了压力动态特征的典型曲线。分析结果表明,介质变形对典型曲线的中晚期形态存在影响,由于渗透率应力敏感性的存在,使得压力导数曲线偏离0.5水平线,后期拟径向流特征段消失,并且渗透率模数越大,压力及压力导数曲线上翘越大。

Low- permeability fractured reservoirs are usually stress -sensitive.Based on elliptical flow model and average mass conservation,a mathematical model of unsteady percolation for wells with finite conductivity vertical fractures in double porosity reservoir is established with consideration of media deformation.Its trial solu- tion and typical pressure behavior curves are given.Analysis shows that media deformation has affected the mid -late section of the typical curve.The derivative curve deviates the O.5 horizontal line because of the existence of stress sensitivity of permeability.In late period,the pseudoradial flow disappears;moreover,the greater the permeability modulus is,the higher the pressure and the derivative curve are.