确定低渗岩心渗透率随有效覆压变化关系的新方法

A new method of determining relationship between permeability and effective overburden pressure for low-permeability reservoirs

低渗储层岩心在有效上覆压力增大的过程中会表现出较强的应力敏感性。提出了一种定义应力敏感系数的新方法,通过室内物理模拟实验,分析得到了应力敏感系数与初始渗透率的关系式。结果表明,用该方法定义的应力敏感系数不受实验中所测数据点个数的影响,并且与实验岩心所受的最大围压无关;用二重乘幂函数式可表征出任意初始渗透率随有效覆压变化的关系,能方便地确定地层条件下储层渗透率,并能对油气井产能作出正确评价。应用该方法可以计算非均质油气储层开发过程中任意渗透率的变化动态,为建立低渗变形介质油气藏渗流模型及进行数值模拟奠定了基础。

The low-permeability cores show stress sensitivity during the effective overburden pressure increasing. A new method of defining stress sensitivity coefficient was presented. The relationship between stress sensitivity coefficient and initial permeability was deduced by physical modeling experiment in room. The results show that the stress sensitivity coefficient defined by this new method is not affected by the numbers of testing data and no related to the maximum confining pressure. The relationship between permeability and effective overburden pressure can be expressed by a dual-power function. By this dual-power function, the core permeability in reservoir condition can be determined conveniently, and variation of permeability of heterogeneous reservoirs can be computed during the process of development, which provides a basis to establish percolation model for low-permeability reservoirs.