一种基于毛细管压力资料获取岩心束缚水饱和度的新方法

A New Method of Obtaining Core Irreducible Water Saturation Based on Capillary Pressure Curve

利用毛细管压力资料获取束缚水饱和度是目前油田生产实践中常用的方法,但针对岩心束缚水饱和度特征毛细管压力值的确定存在较大的人为经验性,给实际生产研究工作带来了较大的不确定性,亟需改进。利用岩心压汞毛细管压力资料建立了区域岩心压汞中值压力与孔隙度的幂函数关系式,结合解析几何学中最大曲率算法可以确定区域孔隙度下限及压汞特征压力,利用毛细管压力与孔喉半径、界面张力、润湿接触角之间的关系可以得到与特征压力对应的孔喉半径,从而可以获得每颗岩心基于毛细管压力实验的束缚水饱和度。将最大曲率法确定的束缚水饱和度结果与半渗透隔板实验经验取值法确定的束缚水饱和度、气柱高度转换法确定的气层含水饱和度进行了对比分析,证实这种新方法效果良好,验证了该方法的可靠性。

Obtaining irreducible water saturation with capillary pressure curveis commonly used in oilfield production practices currently,but the eigenvalues of experiment pressure is mainly determined by human experience.But this experimentally determined irreducible water saturation often cannot agree well with pure reservoir water saturation interpreted by logging.It is required to establish the relationship between the pressure of middle S（hg） and core porosity in the region.Combined with maximum curvature algorithm to determine the eigenvalues of experiment pressure,the pore throat radius can be characterized by the relationship between capillary pressure and pore throat radius,θ,σ,and then irreducible water saturation of every single core can be obtained.Finally,this method proves effective as the result is compared with the results of irreducible water saturation determined by semi-permeable separator experiment and water saturationof pure gas layer converted by gas column height.