三次样条插值在排驱压力计算中的应用

对于川东北部罗 家寨气田飞仙关组鲕滩储集层的非均质性致密岩样及次生作用强烈的碳酸盐岩样品,用压汞法作的毛管压力曲线,多数没有明显的平坦直线段,很难精确作出切线,求取排驱压力。为此,提出了一种利用三次样条插值函数计算排驱压力的新方法。该方法应用三次样条插值拟合毛管压力与其对应的汞饱和度,使求取排驱压力的问题转化为求取毛管压力曲线初始拐点的问题。该方法不但程序设计简单、使用方便、原理符合定义,而且适合于各种形态的毛管压力曲线。

Application of Cubic Spline Interpolating Function to Calculation of Drainage Capillary Pressure

Many mercury-injection capillary pressure curves, which inferred from the samples of compacted and intense secondary carbonate rocks in Luojiazhai gas field, northeastern Sichuan, China, have not very good horizontal line segments. Thus, it is not easy to get the data of drainage capillary pressure. A new way to answer this problem is put forward. That is using cubic spline interpolating data to match the capillary pressure and its corresponding mercury saturation, enabling determination of the drainage capillary pressure to become getting the first turning point of mercury-injection capillary pressure curve. The method is not only accordant with the definition of capillary pressure curves, easy to use, but also fits the calculation of any morphologic capillary pressure curve.