确定储集层物性参数下限的一种新方法及其应用——以鄂尔多斯盆地中部气田为例

A New Method Used to Determine the Lower Limit of the Petrophysical Parameters for Reservoir and Its Application: A case study on Zhongbu Gas Field in Ordos Basin

分布函数曲线法是一种确定储集层物性参数下限的新方法。该方法从统计学角度出发，通过有效含气层与非有效含气层样本分布函数曲线之间的关系确定储集层物性参数下限值，在鄂尔多斯盆地中部气田的实际应用中，效果较好，与采用产能系数法、经验统计法及油田实验测试相比较，得到的结果基本一致，表明这一方法值得进一步推广使用。

It’s important to exactly determine the lower limit of petrophysical parameters for reservoir in calculation of reserves.Laboratory test is commonly used to get the lower limit values.However,the test is complicated and takes a long time.As for intensively anistropic reservoir,a large amount of data should be obtained which means much more time and costs.Therefore an easy,fast and economic method is necessary to be provided instead of traditional test.Distribution function is one of the most important mathematic characteristics of geological body.Distribution curve is often used to analyse the distribution regularity of the studied object.The distribution function curve method presented in this paper is a new statistic method used to determine the lower limit of petrophysical parameters for reservoir.Based on making full use of data from well logging interpretation available in oil gas field,the disribution curves for effective and non effective gas bearing reservoirs are drawn in the same coordinate system respectively.Theoretically,if there exists a point of intersection for the two curves,the corresponding frequency must be zero.Actually,there is a superimposed region because of the mixed effects for the effective and non effective gas bearing reservoir.Under the condition of no seperation of mixed effects,the value corresponding to the intersection point for the two curves is taken as the lower limit.This method is applied to the determination of lower limit for the gas bearing resevoir of Zhongbu Gas Field in Ordos Basin.The results coincides well with the values obtained by methods of accumulative production capacity,experience statistics and laboratory test,which demonstrates that this method is successful and valuable to be extended.