天然气偏差因子计算新方法

天然气偏差因子是油气藏工程相关领域中的重要参数,它在采油采气、气体计量、管线设计、地质储量和最终采收率的估计等油气勘探、开发、化工的诸多工程应用中都不可或缺,快速准确地确定该参数尤为关键。为此,基于Nishiumi-Saito状态方程结合多元非线性回归分析,提出了一种新的偏差因子关系式,相应形成新的计算偏差因子的方法,利用该方法可准确计算整个压力范围内的气体偏差因子。利用偏差因子标准数据对该方法及油气藏工程中常用的DPR、HY、DAK方法进行了对比。误差分析表明,该方法在常用压力范围和高压下的平均绝对误差分别为0.357%、0.066%,其计算精度比DPR、HY和DAK方法高。

A new method for determining the natural gas compressibility factor

The compressibility factor (Z-factor) of natural gas, a critical parameter in many engineering calculations related to oil and gas reservoir engineering, is absolutely necessary in numerous engineering applications of oil and gas exploration, development, and chemical engineering, such as oil and gas production, gas metering, pipeline design, estimation of original gas in place, ultimate recovery and so on. Therefore, it is especially crucial to determine this parameter quickly and accurately. Based on the Nishiumi-Saito (1975) equation of state and multivariate nonlinear regression analysis technique, a new Z-factor correlation is presented in this paper, by which gas compressibility factor in the whole pressure range can be precisely predicted with iteration method. The calculated results of the new method proposed here and DPR, HY, DAK correlations commonly used in oil and gas reservoir engineering are compared with standard data of Z-factor. The results of error analysis indicate that for the cases of general pressure range and relatively high pressure range, the average absolute error of the new method is 0.357% and 0.066% respectively, the calculation accuracy of which is distinctly better than the above three classical methods.