确定凝析气偏差因子的新方法

A new method for determining z-factor of condensate gas

天然气偏差因子是气藏工程计算中的重要参数,确定天然气偏差因子的方法主要分为:实验法、图版法及经验公式法。针对凝析气的特殊性,利用凝析气生产过程中分离器所得干气的相对密度、凝析油的相对密度及原始生产气油比GOR,确定凝析气的视相对分子质量,在凝析气视相对分子质量确定的基础之上,根据相关方法计算凝析气的拟临界压力与拟临界温度,最终利用经典的DAK法即可确定凝析气的偏差因子。实例计算表明,该方法计算所需参数易获取,计算过程相对简单,计算结果准确,实用性强。

Gas deviation factor is an important parameter for gas reservoir engineering calcu- lation. Methods for determining Z-factor of natural gas are divided into experimental method, plate method and empiric equation method. For the specificity of condensate gas, according to dry gas gravity, condensate gravity and produced gas oil ratio which were measured at ground separator, the pseudo molecular weight can be determined, on the basis of the calcu- lated pseudo molecular weight, combining with related methods to calculate pseudo critical pressure and pseudo critical temperature, on the basis of the calculated pseudo critical pres- sure and pseudo critical temperature, Z-factor of condensate gas can be determined by DAK method finally. The case study indicates that required parameters in this new method are easy to obtain, calculation of this new method is relatively simple, new method is accurate and practical.