地层条件下的天然气偏差系数是气藏开发研究中不可缺少的基础数据,对于超高压气藏尤为重要。高压物性实验测定结果准确,但成本高、周期长、工作量大。为适应川西地区超高压气藏开发的需要,通过现场高压物性取样、室内实验测定取得的实测数据,对目前常用的天然气偏差系数计算方法进行对比分析,筛选经济、适用的天然气偏差系数计算方法。研究结果表明:当2.0≤拟对比温度(Tpr)≤3.0,15.0≤拟对比压力(ppr)≤30.0时,SRK状态方程的适应性最好,总的误差在3%以内;经验公式中张国东法(ZGD法)最优,与实测值平均相对误差最小，为1.43%,ZGD法计算过程简单、精度高,建议在该类气藏推广应用。天然气偏差系数的准确取值对油气藏评价、采气工艺实施具有重要意义。

The deviation factor of natural gas under formation conditions is an indispensable basic data in the study of gas reservoir development, especially for ultra-high pressure gas reservoir. The results of high-pressure physical property experiment are accurate, yet with higher capital cost, longer cycle and heavier workload. In order to meet the needs of ultra-high pressure gas reservoir development in western Sichuan area, the measured data are obtained through field high-pressure physical property sampling and indoor experiment. This paper compares and analyzes the commonly used calculation methods of natural gas deviation factor, and selects the economic and applicable calculation methods for natural gas deviation factor. The results show that when 2.0≤Tpr≤3.0,15.0≤ppr≤30.0, the state equation of SRK model is the best, and the total error is less than 3%; in the empirical formula, ZGD method is the best, and the minimum average relative error is 1.43%. ZGD method has simple calculation process and high precision. It is suggested to be popularized and applied in this kind of gas reservoir. The calculation of natural gas deviation factor is of great significance for gas reservoir evaluation and the implementation of gas recovery process.