天然气偏差因子是气藏工程计算中一项相当重要的参数，多采用Standing-Katz图版或经验公式求取,其中图版法人工读值误差较大且不便于计算机应用,而各种经验公式的计算精度和适用范围又难以确定。针对以上难点，采用数字化软件对Standing-Katz图版进行了数字化处理,并以该图版为参照,对目前工程计算最常用的4种经验公式的计算精度和有效适用范围进行了分析和评价,优选出了计算精度高的经验公式,为研究人员的使用提供了依据。

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The deviation factor of natural gas is a great significant parameter for the gasreservoir engineering calculation, which is mainly obtained by the Standing-Katz graphic solution or empirical formula calculation. The graphic solution is with great deviation when the parameters are manually read and is not convenient for computer application. The precision and applicability of the empirical formula calculation are difficult to confirm. To resolve the shortcomings mentioned above, firstly we digitize the Standing-Katz graph with digital software, then with the digital graph we analyze and evaluate the calculations' precision and application range of the 4 kinds of empirical formulas which are widely used for thepresent engineering calculation, finally the most accurate empirical formula isoptimized to offer the reference for our research staff.