Abstract: The pseudo critical parameters of natural gas are the gas-related fundamental calculation data.The pseudo critical parameters of sour gas are calculated mostly by Kay rule and Wichert-Aziz correction, but the sour gas density-based method has not been published at home.This paper collected 93 sour gas samples from several gas fields at home and broad and established a new equation for calculation of the pseudo critical parameters of sour gas integrated with the experimental results.Also, the deviation factors (Z) of sour gas and conventional gas for H2S and CO2 are calculated by the new equation.Compared with the experimental results obtained by Kay rule, Wichert-Aziz correction model and Standing method, the result shows that the new equation is fit for sour gas and the accuracy is higher than Kay rule and Standing equations.However, for conventional gas with low molecular weight, the accuracy of Standing method is the highest.

Key words: sour gas, critical value, density, correction, calculation method