Comparison of calculation methods for HTHP condensate gas compressibility factor

Due to existence of heavy components and large deviations of critical parameters, HTHP condensate gas shows poor accuracy of calculated compressibility factor. Based on state equation and empirical correlation, and combined with SSBV/WA correction methods, the calculation accuracy of 5 models, including SRK, DPR, DAK, HY and Cranmer, are comparatively analyzed. The study results show that SRK state equation has the minimum errors and the best adaptability in the calculation of light gas. With the increase of C₇₊ content and pressure, the empirical correlation models of DPR, DAK, HY and Crammer can enhance model adaptability by integrating with SSBV/WA correction methods. It is superior to SRK state equation. By contrast DAK/DPR methods have more stable error distribution. However, the study methods are more meaningful than the study results because of limited investigation scope, providing new study thoughts for calculating condensate gas compressibility factor.