A Study on Gas Compressibility Factor for Gas-Condensate Systems

Abstract

Gas compressibility factor is the most important gas property. Its value is required in many petroleum engineering calculations. There are many different sources of gas compressibility factor value such as experimental measurements, equations of state, charts, tables, intelligent approaches and empirical correlations methods. In absence of experimental measurements of gas compressibility factor values, it is necessary for the petroleum engineer to find an accurate, quick and reliable method for predicting these values. This study presents a new gas compressibility factor explicit empirical correlation for gas-condensate reservoir systems above dew point pressure. This new correlation is more robust, reliable and efficient than the previously published explicit empirical correlations. It is also in a simple mathematical form. The predicted value using this new correlation can be used as an initial value of implicit correlations to avoid huge number of iterations. This study also presents evaluation of the new and previously published explicit correlations.

Physiochemical, Pseudocritical and Thermodynamic Characterizations of Natural Gases

“…Compressibility factor has been calculated mathematically by using Equation [2]. Due to the presence of impurities in the mixtures that represented by H2S, N2 and CO2, the z factor was corrected by using Wichert-Aziz correlation [6] for these sour gases as shown in Tables 1 through 4.…”