Compressibility of natural gases

• Published in: Journal of petroleum science & engineering 1993-12, Vol.10 (2), p.157-162
• Main Authors: Ghedan, Shawket G., Aljawad, Mohammed S., Poettmann, Fred H.
• Format: Article
• Language: English
• Subjects: Applied sciences; Crude oil, natural gas and petroleum products; Crude oil, natural gas, oil shales producing equipements and methods; Energy; Exact sciences and technology; Fuels; Prospecting and production of crude oil, natural gas, oil shales and tar sands; Reservoir engineering, simulation studies and models
• ISSN: 0920-4105; 1873-4715
• DOI: 10.1016/0920-4105(93)90038-G

Two current methods for determining the isothermal coefficient of the compressibility of a natural gas are discussed, i.e., the Trube method published in 1957 and the Mattar et al. method published in 1975. The Trube method plots the reduced compressibility C r = C g P c as a function of reduced pressure and temperature, whereas the Mattar et al. procedure plots the function C g T c T r, or C r T r as a function of reduced pressure and temperature. The Truber chart, which was constructed in 1957 using a graphical method, was recalculated using the Dranchuk and Abou-Kassem eleven factor equation-of-state for the compressibility factor Z. The recalculated Trube chart has a greater range and accuracy than the original chart, particularly in the critical region. A new procedure for calculating gas compressibility is also presented. This method develops an expression for C g P dimensionless compressibility as a function of reduced pressure and temperature. The results are presented both graphically and as a subroutine for computer use.