Evaluations on Compressibility Factor Calculation Methods for High-Pressure H2S-Containing Natural Gases
Keywords:High-pressure natural gas, H2S, Compressibility factor, Equation of state.
AbstractThe compressibility factor is an essential parameter for natural gas exploitation and processing. The method based on the equation of state (EoS) represents the most popular method for compressibility factor calculations. In this paper, the accuracy of compressibility factor calculations for two traditional cubic-EoSs (Soave-Redlich-Kwong (SRK) EoS, the Peng–Robinson(PR) EoS), the Benedict–Webb–Rubin-Starling (BWRs) EoS, and the Cubic-Plus-Association (CPA) EoS are evaluated based on experimental data for high-pressure H2S-containing natural gases. A total of 234 sets of experimental compressibility factors are applied to validate the above four EoSs, which cover pressures from 70MPa to 131MPa. Results show that for the high-pressure and low H2S content natural gas (35MPa≤P<70MPa, H2S<0.3%), the BWRS EoS yields the best results among the above four EoSs. The average relative deviation (ARD) between the experimental results and the calculated values is 1.07%. For high-pressure and high H2S content natural gas (35MPa≤P<70MPa, H2S≥0.3%), the CPA EoS yields the best results with an ARD of 1.01%. For ultra-high-pressure natural gas (P≥70MPa) without H2S, the BWRS EoS gives the best results with an ARD of 0.32% and the maximum relative deviation is 1.50%.
Fayazi A, Arabloo M, Mohammadi AH. Efficient estimation of natural gas compressibility factor using a rigorous method. J Natl Gas Sci Eng. 2014; 16: 8-17. https://doi.org/10.1016/j.jngse.2013.10.004
Zhao Y, Zhou Y, Luo Z. Study on the surface technology design of abnormally high-pressure sulfur-containing gas wells in Jiulongshan gas field. China Petrol Cheml Stand Qualit. 2014; 34(05): 81. (In Chinese).
Elsharkawy AM, El-Kamel A. Compressibility factor for sour gas reservoirs. 2000; 64284. https://doi.org/10.2118/64284-MS
Alireza B, Saeid M, Brian FT. Rapidly estimating natural gas compressibility factor. J Nat Gas Chem. 2007; 16(4): 349- 353. https://doi.org/10.1016/S1003-9953(08)60003-1
Starling KE. Thermo data refined for lpg. 1. Equation of state and computer prediction. Hydrocarb Process. 1971; 50(3): 101.
Kontogeorgis GM, Voutsas EC, Yakoumis IV, Tassios DP. An Equation of State for Associating Fluids. Indust Eng Chem Res. 1996; 35(11): 4310-4318. https://doi.org/10.1021/ie9600203
Li Z, Firoozabadi A. Cubic-plus-association equation of state for water-containing mixtures: Is “cross association” necessary ? AIChE J. 2009; 55(7): 1803-1813. https://doi.org/10.1002/aic.11784
Sozve G. Equilibrium constants from a modified RedichKwonge equation of state. Chem Eng Sci. 1972; 1203(72): 1197-1200． https://doi.org/10.1016/0009-2509(72)80096-4
Mingjian LUO, Peisheng MA, Shuqian XIA. A Modification of α in SRK Equation of State and Vapor-Liquid Equilibria Prediction. Chinese J Chem Eng. 2007; 15(1): 102-109. https://doi.org/10.1016/S1004-9541(07)60041-X
Li Z, Jia W, Li C. ‘An improved PR equation of state for CO2- containing gas compressibility factor calculation’, J Natl Gas Sci Eng. 2016; 36: 586-596. https://doi.org/10.1016/j.jngse.2016.11.016
Donnez P. Essentials of Reservoir Engineering. 2007; 1, 151.
Starling, KE. Fluid Properties for Light Petroleum Systems. Gulf Publish Company, 1973; ISBN 978-0872012936, 270.
Xiong Y, Zhang LH. Comparative study for Z factor prediction by using different mixture models on natural gas. Chem. Eng. Oil Gas, 2004; 33: 447-449.
Nojoomi E, Hajizadeh S, Moghadasi AS. Velocity Limitation in Pipelines while Performing Welltest Operation, Quality Limitation Regarding Operational Usage of Relevant Equipment. The 1st National Conference on Oil and Gad Fields Development. 2015.
Guo X, Wang F, Chen G. Experimental Determination of Compression Factor of UHV Natural Gas. Petrol Explorat and Develop. 1999; 6: 84-85+11-1. (In Chinese).
Fang Y, Dong X, Wu H. Optimization and Evaluation of Compression Factor Calculation Model for High Sulfur Natural Gas. Oil-Gasfield Surf Eng. 2011; 30(07): 1-3. (In Chinese).
Chen J, Peng C, Wang X. Discussion on calculation method and software development of high-pressure physical property parameters of a high-sulfur natural gas. Inner Mongolia Petrocheml Indus. 2010; 36(03): 41-44. (In Chinese).
Wang Z, Guo P, Zhou K. Comparison of prediction methods for acid gas deviation factors in Luojiazhai gas field. Nat Gas Indus. 2004; 7: 86-88+95-140. (In Chinese).
Liang G, Zuo G. Calculation method of natural gas compression factor based on gas composition. Chem Eng Oil Gas, 2014; 43(04): 395-400. (In Chinese).
Elsharkawy AM. Predicting the properties of sour gases and condensates: equation of state and empirical carrelations. SPE, 2002; 74369: 10-12. https://doi.org/10.2118/74369-MS
Luo Z, Li X, Du C. Study on Compressibility Factor Calculation Method for ultra-High Pressure and SulfurContaining Gas by Use of the CPA EoS. Chem Eng Oil and Gas, 2019; 48(05): 56-61. (In Chinese).