«Automation and Informatization of the fuel and energy complex»

Natural gas compressibility factor: approximations comparison and selection criteria

UDC: 622.691.4
DOI: 10.33285/2782-604X-2023-1(594)-42-54

Authors:

¹ National University of Oil and Gas "Gubkin University", Moscow, Russia
² Gazprom Promgaz, Vidnoye, Russia

Keywords: natural gas, equation of state, compressibility factor, standards, speed of sound

Annotation:

The compressibility factor z(P, T) is introduced into the gas state equation to account for its real properties and depends on the pressure P, temperature T, and gas component composition. The function z(P, T) is required when carrying out various technological calculations. Approximations z(P, T) are used in calculations and depend on the range of function arguments change. The more precisely you need to know the result of the technological calculation, the more requirements are needed for the approximation adequacy. The compressibility factor is used to calculate the speed of sound in gases, which, among other things, allows detecting and locating a leak. With time knowledge about the properties of gases deepens, thus determining the expediency of revising z(P, T) calculation procedure. The article compares some of the currently used approximations of z(P, T) coefficient. The greatest attention is paid to three of them: the industry standard STO Gazprom 2-3.5-051-2006, the Russian National Standard GOST 30319.3-2015, and the international standard ISO 20765-2:2015. It was revealed that the model in STO Gazprom, meeting the goals set for the standard during development, does not accurately approximate the derivatives of the functions z(P, T), in particular, it is unsuitable for calculating the speed of the sound. The article also compares the calculation speed of the considered models.

Bibliography:

1. ISO 20765-2:2015. Natural gas – Calculation of thermodynamic properties – Part 1: Gas phase properties for transmission and distribution applications. – ISO, 2015. – VI, 9 p.
2. GOST 30319.3-2015. Gaz prirodnyy. Metody rascheta fizicheskikh svoystv. Vychislenie fizicheskikh svoystv na osnove dannykh o komponentnom sostave. – Vved. 2017–01–01. – M.: Standartinform, 2016. – III, 28 s.
3. STO Gazprom 2-3.5-051-2006. Normy tekhnologicheskogo proektirovaniya magistral'nykh gazoprovodov. – M.: Poligrafiya, 2006. – VIII, 197 s.
4. Lur'e M.V. Teoreticheskie osnovy truboprovodnogo transporta nefti, nefteproduktov i gaza. – M.: Nedra, 2017. – 477 s.
5. Sukharev M.G., Samoylov R.V. Analiz i upravlenie statsionarnymi i nestatsionarnymi rezhimami transporta gaza. – M.: Izdat. tsentr RGU nefti i gaza im. I.M. Gubkina, 2016. – 397 s.
6. Dranchuk P.M., Abou-Kassem H. Calculation of Z Factors for Natural Gases Using Equations of State // J. of Canadian Petroleum Technology. – 1975. – Vol. 14, Issue 03. – P. 34–36. – DOI: 10.2118/75-03-03
7. Takacs G. Comparisons made for computer Z-factor calculations // Oil and Gas J. – 1976. – Vol. 74, Issue 51. – P. 64–66.
8. Kareem L.A., Iwalewa T.M., Al-Marhoun M. New explicit correlation for the compressibility factor of natural gas: linearized z-factor isotherms // J. of Petroleum Exploration and Production Technology. – 2016. – Vol. 6. – P. 481–492. – DOI: 10.1007/s13202-015-0209-3
9. Validation of 1D flow model for high pressure natural gas pipelines / J.F. Helgaker, A. Oosterkamp, L.I. Langelandsvik, T. Ytrehus // J. of Natural Gas Science and Engineering. – 2014. – Vol. 16. – P. 44–56. – DOI: 10.1016/j.jngse.2013.11.001
10. Aleksanochkin A.A., Sardanashvili S.A. Raschetnye metody opredeleniya svoystv prirodnogo gaza po dannym o plotnosti pri standartnykh usloviyakh, soderzhanii azota i dioksida ugleroda // Delovoy zhurn. Neftegaz.RU. – 2020. – № 1(97). – S. 78–85.
11. Kunz O., Wagner W. The GERG-2008 Wide-Range Equation of State for Natural Gases and Other Mixtures: An Expansion of GERG-2004 // J. of Chemical & Engineering Data. – 2012. – Vol. 57, Issue 11. – P. 3032–3091. – DOI: 10.1021/je300655b
12. The GERG-2004 wide-range equation of state for natural gases and other mixtures / O. Kunz, R. Klimeck, W. Wagner, M. Jaeschke. – Düsseldorf: VDI Verlag, 2007. – XVII, 534 p.
13. Modisette J.L. Equation of State Tutorial // 32nd Annual Meeting PSIG, Savanah, Georgia. – 2000.
14. Shashi Menon E. Gas Pipeline Hydraulics. – 1st Edition. – Boca Raton: CRC Press, 2005. – 416 p.
15. Lagoni P., Barley J. On Simulation Accuracy // PSIG Annual Meeting. – 2007. – 23 p.
16. Sundar K., Zlotnik A. State and Parameter Estimation for Natural Gas Pipeline Networks Using Transient State Data // IEEE Transactions on Control Systems Technology. – 2019. – Vol. 27, Issue 5. – P. 2110–2124. – DOI: 10.1109/TCST.2018.2851507
17. Study on the natural gas pipeline safety monitoring technique and the time-frequency signal analysis method / Zhigang Qu, Yanfen Wang, Huanhuan Yue [et al.] // J. of Loss Prevention in the Process Industries. – 2017. – Vol. 47. – P. 1–9. – DOI: 10.1016/j.jlp.2017.02.016
18. Lur'e M.V., Musailov I.T. Issledovanie zavisimosti skorosti zvuka ot davleniya v magistral'nykh gazoprovodakh vysokogo i sverkhvysokogo davleniya // Gazovaya prom-st'. – 2019. – № 5(784). – S. 80–84.
19. O standartizatsii v Rossiyskoy Federatsii: Feder. zakon ot 29 iyunya 2015 g. № 162-FZ (s izmeneniyami na 30 dekabrya 2020 g.).