Natural gas density under extremely high pressure and high temperature: Comparison of molecular dynamics simulation with corresponding state model

doi:10.1016/j.cjche.2020.07.043

Abstract

Abstract: This work applied molecular dynamics (MD) simulation to calculate densities of natural gas mixtures at extremely high pressure (>138 MPa) and high temperature (>200 ℃) conditions (xHPHT) to bridge the knowledge and technical gaps between experiments and classical theories. The experimental data are scarce at these conditions which are also out of assumptions for classical predictive correlations, such as the Dranchuk & Abou-Kassem (DAK) equation of state (EOS). Force fields of natural gas components were carefully chosen from literatures and the simulation results are validated with experimental data. The largest relative error is 2.67% for pure hydrocarbons, 2.99% for C1/C3 mixture, 7.85% for C1/C4 mixture, and 8.47% for pure H₂S. These satisfactory predictions demonstrate that the MD simulation approach is reliable to predict natural- and acid-gases thermodynamic properties. The validated model is further used to generate data for the study of the EOS with pressure up to 276 MPa and temperature up to 573 K. Our results also reveal that the Dranchuk & Abou-Kassem (DAK) EOS is capable of predicting natural gas compressibility to a satisfactory accuracy at xHPHT conditions, which extends the confidence range of the DAK EOS.

Key words: High-pressure high temperature, Z-factor, Molecular dynamics simulation, Natural gas density, Correlations

摘要： This work applied molecular dynamics (MD) simulation to calculate densities of natural gas mixtures at extremely high pressure (>138 MPa) and high temperature (>200 ℃) conditions (xHPHT) to bridge the knowledge and technical gaps between experiments and classical theories. The experimental data are scarce at these conditions which are also out of assumptions for classical predictive correlations, such as the Dranchuk & Abou-Kassem (DAK) equation of state (EOS). Force fields of natural gas components were carefully chosen from literatures and the simulation results are validated with experimental data. The largest relative error is 2.67% for pure hydrocarbons, 2.99% for C1/C3 mixture, 7.85% for C1/C4 mixture, and 8.47% for pure H₂S. These satisfactory predictions demonstrate that the MD simulation approach is reliable to predict natural- and acid-gases thermodynamic properties. The validated model is further used to generate data for the study of the EOS with pressure up to 276 MPa and temperature up to 573 K. Our results also reveal that the Dranchuk & Abou-Kassem (DAK) EOS is capable of predicting natural gas compressibility to a satisfactory accuracy at xHPHT conditions, which extends the confidence range of the DAK EOS.

关键词: High-pressure high temperature, Z-factor, Molecular dynamics simulation, Natural gas density, Correlations

Luchao Jin, Yongming He, Guobing Zhou, Qiuhao Chang, Liangliang Huang, Xingru Wu. Natural gas density under extremely high pressure and high temperature: Comparison of molecular dynamics simulation with corresponding state model[J]. Chinese Journal of Chemical Engineering, 2021, 29(3): 2-9.

References

[1] M.L. Payne, D. Pattillo, R. Miller, C.K. Johnson, Advanced Technology Solutions for Next Generation HPHT Wells, in International Petroleum Technology Conference, International Petroleum Technology Conference, Dubai, U.A.E, 2007.
[2] I.K. Gamwo, W.A. Bllrgess, B.D. Morreale, Y. Soong, B.A. Bamgbade, M.A. McHugh, H.O. Baled, R.M. Enick, Y. Wu, D. Taprigal, Status of Equation of State Project at the NETL, in Offshore Technology Conference, Offshore Technology Conference, Houston, Texas, 2014.
[3] A. Shadravan, M. Amani, HPHT 101-What petroleum engineers and geoscientists should know about high pressure high temperature wells environment, Energy Sci. Technol. 4 (2) (2012) 36-60.
[4] A.L. Lee, Viscosity of Light Hydrocarbons, American Petroleum Institute, 1965.
[5] J. Diehl, M. Gondouin, A. Houpeurt, J. Neoschil, M. Thelliez, J.P. Verrien, R. Zurawsky, Viscosity and Density of Light Paraffins, Nitrogen and Carbon Dioxide, CREPS/Geopetrole, 1970.
[6] I.j.F. Golub’ev, Viscosity of Gases and Gas Mixtures: a Handbook, Israel Program for Scientific Translations;[available from the US Department of Commerce, Clearinghouse for Federal Scientific and Technical Information, Springfield, Va.], 1970.
[7] K. Stephan, Viscosity of Dense Fluids, Springer Science & Business Media, 2013.
[8] U. Setzmann, W. Wagner, A new equation of state and tables of thermodynamic properties for methane covering the range from the melting line to 625 K at pressures up to 100 MPa, J. Phys. Chem. Ref. Data 20 (6) (1991) 1061-1155.
[9] K. Liu, Y. Wu, M.A. McHugh, H. Baled, R.M. Enick, B.D. Motteale, Equation of state modeling of high-pressure, high-temperature hydrocarbon density data, J. Supercrit. Fluids 55 (2) (2010) 701-711.
[10] H. Miyamoto, M. Uematsu, Measurements of vapor pressures from 280 to 369 K and (p, q, T) properties from 340 to 400 K at pressures to 200 MPa for propane, Int. J. Thermophys. 27 (4) (2006) 1052-1060.
[11] K.R. Hall, L. Yarborough, A new equation of state for Z-factor calculations, Oil Gas J. 71 (7) (1973) 82-92.
[12] P. Dranchuk, H. Abou-Kassem, Calculation of Z factors for natural gases using eqeuations of state, J. Can. Pet. Technol. 14 (03) (1975).
[13] M.B. Standing, D.L. Katz, Density of natural gases, Trans. AIME 146 (01) (1942) 140-149.
[14] M.G. Martin, J.I. Siepmann, Transferable potentials for phase equilibria. 1. United-atom description of n-alkanes, J. Phys. Chem. B 102 (14) (1998) 2569-2577.
[15] S.K. Nath, Molecular simulation of vapor-liquid phase equilibria of hydrogen sulfide and its mixtures with alkanes, J. Phys. Chem. B 107 (35) (2003) 9498-9504.
[16] J.G. Harris, K.H. Yung, Carbon dioxide’s liquid-vapor coexistence curve and critical properties as predicted by a simple molecular model, J. Phys. Chem. 99 (31) (1995) 12021-12024.
[17] J.-P. Ryckaert, G. Ciccotti, H.J. Berendsen, Numerical integration of the cartesian equations of motion of a system with constraints: Molecular dynamics of n-alkanes, J. Comput. Phys. 23 (3) (1977) 327-341.
[18] C. Nieto-Draghi, T.de Bruin, J.Perez Pellitero, J.B. Avalos, A.D. Mackie, Thermodynamic and transport properties of carbon dioxide from molecular simulation, J. Chem. Phys. 126 (6) (2007) 064509.
[19] S. Plimpton, Fast parallel algorithms for short-range molecular dynamics, J. Comput. Phys. 117 (1) (1995) 1-19.
[20] C. Murthy, K. Singer, I. McDonald, Interaction site models for carbon dioxide, Mol. Phys. 44 (1) (1981) 135-143.
[21] J.J. Potoff, J.I. Siepmann, Vapor-liquid equilibria of mixtures containing alkanes, carbon dioxide, and nitrogen, AIChE J. 47 (7) (2001) 1676-1682.
[22] J.R. Errington, The Development of Novel Simulation Methodologies and Intermolecular Potential Models for Real Fluids, 1999.
[23] T.T. Trinh, T.J. Vlugt, S. Kjelstrup, Thermal conductivity of carbon dioxide from non-equilibrium molecular dynamics: A systematic study of several common force fields, J. Chem. Phys. 141 (13) (2014) 134504.
[24] N. Sakoda, M. Uematsu, A thermodynamic property model for fluid phase hydrogen sulfide, Int. J. Thermophys. 25 (3) (2004) 709-737.
[25] W. Edward, K. Aziz, Compressibility factor of sour natural gases, Can. J. Chem. Eng. 49 (2) (1971) 267-273.
[26] M. Standing, Volumetric and Phase Behavior of Oil Field Hydrocarbon Systems, Society of Petroleum Engineers of AIME. Dallas, Texas, Hydrocarbon Systems, 1977.
[27] L. Thomas, R. Hankinson, K. Phillips, Determination of acoustic velocities for natural gas, J. Pet. Technol. 22 (07) (1970) 889-895.
[28] R.V. Smith, Practical Natural Gas Engineering, in: PennWell Books, 1990.
[29] R. Sutton, Compressibility factors for high-molecular-weight reservoir gases, in: Paper SPE 14265 presented at the SPE Annual Technical Conference and Exhibition, Las Vegas, Nevada, 22-26(1985). September https://doi.org/10.2118/14265-MS.
[30] L. Piper, W. McCain Jr., J. Corredor, Compressibility factors for naturally occurring petroleum gases (1993 version), in: SPE Annual Technical Conference and Exhibition, Society of Petroleum Engineers, 1993, https://doi.org/10.2118/26668-MS.
[31] M. Atilhan, P. Patil, S. Ejaz, D. Cristancho, J. Holste, K. Hall, Wide Range, High Accuracy PqT Measurements by Single Sinker Magnetic Suspension Densimeter for Natural Gas-Like Mixtures, in: Proceedings of the 1st Annual Gas Processing Symposium, Elsevier, 2009.
[32] G.H. Brunner, Supercritical fluids as solvents and reaction media, Elsevier, 2004.
[33] P. Colonna, N. Nannan, A. Guardone, T. Van der Stelt, On the computation of the fundamental derivative of gas dynamics using equations of state, Fluid Phase Equilib. 286 (1) (2009) 43-54.