MODEL DEVELOPMENT OF A SUITABLE EQUATION OF STATE FOR MULTICOMPONENT MULTIPHASE SYSTEMS: APPLICATION TO CRUDE OIL PHASE STABILITY REQUIREMENTS

Year 2018, Volume: 21 Issue: 2, 111 - 118, 30.05.2018

Faith Babalola , Alfred Susu

https://doi.org/10.5541/ijot.419923

Cited By: 3

Abstract

A suitable Equation of State (EOS) was developed
for multi component, multi phase systems from the Peng-Robinson Equation of
State using a newly developed variable parameter ‘a’ approach (VPAA) which
treats the attractive term parameter as a variable regressed by two straight
lines. This EOS was used to determine the stability limit curves for crude oils
from three different oil wells on the application of the Helmholtz free energy
criterion for intrinsic stability. This was used along with the T-isotherm for
the crude oils and the stability limit was found by locating the point of
intersection of the two curves. For Well-1, the vapor phase was unstable while
the liquid phase was stable at 47.4 atm. For Well-2, the vapor phase was stable
at 209 atm. while the liquid phase was stable at two pressure values of 191atm.
and 213 atm. For Well-3 however, the vapor phase was stable at 45.7 atm. while
two liquid phases were identified. The lighter one was unstable at the
temperature of interest, while the heavier one was stable at 115.9 atm.

Keywords

Equation of state, phase stability, reservoir fluids, model, EOS parameter

References

• 1. Danesh A. PVT and phase behavior of petroleum reservoir fluids. New York: Elsevier; 1998. 179-206, 301-341 p.
• 2. England WA, Mackenzie AS. Geochemistry of petroleum reservoirs. Geolo Rundsch. 1989;78:214-237.
• 3. Smith JM, Van Ness HC, Abbott M. N. Introduction to Chemical Engineering Thermodynamics. New Delhi: Tata McGraw-Hill; 1996. 470 p.
• 4. Peng DY, Robinson DB. A new two–constant equation of state. Ind Eng Chem Fundam 1976;15(1):59-64.
• 5. Patel NC, Teja AS. A new cubic equation of state for fluids and fluid mixtures. Chem Eng Sci. 1982;77(3):463-473.
• 6. Ihaveri BS, Yuongren GK. Three parameter modification of the Peng-Robinson equation of state to improve volumetric prediction. Soc Petrol Eng J. 1984;3(03):SPE-13118-PA.
• 7. Erdogmus M, Adewumi MA. A modified equation of state for gas condensate systems. Proc. SPE Conf., Morgantown, USA, Oct 17-19, 2000.
• 8. Baker LE, Pierce AC, Luks KD. Gibbs energy analysis of phase equilibrium. Soc Petrol Eng J. 1982; 731-742.
• 9. Michelsen, M. L. The isothermal flash problem Part I: Stability. Fluid Phase Equilibr. 1982a;9:1-19.
• 10. M ichelsen ML. The isothermal flash problem. Part II. Phase split calculation. Fluid Phase Equilibr. 1982b;9: 21-40.
• 11. Firoozabadi A. Reservoir fluid phase behavior and volumetric prediction with equations of state. J Petrol Technol. 1988;40(4):397-406.
• 12. Firoozabadi A, Pan H. Fast and robust algorithm for compositional modeling: Part I – Stability analysis testing. Soc Petrol Eng J. 2002;7(01) SPE-77299-PA:78-89
• 13. Nghiem LX, Li YK, Heidemann RA. Application of the tangent plane criterion to saturation pressure and temperature computations. Fluid Phase Equilibr. 1985;21:39-60.
• 14. Hendricks EM, van Bergen ERD. Application of a reduction method to phase equilibria calculations. Fluid Phase Equilibria 1992;74:17-23.
• 15. Michelsen ML. Phase equilibrium calculations: What is easy and what is difficult. Comp Chem Eng. 1992;17(5/6):431-439.
• 16. Babalola FU, Susu AA. Stability limit determination for pure compounds. 2008a; Pet Sci Technol. 2008;26(12):1481-1497.
• 17. Knudsen K, Stenby EH, Fredenslund A. (1993) A comprehensive comparison of mixing rules for calculation of phase equilibria in complex systems. Fluid Phase Equilibr. 1993;82:361-368.
• 18. Babalola FU, Susu AA. Deterioration in performance of mixing rules in phase behavior modeling of high density reservoir fluids. 2008b; Pet Sci Technol. 2008;26(13):1522-1544.
• 19. Mathias PM, Naheiri T, Oh EM. A density correction for the Peng-Robinson equation of state. Fluid Phase Equilibr. 1989;47:77-87.
• 20. Lin HM, Kim H, Gao TM, Chao KC. Cubic equation of state and VLE calculations. Fluid Phase Equilibr. 1985;13:143-152.
• 21. Kaul P, Thrasher RL. A pa rameter-based approach for two-phase equilibrium prediction with cubic equations of state. Soc Petrol Eng J. 1996;11(04) SPE-26640-PA: 273-281.
• 22. Perdersen KS, Thomassen P, Fredenslund A. On the dangers of ‘tuning’ equation of state parameters. Chem Eng Sci. 1988;43(2):269-278.
• 23. Jenson VG Jeffreys GV. Mathematical methods in chemical engineering. Birmingham: Academic Press; 1977. 354 p.
• 24. Spiegiel MR. Theory and problems of advanced calculus. 1981; Schaum’s Outline Series New York: McGraw Hill; 1981 .3 p.