PREDICTION OF THERMODYNAMIC PROPERTIES AND PHASE BEHAVIOR OF RESERVOIR FLUIDS FOR THE DESIGN OF OIL AND GAS FIELDS
UDC: 622.276
DOI: 10.33285/2073-9028-2020-1(298)-47-61
Authors:
Grigoriev Boris A.
1,
Alexandrov Igor S.2,
Gerasimov Anatoly A.2,
Grigoriev Evgeny B.1
1 Gubkin Russian State University of Oil and Gas (National Research University), Moscow, Russian Federation
2 Kaliningrad State Technical University, Kaliningrad, Russian Federation
Keywords: density, heat capacity, saturation pressure, equation of state, reservoir fluid, oil, gas condensate
Annotation:
This article proposes methods for calculating the thermodynamic properties and phase equilibria of reservoir fluids based on both empirical multi-constant equations of state and theoretically based equations obtained in the framework of the statistical theory of associated fluid (SAFT). The article also proposes an alternative technique based on the author's generalized PC-SAFT equation of state. The article presents the results of comparative calculations of the thermodynamic properties of model hydrocarbon mixtures, as well as real reservoir systems based on the proposed methods. The most accurate calculation of thermodynamic properties in the single-phase region was shown by the multiconstant model. In particular, the accuracy of density calculation is 3-4 times higher than according to cubic equations of state. When testing this model regarding the calculation of phase equilibria, limitations were established that recommend its use for light gas condensates, in which the molar mass of the residue does not exceed 140 g/mol and the relative density of the residue does not exceed 0,730. For reservoir fluids that do not satisfy the condition described above, it is proposed to calculate phase equilibria using a model based on the author's PC-SAFT equation of state that can be used to calculate phase equilibria and near the freezing point of the mixture, where cubic and multi-constant equations can lead to nonphysical phase diagram.
Bibliography:
1. Span R. Multiparameter Equation of State: An Accurate Source of Thermodynamic Property Data. — Berlin: Springer, 2000. — 367 p.
2. The Gerg-2004 Wide-Range Equation of State for Natural Gases and Other Mixtures/O. Kunz, R. Klimeck, W. Wagner, M. Jaeschke. — Dusseldorf, 2007. — 535 p.
3. Alexandrov I., Gerasimov A., Grigor’ev B. Generalized Fundamental Equation of State for Normal Alkanes (C5 — C50)//Int. J. Thermophys. — 2013. — Vol. 34. — P. 1865-1905.
4. Grigoriev B., Alexandrov I., Gerasimov A. Generalized equation of state for the cyclic hydrocarbons over a temperature range from the triple point to 700 K with pressures up to 100 MPa//Fluid Phase Equilibria. — 2016. — Vol. 418. — P. 15-36.
5 Ke-Le Yan, Liu Huang, Sun Chang-Yu et. al. Measurement and calculation of gas compres- sibility factor condensate gas and natural gas under pressure up to 116 MPa//J. Chem. Thermodyna- mics. — 2013. — Vol. 63. — P. 38-43.
6. Huang Liu, Sun Chang-Yu, Yan Ke-Le, et. al. Phase behavior and compressibility factor of two China gas condensate samples at pressures up to 95 MPa//Fluid Phase Equilibria. — 2013. — Vol. 337. — P. 363-369.
7. Shariati A., Peters C.J., Moshfeghian M. Bubble-point pressures of some selected methane + synthetic C6+ mixtures//J. Chem. Eng. Data. — 1998. — Vol. 43. — P. 280-282.
8. Александров И.С., Григорьев Б.А. Моделирование термодинамических свойств и фазового поведения углеводородов и сложных углеводородных смесей на основе нового PC-SAFT уравнения состояния//Научно-технический сборник — Вести газовой науки. Современные подходы и перспективные технологии в проектах освоения нефтегазовых месторождений российского шельфа. — М.: “Газпром ВНИИГАЗ”, 2018. — № 4 (36). — С. 237-248.
9. Отчет о НИР “Математическое моделирование фазового поведения пластовых углеводородных смесей в критической области. определение плотностей сосуществующих фаз”. — М.: РГУ нефти и газа (НИУ) имени И.М. Губкина, 2018. — 50 с.
Back to issue