Calculation of the Phase Equilibrium of a Hydrocarbon Mixture with Regard for the Capillary Pressure Jump in It by the Example of the Astrakhan Field

The influence of a capillary pressure jump in a porous medium on the equilibrium between its liquid and gas phases, defined by the Peng–Robinson equation of state, was investigated. A numerical analysis of the phase diagrams of a gas–condensate mixture, constructed in gas-pressure and liquid-pressure coordinates for different capillary pressure jumps in the mixture, has been performed. The boundary of the two-phase region of such a mixture was determined as a domain of its existence in the two-phase state. The calculations were not associated with a concrete porous medium, and they were based on the condition of phase equilibrium of such a medium at different capillary pressure jumps in it.