The effect of water vapor on the phase behaviors during depletion and CO2 injection in gas condensate reservoir

Gas condensate reservoirs are generally a mixed system of hydrocarbon and water. This paper is aimed to investigate the phase behavior change influenced by water vapor during the development of depletion and CO2 injection. The Gnorth reservoir of Zhanazhol oilfield in Caspian Basin is taken as an example. Two-phase flash was based on QNSS\Newton method, and multiple contact calculations were performed through cell-to-cell method. The research results indicate that, for the remaining reservoir fluid of depletion development, water vapor has the largest effect on the content change of CH4, followed by C7+, and the smallest effect on C-2 to C-6. The presence of water vapor makes it easier for the condensate to drop out of the gas phase. For CO2 injection, water vapor is not beneficial to re-evaporation for the formation condensate. Further, the multiple contact miscibility of CO2 and condensate is less affected by water vapor.