Abstract
Injecting supercritical CO(2) into gas reservoir is a novel trial to improve condensate gas recovery and decrease the hydrocarbon liquid dropout. A good understanding of the effect of supercritical CO(2) on the phase behavior properties of these hydrocarbons is essential for accurately forecasting the displacing performance and storing process of the reservoirs with numerical simulators. This paper presents novel phase behavior experimental procedures and phase equilibrium evaluation methodology for gas-condensate phase system mixed with supercritical CO(2) over a wide range of temperatures and pressures. A unique phase behavior phenomena was also reported. The mass transfer between two vapour phases was also measured. In order to interpret and identify the interface property between condensate gas and supercritical CO(2), a multiphase thermodynamic VLV equilibrium model was established. Finally, taken YKL condensate gas in Northwest China as an example, the region where the conditions in terms of pressure, temperature and CO(2) concentration can yield VLV equilibrium was found. The calculation results of multiphase thermodynamic model for condensate-CO(2) system in this paper are close to the experimental data and can truthfully reflect the phase behavior of interface between CO(2) and condensate gas. The research results indicate that it is the existence of the interface between CO(2) and condensate gas that makes CO(2) possible be an attractive option to successfully displace condensate gas and decrease CO(2) emissions.