Experiment and Simulation Study on the Special Phase Behavior of Huachang Near-Critical Condensate Gas Reservoir Fluid

Due to the special phase behavior of near-critical fluid,the development approaches of near-critical condensate gas and near-critical volatile oil reservoirs differ from conventional oil and gas reservoirs. in the near-critical region,slightly reduced pressure may result in considerable change in gas and liquid composition since a large amount of gas or retrograde condensate liquid is generated. it is of significance to gain insight into the composition variation of near-critical reservoir during the depletion development. in our study,we performed a series of pvt experiments on a real near-critical gas condensate reservoir fluid. in addition to the experimental studies,a commercial simulator combined with the preos model was utilized to study retrograde condensate characteristics and reevaporation mechanism of condensate oil with co2 injection based on vapor-liquid phase equilibrium thermodynamic theory. the research shows that when reservoir pressure drops below a certain pressure,the variation of retrograde condensate liquid saturation of the residual reservoir fluid exhibits the phase behavior of volatile oil. © 2016 dali hou et al.