Compositional and Phase Behavior Effects in Conventional and Exotic Heavy Oil EOR Processes

The pseudo binary concept can be applied to CO₂–crude oil systems in order to better understand the intricate phase behavior. As far as CO₂–crude oil systems are concerned, the nontrivial phase behavior and in particular the liquid–liquid phase split can be considered as occurrence or outcome of injecting CO₂ in enhanced oil recovery applications. One of the most difficult aspects of vapor-liquid equilibrium (VLE) calculations using an equation of state model is the splitting of a given mixture into two or more phases at a given temperature and pressure, which could be VLE; liquid-liquid equilibrium, and vapor-liquid 1-liquid 2. The exact same methodology can be theoretically extended to identify liquid–liquid and vapor–liquid 1––liquid 2 split, that is, two lobes and three lobes on the Gibbs energy surface. In CO2 injection-based low-temperature floods, the formation of a third CO₂-rich liquid phase necessitates the inclusion of three-phase equilibria or flash calculations in compositional reservoir simulation.