Interfacial Properties of H2O+CO2+Oil Three-Phase Systems: A Density Gradient Theory Study

The interfacial property of H2O+CO2+oil three-phase systems is crucial for CO2 flooding and sequestration processes but was not well understood. Density gradient theory coupled with PC-SAFT equation state applied to investigate the tension (IFT) (hexane, cyclohexane, benzene) under conditions (temperature in range 323–423 K pressure 1–10 MPa). IFTs aqueous phase+vapor phase were smaller than H2O+CO2 two-phase systems, which could be explained by enrichment oil region. difference between system largest benzene case smallest cyclohexane due different degrees interface. Meanwhile, observed region phase+oil-rich phase, led reduction IFT increasing while effects H2O+oil systems. effect on phase+benzene-rich interface small contrast that phase+alkane (hexane or cyclohexane)-rich H2O had little properties oil-rich low solubilities vapor phase. Further, spreading coefficients presence followed this sequence: > hexane cyclohexane.