Measurement and correlation of the interfacial tension for paraffin + CO2 and (CO2+N2) mixture gas at elevated temperatures and pressures

Interfacial tension (IFT) is crucial for characterizing the phase and interphase behavior in the enhanced oil recovery (EOR) process. CO 2 and N 2 are commonly used as injection gases in the EOR process. In this work, an experimental apparatus using the pendent drop method was adopted to measure IFTs for the EOR process with different injection gases, temperatures (40.0–120.0 °C) and pressures (0.22–17.32 MPa). The relative Gibbs adsorption isotherm ( Γ ij ) of a species i on species j were calculated by the experimental IFTs. Theoretically, new correlations were proposed to predict paraffin IFTs for pure CO 2 and mixture gas (CO 2  + N 2 ) injection. A total of 561 and 268 experimental IFTs were used to derive the correlations for pure CO 2 and mixture gas injection, respectively. The square of correlation coefficient ( R 2 ), root mean square error ( RMSE ) and average absolute relative deviations ( AARD ) for pure CO 2 were 0.9884, 0.58 and 5.45%, respectively. For the mixture gas injection, the R 2 , RMSE and AARD of the correlation were 0.9851, 0.57 and 4.47%, respectively.