Measurement of the Interfacial Tension and Wettability for CO ₂ –Oil–Rock Systems under Reservoir Conditions

The accurate prediction of reservoir fluid flow dynamics under reservoir conditions based on the interfacial tension (IFT) and contact angle (CA) is critical to the flexibility of the carbon dioxide-enhanced oil recovery (CO₂-EOR) scheme. Thus, in this paper, a novel data set consisting of IFT and CA data for the CO₂-oil-rock systems was established via a high-temperature and high-pressure visualization platform based on the axisymmetric drop shape analysis (ADSA) method. Experimental measurements were carried out covering a large temperature range from 308 to 368 K and pressures up to 17 MPa. The densities of CO₂-dissolved oil samples used in the CO₂-oil IFT determination were estimated via the volume-translated Peng-Robinson Equation of State (VTPR EOS) method, and molar volume translation parameters (<i>v</i>_c,<i>i</i>) for multicomponent hydrocarbon mixtures were obtained. The findings indicate that there was a strong correlation between the interfacial behaviors and CO₂-oil interactions: the CO₂-oil IFT decreased with increasing pressure, while the CO₂- oil-rock CAs for all three substrates (calcite, kaolinite, and quartz) increased with the pressure. Variations in the CA with dependent on the substrate suggested that the oil-wetting characteristics were enhanced on quartz surfaces. Furthermore, dodecane bouncing and spreading on core surfaces were observed under supercritical CO₂ conditions. Additionally, a robust empirical correlation was developed to predict the CO₂-oil IFT at a specified temperature, pressure, and oil composition. Based on this model, the near-miscible displacement pressure window was determined. This research offers crucial experimental data and insights into interfacial phenomena to enhance the efficiency of CO₂-EOR processes.