The Role of Supercritical/Dense CO2 Gas in Altering Aqueous/Oil Interfacial Properties: A Molecular Dynamics Study

Abstract

One of the main mechanisms contributing to enhanced oil recovery (EOR) processes using compressed (supercritical) carbon dioxide (sc-CO2) is alterations in the oil-water interfacial properties. However, it has been a challenge to experimentally investigate such effects. In our investigation presented here, we performed molecular dynamics (MD) simulation to explore these changes. We studied the role of sc-CO2 in changing the interfacial and transport properties of systems composed of water and pure hydrocarbons, namely hexane, octane, benzene, and xylene. The simulations were performed at 100bar and 350K. It was observed that sc-CO2 accumulates at the interface which leads to a reduction in the interfacial tension (IFT) of water-oil systems. Our further analysis of such accumulation showed that the ratio of sc-CO2 density at the interface to sc-CO2 bulk density decreases as the sc-CO2 mole fraction increases. This interesting behavior owed to the difference in the interaction between CO2-water and CO2-hydr...