Carbonic Acid Improves Prediction of Interfacial Tension and Contact Angle of CO2/Water/Quartz Systems

摘要

The successful sequestration of carbon dioxide in deep geological formations requires a minimum leakage of CO2 through the cap rock. The amount of leakage could be estimated from the threshold capillary pressure, which in turn is affected by the interfacial tension (IFT) between CO2 and water, and the contact angle (CA) between fluids and the solid surface. The measurement of IFT and CA at reservoir conditions is usually very challenging, especially in the presence of co-contaminants. Therefore, the ability to accurately predict these properties at reservoir conditions can be very useful. Although the majority of existing molecular dynamics studies of CO2/water/mineral systems were able to capture the trends in IFT and CA variations with pressure and temperature, their predictions often deviated from experimental data, possibly due to erroneous models and/or overlooked chemical reactions. The goal of this study was to improve the predictions of IFT and CA of CO2/water/α-quartz systems under a wide range of T and P by considering chemical reactions between CO2 and water and using a novel molecular model for the α-quartz surface.