(37i) Calculating the Interfacial Properties of CO2/Water/Silica Systems Using Monte Carlo Molecular Simulations

Authors: 
Rall, A. R., University at Buffalo, The State University of New York
Errington, J. R., University at Buffalo
Geological sequestration has the potential to occupy a strategic role in the reduction of carbon dioxide emissions. Before injecting CO2 into a potential storage site, one must first assess the capability of the site to retain the injected CO2. Understanding the interactions between the fluid CO2-rich and water-rich phases and the caprock mineral of a site is particularly important. These interactionsâ??in the form of the CO2/water/caprock contact angle and CO2/water interfacial tensionâ??dictate the breakthrough pressure, that is, the pressure at which the CO2-rich phase may leak due to capillary failure. We present here the use of Monte Carlo methods to measure the interfacial tension and contact angles of CO2/water mixtures near a silica surface. We apply a combination of interface potential free energy techniques and expanded ensemble simulations to measure differences in these interfacial properties over a range of temperature and pressure conditions for several combinations of available water and CO2 molecular models.