Wettability of Quartz Sandstone in Contact with Supercritical CO2 and Aqueous Solutions – Novel Insights from Updated DLVO Model

Abstract

CO2 geological storage (CGS) is suggested to be one of the most promising technologies to sequester anthropogenic CO2 to mitigate climate change. However, implementation of the method is still challenging due to lack of fundamental understanding of controls of wettability, which is responsible for residual trapping of the gas and its flow dynamics. Thermodynamics of wettability is described by a modified Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, which is expanded to include the structural forces. However, due to lack of experimental data the model could not be accurately used for CGS systems, and previously published papers invoked multiple assumptions and used input parameters with a broad range of variation and sometimes contrasting values. In this study, all available data at CGS conditions were collated, the model was adjusted accordingly, a rigorous sensitivity analysis was performed and the produced results were compared against available experimental data. Furthermore, for the first the model was updated using recently published new insights into critical interfacial properties, thus improving our understanding of the CGS process. The modelled results helped in explaining the observations and shed light on physical mechanisms responsible for wettability variation within the range of tested parameters.