Interfacial tension measurements and wettability evaluation for geological CO2 storage

Interfacial interactions, namely interfacial tension, wettability, capillarity and interfacial mass transfer are known to govern fluid distribution and behavior in porous media. Therefore the interfacial interactions between CO2, brine and oil and/or gas reservoirs have a significant influence on the effectiveness of any CO2 storage operations. However, data and knowledge of interfacial properties in storage conditions are scarce. This issue becomes particularly true in the case of deep saline aquifers where limited, economically driven, data collection and archiving are available. In this paper, we present a complete set of brine–CO2 interfacial tension data at pressure, temperature and salinity conditions, representative of a CO2 storage operation. A semi-empirical correlation is proposed to calculate the interfacial tension from the experimental data. Wettability is studied at pore scale, using glass micromodels in order to track fluids distribution as a function of the thermodynamic properties and wettability conditions for water–CO2 systems. With this approach, we show that, in strongly hydrophilic porous media, the CO2 does not wet the solid surface whereas; if the porous media has less hydrophilic properties the CO2 significantly wets the surface.