Towards carbon geosequestration: comparing the wettability performance of Western Australian altered basaltic rock/CO2/water systems

• The capacity of altered basaltic rocks to store carbon dioxide is heavily influenced by their wetting characteristics. • The wetting characteristics includes total organic carbon, pressure, surface roughness, mineralogy, and water chemistry. • The estimates of the CO 2 storage column height suggest that injection depth should be limited to 700 m. Geosequestration of carbon dioxide in basaltic rock formations is considered to have the potential to safely and permanently store significant quantities of this greenhouse gas and thereby mitigate its potential global warming effect. The success of this storage method is primarily dependent on the wettability behaviour of the rock-water-CO 2 system, which significantly affects fluid distribution, fluid transport, storage capacity and containment security. This study investigates the wettability performance of several Western Australian altered basaltic rocks, of similar geochemistry, porosity and inter-connection. The wettability behaviour of the basaltic materials is assessed using water containing ions that have been leached from the rock samples used in this investigation (Synthetic Formational Water). Under realistic geo-storage conditions, most samples exhibited intermediate -wet behaviour at pressures of 10 to 80 bar and a temperature of 50 °C. Further increase in pressure from 80 to 100 bar at 50 °C changed the wettability of the altered basaltic rock samples with most samples changing from an intermediate-wet state to weakly CO 2 -wet state, while the other sample maintained this intermediate-wet at 100 bar and 50 °C temperature. This study highlights the potential of Western Australian altered basaltic rocks to be used for the mineral storage of CO 2 .