Wettability Alteration of Basalt Induced by Carbon Mineralization Reactions

Carbon mineralization in basalt provides an effective approach to achieve rapid and permanent storage of anthropogenic CO₂ by converting it to stable carbonates. Wettability, a critical factor governing the migration behavior and trapping mechanisms of CO₂, would be impacted by dissolution and precipitation reactions of minerals. However, the evolution of basalt wettability during rock–fluid interaction process remains uncharacterized. In this work, CO₂–basalt–fluid batch experiments were carried out. And the wettability alteration, surface geometry, and chemistry were characterized and comprehensively analyzed. The results showed the transition of basalt wettability from a weakly water-wet state to a strongly water-wet state as the reaction progressed. This transformation can be attributed to two factors. First, the increased surface roughness promoted a stronger water-wet rock surface, especially during the dissolution stage. Second, there was a decline in the abundance of hydrophobic minerals and an increase in those with hydrophilic properties as silicates dissolved and carbonates and clays precipitated, which further contributed to the hydrophilic wetting state during the dissolution–precipitation stage. This change in wettability leads to an increase in capillary entry pressure for CO₂, thus restricting its migration distance and reducing the potential for leakage. Moreover, this alteration promotes the effective trapping of CO₂ through structural and residual trapping, although additional research is required to fully understand its impact on mineral trapping.