The need to meet rising energy demands while mitigating climate change driven by associated CO2 emissions has motivated the development of geologic carbon storage systems. Until recently, most research focused on sedimentary reservoirs that rely primarily on short-term solubility and physical trapping mechanisms, where CO2 can migrate if structural security is compromised. This inherent leakage risk could be eliminated by leveraging the natural reactivity of basalt reservoirs, which are abundant in silicate minerals that dissolve rapidly under acidic conditions and can ultimately trap dissolved CO2 as solid carbonate minerals. However, our fundamental understanding of the conditions under which CO2 mineralization occurs and its viability as a permanent carbon sequestration pathway remain limited. This talk will highlight series of high-pressure core flooding experiments and complementary reactive transport modeling designed to evaluate the effects of temperature, fluid chemistry, and transport regimes on basalt dissolution and carbonate precipitation. Results indicate that basalts can effectively mineralize CO2 at representative subsurface stress conditions, but predominantly within buffered diffusion-limited zones (e.g. dead-end fractures) where reaction fronts developed from competing geochemical gradients. Carbonate precipitation was highly localized on reactive silicate minerals contributing key divalent cations and was significantly enhanced by elevated temperature and alkalinity. In combination, this work reveals how complex interactions between reservoir geochemistry and transport conditions drive the extent and spatial distribution of carbon mineralization reactions in basalt fractures, which will inform selection of storage sites and injection.

Anne Menefee in a PhD candidate in the Civil and Environmental Engineering Department at the University of Michigan. Anne received her B.S.E. in Environmental Engineering from the University of Viginia. Her reserach is focused on improving our knowledge of fluid transport and geochemical controls for enhancing CO2 mineral carbonation in fractured basalt reservoirs.