No abstract

No abstract

No abstract

No abstract

Basalt formations are often fractured, which poses the risk of CO 2 leakage from a geological CO 2 storage reservoir. Despite their fractured nature, basalts are considered for large-scale CO 2 injection and storage due to large potential storage capacity and rapid carbon mineralization (Matter et al., 2016;McGrail et al., 2016;Xiong et al., 2018). The advantage of fractures is the connectivity to a larger pore network adjacent to fracture surfaces, which provide a large mineral reactive surface area for chemical reactions, and may play a dominant role in changing the porosity of basaltic rock. Mineral precipitation in fractures and connected pores could act as a self-sealing process in the case of a CO 2 leakage from a CO 2 storage reservoir, thus reducing the risk of the longterm leakage of CO 2 . Mineral precipitation in basalt fractures has been observed in natural analogue systems where hydrothermal fluids have migrated upwards through basalts over geological time (Eggleton et al., 1987;Goldberg et al., 2008;Rogers et al., 2006). However, a range of factors including the flow velocity of the CO 2 -enriched plume, fluid chemistry, pressure and temperature conditions, and the fracture aperture size need to be considered in order to predict the rate and extent of the potential self-sealing of fractures (Brunet et al., 2016).Several laboratory studies have been performed to understand the influence of transport limitations on the extent of mineral formation and pore network alterations in natural basalt cores when exposed to acidic CO 2 -rich fluids under relevant geologic storage conditions (