Carbon mineralization in mafic formations: fracture topology and hydro-chemo-mechanical coupling

Abstract

[Abstract:] Coupled hydro-chemo-mechanical processes affect engineered geosystems, including geothermal energy recovery, long-term nuclear waste disposal, and carbon geological storage. In particular, dissolution-transport-precipitation can significantly alter the permeability field and alter the evolution of these coupled processes. Carbon mineralization in mafic rocks is a salient example. Fractures within these rocks, including column-normal and entablature fractures, serve as conduits for fluid transport and host associated chemical processes. This study investigates fracture characteristics in mafic formations, using photographic records from published studies and data collected by the authors during site visits. Different fracturing topologies – from well-developed columnar structures to irregular patterns – exhibit distinct aperture and spacing characteristics. Additionally, new experimental results reveal the intricate interplay between water absorption kinetics and induced strains, which could potentially impact fracture aperture and, subsequently, permeability. The study also highlights the importance of flow rate and residence time in influencing the evolving pore fluid chemistry, including variations in pH and dissolved species.