Flow-rate control of carbonate precipitation and permeability evolution in fractured basalt: Implications to geologic carbon mineralization

Carbon mineralization in basaltic formations stores CO2 as solid carbonates, but precipitation-induced clogging can degrade injectivity and storage capacity of the reservoir. This study examines how flow rate controls abiotic calcite precipitation patterns and permeability evolution in fractured basalt. A supersaturated solution was circulated at two flow rates (1 and 5 mL/min), and X-ray CT imaging quantified precipitation and porosity changes, revealing distinct precipitation patterns. Low flow caused localized clogging near the inlet, reducing permeability by two orders of magnitude with only 2.8% pore-volume calcite. High flow distributed precipitation along the fracture surfaces, yielding 7.6% pore-volume calcite and a four-order-of-magnitude permeability reduction, but with weaker sensitivity of permeability changes to porosity loss. Fracture-surface passivation occurred at both flow rates, diminishing growth of precipitation in the matrix. We demonstrate that the transport regime (Damköhler number) controls the formation of a localized barrier, with implications for injection strategies to limit near-well clogging.