Multiple factors conditions on calcite dissolution kinetics in CO ₂ -brine systems: mechanistic insights and implications for geological carbon sequestration

Mineral trapping efficiency in geological carbon sequestration (GCS) is fundamentally constrained by mineral dissolution kinetics. This study systematically evaluates the impacts of critical parameters – temperature (303.15–363.15 K), system pressure (Psys, 5–25 MPa), water-rock ratio, and brine chemistry – on calcite dissolution within CO2-brine-rock systems. Experimental results demonstrate that as temperature rises from 303.15 to 363.15 K, the pseudo-second-order rate constant (k2) increases by 284%, while the equilibrium concentration (Ce,q) decreases by 67.1% due to reduced CO2 solubility. Psys exhibits a non-monotonic impact on k2, reaching a minimum at 15 MPa, while exerting a linear positive effect on Ce,q, which increases by 33.7% from 5 to 25 MPa. From a kinetic perspective, an apparent activation energy (Ea) of 20.71 kJ mol−¹ indicates that the dissolution process is jointly controlled by surface reactions and diffusion. Brine chemistry further modulates dissolution: Ca2+ significantly inhibits the process through the common-ion effect, whereas Mg2+ promotes it. PHREEQC simulations quantitatively corroborate these findings, revealing that Mg2+-induced promotion is driven by dolomite supersaturation (SI > 1.5) while elevated Ca2+ activity governs the observed inhibition. These findings offer critical technical constraints for site selection, to maximise GCS efficiency and mineralisation security, this study suggests that reservoirs characterised by moderate temperatures (< 348.15 K), high pressure (>20 MPa), and Mg-rich/low-Ca brine chemistry exhibit highly favourable kinetic baselines for mineralisation, though field-scale implementation will require further site-specific modelling.