Multiple factors conditions on calcite dissolution kinetics in CO₂-brine systems: mechanistic insights and...

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 (P_sys, 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 (C_e,q) decreases by 67.1% due to reduced CO₂ solubility. P_sys exhibits a non-monotonic impact on k₂, reaching a minimum at 15 MPa, while exerting a linear positive effect on C_e,q, which increases by 33.7% from 5 to 25 MPa. From a kinetic perspective, an apparent activation energy (E_a) 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.