Investigation of CO2 Mineralization under Dynamic Conditions in Carbonate Formations.

Carbon capture and storage (CCS) via mineral trapping offers a permanent sequestration pathway; however, its slow kinetics in carbonate reservoirs remain a major challenge. This study investigates an accelerated mineralization strategy under dynamic conditions by evaluating the effectiveness of a chemical additive formulation in promoting carbonate precipitation while preserving formation integrity. Core-flooding experiments were conducted at 60 °C and 1300 psi using alternating injections of supercritical CO2 and synthetic brine, with and without additives (0.02 M Ba-(OH)2, 0.02 M SrCl2, and 0.1 wt % GLDA glutamic acid diacetate). Rock-fluid interactions were characterized using real-time pressure monitoring, nuclear magnetic resonance (NMR) relaxometry, medical X-ray computed tomography (CT), and helium porosity measurements. The additive-free core exhibited a progressive decline in differential pressure, a net porosity increases from 16.3% to 17.25%, and a pronounced rightward shift in NMR T2 distributions, indicating extensive dissolution and wormhole formation, as confirmed by 3D CT imaging. In contrast, the additive-treated core maintained a stable pressure profile, showed negligible net porosity change (16.45% to 16.25%), and preserved its original pore-size distribution. CT imaging revealed reaction features, with substantial suppression of wormhole growth. These results demonstrate that the additive formulation effectively shifts the system from a dissolution-dominated regime to one in which acid-driven dissolution is counterbalanced by concurrent precipitation of secondary carbonate minerals. These findings strongly indicate that engineered brine chemistry can fundamentally alter CO2-rock interaction pathways under dynamic flow, enabling accelerated mineral trapping while maintaining rock fabric integrity and enhancing the long-term security of geological CO2 storage in carbonate formations.