Accelerated CO2 mineralization in basalt via reaction process control: Mineralization effect, mineral evolution, and reservoir property implications

The lack of effective reaction rate regulation technology in CO₂ sequestration of basalt poses challenges for controlling CO₂-basalt reaction rate.To address this, we propose a method to accelerate basalt CO₂ mineralization by regulating reaction process, introducing HCl and NH₃ as reaction accelerants for the first time. Experimental and numerical simulation methods were employed to investigate the acceleration effects, mineral evolution patterns, and reservoir property changes during the accelerated mineralization process. The results demonstrate that the proposed method significantly enhances mineralization efficiency. Static experiments revealed a 119-fold increase in maximum mineralization capacity (Group B5) with a peak mineralization rate of 56.43 %. Dynamic experiments showed a 101-fold enhancement in mineralization capacity, while three-dimensional numerical simulations indicated a 20-fold acceleration during NH₃ injection.In terms of mineral evolution,the accelerated mineralization process led to a significant increase in the precipitation rates of calcite, dolomite, and magnesite, as well as enhanced dissolution rates of anorthite, diopside, and sanidine. Compared to conventional mineralization methods, the dissolution and precipitation domains of the primary minerals expanded, and the intensity of these reactions was also amplified. Reservoir property analysis revealed reduced pore space and specific surface area post-acceleration, as secondary mineral precipitation dominated over dissolution-induced pore expansion. Numerical simulations demonstrated acid injection promotes pore expansion, while alkaline injection induces contraction. The coupled acid-base interactions led to net porosity reduction, suggesting adjustable acid/alkali ratios to mitigate excessive porosity changes.The basalt CO₂ sequestration process was categorized into three stages: CO₂ carbonation, mineral ionization, and ionic carbonation. Optimizing acidity in Stage II and alkalinity in Stage III significantly enhanced mineralization efficiency. This work provides a strategic framework for developing rapid and secure CO₂ sequestration methods.