Objectives CO₂−induced mineral reactions can significantly alter rock pore structures, thereby affecting their seepage and mechanical properties, which is crucial for the suitability and long-term safety of CO₂ geological storage engineering.

Methods This study focuses on calcite-bearing rock samples, employing a coupled simulation technique combining the Lattice Boltzmann Method (LBM) and Finite Element Method (FEM) to systematically analyze calcite dissolution characteristics under different CO₂−saturated solution injection rates and further reveal the dynamic evolution patterns of rock permeability and elastic moduli (including bulk modulus and shear modulus).

Results and Conclusions (1) At low injection rates, the accumulation of reaction products in the mid-to-distal regions inhibits calcite dissolution, thereby limiting reactions to areas near the injection point. As the injection rate increases, the enhanced penetration of fresh solution dilutes reactants, enabling calcite dissolution to occur more uniformly across the mid-to-distal regions. (2) Calcite dissolution significantly enhances rock permeability, with the effect intensifying at higher injection rates. In the low-rate range (30~150 m/a), permeability improvement is limited due to diffusion-dominated solute transport. However, when the injection rate rises to 750~18750 m/a, advection gradually dominates solute transport, leading to greater difference in the rock matrix and more pronounced permeability enhancement. Overall, the fitting exponent n for the relationship between permeability and porosity in the power-law model falls within the range of 2.8~6.5, while the n value in the Carman−Kozeny model ranges between 0.9 and 4.6. Additionally, the n values of both models show a monotonically increasing trend with the increase of injection rate, and the Carman−Kozeny model demonstrates superior characterization capability. (3) Calcite dissolution markedly reduces rock elastic mechanical properties. When porosity increases from 0.44 to 0.56, both shear and bulk moduli decrease by approximately 20%. Additionally, the reduction rate is faster in the early dissolution stage and slows later, exhibiting nonlinear behavior that makes the power-law model more representative than traditional linear models. The study also finds that higher injection rates exacerbate rock elastic mechanical property degradation, with shear modulus showing greater sensitivity to injection rate variations compared to bulk modulus. This study reveals the key mechanism by which the fluid injection rate dominates the evolution of rock permeability and mechanical properties through controlling the spatial distribution of dissolution, providing a theoretical basis for assessing the long-term safety of CO₂ geological storage sites.