Differential dissolution of multiple carbonate minerals: Impacts on pore network evolution and permeability

A substantial body of research has been conducted to explore the multi-scale dynamic evolution and nonlinear coupling relationships from microstructure to macroscopic properties of carbonate rocks under reactive solute transport at the pore scale. However, these studies primarily focus on single-mineral systems, neglecting the influence of mineralogical diversity. This study examined the dissolution characteristics of calcite and dolomite under varying hydrodynamic conditions and introduced a pore-scale reaction transport model. The kinetic mechanism of mineral dissolution, microscopic pore network evolution and macroscopic seepage response were systematically analyzed. Results demonstrated that the calcite dissolution rate substantially exceeded that of dolomite, leading to heterogeneous features including discretized pore size distributions and distorted hydraulic pathways in a multi-mineral system. Low-velocity flow regimes shift the dissolution process from reaction-limited to mass-transfer-limited, further exacerbating dissolution unevenness and promoting the development of irregular pore geometries. By integrating pore-scale simulations with quantitative characterization of pore size distributions and pore shape parameters from natural carbonate rock samples, this study confirms the critical role of mineral composition and hydrodynamic conditions in governing the evolution of pore network heterogeneity. These heterogeneous features significantly impede fluid transport efficiency. Enhanced mineralogical complexity and reduced hydrodynamic conditions amplify the heterogeneity of pore structures during ongoing dissolution, consequently constraining the extent of permeability improvement. Furthermore, under low-velocity flow regimes, dissolution tends to concentrate in pore spaces that contribute less to permeability.