Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Recent numerical investigations revealed that the heterogeneity of the dissolution rate observed in numerous experiments cannot be explained by fluid transport effects. This heterogeneity is attributed to intrinsic surface reactivity. Therefore, reactive transport models (RTM) require parameterization of the surface reactivity for accurate predictions. For this purpose, a nanotopographic parametrization based on surface slope has been recently suggested. In this study, we utilize and improve this parametrization for RTMs of pore-scale systems, from the crystal surface to the single crystal geometry, going beyond the previous reactivity parametrization. 2D and 3D RTMs were developed using COMSOL Multiphysics for calcite systems based on experimental measurements. We compared the results between classically parameterized RTMs, RTMs with new slope parameterization, and experimental data. The effect of flow on dissolution under conditions far-from-equilibrium is found to be negligible, highlighting the importance of surface reactivity in the dissolution reaction. For the first time, the new slope factor was able to accurately reproduce the experimental results on a crystal surface with large field-of-view, large height variability of the topography, and over a long-term reaction period. The new parameterization had greatly improved sensitivity for intermediate reactivity ranges compared to the previous parameterization. A 3D model is used to present the general applicability of the parameterization for use in realistic geometric data sets. Thus, we also show that neglecting surface reactivity in an RTM leads to incorrect predictions regarding the porosity, pore geometry, and surface topography of the system. Our new slope factor can successfully serve as a first-order proxy for the distribution of surface reactivity in 3D pore-scale rock systems. The description of surface reactivity is crucial for accurate long-term modeling of natural rock systems.