On the permeability-surface area-porosity relationship for dissolving porous media

Abstract

Dissolution in porous media is widespread in natural and engineered systems, accompanied by the evolution of geometric structure, permeability and surface area of the porous matrix. Although extensive research has examined dissolution dynamics in porous media, there is a lack of quantitative characterization of the relationships among permeability, surface area and porosity, which depend on dissolution patterns. Here, we combine dissolution experiments and pore-scale simulations of millimeter-scale porous media to delve into the transitions of dissolution patterns, permeability-porosity relation and surface area-porosity relation. The pore-scale model incorporates the improved volume-of-solid formulation and is subsequently validated by experimental results. Based on a large number of 2D porous media dissolution simulations with different flow rates, reaction rates, and spatial heterogeneity of the pore space, we identify three distinct dissolution patterns and propose a theoretical equation to describe the transitions between these patterns. We further correlate dissolution patterns with the evolution of permeability and surface area as functions of porosity, and quantitatively characterize permeability-porosity and surface area-porosity relationships for different patterns. Finally, we develop a predictive model for the correction factor of surface area, thereby completing the system for modeling the flow-dissolution processes at the Darcy scale. This work is pivotal for upscaling the flow properties and dissolution properties for the Darcy scale and advances field-scale modeling techniques. It also deepens our understanding of dissolution dynamics in porous media and is instructive for underground engineering.