Dynamic Evolution of Pore-scale Heterogeneity and Transport Conditions Control Mineral Dissolution Regimes

TL;DR

This study uses micro-CT simulations to show how pore-scale heterogeneity influences mineral dissolution regimes, revealing dynamic behaviors and non-power-law permeability relationships in complex rocks.

Contribution

It introduces a dynamic framework linking initial heterogeneity to evolving dissolution regimes, challenging static classical models.

Findings

Flow heterogeneity controls dissolution accessibility.

Channeled dissolution reorganizes structure and flow.

Permeability-porosity relationship deviates from a single power-law.

Abstract

Mineral dissolution in porous media is classically partitioned into static regimes within the Pe-Da plane, but this framework fails to capture the dissolution behavior of structurally complex rocks. Using three-dimensional micro-continuum simulations on micro-CT images of three rock samples spanning a wide range of pore-space heterogeneity, we track the joint evolution of dissolution morphology, velocity distribution, and reaction rate. Our results reveal that initial flow heterogeneity controls accessibility of reactants, thereby controlling the dissolution regime,reshaping them as dynamic trajectories. Channeled dissolution emerges as a simultaneous reorganization of structure and flow, and the resulting permeability-porosity relationship cannot be captured by a single power-law. The effective power-law exponent increases with heterogeneity and changes over time, reaching a maximum of 9.8, 18.0, and 40.9 for the three samples. Consequently, the effective reaction rate falls one to three orders of magnitude below the uniform dissolution prediction, with the suppression scaling with flow heterogeneity due to mass transfer limitations in channeled dissolution.