Pore scale investigation of reaction induced mechanical weakening of rock

• A pore-scale model is proposed to analysis the impact of dissolution patterns on the elastic properties of carbonate rocks. • Advection-dominated flow causes uniform dissolution, resulting in a gradual and stable decrease in elastic moduli. • Reaction-dominated flow induces face dissolution, causing rapid modulus drop and accelerated elastic weakening. Reaction flow in porous media fundamentally couples fluid flow and chemical reactions, dynamically altering material properties, including permeability, porosity, and mechanical strength. This study utilizes a pore-scale model to analyze how dissolution patterns, classified by the Damköhler (Da) and Péclet (Pe) numbers, affect the elastic properties of carbonate rocks. Our simulations establish two distinct structural degradation mechanisms and corresponding mechanical responses. Advection-dominated conditions (high Pe, low Da) promote uniform dissolution throughout the porous structure, resulting in a gradual and stable decrease in elastic moduli. Conversely, reaction-dominated conditions (high Da, low Pe) induce face dissolution localized near the injection source, causing a rapid, significant decline in moduli and accelerated elastic weakening. This divergence is attributed to varying acid transport efficiencies, which dictate the spatial distribution of dissolution and the resulting structural damage. A critical finding is that during face dissolution under high-concentration scenarios, the shear modulus decreased faster than the bulk modulus, indicating that localized chemical attack heightens the rock’s susceptibility to shear deformation. These findings provide essential pore-scale insight into the stability of carbonate rocks during processes like CO 2 geological sequestration and acid treatment, supporting the development of more accurate predictive models and safer reservoir management strategies.