We study reactive transport in a stressed porous media, where dissolution of the solid matrix causes two simultaneous, competing effects: pore enlargement due to chemical deformation, and pore compaction due to mechanical weakening. We use a novel, mechanistic pore-scale model to simulate flooding of a sample under fixed confining stress. Our simulations show that increasing the stress inhibits the permeability enhancement, increasing the injected volume required to reach a certain permeability, in agreement with recent experiments. We explain this behavior by stress concentration downstream, in the less dissolved (hence stiffer) outlet region. As this region is also less conductive, even its small compaction has a strong bottleneck effect that curbs the permeability.Our results also elucidate that the impact of stress depends on the dissolution regime. Under wormholing conditions (slow injection, i.e. high Damkohler number, Da), the development of a sharp dissolution front and high porosity contrast accentuates the bottleneck effect. This reduces transport heterogeneity, promoting wormhole competition. Once the outlet starts eroding, the extreme focusing of transport and hence dissolution-characteristic of wormholing-becomes dominant, diminishing the bottleneck effect and hence the impact of stress at breakthrough. In contrast, at high flow rates (low Da), incomplete reaction upstream allows some of the reagent to traverse the sample, causing a more uniform dissolution. The continuous dissolution and its partial counteraction by compaction at the outlet provides a steady, gradual increase in the effect of stress. Consequently, the impact of stress is more pronounced at high Da during early stages (low permeability), and at low Da close to breakthrough. Our work promotes understanding of the interplay between dissolution and compaction and its effect on the hydromechanical property evolution, with important implications for processes ranging from diagenesis and weathering of rocks, to well stimulation and carbon geosequetration.This further enhances their conductivity relative to other, less conductive regions, leading eventually to runaway permeability increase [12,4,18,39].In many cases, for instance in the subsurface, the medium is under appreciable stress, such that dissolution ("chemical deformation") also induces mechanical deformation. Chemomechanical deformation and the coupled changes in the transport and mechanical properties is key in many applications, such as enhanced energy recovery and carbon geosequestration [35,26,11,32,44,7]. A large body of literature exists on rough fractures, due to their importance, e.g. dominance of fracture flow, and their quasi two-dimensional (2-D) nature, which simplifies experimental setup and imaging as well as numerical simulations [e.g. 22, 14, 15, 19, 2]. Relatively fewer works addressed porous media such as soils [8] and rocks [e.g. 46, 11, 47, 16, 6, 29, 32, 23], mostly focusing on the evolution of the mechanical properties.The evolution of transport properties i...

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The evolution of heterogeneous and anisotropic media in the uniform dissolution regime (low Damköhler number) is studied here using a numerical network model. The uniform dissolution extensively homogenizes the medium and therefore the flow field. The homogenization is further enhanced when the surface reaction is transport controlled-when slow diffusion of dissolved ions away from the mineral surface leads to the reduction of the global dissolution rate. Under those conditions, diffusive transport is more effective in narrow channels, which selectively enlarge, leading to an initial steep rise of the permeability. However, as dissolution proceeds, the void space widens and the overall dissolution rate drops, and permeability enhancement slows down. Finally, we review the relevance of these results to various processes in geological systems ranging from diagenesis and karst evolution, to carbon geosequestration. These findings provide fundamental insights into reactive transport processes in fractured and porous media and evolution of permeability, tortuosity, anisotropy, and bulk reaction rates in geological systems. Plain Language Summary When corrosive fluids flow in an aquifer, they dissolve the rocks and change the void-space structure (e.g., acidic water invading limestone). In many geological processes and applications, the flow velocity is high compared to the chemical dissolution rate, and the corrosive fluid penetrates large distances before it loses its reactivity, resulting in relatively uniform dissolution everywhere. Here, using analog numerical model, we study how the void-space structure of porous rocks and aquifers change during uniform dissolution. In particular, we study how different initial structures and reaction conditions change the flow field and transport properties. Finally, we review the relevance of these results to various geological systems. The study improves our understanding of rock and aquifer evolution, with implications to groundwater management and other subsurface flow-related processes, such as CO 2 geosequestration.

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