Numerical modeling of reaction‐induced cavities in a porous rock

The interaction between mineral reaction and mass transport in a rock can lead to reaction front instability and the development of channel‐like voids. This phenomenon is studied with a two‐dimensional model accounting for the nonlinear feedback between flow, reaction, and matrix porosity‐permeability evolution. In our model we calculate the flow field in both the porous medium and the reaction‐induced voids, using the Brinkman equation. While a linear analysis cannot determine the length scale of the channels which can develop in a typical geological system, our simulations indicate that the channel size is actually unique and well characterized. While the onset of instability is favored at a preexisting heterogeneity, the channel growth and orientation is governed by the global flow pattern, even in an initially heterogeneous system.