Pore-merging methodology for reactive transport and mineral dissolution in pore-network models

Abstract

This study proposes a pore-network modeling algorithm to simulate single-phase reactive transport and mineral dissolution in porous media. A novel pore-merging approach is introduced to guarantee the conservation of the most critical variables during the merging process by using correction factors and effective properties for throat conductances and surface areas. Our approach solves a coupled transport and reaction pore-network model that implements a kinetic model with a single heterogeneous chemical reaction describing the dissolution of calcite by acidic solutions. The network geometry is updated based on the dissolution process occurring at the mineral surface and the network topology is updated based on the pore-merging processes occurring throughout the network. The main results include the exploration of different dissolution regimes through porosity-permeability evolution curves, acid concentration profiles, and the use of statistical criteria. Importantly, this methodology simulates permeability increases larger than 100-fold during the formation of preferential pathways (i.e., wormholes).