  A pore-scale numerical model for reactive transport processes based on the
Lattice Boltzmann method is used to study the dissolution-induced changes in
hydrologic properties of a fractured medium and a porous medium. The solid
phase of both media consists of two minerals, and a structure reconstruction
method called quartet structure generation set is employed to generate the
distributions of both minerals. Emphasis is put on the effects of undissolved
minerals on the changes of permeability and porosity under different Peclet and
Damkohler numbers. The simulation results show porous layers formed by the
undissolved mineral remain behind the dissolution reaction front. Due to the
large flow resistance in these porous layers, the permeability increases very
slowly or even remains at a small value although the porosity increases by a
large amount. Besides, due to the heterogeneous characteristic of the
dissolution, the chemical, mechanical and hydraulic apertures are very
different from each other. Further, simulations in complex porous structures
demonstrate that the existence of the porous layers of the nonreactive mineral
suppresses the wormholing phenomena observed in the dissolution of
mono-mineralic rocks.
