Permeability Changes in a Rock Fracture During Coupled Fluid Flow and Chemical Dissolution Processes

A coupled fluid flow and chemical dissolution model in rock fracture is developed in this paper and applied to explain spontaneous changes in permeability that develop within a fracture in limestone under invariant water flow-through condition. This model is solved by using COMSOL Multiphysics and validated through comparing our numerical results with the known experimental measurements in salt rock, which shows our model is credible. The simulated results of coupled fluid flow and chemical dissolution processes of a rough fracture in limestone indicate that: (1) The solute concentration plays an important role on the dissolution process, this causes that the dissolved thickness at inlet is bigger than that at outlet. (2) Flow paths in fracture have no obvious dynamic change but become larger with time during chemical dissolution process. (3) The flux through fracture increases exponentially with time during the dissolution process, which means that related permeability of fracture increases exponentially with time during the dissolution process.