TEMPROAL EVOLUTION OF PERMEABILITY FOR POROUS ROCK DURING MINERAL DISSOLUTION AND PRECIPITATION PROCESS BASED ON FRACTAL THEORY

Abstract

Mineral dissolution and precipitation reactions occur in a variety of porous rocks due to the deviations from a geochemical equilibrium between solid matrix and flow fluid, resulting in the alteration of the petrophysical properties of rocks. A physically-based theoretical model is proposed based on fractal theory for quantitatively assessing the temporal evolution of permeability for porous rocks undergoing mineral dissolution and precipitation reactions. The proposed model is associated with pore structure parameters, such as initial porosity [Formula: see text], the tortuosity fractal dimensions [Formula: see text], the initial fractal dimension [Formula: see text], and the overall dissolution rate [Formula: see text] considering the precipitation reactions in porous rocks. The proposed model provides a better prediction of the time dependence of permeability compared with the available experimental data. The essential effects of the overall dissolution rate and pore structural parameters of porous rocks on the dimensionless time-dependent permeabilities are investigated in detail. It is found that the overall dissolution rate has obvious effects on the dimensionless time dependence of permeabilities. The present model may provide useful insights into the understanding of permeability change during mineral dissolution and precipitation reactions in porous rocks.