Kinetic feedback effects induced by dissolution/precipitation processes in a geothermal context

Abstract

The relative intensities of primary mineral leaching and secondary phase formation may significantly affect porosity and permeability of the reservoir of a given geothermal site, thereby influencing its hydraulic performance and the efficiency of the geothermal power plant. In the present study, we estimated the impact of secondary coating formation on K-feldspar dissolution kinetics at conditions relevant for the context of Soultz-sous-Forêts (Alsace, France). Our results demonstrate that ?m-thick coatings formed on K-feldspar surface negligibly impact its dissolution rate, because of the porous texture of the coatings. Ongoing efforts are directed to ascertaining the critical size of fracture filling which has to be reached prior to preventing a continuous supply of dissolved cations from the fracture walls.