Revisiting classical silicate dissolution rate laws under hydrothermal conditions

Abstract

Prediction of reaction kinetics of fluid/rock interactions represents a critical issue for several geological and engineering concerns, including geothermal systems. For example, in the context of the Soultz-sous-Forêts enhanced geothermal system (Alsace, France), the pumping of hot water and exploitation of heat at surface may provoke a partial re-equilibration of the aqueous fluid composition, and re-injection of cooled water at depth may favor the dissolution of the main rock-forming minerals of the reservoir, such as K-spar and plagioclase, while promoting the precipitation of secondary phases, such as calcite and/or Al-(hydr)oxides (Fritz et al., 2010). The relative intensities of primary mineral leaching and secondary phase formation significantly affect porosity and permeability of the reservoir, thereby influencing its hydraulic performance and the efficiency of the geothermal site.