Fluid–Rock Interactions in Geothermal Reservoirs, Germany: Thermal Autoclave Experiments Using Sandstones and Natural Hydrothermal Brines

Abstract As renewable energy, geothermal can contribute substantially to the energy transition. To generate electricity or harvest heat, high-saline fluids are tapped by wells of a few kilometres and extracted from hydrothermal reservoirs. After heat exchanger units have been passed by, these reinjected into reservoir. Due pressure temperature differences between subsurface surface, as well cooling in power plant, unwanted chemical reactions occur within reservoir, borehole, plant itself. This reduce permeability reservoir output plant. study aims simulate real using batch leaching experiments with sandstone powder solid phase, deionised water natural brine liquid phase. It is demonstrated that fluid composition changes after only days. In particular, calcite, aragonite, clay minerals, zinc phases precipitate brine. contrast, particular minerals containing potassium, arsenic, barium, silica dissolved. experimental set-up, mineral mainly took place on surface samples, which why no substantial petrophysical properties could be observed. However, it assumed observed scale relevant influence parameters such permeability.