Numerical Simulation of Pore Size Dependent Anhydrite Precipitation in Geothermal Reservoirs

Porosity and permeability of reservoirs are key parameters for an economical use of hydrogeothermal energy. Both may be significantly reduced by precipitation of minerals. The Allermöhe borehole near Hamburg (Germany) represents a case in which precipitation of anhydrite resulted in a failed reservoir development. We introduce a new numerical approach for better understanding of this, considering both the spatial variations of supersaturation on the pore scale and the pore space structure. Besides pore size this requires consideration of the effects of surface charge density on the fluid supersaturation in porous media and of the role of fluid flow velocity.