The chemistry of the geothermal fluids is mainly governed by the mineralogy of the reservoir rocks, the fluid inclusions, respectively, and within the circulation of the deep fluids. The fluids are in geochemical equilibrium with the surrounding rocks. Through the production, within the heat extraction and the pressure release, the system will be disturbed. Therefore the physical, hydrochemical and the thermodynamical parameters were modified. As a result of this Pressure and Temperature changes, precipitation and dissolution of minerals may occur in the pipe system as well as close to the injection borehole. In a geothermal loop the fluid and the materials are in direct contact and some installations like the production well with the pump, the pipes, the heat exchangers, and the injection well are affected. Due to the chemical characteristics of the geothermal fluid, it is also corrosive with respect to the installations.

The objective of the research is to obtain a better understanding of the chemical modification during the circulation of the saline fluid in the entire geothermal system. On this basis it is possible to evaluate the resulting chemical processes in the geothermal loop and the reinjection formation. A better predictability with respect to long-term processes can be established. In the nearfield of the injection well fluid-rock interactions are leading to a variation of the permeability and therefore a change of the injectivity of the well.

The approach aims to fuse experimental research with numerical investigations. For the experiments the ideal goal is to adjust the experimental conditions to the in-situ parameters and to mimic the chemical environment inside the geothermal loop and the reservoir. Complementary a numerical modeling will be carried out with T(hermic)- H(ydraulic)- M(echanical)- C(hemical)-Codes. Thereby the conceptional understandings of the associated processes are obtained. Applied Codes are TOUGHREACT, PhreeqC and Elmer.

The outcome of this research will help to identify fundamental, geochemical processes which are related to the long-term and trouble-free reservoir and power plant performance, additional the corrosion-related processes in the geothermal loop are important to predict.