A substantial prerequisite for a successful and sustainable operation of geothermal plants is an understanding of the complex composition of geothermal fluids and the various chemical processes that occur during fluid circulation. As an example, during injection of geothermal fluids into the hot reservoir permeability changes and a concurrent decrease in injectivity might be induced due to mineral dissolution and precipitation. Furthermore, saline fluids might provoke scaling (mineral precipitation) and corrosion in plant components. Apart from investigations in real geothermal systems and laboratory experiments (e.g. selected fluid-mineral interactions at high temperatures), geochemical modeling of the circulation process contributes 

• to describing redox-conditions, and
• to determine the controlling factors for mineral precipitation and saturation.

Furthermore, geochemical modeling is a prerequisite

• to estimate long-term process propagation, also over long distances, and
• to evaluate the spatio-temporal evolution of permeability within a reservoir.

Here, experimental feasibility is limited.

In this respect, such models are indispensable to estimate the sustainability of a geothermal reservoir and provide a milestone for geothermal development.
In the framework of this project, simulation results and operation experiences from experimental data acquisition within the in situ laboratory Groß Schönebeck will be linked. This yields an immediate applicability of the project results to plant operation. The project results will therefore significantly improve the quality and safety of the planning process as well as the operation of geothermal plants.

In close cooperation with the Gesellschaft für Anlagen- und Reaktorsicherheit and the TU Bergakademie Freiberg the following objectives will be achieved:

• state of knowledge of existing thermodynamic data for geochemical modeling of fluids of the North-German Basin,
• determination of the most important missing thermodynamic data for these fluids, and
• the set-up of a generic geothermal reservoir model.