Conceptual Model for Coupling Geothermal Power Plants with Deep Reservoirs

Abstract

During geothermal power production the hydro-mechanical-thermal conditions of a geothermal reservoir will vary. Temperature and pore-pressure variations lead to a change of the reservoir properties such as porosity, permeability, electric conductivity and fluid properties. The variations are dependent on input and output parameters of the geothermal power plant such as the injection temperature and flow rate of the thermal water. The simulation of geothermal power plants and the reservoir behavior are usually treated separately, leading to a strong simplification of the interactions between both systems. Therefore a holistic approach including a reservoir-power plant coupling is necessary to predict the life cycle behavior and hence the cumulated electricity provision of the overall geothermal system.
We present a conceptual model, which is capable to combine all different aspects of geothermal power production including coupled processes. Power plant and geothermal reservoir are connected by injection and production wells, therefore changes of fluid properties due to heating and cooling inside the wells have to be taken into account. For this reason, interfaces between all model components such as geothermal power plant, boreholes and reservoir will be developed to simulate the circulation of the geothermal fluid inside the overall system. By means of a case study of the geothermal research site Groß Schönebeck, Germany, the application of the conceptual model will be presented taking into consideration a total operation time of 30 years.