Research aims at the determination of petrophysical (thermal) parameters of geological formations of Mesozoic and Cenozoic age in the North German Basin. A methodology will be developed to calculate rock thermal conductivity based on geophysical well-log parameters. The calculated thermal-conductivity values will be validated by a large suite of values from laboratory measurements. The well-log based prediction of thermal conductivity allows the calculation of temperature-depth profiles using a respective value of surface heat-flow density. Thermal parameters are important to define the targets for the utilization of geothermal energy in sedimentary basins.
For the assessment of sustainability of geothermal reservoirs, natural fault systems, as a primary fluid conduit, and conductive thermal losses along the production well play a major role. The numerical representation of fault systems and wells is being automated up to the finite-element model. Additionally, processes like heat transfer at the borehole wall and turbulent flow are integrated into the borehole-matrix model. Model results are validated by laboratory experiments and field measurements. As an example, field data about the temperature profile during operation are acquired at the Groiß Schönebeck research wells. These are augmented by characterization of the hydraulic behaviour of fracture and fault systems and the poro-elastic behaviour of the rock matrix.
Investigations on materials are conducted under in situ operational conditions in a corrosion test cell at 1200 m depth below the production pump and within three bypasses included in the thermal loop containing different materials and plant components. An installation forming a central part in this research topic is a corrosion test track comprising 30 openings for experiments with different materials coupons and monitoring systems. The materials scientific data obtained will enter a compendium on site-specific materials selection for geothermal plants.
Here, fluids and reactions are characterized within the geothermal plant (fluid-component interactions) as well as within the reservoir (fluid-rock interactions). Also, processes that affect plant operation are investigated. The research focus in this topic is on investigations related to process engineering aspects (materials research, catalytic combustion, heat exchangers, and multiphase flow) as well as on comprehensive geochemical monitoring of thermal fluids, gases, and solid particles at the Groß Schönebeck geothermal site.