Assessment of Deep Geothermal Resources and Potentials with a Multi-Criteria Approach Based on Multi-Scale Datasets and Models
Kristian BĂ„R, Judith BOTT, Meike HINTZE, Sebastian WEINERT, Nora KOLTZER, Magdalena SCHECK-WENDEROTH, Ingo SASS
[Technische Universität Darmstadt, Germany]
Assessing resources of enhanced geothermal (EGS) or medium deep geothermal systems (MDGS) for direct heat use and underground thermal energy storage (UTES) is a challenging task where usually diverse data sets of multiple origin and scale have to be compiled to obtain a comprehensive conceptual model of the subsurface, its structure and its properties. Within the research project â€śHessen 3D 2.0â€ť (BMWI-FKZ: 0325944), which aims to significantly enhance the assessment of the prospective risk (â€šFĂĽndigkeitsrisikoâ€™) for these kinds of geothermal projects, we established a workflow to implement and analyse such broad data sets. In a first step, comprehensive datasets of physical rock-, fluid- and reservoir properties based on investigations on relevant reservoir analogues, hydraulic test data from boreholes and borehole geophysical logs are compiled. The second step comprises the development of 3D geological models from a combination of borehole data, geological cross sections, seismic profiles, gravity anomalies and geological maps to significantly increase the detail on subsurface structure. This is prerequisite to distinguish the potentially usable reservoir units both within the crystalline or metamorphic basement and the sedimentary cover. Geostatistical analysis of the comprehensive geothermal database is performed in a third step for parametrization of the geological model to allow for geothermal resource assessment and thermohydraulic subsurface modelling. Such models, which consider the variability of rock and reservoir properties can provide a much better understanding of the subsurface temperature distribution, the dominant heat transport processes and hydraulic conditions. Finally, under consideration of both technical and economic boundary conditions and the statistics for the different relevant reservoir properties of the different geological units, assessment of hydrothermal, petrothermal and UTES potentials is performed directly with the 3D model. Therefore, a multiple-criteria approach, which assesses the quality of various rock and reservoir properties and their relevance for the different geothermal utilizations is implemented. This 3D-grid based method can be used for an identification and visualization of different geopotentials using various parameters to determine each potential. Threshold values for each parameter to specify the grade of each potential under technical and economic requirements are defined. This approach allows for stochastic assessment of the geothermal resources including the determination of the probability of success and provides the necessary numbers to attract investors to geothermal projects.
|        Topic: Resource Assessment||Paper Number: 16087|