Rüdiger Thomas

3D seismic survey for geothermal exploration in crystalline rocks in Saxony, Germany

A 3D seismic survey was recorded in 2012 to explore a petrothermal reservoir in a late-Variscan granitic pluton within the Erzgebirge (Ore Mountains) in Saxony, Germany. The main objective was to test this area in the context of the Enhanced Geothermal System concept and to test the 3D seismic technique as an exploration tool. The intention and challenge are to image and characterize potentially permeable fracture zones at target depths of 5–6 km, with temperatures above 150 °C. Unconventional methods were applied for field acquisition and data processing. The vibroseis technique was used in the core experiment, accompanied by a special explosive seismic experiment. Field acquisition was characterized by severe noise conditions and a highly irregular layout. These conditions required extensive preprocessing and data conditioning. The imaging started with conventional Common Midpoint processing for quality control and for a first reference. Better images were obtained by Common Reflection Surface processing with subsequent post-stack time migration. Prestack time migration was also used for comparison. Outstanding results were obtained by the ‘operator-oriented’ version of the Common Reflection Surface technique. A rich repertoire of structures within the granite pluton was imaged, including steeply dipping fault zones and conjugate faults. Images and indications of fracture and crack porosity of a prominent fault zone provide the background to define an optimum drill path. This is considered as the next stage for a possible geothermal plant, if a decision is taken to drill a research well in the future. The 3D seismic reflection technique was shown to be an indispensable tool for geothermal exploration, even in crystalline basement rocks.

3D Seismic Survey for a Petrothermal Research Project in Crystalline Rocks of Saxony

3D seismic measurements have been performed in 2012 to explore a petrothermal reservoir in a crystalline environment (granite intrusion, metamorphic cover) within the Erzgebirge in Saxony. The intention and challenge is to image and characterize a steeply dipping fault zone and therewith potentially permeable fracture zones at target depths of 5-6 km and temperatures well above 150 °C. The vibroseis technique was used in the experiment, accompanied by a special explosive seismic experiment. Common-reflection- surface (CRS) processing with subsequent post-stack and pre-stack time migration was highly successful. A rich repertoire of structures within the granite pluton has been imaged. Many of these structures are steeply dipping normal faults and their conjugate faults with high impdedance contrasts and subhorizontal reflectors at the base of the granite. The 3D seismic technique has been proven as an indispensable tool to define an optimum drill path in a crystalline environment.

3D Seismic Exploration of a Carbonate Geothermal Reservoir in Southern Germany

The target of seismic exploration for geothermal energy within the Southern German Molasse Basin is the Upper Jurassic (Malm) carbonate platform. Several factors govern its hydraulic transmissivity. The formation of the platform led to different carbonate facies, i.e. reefs and small sedimentary troughs. Further on, fault systems play an important role since the formation of the basin was accompanied by complex faulting. Additionally, local carstification has taken place. A reservoir model of the aquifer has to take into account all of this geological heterogeneity. The seismic interpretation on the other hand has to provide the necessary geological information. Based on a 3D seismic survey a structural model was built, the facies distribution was analysed and carst structures were mapped. For these different tasks mathematical transforms have been evaluated.

Faults, Facies, and Karst - Intergrated Seismic Interpretation of a Hydro-geothermal Reservoir

Taking into account the heterogeneity of a hydro-geothermal reservoir, sedimentological and diagenetic information must be combined for a sound estimation of hydraulic parameters. Based on a newly processed 3D dataset from the Bavarian Molasse, we evaluat

Structure and Facies Analysis of a Carbonate Hydrogeothermal Reservoir within the Southern German Molasse Basin

Geothermal energy is an increasing part of the worldwide energy supply. There are three geological provinces in Germany with hydrogeothermal potential: the North German Basin, the Upper Rhine Graben, and the Southern German Molasse Basin. Within the South