Geothermal Exploration in Megacities – Results from Reflection Seismic Surveying in Berlin (Germany)

Abstract

Geothermal exploration in sedimentary basin settings requires essentially seismic surveying to image the subsurface structure. Urban areas are favorable areas for geothermal development because the high demand on heat and electricity is accumulated especially in megacities. Reflection seismic surveys in megacities are however challenging due to seismic noise, infrastructural issues and high population density. A vibroseismic pilot study was conducted at the former city airport Berlin-Tempelhof, basically located in the center of Germany’s capital city. Two major questions were addresses to this reflection seismic experiment: (I) Can vibroseis provide sufficient data quality despite the intensive background noise of a mega city, and (II) what is the subsurface geological structure of Berlin focusing on depth and thickness of the Middle Triassic and Lower Permian as potential hydrothermal reservoirs. Various layouts were applied for the seismic survey on both day and at night to evaluate the impact of background noise. With modern processing approaches like CRS stacking unavoidable shortcomings during acquisition like high noise and coverage irregularities could be compensated without unacceptable quality loss in the final results. The final interpretation shows a general southwest dipping of Cenozoic to Paleozoic strata obviously caused by uplifted Upper Permian (Zechstein) salt rock. In particular, seismic stratigraphy was used to identify successions in Lower, Middle and Upper Triassic, in Upper and Lower Permian. This new results help to extend the hitherto incomplete picture of deep subsurface geology in Berlin and to define seismic survey layouts with subsequent processing techniques for mega city environments.