Deep geothermal energy potential at Weisweiler, Germany: Exploring subsurface mid-Palaeozoic carbonate reservoir rocks

Carboniferous and Devonian carbonate rocks are present in the subsurface of the Weisweiler lignite-fired power plant near Aachen, Germany. The utilisation of these rocks for the purpose of deep geothermal energy extraction using hydrothermal techniques is currently being explored. First steps are undertaken as green field exploration in the course of the transnational EU-Interreg-funded ""Roll-out of Deep Geothermal Energy in North-West Europe"" (DGE-ROLLOUT) project, which aims to provide solutions to reduce carbon-dioxide emissions using a variety of geoscientific approaches. As a result of multiphase deformation and faulting through Variscan and Alpine (post-)orogenic processes, a complex geological setting has emerged in the Weisweiler subsurface. However, considering the formation of both syncline-anticline and horst-graben structures the geological setting appears to exhibit favourable conditions for deep geothermal exploitation at several depth levels. Besides ongoing mapping campaigns, as well as lithological and structural studies, a preliminary geological 3D model of the subsurface of the Weisweiler area has been constructed on the basis of which a first drilling operation is currently being planned. At the same time, the subsurface 3D model is currently being transferred into a thermohydraulic 3D model to obtain first impressions on possible fluid pathways within the targeted carbonate horizons. In addition, a variety of petrophysical and (isotope) geochemical analyses of analogue rock samples are also underway.