3D Geomechanical Model of the Lower Rhine Graben in the Cross-Boarder Region (BE–DE–NL)

Subsurface exploration for geoenergy resources within the seismically-active Lower Rhine Graben (LRG) in the cross-boarder region of Belgium, Germany and the Netherlands (NW Europe) needs to consider the tendency for induced seismic events as well as the effect of subsurface operations to the present-day crustal stresses. Regionally, geomechanical investigations are challenged by inconsistent coverage of reliable geologic and stress data below the Tertiary Rhineish lignite deposits. As deep geothermal exploration is currently focused entirely below these formations within marine sediments from Lower Carboniferous to the Devonian period, a first order 3D regional stress model to seismogenic depths up to 10 km is developed using a newly compiled 3D structural geological model combining data from three national datasets of the cross-boarder region. The structural geological model is distilled to a parameterized FEM mesh and used as input for numerical simulations of crustal stresses based on linear elasticity theory using the open-source MOOSE framework. Calibration of the resulting geomechanical model is completed using focal mechanisms from seismic catalogues, borehole failure observations, and hydraulic fracturing tests in boreholes within the LRG. 3D geomechanical model results of the LRG region provide a quantitative footing to support deep geothermal development through a spatially-continuous characterization of in situ stresses, even in greenfield prospects with little to no stress information, and an improved assessment of the reactivation potential of major faults in the region targeted for future geothermal development.