A desk study of the geological succession below a proposed energy island, Danish North Sea. Report prepared for EnergiNet

Construction of energy islands acting as hubs for large windfarms is a key element in the transition to sustainable energy forms as endorsed by the Danish Government. A shallow water area with depths of <30 m covering 2.5 km by 2.5 km on the southernmost part of “Lille Fiskerbanke”, ca. 100 km due west of Thorsminde, has been designated as a potential location for the first energy island in the North Sea (Fig. 1).

EnergiNet has requested GEUS to provide a desk-top study of the geology below the proposed Energy Island location, hitherto named Area of Interest (AOI), and its immediate surroundings, based on existing data and information. Previously, GEUS has published a screening report with focus on shallow data, e.g. seismic and cores, requested by the Danish Energy Agency (Owen et al. 2020). The present study involves a closer inspection of the geological succession down to Top Chalk (ca. 1200 m depth), based on the available seismic data and nearby industry wells. Special attention is placed on the uppermost 500 m interval of Miocene and Quaternary deposits that are well covered by existing data. As part of the project data base GEUS has received selected shallow seismic survey lines and reports from geotechnical boreholes that were acquired in 2022.