Lower Cretaceous Sandstones in the Lower Saxony Basin – a potential geothermal play

This study focusses on Lower Cretaceous sandstone units of Valanginian and Berriasian age in Lower Saxony. The understanding of the distribution and the hydraulic properties of these aquifers is essential to identify suitable areas for geothermal applications. Relevant aquifer units were defined in this study by a significant regional distribution, a thickness of more than 5 m and suitable hydraulic properties.

Three sandstone units can be mapped for the Valanginian stage: The Bentheim Sandstone, the Dichotomiten Sandstone and the so called Hauptsandstein. For the Berriasian stage, the most important sandstone units are the so-called Kopf-Sandstein (Fuhse Formation) and the sandstones of the Basinghausen Subformation. All of these sandstones are located in depths between several hundreds of meters up to 1500 m with a resulting temperature between 30°C to around 50°C.

Aquifers of Valanginian age have the best transmissivities and could be a target for geothermal application. Sandstone units of Berriasian age barely meet the minimum requirements for geothermal use on a regional scale. Nevertheless, suitable aquifer conditions may be developed locally.

All maps of the Lower Cretaceous sandstones can be found at the NIBIS mapserver and the data compilation is free to download. A base map with the relevant sandstone units and all analyzed data points such as well logs, cores and outcrops are available for each geological unit. Parameters for geothermal applications (e.g. depths of the formation, total thickness, sandstone thickness, porosity, permeability and transmissivity) are available as individual layers.