3D Seismic Analysis of a Salt Tectonic-Controlled Geothermal Reservoir in the North German Basin

The calcarenites of the Reitbrook Formation represent a promising mid-depth geothermal reservoir in the North German Basin. A comprehensive re-evaluation of borehole data from the hydrocarbon industry indicates that these units were variably truncated by the Paleocene transgression and exhibit significant variations in depth and thickness. To better constrain their spatial distribution and reservoir geometry, a 3D seismic dataset was reinterpreted, focusing on salt structures, faults, and key stratigraphic horizons.

The results indicate that (i) inversion tectonics ceased during the Campanian, whereas salt structures continued to evolve independently during the Maastrichtian, and (ii) each salt structure, together with its associated marginal trough, experienced a distinct developmental history that directly influenced reservoir configuration. Salt movement shaped the reservoirs during both synsedimentary and post-sedimentary phases. Synsedimentary salt tectonics, in particular, led to the formation of minibasins, localized highs, and differential subsidence. These processes controlled sediment thickness, facies distribution, and early reservoir compartmentalization. In contrast, post-depositional salt movement deformed pre-existing stratigraphy, generating folds, faults, and structural traps that affect fluid compartmentalization, vertical migration, and pressure regimes.

This study emphasizes salt tectonics as a key control on the geometry and heterogeneity of the Reitbrook calcarenites. Accurate reservoir models, geothermal assessments, and sustainable energy development require a thorough understanding of the temporal interplay between salt deformation and sedimentation. Understanding the salt-tectonic evolution of the basin is essential for the development of exploration strategies, such as identifying thick, well-preserved zones, deeper areas with elevated reservoir temperatures, and fault zones that enhance permeability.