Influence of Salt Diapirism and Glacial Effects on the Development of the Mittelplate Oil Field, Northern Germany

Grassmann, Stefan¹, Bernhard Cramer¹, Georg Delisle¹, Juergen Messner², Jutta Winsemann³ (1) Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany (2) Geological Survey of Lower Saxony, Hannover, Germany (3) University Hannover, Hannover, Germany

The Mittelplate oil field is the most productive hydrocarbon accumulation in Germany. As part of the Central European Basin System the field is located in northern Germany at the transition from the Schleswig-Holstein mainland to the German North Sea sector. The pro­lific petroleum system is linked to the Jurassic West Holstein Trough which contains the Lower Jurassic Posidonia shale as prominent source rock. The Mittelplate oil field forms a structural trap at the western flank of the Buesum salt dome with the Middle Jurassic reser­voir sandstones pinching out at the domes flank. Hydrocarbon migration from the Lower Jurassic Posidonia shale into the reservoirs occurred up-dip from the deeper subsiding rim syncline into the structural trap at the salt dome flank. Besides the dominating influence of halokinesis on the entire West Holstein Trough petroleum system, advances of the Scandinavian ice sheet during the Pleistocene intensively influenced the physicochemical habitat within the sediments of the study area. In order to reconstruct petroleum generation and migration and to quantify the influences of halokinesis and glacial processes on the structural and thermal evolution, basin modelling (PetroMod, IES Aachen) was performed along a 2D section. Sediment-surface temperatures for Quaternary times as well as per­mafrost and loading of ice sheets were implemented into the model. The simulated conti­nental glaciations show considerable effects on the pressure and temperature regime in the deeper subsurface. Despite the fact that glacial processes are not an integral part of Petroleum Systems Modelling we suggest that glacial processes need to be considered in formerly glaciated areas.