POTENTIAL ECONOMIC USE OF MIDDLE BUNTSANDSTEIN SALINE AQUIFERS IN MECKLENBURG-WESTERN POMERANIA (NE GERMANY)

Clastic sediments of the Middle Buntsandstein are widely distributed in the eastern part of the North German Basin. Several sandstone horizons are intercalated with silt- and claystones. They form a multi-layered system of saline aquifers (Detfurth formation to Solling formation). The potential of these aquifers for geothermal heat production and geological storage of natural gas or carbon dioxide varies regionally.

The sandstones of the Middle Buntsandstein are fine- to medium-grained with clay content higher than 10 % in average. They show good reservoir properties at the north-eastern margin of the basin, e.g. porosities between 15-30 % and mean permeabilities of about 500 mD. Towards the central basin areas in the SW, the porosities of the sandstones are reduced either due to higher silt and clay content or by secondary cementation of the pore space. Changing facies conditions and burial effects led to rather low permeabilities <<100 mD (Wolfgramm et al. 2008).

Based on seismic investigations and abundant lithostratigraphic information obtained from deep well records in NE Germany the depth of the aquifer base (that coincide mostly with the base of Detfurth formation), the estimated temperature of the thermal water reservoirs and the sandstone thicknesses in total can be shown as isolines or isopaches (Feldrappe et al. 2008, Obst & Brandes 2009).

All these information are now presented in a new geological map of the State of Mecklenburg-Western Pomerania in the scale 1:500,000 (Obst & Brandes 2011). Furthermore, anticline structures above Zechstein salt pillows are marked as suitable storage sites. In addition, the map also shows the distribution of claystones and salt layers of the Upper Buntsandstein on top of the aquifer system that have seal potential. Finally, short descriptions of the sandstone reservoir properties and usage opportunities will inform policy-makers and possible investors.

A few geothermal projects in the Detfurth sandstone were already planned 25 years ago. Recently, a new attempt is made to install a hydrothermal heating system in Heringsdorf (Usedom) to supply hotels and a spa with renewable energy and thermal water. Another private investor is now searching a suitable Middle Buntsandstein reservoir in the Serrahn/Triepkendorf anticline to store natural gas that will be delivered by the Baltic Sea gas pipeline Nord Stream.