3-D Lithofacies Model Building of the Rotliegend Sediments of the Northeast German Basin

Moeck, Inga¹, H.-G. Holl¹, H. Schandelmeier² (1) GeoForschungsZentrum Potsdam, Potsdam, Germany (2) Technical University Berlin, Berlin, Germany

Static 3D geological models are essential to reservoir characterization and dynamic models. We introduce an approach of combining pre-existing and newly generated data to assess lithofacies distributions and sandstone permeability of a clastic reservoir within the Rotliegend II of the NE German Basin. The target is in 4300 m depth and situated north of Berlin (Germany) in the vicinity of a former gas exploration well, drilled in 1990 and currently acting as geothermal in-situ laboratory.

This second hand well was reopened in 2000 and deepened in two steps to 4309m TVD. An extensive logging program was performed between various stimulations and hydraulical tests. Porosity/permeability data are available from logging data as well as from abundant porosity (290 samples) and permeability measurements (109) on cores.

A basic 3D structural geological model of an area of 120 km2 was calculated using pre-existing well data and 2D seismic profiles. Detailed well data provided information to develop a 3D lithofacies model, comprising five lithotypes. The facies grids were calculat­ed with a 3D minimum tension technique. In this procedure each facies grid was normal­ized, calculated against each other and reconciled by creating a 0-isoenvelop, that clearly defines the faciestype body. The isoshells were set in each fault block of the structural model and processed to a comprehensive 3D structural lithofacies model. This volumet­ric 3D model allows an assessment of both matrix driven and fracture driven permeabili­ty. This approach can be applied to any region, where detailed structural and sedimento­logical data are available.