THE IN-SITU GEOTHERMAL LABORATORY GRO? SCH÷NEBECK- LEARNING TO USE LOW PERMEABILITY AQUIFERS FOR GEOTHERMAL POWER

Abstract

An in-situ downhole laboratory was established with the purpose of developing appropriate stimulation methods to increase permeability of deep aquifers by enhancing or creating secondary porosity and flow path. Effective stimulation is needed to use low permeability aquifers for generating electricity from geothermal energy. The laboratory was installed in the former gas exploration well Gro? Schˆnebeck about 50 km northeast of Berlin. Before Christmas of 2000 this well was re-opened and deepened another 60 m to 4294 m. The openhole section of this well cuts through 400 m of the Rotliegend formation, comprising siltstones, sandstones, conglomerates and andesites. The maximum temperature measured was 149 ?C. A first production test showed that most of the flow at present occurs in a section of volcanic rock and not in the overlying sandstones as was initially expected. Formation fluids were sampled and contain more than 250 g/l of total dissolved solids. Presently stimulation experiments are being carried out in the sandstone section. In these experiments the bottom part is isolated from the test interval by sanding up and a mechanical packer-system at the top.