First hand experience in a second hand borehole: Hydraulic experiments and scaling in the geothermal well Gro? Sch??nebeck after reopening

Abstract

Stimulation procedures applicable to great depths are needed for geothermal electricity generation in Germany. More than 50 former oil and gas exploration wells in northeast Germany were screened to select an abandoned well to install an in situ laboratory for hydraulic experiments. Technical feasibility of renewed access and temperatures of 130-
140?C at the bottom were the criteria for selection. The 4240 m deep well Gro? Sch??nebeck 3/90 was picked out. It was abandoned soon after completion in 1990. Access was gained in 2000, by drilling through only a few hundred meters of cement, because the sections between cement plugs were filled with drilling mud. This operation required a fraction of the costs for a new well. Furthermore, the well was deepened to
4294 m. Since, two intervals of the Rotliegend sandstones were hydraulically stimulated in January 2002. After a moderate pumping test over several weeks, scaling began to occur with the precipitation of native metals from the brine. Another set of open-hole stimulation experiments is planned for 2003.