Stimulation tests in a deep Rotliegend sandstone formation ?? Geochemical aspects

Abstract

A multidisciplinary approach to make feasible the generation of geothermal electricity in the North-German Basin (NGB) was initiated in 2000. To attain this goal, formation fluids from the 4,000 m deep Rotliegend rocks (a well-known gas reservoir) in the NGB needed to be extracted and their geochemistry determined. An in-situ laboratory was established by opening and deepening the former gas well Gro? Sch??nebeck. Subsequenthydraulic and stimulation tests focused on the aeolian sandstones. The in-situ downhole samples of the 150?C hot fluids contain high amounts of dissolved solids (with salinities of up to 265 g/l). To increase permeabilities, rocks were stimulated hydraulically. Temperature and chemistry of injected fluids and the condition of the applied equipmenthave an important influence, as these control the solution and precipitation of different minerals such as iron hydroxides, sulphates, and carbonates.