Results of Stimulation Treatments at the Geothermal Research Wells in Groß Schönebeck, Germany

The aim of this work is to present results of previously performed fracture treatments in the geothermal research well GtGrSk4/05 at Groß Schönebeck. The fracture treatments included three hydraulic stimulations, two in the sandstone section of the Lower Permian and one in the volcanic section. In low permeable volcanic rocks we performed a cyclic waterfrac treatment over 6 days in conjunction with adding low sand concentrations. Flow rates of up to 150 l/s were realized with a total amount of injected water of 13170 m³. Monitoring water level in the offsetting well EGrSk3/90, which is 475 m apart at the final depth, showed a very rapidly water level increase due to the stimulation treatment. A possible explanation might be a fault zone in the volcanic rocks. It was known from previous treatments in the offsetting well that high permeable sandstones do not show a self propping effect, hence we performed two gel proppant treatments in these sandstones to maintain long-term access to the reservoir. A total amount of 100 to of high strength proppants with 500 m³ of cross-linked gel were injected during each treatment. The subsequent production test in conjunction with flowmeter logging showed the success of the treatments.