From Gas to Geothermal Exploration - A Case Study from the NE-German Basin

The sedimentary Lower Permian is a well known target for gas exploration in the North German Basin as part of the South Permian Basin System. In East Germany a huge quantity of well and 2D seismic data were generated from the 1960’s to 1990. We re-evaluated and re-processed some of these data to define potential geothermal reservoirs for power production. Since 2000, a non-productive gas exploration well, drilled in 1990 in the NE German Basin, is used as a geothermal in-situ laboratory for testing recovery strategies in terms if enhancing geothermal systems. After increasing the productivity of the well by several stimulation treatments, a second well was drilled from 2006-2007 to install a well doublet. The design of the new well differs considerably from gas well designs since geothermal wells need to satisfy some requirements like large diameters for housing the submersible pump, directional drilling to allow a set of parallel hydraulic fractures and drilling under near-balanced mud pressure conditions to minimize formation damage. Recently, a massive stimulation campaign increased the productivity of the new well considerably. This article shows the field development of a deep sedimentary reservoir as a integrated study from gas to geothermal exploration using latest technologies.