| Title | Geothermal Reservoir Characterization in Crystalline Rock Using 3D Seismics (Schneeberg, Germany) |
|---|---|
| Authors | Felix HLOUSEK, Olaf HELLWIG, Stefan BUSKE |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | exploration, 3D seismic imaging, fault zones, enhanced geothermal systems |
| Abstract | We present the results of a 3D seismic survey acquired near Schneeberg in the western Erzgebirge (Germany). The aim of the project is to use seismic exploration methods to image and to characterize a major fault zone in crystalline rock, which could be used as a natural heat exchanger at a target depth of about 5-6 km with expected temperatures between 160-180°C. The region itself is dominated by the NW-SE striking Gera-Jáchymov fault system. The main geological features in the survey area are well known from intensive mining activities down to a depth of about 2 km. The seismic investigations aimed at imaging the partly steeply dipping fault branches at greater depth, in particular a dominant NE dipping fault in the central part of the survey area with displacements up to 500 m. Beside this main structure, the Gera-Jáchymov fault zone consists of a couple of SW dipping conjugated faults. For the purpose of imaging and characterizing this fault zone, a high resolution 3D Vibroseis survey with more than 5300 source and approximately 8000 receiver locations was performed at the end of 2012 and covered an area of approximately 10 km x 13 km. The 3D survey was complemented by an additional wide-angle seismic survey using explosives along ten profile lines radially centered at the target area. Advanced processing and imaging methods have been applied to the data set. 3D Kirchhoff pre-stack depth migration delivered a clear image of various fault branches at depths of around 2-5 km. Furthermore, focusing migration methods (e.g. coherency migration) have been applied and have improved the image such that the 3D seismic result allows for a profound characterization of this potential geothermal reservoir in crystalline rock. Based on the 3D seismic image of the fault zone, potential drilling targets and paths are defined. |