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Stimulation of reservoir and induced microseismicity - Zurich, Switzerland, Workshop3
Stimulation of reservoir and induced microseismicity - Zurich, Switzerland, Workshop3
from 29 June 2006 to 01 July 2006 Kartause Ittingen, Switzerland
Hydraulic Stimulation and Geophysical Fracture Monitoring in the GeneSys-Project
The objective of the GeneSys-Project is to develop concepts for the geothermal 
exploitation of low permeable sedimentary rocks. In a second step it also aims to 
supply direct heat to the GeoCenter Hannover, located in the Northern German 
Sedimentary Basin. Porosity and per-meability of the rocks at depth interesting for 
geothermal use however, are too low to allow classical hydrothermal use. Therefore 
concepts developed by EGS-projects in mainly crystal-line rocks need to be 
transferred to the adjacent tight sedimentary rocks. The creation of large fracture 
areas using the waterfrac technology is considered as the key challenge. To test 
transferability, a 4100 m deep research well is operated in the Northern German 
Sedimentary Basin. An extensive test program including massive waterfrac tests and 
geophysical fracture monitoring has been carried out in the last years. Water fracs 
tests were performed using un-treated freshwater. Injection rates went up to 50 l/s 
at wellhead pressures of 330 bar during fracture propagation. Test analysis shows 
that the tensile fracture that was created covers an area in the order of 100.000 m² 
and has a vertical extension of approximately 200 m.
For microseismic fracture monitoring a network consisting of eight stations was 
installed. At each station 4.5 Hz 3D geophones were installed in a 100 m deep well 
and in addition seis-mometers were placed at the surface. Despite the detection 
level of the network being low enough to detect events with magnitudes observed 
during stimulation tests in crystalline rock (e.g. in Soultz project), only a very 
low number of events was registered. Stress conditions suggest that shearing seems 
to be unlikely. It is concluded that the propagation of the tensile fracture is 
Measurements of the variation of the self-potential along two perpendicular profiles 
in the vicinity of the well, and tiltmeter measurements along a profile completed 
the geophysical fracture monitoring program. For the later methods a number of 
methodological challenges were identified. Hence no direct information about 
fracture geometry was derived. 
For the stimulation of the well planned at the Hannover site, a microseismic network 
will also be installed. Likewise more experience will be gained about the 
stimulation process in low permeable sediments.
Id: 19
Place: Kartause Ittingen, Switzerland
CH-8532 Warth TG
Starting date:
30-Jun-2006   10:50
Duration: 15'
Primary Authors: ORZOL, Jens (GGA-Institute)
Co-Authors: JUNG, Reinhard (GGA-Institute)
BUNESS, Hermann (GGA-Institute)
JATHO, Reiner (BGR)
Presenters: ORZOL, Jens
Material: slides Slides

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