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Induced seismicity - Soultz-sous-Forêts 1993

The Soultz-sous-Forêts geothermal site is located in France, in the north of the Upper Rhine Graben. Since 1987, the site is used for research on geothermal energy. Previously a Hot Dry Rock research site, the Soultz-sous-Forêts geothermal site is nowadays a well-known Enhanced Geothermal System example. Hydraulic tests were carried out in the HDR research program, and induced microseismicity was monitored during injection tests. The purpose of the 1993 experimental program was to characterize the hydraulic behavior of the granite rockmass over the openhole section of the GPK1 borehole.

Description of the sismological network

The induced microseismicity has been monitored with two networks during injection tests :

  • A borehole network composed by 3 four-components accelerometer probes and a single hydrophone. The accelerometer probes were cemented in place at the bottom of three observation boreholes, located in granite at a depth of 1400m. The single hydrophone was deployed in an observation borehole at a depth of 2100m.

Coordinates of the borehole network sondes (CSMA)
Distance in meters from the GPK1 borehole (taken as reference).

Station X, East (m) Y, North (m) Z, Up (m)
4550 300.3 184.1 -1483.5
4601 -1178.1 -782.6 -1571.2
4616 -16.6 354.0 -1376.0
Hydr (EPS1) 214.2 -343.6 -2075.7
  • A surface network composed by 3 permanent seismic sensors and 11 temporary seismic sensors (which were deployed in 1993 for the monitoring of potential seismic repercussions at the surface during the fluid injection).

In total, about 15800 microseismic events have been recorded between September 2, 1993 and October 26, 1993. Events location determined with downhole stations are available in file Csma_fctn_lu.s93. Wave forms of these events will be soon available on this site.

Bibliography :

  • Cornet and Jones ; 1994. Field evidences on the orientation of forced water flow with respect to the regional principal stress directions,Rock mechanics. Nelson &Laubach.
  • Jones et al ; 1995,Imaging induced microseismicity during the 1993 injection tests atsoultz-sous-forets.France,WGC.
  • Cornet, F.H., Helm, J., Poitrenaud, H., Etchecopar, A., 1998, Seismic and Aseismic Slips Induced by Large-scale Fluid Injections. Seismicity Associated with Mines, Reservoirs and Fluid Injections, Pageoph Topical Volumes, pp 563-583.
  • Baria et al ; 1999. European HDR research programme at Soultz-sous-Forêts (France) 1987-1996, Geothermics 28.
  • Moriya, H., Niitsuma, H., Baria, R., 2003, Multiplet-Clustering Analysis Reveals Structural Details within the Seismic Cloud at the Soultz Geothermal Field, France. Bulletin of the Seismological Society of America, vol. 93, no. 4, pp 1606-1620, doi : 10.1785/0120020072
  • Bourouis, S., Bernard, P., 2007, Evidence for coupled seismic and aseismic fault slip during water injection in the geothermal site of Soultz (France), and implications for seismogenic transients. Geophys. J. Int. 169 (2) : 723-732. doi : 10.1111/j.1365-246X.2006.03325.x
  • Cornet F.H., Th. Berard and S. Bourouis ; 2007. How close to failure is a natural granite rock mass at 5 km depth Int. J. Rock Mech. Min.Sc. Volume 44, 1, pp 47-66.
  • Extract from the PhD thesis of S. Bourouis
  • PhD thesis of Emmanuel Gaucher,1998, Comportement hydromécanique d’un massif fracturé : apport de la microsismicité induite - Application au site géothermique de Soultz-sous-Forêts

11 mars 2015