The Hot Dry Rock (HDR) site of Soultz-sous-Forêts in Alsace was chosen in 1986 for scientific investigation. During the first phase of the project (1987-988), a first borehole (GPK1) was drilled which reached a final depth of 2000 m and various investigations were undertaken during the period. A first hydraulic injection was made at the bottom zone of this borehole with a relatively low flow rate of 3.3L/s for a period of 50 hours. Induced seismicity recorded was detected by 3-axis geophone probes deployed in three old recovered oil wells at depth ranging from 850 to 1350 m. A small amount of the detected seismicity could be located and this showed a trend to grow towards greater depths than the injection zone.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

Parameters for the stimulation are the following (Beauce, 1991):

Test dates	Test interval (m)	Fluid volume (m3)	Type of test	Number of sesimic events
14-16 December 1988	1968.4 - 2000	524	Frac test, hydraulics	58

References

- Beauce, A., R. H. Jones, H. Fabriol, et C. Hulot. 1992. « Seismic studies on the HDR site of Soultz-sous-Forets during Phase IIa ». BRGM Report 3 (1‑4): 239–266.
- Bresee, James C. 1992. Geothermal Energy in Europe: The Soultz Hot Dry Rock Project. CRC Press.
- Brun, J. P., et F. Wenzel. 1991. « Crustal-scale structure of the southern Rhinegraben from ECORS-DEKORP seismic reflection data ». Geology 19 (7): 758–762.
- CHEN, XIN KAI. 1990. « Geothermie roches chaudes seches. Etudes sismiques sur le site de soultz-sous-forets ». Paris 6.
- Cornet, F. H., et Th Bérard. 2003. « A case example of integrated stress profile evaluation ». In 3rd International Symposium on Rock Stress, edited by K. Sugawara, Y. Obara, and A. Sato, 23–24.
- Cornet, F. H., Th Bérard, et S. Bourouis. 2007. « How close to failure is a granite rock mass at a 5km depth? » International Journal of Rock Mechanics and Mining Sciences 44 (1): 47–66.
- Kappelmeyer, O., A. Gérard, W. Schloemer, R. Ferrandes, F. Rummel, et Y. Benderitter. 1991. « European HDR project at Soultz-sous-Forêts: general presentation ». Geothermal science and technology 2 (4): 263–289.

In 1991, two 50 hours hydraulic injection tests at flowrates of 7 and 15 L/s were carried out at the bottom of the 2000 m deep GPK1 well. The microseismicity induced by these tests was monitored by new seismic probes composed of 3-axis accelerometers. The latter were deployed at the bottom of three boreholes: 4601, 4550, 4616. The network was supplemented with a hydrophone installed in a new borehole EPS1. More than 400 induced seismic events were recorded which 60% were located. (Beauce et al., 1992)

Data available

Note: No dataset have been retrieved for this stimulation test. However useful information can be found in the literature. In particular, the following data are described:

Stimulation phases

The stimulation programme for 1991 is the following (Beauce et al., 1992):

Test dates	Test type	Injection rates (L/s)	Number of events on the downhole network
11-17 July 1991	Injection test	7	135
18-23 July 1991	Injection test	15	239

References

- Beauce, A., R. H. Jones, H. Fabriol, et C. Hulot. 1992. « Seismic studies on the HDR site of Soultz-sous-Forets during Phase IIa ». BRGM Report 3 (1‑4): 239–266.

In June and July 1994, the hydraulic experimental programme consisted of a production and injection test in GPK1. To monitor the induced seismicity, a microseismic nework at Soultz-sous-Forêts was installed. It was essentially the same as that used in the 1993 experimental programme. It consisted of three four component sondes in boreholes 4550, 4601 and 4616 and a single hydrophone in EPS1 at a depth of 2170 m. The goal of the production test was to determine the productivity of GPK1.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The stimulation programme for the June-July 1994 period is the following (Baria, 1996):

Test dates	Test type	Injection rates (L/s)	Number of events detected by the downhole network
16 - 18 June 1994	Production GPK1 (3600m)	Production: 18-5-8 L/s/ Injection : 5-10 L/s	500
5-13 July 1994	Injection GPK1 (3600m)	Injection: 6-18 L/s	15

References

- Baria, Roy. 1996. « The European HDR programme 1992 - 1995 ». Socomine, Route de Kutzenhausen, Soultz sous Forets, FR.
- Baumgartner, J., R. Jung, A. Gérard, R. Baria, et J. Garnish. 1996. « The European HDR project at Soultz sous forets: Stimulation of the second deep well and first circulation experiments ». Socomine, Route de Kutzenhausen, Soultz sous Forets, FR; Bundesanstalt fur Geowissenschaften und Rohstoffe, Stilleweg, Hannover, DE; DGXII, European Commission, Brussels, BE.
- Evans, Keith F. 2000. « The effect of the 1993 stimulations of well GPK1 at Soultz on the surrounding rock mass: evidence for the existence of a connected network of permeable fractures ». In World Geothermal Congress, 3695–3700.
- Kohl, T., D. Bächler, et L. Rybach. 2000. « Steps towards a comprehensive thermo-hydraulic analysis of the HDR test site Soultz-sous-Forêts ». In Proceedings World Geothermal Congress, 2671–2676.

In 1995, the purpose of hydraulic injections into GPK2 was to stimulate the fracture network allowing the circulation of fluids between injection (GPK2) and production (GPK1) boreholes. The microseismic network in operation during the 1995 stimulation and circulation experiments represents a slightly modified version of the 1993 system. It consisted of 3 permanent stations and deployment of a hydrophone in EPS1 at a depth of 2170 m. These sensors were used throughout the 1995 experimental programme, a further hydrophone was deployed in GPK1 at a depth of 3480 m to monitor the brine injection.
Injection and production tests took place between May and August 1995 at Soultz-sous-Forêts. In order to assist in the creation of homogenous distribution of flow exits (opened fractures) with depth it has been decided to use as heavy brine as possible as injection fluid. During fracture initiation GPK1 was kept shut-in to monitor the pressure response. Once the brine stored on the surface was nearly used up, GPK1 was vented in order to produce further brine for fracture extension. The produced brine was cooled in a surface heat exchanger and then injected in GPK2.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The stimulation programme for the June-August 1995 period is the following (Baria, 1996):

Test dates	Test type	Injection rates (L/s)	Number of events detected
10-26 June 1995	Stimulation GPK2 (3900 m)	1-56 L/s	~6000
01-02 July 1995	Injection GPK2 (3900 m)	5-25 L/s	30
09-24 July 1995	Circulation GPK1 (productor) GPK2 (reinjector)	Production: 15 L/s - Reinjection: 15-20 L/s	50
31 July - 11 August 1995	Circulation GPK1 (productor) GPK2 (reinjector)	Production: 22 L/s - reinjection: 22 L/s	3

References

- Audigane, Pascal, Jean-Jacques Royer, et Hideshi Kaieda. 2002. « Permeability characterization of the Soultz and Ogachi large-scale reservoir using induced microseismicity ». Geophysics 67 (1): 204–211.
- Baria, Roy. 1996. « The European HDR programme 1992 - 1995 ». Socomine, Route de Kutzenhausen, Soultz sous Forets, FR.
- Baumgartner, J., R. Jung, A. Gérard, R. Baria, et J. Garnish. 1996. « The European HDR project at Soultz sous forets: Stimulation of the second deep well and first circulation experiments ». Socomine, Route de Kutzenhausen, Soultz sous Forets, FR; Bundesanstalt fur Geowissenschaften und Rohstoffe, Stilleweg, Hannover, DE; DGXII, European Commission, Brussels, BE.
- Kohl, T., D. Bächler, et L. Rybach. 2000. « Steps towards a comprehensive thermo-hydraulic analysis of the HDR test site Soultz-sous-Forêts ». In Proceedings World Geothermal Congress, 2671–2676.

Stimulation and stepped injection tests in GPK2 and the production test from GPK2 took place between August and October 1996 at Soultz-sous-Forêts. The open hole section of the well GPK2 had been re-stimulated at flow rates of up to 78 L/s. This stimulation experiment was followed by a series of step rate hydraulic injection tests in GPK2 (determination of injectivity) and production and interference tests during which the water produced from GPK2 as reinjected in GPK1.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The stimulation programme for the September-October 1996 period is the following (Baumgärtner et al., 1998):

Test dates	Test type	Injection rates (L/s)	Number of events localised
18-25 September 1995	Stimulation GPK2 (3900m)	25 - 80 L/s	~5700
30 September - 6 October 1995	Injection GPK2 (3900 m)	6 - 37.5 L/s	60

References

- Audigane, Pascal, Jean-Jacques Royer, et Hideshi Kaieda. 2002. « Permeability characterization of the Soultz and Ogachi large-scale reservoir using induced microseismicity ». Geophysics 67 (1): 204–211.
- Baumgärtner, J., A. Gérard, R. Baria, R. Jung, T. Tran-Viet, T. Gandy, L. Aquilina, et J. Garnish. 1998. « Circulating the HDR reservoir at Soultz: maintaining production and injection flow in complete balance ». In Proceedings of the 23rd workshop on geothermal reservoir engineering, Stanford University, Stanford, CA, USA, 11–20.

In summer and autumn 1997 a 4-month circulation experiment between GPK1 (injector) and GPK2 (productor) was performed in order to demonstrate that it is possible to circulate in such an environment continuously. During this experiment 244000 tons of brine at temperature of up to 142°C and at flow rates of up to 25 kg/s were circulated.
Downhole hydraulic monitoring was performed during the test: this includes flowrates, downhole pressures, fluid temperature.

Data available

Note: No dataset have been retrieved for this circulation test. However useful information can be found in the literature. See below for some references.

Stimulation phases

The stimulation programme for the July-November 1997 period is the following (Baumgärtner et al., 1998):

Test dates	Test type	Injection rates (L/s)	Number of events detected
12 July to 16 November 1997	Production	20 L/s	0

References

- Aquilina, Luc, Jean-Raynald de Dreuzy, Olivier Bour, et Philippe Davy. 2004. « Porosity and fluid velocities in the upper continental crust (2 to 4 km) inferred from injection tests at the Soultz-sous-Forêts geothermal site ». Geochimica et Cosmochimica Acta 68 (11): 2405–2415.
- Azaroual, M., et A. M. Fouillac. 1999. « Traçage au deutérium du réservoir géothermique Roche Chaude Sèche de Sotiltz-sous-Forêts, Alsace (France) ». Rapport BRGM R-/0730.
- Bächler, D., et Th Kohl. 2005. « Coupled thermal–hydraulic–chemical modelling of enhanced geothermal systems ». Geophysical Journal International 161 (2): 533–548.
- Bächler, Dominique. 2003. « Coupled thermal-hydraulic-chemical modelling at the Soultz-sous-Forêts HDR reservoir (France) ». SWISS FEDERAL INSTITUTE OF TECHNOLOGY ZURICH.
- Baria, Roy, Jörg Baumgärtner, André Gérard, et John Garnish. 2000. « The European HDR Programme: main targets and results of the deepening of the well GPK2 to 5000 m ». In Proceedings of the world geothermal congress, 3643–3652.
- a href="https://www.geothermal-energy.org/pdf/IGAstandard/WGC/2010/2721.pdf"> Baticci, Francesca, Albert Genter, Petra Huttenloch, et Roman Zorn. 2010. « Corrosion and scaling detection in the Soultz EGS power plant, Upper Rhine Graben, France ». In World Geothermal Congress, WGC2010, Bali, Indonesia.
- Baumgärtner, J., A. Gérard, R. Baria, R. Jung, T. Tran-Viet, T. Gandy, L. Aquilina, et J. Garnish. 1998. « Circulating the HDR reservoir at Soultz: maintaining production and injection flow in complete balance ». In Proceedings of the 23rd workshop on geothermal reservoir engineering, Stanford University, Stanford, CA, USA, 11–20.
- Bruel, D. 2002. « Impact of induced thermal stresses during circulation tests in an engineered fractured geothermal reservoir: example of the Soultz-sous-Forets European hot fractured rock geothermal project, Rhine Graben, France ». Oil & Gas Science and Technology 57 (5): 459–470.
- Durst, Pierre, et François-D. Vuataz. 2000. « Fluid-rock interactions in hot dry rock reservoirs. A review of the HDR sites and detailed investigations of the Soultz-sous-Forets system ». In Proceedings World Geothermal Congress, 3677–3682.

During June/ July 2000 a hydraulic stimulation program was conducted in the well GPK2. The stimulation was performed over the open hole section of GPK2 from 4431 m (measured depth) to the bottom of the well at around 5084 m. A total of 27 800 m3 of water were injected. At the start of the stimulation 700m3 of brine were injected in an effort to encourage downward growth of the stimulated region. The stimulation covered a period of six days. After a break of seven days a post-fracturing injection test was performed. Microseismic emissions have been monitored and recorded throughout the experiment and continued for a further 11 days after the injection test.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The stimulation programme for the June-July 2000 period is the following (Cuenot, 2006):

Test dates	Test type	Injection rates (L/s)	Number of events detected
30 June to 7 July 2000	Stimulation GPK2 (5000 m)	30-50 L/s	11000 (~7200 localised)

References

- Baria, R., S. Michelet, J. Baumgärtner, B. Dyer, A. Gerard, J. Nicholls, T. Hettkamp, et al. 2004. “Microseismic Monitoring of the World’s Largest Potential HDR Reservoir.” In Proceedings, Twenty-Ninth Workshop on Geothermal Reservoir Engineering. .
- Baria, Roy, Sophie Michelet, Joerg Baumgärtner, Ben Dyer, Jonathan Nicholls, Thomas Hettkamp, Dimitra Teza, et al. 2005. “Creation and Mapping of 5000 M Deep HDR/HFR Reservoir to Produce Electricity.” Proceedings, Paper 1627. Pdf.
- Calò, M., C. Dorbath, F. H. Cornet, et N. Cuenot. 2011. « Large-scale aseismic motion identified through 4-D P-wave tomography ». Geophysical Journal International 186 (3):1295 1314.
- Calo, Marco, and Catherine Dorbath. 2013. “Different Behaviours of the Seismic Velocity Field at Soultz-Sous-Forêts Revealed by 4-D Seismic Tomography: Case Study of GPK3 and GPK2 Injection Tests.” Geophysical Journal International. .
- Charlety, J., N. Cuenot, Louis Dorbath, Catherine Dorbath, H. Haessler, and M. Frogneux. 2007. “Large Earthquakes during Hydraulic Stimulations at the Geothermal Site of Soultz-Sous-Forêts.” International Journal of Rock Mechanics and Mining Sciences 44 (8):1091–1105.
- Charléty, Jean, Nicolas Cuenot, Catherine Dorbath, and Louis Dorbath. 2006. “Tomographic Study of the Seismic Velocity at the Soultz-Sous-Forêts EGS/HDR Site.” Geothermics 35 (5):532–543.
- Cuenot, Nicolas, Jean Charléty, Louis Dorbath, and Henri Haessler. 2006. “Faulting Mechanisms and Stress Regime at the European HDR Site of Soultz-Sous-Forêts, France.” Geothermics 35 (5):561–575.
- Cuenot, Nicolas, Catherine Dorbath, and Louis Dorbath. 2008. “Analysis of the Microseismicity Induced by Fluid Injections at the EGS Site of Soultz-Sous-Forêts (Alsace, France): Implications for the Characterization of the Geothermal Reservoir Properties.” Pure and Applied Geophysics 165 (5):797–828.
- Darnet, Mathieu, Guy Marquis, and Pascal Sailhac. 2006. “Hydraulic Stimulation of Geothermal Reservoirs: Fluid Flow, Electric Potential and Microseismicity Relationships.” Geophysical Journal International 166 (1):438–444.
- Delepine, Nicolas, Nicolas Cuenot, Elmar Rothert, Miltiadis Parotidis, Susanne Rentsch, and Serge A. Shapiro. 2004. “Characterization of Fluid Transport Properties of the Hot Dry Rock Reservoir Soultz-2000 Using Induced Microseismicity.” Journal of Geophysics and Engineering 1 (1):77.
- Dorbath, Louis, Nicolas Cuenot, Albert Genter, and Michel Frogneux. 2009. “Seismic Response of the Fractured and Faulted Granite of Soultz-Sous-Forêts (France) to 5 Km Deep Massive Water Injections.” Geophysical Journal International 177 (2):653–675.
- Dyer, B. 2001. “Soultz GPK2 Stimulation June/July 2000. Seismic Monitoring Report.” Semore Seismic for Socomine.
- Evans, Keith, Benoît Valley, Markus Häring, R. Hopkirk, Clément Baujard, Thomas Kohl, Thomas Mégel, Laurent André, Sandrine Portier, and F. Vuataz. 2009. “Studies and Support for the EGS Reservoirs at Soultz–sous–Forêts.” Technical report, Centre for Geothermal Research–CREGE, c/o CHYN, University of Neuchâtel. .
- Gentier, S. 2003. “‘Hot Dry Rock Energy’ Project - Soultz-Sous-Forêts - BRGM Contribution.” BRGM/RP-52730-FR. BRGM. .
- Weidler, R., A. Gerard, R. Baria, J. Baumgärtner, and R. Jung. 2002. “Hydraulic and Micro-Seismic Results of a Massive Stimulation Test at 5 Km Depth at the European Hot-Dry-Rock Test Site, Soultz, France.” In Proceedings, 27th Workshop on Geothermal Reservoir Engineering. Stanford, California, 95–100. .

The stimulation performed in 2003 mainly by massive injection into the well GPK3. The stimulation strategy can be divided in five parts:
- Injection into GPK3
- Injection into both GPK2 and GPK3 (“dual” or “focused” stimulation, Baria et al., 2004)
- Shut in GPK2
- Shut in both GPK2 and GPK3 and production from GPK2
- Circulation test GPK2-GPK3 following stimulation

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The stimulation programme for the January-Mars 2003 period is the following (Cuenot, 2006):

Test dates	Test type	Injection rates (L/s)	Number of events detected
23-30 January 2003	Injection GPK2 (5000 m)	15 L/s	10
12-16 February 2003	Acidification GPK2 (5000 m)	15 -30 L/s	290
11-15 March 2003	Injection GPK2 (5000 m)	-	-
14-20 March 2003	Production GPK3 (5000 m)	Injection: 15-30 L/s - Production: 4-5 L/s	4400

References

- Baisch, Stefan, Robert Vörös, Elmar Rothert, Henrik Stang, Reinhard Jung, et Rüdiger Schellschmidt. 2010. « A numerical model for fluid injection induced seismicity at Soultz-sous-Forêts ». International Journal of Rock Mechanics and Mining Sciences 47 (3): 405–413.
- Baria, R., S. Michelet, J. Baumgärtner, B. Dyer, A. Gerard, J. Nicholls, T. Hettkamp, et al. 2004. « Microseismic monitoring of the world’s largest potential HDR reservoir ». In Proceedings, Twenty-Ninth Workshop on Geothermal Reservoir Engineering.
- Baria, Roy, Sophie Michelet, Joerg Baumgärtner, Ben Dyer, Jonathan Nicholls, Thomas Hettkamp, Dimitra Teza, et al. 2005. « Creation and mapping of 5000 m deep HDR/HFR reservoir to produce electricity ». Proceedings, Paper 1627. pdf.
- Calo, Marco, et Catherine Dorbath. 2013. « Different behaviours of the seismic velocity field at Soultz-sous-Forêts revealed by 4-D seismic tomography: case study of GPK3 and GPK2 injection tests ». Geophysical Journal International.
- Charlety, J., N. Cuenot, Louis Dorbath, Catherine Dorbath, H. Haessler, et M. Frogneux. 2007. « Large earthquakes during hydraulic stimulations at the geothermal site of Soultz-sous-Forêts ». International Journal of Rock Mechanics and Mining Sciences 44 (8): 1091–1105.
- Charléty, Jean. 2007. « Propriétés physiques du réservoir de Soultz-sous-Forêts à partir de l’analyse fine de la sismicité induite ». Université Louis Pasteur (Strasbourg).
- Charléty, Jean, Nicolas Cuenot, Catherine Dorbath, et Louis Dorbath. 2006. « Tomographic study of the seismic velocity at the Soultz-sous-Forêts EGS/HDR site ». Geothermics 35 (5): 532–543.
- Cuenot, Nicolas, Jean Charléty, Louis Dorbath, et Henri Haessler. 2006. « Faulting mechanisms and stress regime at the European HDR site of Soultz-sous-Forêts, France ». Geothermics 35 (5): 561–575.
- Dorbath, Louis, Nicolas Cuenot, Albert Genter, et Michel Frogneux. 2009. « Seismic response of the fractured and faulted granite of Soultz-sous-Forêts (France) to 5 km deep massive water injections ». Geophysical Journal International 177 (2): 653–675.
- Dyer, B., R. Baria, S. Michelet, et J. Baumgärtner. s. d. « MICROSEISMIC MONITORING OF SINGLE AND DUAL WELL (FOCUSSED) STIMULATIONS OF THE WORLD’S LARGEST POTENTIAL HDR RESERVOIR ». Consulté le 14 décembre 2017.
- Evans, Keith, Benoît Valley, Markus Häring, R. Hopkirk, Clément Baujard, Thomas Kohl, Thomas Mégel, Laurent André, Sandrine Portier, et F. Vuataz. 2009. « Studies and support for the EGS reservoirs at Soultz–sous–Forêts ». Technical report, Centre for Geothermal Research–CREGE, c/o CHYN, University of Neuchâtel.
- Fischer, Tomáš, et Sebastian Hainzl. 2017. « Effective stress drop of earthquake clusters ». Bulletin of the Seismological Society of America 107 (5): 2247–2257.
- Hettkamp, T., J. Baumgärtner, R. Baria, A. Gérard, T. Gandy, S. Michelet, et D. Teza. 2004. « Electricity production from hot rocks ».

The 2004 stimulation was aimed at improving the hydraulic performances of the well GPK4. This borehole was stimulated twice. The present test corresponds to the first stimulation of GPK4. Included are the data from a pre-stimulation low flow injection test that was performed to evaluate the initial injectivity of GPK4.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The stimulation programme for the August-September 2004 period is the following (Dorbath et al., 2009):

Test dates	Test type	Injection rates (L/s)	Number of events detected
17-23 August 2004	Injection GPK3 (5000 m)	-	-
28-31 August 2004	Production GPK3 (5000 m)	Injection: 12-24 L/s - Production 20-8 L/s	1
8-12 September 2004	Injection GPK4 (5000 m)	0.8 L/s	151
13-16 September 2004	Stimulation GPK4 (5000 m)	30-45 L/s	15400

References

- Baisch, Stefan, Robert Vörös, Elmar Rothert, Henrik Stang, Reinhard Jung, et Rüdiger Schellschmidt. 2010. « A numerical model for fluid injection induced seismicity at Soultz-sous-Forêts ». International Journal of Rock Mechanics and Mining Sciences 47 (3): 405–413.
- Calo, Marco, et Catherine Dorbath. 2013. « Different behaviours of the seismic velocity field at Soultz-sous-Forêts revealed by 4-D seismic tomography: case study of GPK3 and GPK2 injection tests ». Geophysical Journal International.
- Charlety, J., N. Cuenot, Louis Dorbath, Catherine Dorbath, H. Haessler, et M. Frogneux. 2007. « Large earthquakes during hydraulic stimulations at the geothermal site of Soultz-sous-Forêts ». International Journal of Rock Mechanics and Mining Sciences 44 (8): 1091–1105.
- Charléty, Jean. 2007. « Propriétés physiques du réservoir de Soultz-sous-Forêts à partir de l’analyse fine de la sismicité induite ». Université Louis Pasteur (Strasbourg).
- Dezayes, Ch, Ph Chèvremont, B. Tourlière, G. Homeier, et A. Genter. 2005. « Geological study of the GPK4 HFR borehole and correlation with the GPK3 borehole (Soultz-sous-Forêts, France) ». Final Report, BRGM report, Orléans, France, RP-53697-FR.
- Dorbath, Louis, Nicolas Cuenot, Albert Genter, et Michel Frogneux. 2009. « Seismic response of the fractured and faulted granite of Soultz-sous-Forêts (France) to 5 km deep massive water injections ». Geophysical Journal International 177 (2): 653–675.
- Evans, Keith, Benoît Valley, Markus Häring, R. Hopkirk, Clément Baujard, Thomas Kohl, Thomas Mégel, Laurent André, Sandrine Portier, et F. Vuataz. 2009. « Studies and support for the EGS reservoirs at Soultz–sous–Forêts ». Technical report, Centre for Geothermal Research–CREGE, c/o CHYN, University of Neuchâtel.

The 2005 stimulation is the second stimulation of GPK4, after the previous one, performed in September 2004. The stimulation was followed a few days later by a program of chemical stimulation (injection of diluted HCl). This program involved the chemical stimulation itself and two identical step-rate injection tests: the first was performed before the chemical stimulation and the second after, in order to observe the efficiency of the chemical stimulation. The program was in the following order:
- Second hydraulic stimulation of GPK4
- First step-rate test
- Chemical stimulation of GPK4 with HCl
- Second step-rate test

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The stimulation programme for the February-March 2005 period is the following (Dorbath et al., 2009):

Test dates	Test type	Injection rates (L/s)	Number of events detected
7-11 February 2005	Stimulation GPK4 (5000 m)	25-45 L/s	-
22-25 February 2005	Injection GPK4 (5000 m)	9-25 L/s	-
2-5 March 2005	Acidification GPK2 (5000 m)	27-9 L/s	-
13-16 March 2005	Injection GPK4 (5000 m)	9-25 L/s	7200

References

- Baisch, Stefan, Robert Vörös, Elmar Rothert, Henrik Stang, Reinhard Jung, et Rüdiger Schellschmidt. 2010. « A numerical model for fluid injection induced seismicity at Soultz-sous-Forêts ». International Journal of Rock Mechanics and Mining Sciences 47 (3): 405–413.
- Calo, Marco, et Catherine Dorbath. 2013. « Different behaviours of the seismic velocity field at Soultz-sous-Forêts revealed by 4-D seismic tomography: case study of GPK3 and GPK2 injection tests ». Geophysical Journal International.
- Charlety, J., N. Cuenot, Louis Dorbath, Catherine Dorbath, H. Haessler, et M. Frogneux. 2007. « Large earthquakes during hydraulic stimulations at the geothermal site of Soultz-sous-Forêts ». International Journal of Rock Mechanics and Mining Sciences 44 (8): 1091–1105.
- Charléty, Jean. 2007. « Propriétés physiques du réservoir de Soultz-sous-Forêts à partir de l’analyse fine de la sismicité induite ». Université Louis Pasteur (Strasbourg).
- Cuenot, Nicolas, Louis Dorbath, Michel Frogneux, et Nadège Langet. 2010. « Microseismic activity induced under circulation conditions at the EGS Project of Soultz-sous-Forêts (France) ». In Proceedings World Geothermal Conference, Bali, Indonesia, 25–29.
- Cuenot, Nicolas, M. Frogneux, C. Dorbath, et M. Calo. 2011. « Induced microseismic activity during recent circulation tests at the EGS site of Soultz-sous-Forêts (France) ». In Proc. 36th Workshop on Geothermal Reservoir Engineering Stanford University.
- Dorbath, Louis, Nicolas Cuenot, Albert Genter, et Michel Frogneux. 2009. « Seismic response of the fractured and faulted granite of Soultz-sous-Forêts (France) to 5 km deep massive water injections ». Geophysical Journal International 177 (2): 653–675.
- Evans, Keith, Benoît Valley, Markus Häring, R. Hopkirk, Clément Baujard, Thomas Kohl, Thomas Mégel, Laurent André, Sandrine Portier, et F. Vuataz. 2009. « Studies and support for the EGS reservoirs at Soultz–sous–Forêts ». Technical report, Centre for Geothermal Research–CREGE, c/o CHYN, University of Neuchâtel.

The 2005 circulation test was the first test involving the 3 deep geothermal boreholes GPK2, GPK3 and GPK4. It was performed in artesian conditions: GPK2 and GPK4 were the production wells and the geothermal fluid was reinjected into GPK3 after being cooled through a heat exchanger.
During the stimulation around 16500 m3 of geothermal fluid were produced from GPK2 at an average flowrate of 12 kg/s. The temperature of the produced fluid was around 160°C.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The circulation programme for the July-December 2005 period is the following (Cuenot et al., 2011):

Test dates	Test type	Injection rates (L/s)	Number of events detected
11 July - 23 December 2005	Circulation GPK2 (productor) - GPK3 (reinjector) - GPK4 (productor)	Production GPK2: 12 L/s - Production GPK4: 3-4 L/s - Reinjection GPK3: 15-19 L/s	780

References

- Baisch, Stefan, Robert Vörös, Elmar Rothert, Henrik Stang, Reinhard Jung, et Rüdiger Schellschmidt. 2010. « A numerical model for fluid injection induced seismicity at Soultz-sous-Forêts ». International Journal of Rock Mechanics and Mining Sciences 47 (3): 405–413.
- Calo, Marco, et Catherine Dorbath. 2013. « Different behaviours of the seismic velocity field at Soultz-sous-Forêts revealed by 4-D seismic tomography: case study of GPK3 and GPK2 injection tests ». Geophysical Journal International.
- Charlety, J., N. Cuenot, Louis Dorbath, Catherine Dorbath, H. Haessler, et M. Frogneux. 2007. « Large earthquakes during hydraulic stimulations at the geothermal site of Soultz-sous-Forêts ». International Journal of Rock Mechanics and Mining Sciences 44 (8): 1091–1105.
- Charléty, Jean. 2007. « Propriétés physiques du réservoir de Soultz-sous-Forêts à partir de l’analyse fine de la sismicité induite ». Université Louis Pasteur (Strasbourg).
- Cuenot, Nicolas, Louis Dorbath, Michel Frogneux, et Nadège Langet. 2010. « Microseismic activity induced under circulation conditions at the EGS Project of Soultz-sous-Forêts (France) ». In Proceedings World Geothermal Conference, Bali, Indonesia, 25–29.
- Cuenot, Nicolas, M. Frogneux, C. Dorbath, et M. Calo. 2011. « Induced microseismic activity during recent circulation tests at the EGS site of Soultz-sous-Forêts (France) ». In Proc. 36th Workshop on Geothermal Reservoir Engineering Stanford University.
- Dorbath, Louis, Nicolas Cuenot, Albert Genter, et Michel Frogneux. 2009. « Seismic response of the fractured and faulted granite of Soultz-sous-Forêts (France) to 5 km deep massive water injections ». Geophysical Journal International 177 (2): 653–675.
- Evans, Keith, Benoît Valley, Markus Häring, R. Hopkirk, Clément Baujard, Thomas Kohl, Thomas Mégel, Laurent André, Sandrine Portier, et F. Vuataz. 2009. « Studies and support for the EGS reservoirs at Soultz–sous–Forêts ». Technical report, Centre for Geothermal Research–CREGE, c/o CHYN, University of Neuchâtel.

Two 2 months long circulation tests were performed in 2008, following the building of the power plant and the installation of the downhole production pumps. The test performed in July-August 2008 was aimed at testing the performance of the Line-shaft pump (LSP) installed in GPK2 and of the ORC conversion unit. Thus it involved only GPK2 as a production well and GPK3 as a reinjection well.
The 2008 second circulation test was performed in November-December 2008 after the installation of the second production pump (ESP – Electro-submersible Pump) into GPK4 and the reinstallation of the LSP into GPK2. Thus, the test involved GPK2 and GPK4 as production wells and GPK3 as reinjection well. At first, the ESP was starts on the 17th of November, then the LSP one week later. Unfortunately, the LSP encountered problems and has to be stopped. It was restarted on the 1st of December. Since this date, the circulation involved the three deep boreholes until the 17th of December: at that time a problem of the automation system caused the LSP to stop. 3 days later, the ESP was also stopped due to a problem on the air cooling system.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The circulation programme for the two 2008 circulations is the following (Cuenot et al., 2010):

Test dates	Test type	Injection rates (L/s)	Number of events detected
08 July - 17 August 2008	Circulation GPK2 (productor) - GPK3 (reinjector)	Production GPK2: 17-25 L/s - Reinjection GPK3: 15-25 L/s	190
17 November - 20 December 2008	Circulation GPK2 (productor) - GPK3 (reinjector) - GPK4 (productor)	Production GPK2: 17L/s - Production GPK4: 11-17 L/s - Reinjection GPK3: 11-27 L/s	53

References

- Cuenot, Nicolas, Louis Dorbath, Michel Frogneux, et Nadège Langet. 2010. « Microseismic activity induced under circulation conditions at the EGS Project of Soultz-sous-Forêts (France) ». In Proceedings World Geothermal Conference, Bali, Indonesia, 25–29.
- Cuenot, Nicolas, M. Frogneux, C. Dorbath, et M. Calo. 2011. « Induced microseismic activity during recent circulation tests at the EGS site of Soultz-sous-Forêts (France) ». In Proc. 36th Workshop on Geothermal Reservoir Engineering Stanford University.
- Cuenot, Nicolas, et Albert Genter. 2015. « Microseismic activity induced during recent circulation tests at the Soultz-sous-Forêts EGS power plant ». In Proceedings World Geothermal Congress, Melbourne, Australia.

The 2009 circulation test was the first involving 4 geothermal wells: geothermal fluid was produced from GPK2 and GPK4, equipped with LSP and ESP respectively. Reinjection was performed into GPK3 as in the previous tests. But in order to avoid a large reinjection flowrate and the resulting high overpressure in GPK3, which could increase the seismicity level both in terms of activity and larger magnitude events, a part of the fluid was reinjected into GPK1.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The circulation programme for the 2009 circulation is the following (Cuenot et al., 2015):

Test dates	Test type	Injection rates (L/s)	Number of events detected
2 March - 16 October 2009	Circulation GPK2 (productor) - GPK3 (reinjector) - GPK4 (productor) - GPK1 (reinjector)	Production GPK2: 17-22L/s - Production GPK4: 12 L/s - Reinjection GPK3: 10 - 20 L/s - Reinjection GPK1: 8-20 L/s	206

References

- Cuenot, Nicolas, M. Frogneux, C. Dorbath, et M. Calo. 2011. « Induced microseismic activity during recent circulation tests at the EGS site of Soultz-sous-Forêts (France) ». In Proc. 36th Workshop on Geothermal Reservoir Engineering Stanford University.
- Cuenot, Nicolas, et Albert Genter. 2015. « Microseismic activity induced during recent circulation tests at the Soultz-sous-Forêts EGS power plant ». In Proceedings World Geothermal Congress, Melbourne, Australia.

The circulation test began in November 2009 after a maintenance period and lasted until October 2010, when a new maintenance period was programmed. This 11 months’ experiment is the longest circulation ever performed on the Soultz project. This test involved GPK2 (production), GPK3 and GPK1 (reinjection), because the ESP installed in GPK4 encountered a failure and could not be easily and quickly repaired.

Data available

Note: Data still needs to be processed and curated. To have more information, please contact the CDGP. Here is the list of the data being processed:

Stimulation phases

The circulation programme for the 2010 circulation is the following (Cuenot et al., 2015):

Test dates	Test type	Injection rates (L/s)	Number of events detected
17 November 2009 - 14 October 2010	Circulation GPK2 (productor) - GPK3 (reinjector) - GPK1 (reinjector)	Production GPK2: 18L/s - Reinjection GPK3: 17-15 L/s - Reinjection GPK1: 1-2 L/s	411

References

- Cuenot, Nicolas, M. Frogneux, C. Dorbath, et M. Calo. 2011. « Induced microseismic activity during recent circulation tests at the EGS site of Soultz-sous-Forêts (France) ». In Proc. 36th Workshop on Geothermal Reservoir Engineering Stanford University.
- Cuenot, Nicolas, et Albert Genter. 2015. « Microseismic activity induced during recent circulation tests at the Soultz-sous-Forêts EGS power plant ». In Proceedings World Geothermal Congress, Melbourne, Australia.