In order to improve the seismic monitoring of the Soultz-sous-Forêts geothermal site, a new seismic observation well was drilled in 2000. After two months of drilling, OPS4 reached the final depth of 1537m. Location of the OPS4 wellhead (in WGS84): - Latitude: 48.92108705 | 48° 55' 15" N - Longitude: 7.88306364 | 7° 52' 59" E - Altitude: 204m

The 4616 well was an old oil well drilled in 1950-1951. The well was recovered and used as seismic observation well of the Soultz-sous-Forêts geothermal project from 1987. It has been deepened in the framework of the project to 1414m in 1990. Location of the 4616 wellhead (in Lambert coordinates): - Latitude: 48.93879707 | 48° 56' 19" N - Longitude: 7.86502087 | 7° 51' 54" E - Altitude: 155.4m

The 4601 well was an old oil well drilled in 1951. It has been deepened in the framework of the Soultz-sous-Forêts project from 1010m to 1604m. A seismic probe was deployed at the bottom of the well to monitor the microseismic activity induced by the several experiments conducted on the geothermal site of Soultz-sous-Forêts. Location of the 4601 wellhead (in WGS84): - Latitude: 48.92805654 | 48° 55' 41" N - Longitude: 7.84882476 | 7° 50' 55" E - Altitude: 169m

The 4550 well was an old oil well drilled in 1949-1950. It has been deepened in the framework of the Soultz-sous-Forêts project from 1050m to 1500m in 1990. A seismic probe was deployed at the bottom of the well to monitor the microseismic activity induced by the geothermal site of Soultz-sous-Forêts. Location of the 4550 wellhead (in WGS84): - Latitude: 48.93750535 | 48° 56' 15" N - Longitude: 7.86972203 | 7° 52' 10" E - Altitude: 151m

GRT-2 is the second well drilled within the framework of the geothermal project ECOGI at Rittershoffen. The drilling of the well started in March 2014 and ended in July 2014. GRT-2 is a deviated well of 3196 m in length that reaches 2708 m TVD GL (true vertical depth from ground level) within the fractured granite basement. No reservoir enhancement was necessary at GRT-2. Production and circulation tests were realized from July to October 2014. The GRT-2 well is currently used as production well. It produces hot water at a temperature of 170 °C and with production flow rate of 70 L/s. Location of the GRT-2 wellhead (in WGS84): Latitude: 48.8970814354199° Longitude: 7.93865503246575°

GRT-1 is the first well drilled within the framework of the geothermal project ECOGI at Rittershoffen. The drilling of the well began at the end of September 2012. The well reached a final measured depth of 2580 m within the fractured granite basement at the end of December 2012. Hydraulic tests of the well were carried out from December 2012 to June 2013. The tests realized at GRT-1 allowed to increase its injectivity index by a factor five. The GRT-1 well is currently used as injection well. Location of the GRT-1 wellhead (in WGS84): Latitude: 48.8965633979049 Longitude: 7.93818621036716

GPK1 was the first well drilled for geothermal purposes at Soultz-sous-Forêts. The well was first drilled in 1987. It reached 2000 m and the temperature at the bottom hole was 140°C. Several hydraulic injections have been done associated with tracer tests and temperature and flow logs. In order to get deeper information, the GPK1 well was deepened to 3600 m in 1992. The downhole temperature reached 160°C. Location GPK1 WGS84: Latitude: 48.93525543 | 48° 56' 6'' N Longitude: 7.86535117 | 7° 51' 55'' E

GPK4 well was drilled after GPK3 well in order to exploit a lower level at 5000 m depth, where the temperature reaches 200°C. GPK4 has been drilled in 2004 to build a triplet exchanger along ith GPK2 and GPK3 wells. It reaches a depth of 5260 m. Location GPK4 WGS84: Latitude: 48.93079836 | 48° 55' 50'' N Longitude: 7.86652359 | 7° 51' 59'' E

GPK3 well was drilled after GPK2 well in order to exploit a lower level at 5000 m depth, where the temperature reaches 200°C. GPK3 has been drilled in 2002 to build a triplet exchanger along ith GPK2 and GPK4 wells. It reaches a depth of 5090 m. Location GPK3 WGS84: Latitude: 48.93084122 | 48° 55' 51'' N Longitude: 7.86656943 | 7° 51' 59'' E

In 1990/1991, an old oil well, EPS1 has been deepened and cored to characterize the granite reservoir and perform some deep hydraulic tests in view of a future experimental doublet. Unfortunately, the well had an important not controlled deviation and could not reach the expected depth. However, it was cored from 930 m to the bottom hole at 2227 m depth and provided a lot of scientific data. Location EPS1 WGS84: Latitude: 48.93118507 | 48° 55' 52'' N Longitude: 7.86766157 | 7° 52' 3'' E