Description

During May/June 2003 a hydraulic stimulation program was conducted in the well GPK3; at the European Hot Dry Rock Project, Soultz-sous-Forêts, France. The stimulation was followed in June/July 2003 by a circulation test between GPK3 and GPK2. The stimulation was performed over the openhole section of GPK3 from 4556 m measured depth (MD) to the bottom of the well at around 5101 m MD. A total of 34,000 m3 of water was injected. At the start of the stimulation 450 m3 of brine were injected in an effort to encourage downward growth of the stimulated region. The stimulation covered a period of 11 days. After a break of 7 days, a post-fracturing and circulation test was performed between GPK3 and GPK2 for a period of 17 days (Dyer, B.C., Baria, R. and Michelet, S., 2004. Soultz GPK3 stimulation and GPK3-GPK2 circulation May to July 2003. Seismic monitoring report. Semore Seismic report for Socomine.). 

Microseismic emissions have been monitored and recorded throughout the experiment, and continued until August 26th.

The five principle phases of the hydraulic programme were the following:
- Phase 1: GPK3 injection
- Phase 2: GPK3 and GPK2 injection
- Phase 3: GPK3 injection and GPK2 shut-in
- Phase 4a: GPK3 and GPK2 shut-in
- Phase 4b: GPK3 shut-in and GPK2 venting
- Phase 5: GPK3 to GPK2 circulation