Complications with stress tests - insights from a fracture experiment in the ultra-deep KTB borehole
In the main KTB-well (Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland), we pumped 210 m{sup 3} of brine to make a hydraulic fracturing stress measurement and to induce seismic events. We observed a peculiar pressure behavior: a clear breakdown occurred at low flow rate, but at higher flow rate the pressure kept rising until we reached the pressure limit. During the later injection stages, a large number of triggered seismic events occurred. The events mostly came from faults at a depth of 8.6 and 8.9 km, whereas the fluid was injected at 9.1 km depth. A few events came from faults as shallow as 7.2 km. Careful analysis of the pressure record showed that no tensile fracture was created. The seismic events indicated that the injected fluid was most probably going into pre-existing shear faults.
- OSTI ID:
- 457298
- Report Number(s):
- CONF-961003-; TRN: 96:006576-0020
- Resource Relation:
- Conference: 71. annual technical conference and exhibition of the Society of Petroleum Engineers, Denver, CO (United States), 6-9 Oct 1996; Other Information: PBD: 1996; Related Information: Is Part Of 1996 SPE annual technical conference and exhibition: Drilling and completion; PB: 944 p.
- Country of Publication:
- United States
- Language:
- English
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