Report on televiewer log and stress measurements in core hole USW G-2, Nevada Test Site, October-November, 1982
- Creators
- Stock, J. M.
- Healy, J. H.
- Hickman, S. H.
Abstract
Hydraulic fracturing stress measurements and a borehole televiewer log were obtained in hole USW G-2 at Yucca Mountain, Nevada, to depths of 1200 m. Results indicate that at the depths tested, the minimum and maximum horizontal stresses are less than the vertical stress, corresponding to a normal faulting stress regime. Drilling-induced hydrofractures seen in the televiewer log imply a least horizontal principal stress direction of N 60° W to N 65° W. For reasonable values of the coefficient of friction, the magnitude of the least horizontal stress is close to the value at which slip would occur on preexisting faults of optimal orientation (strike N 25° E to N 30° E and dipping 60° to 67°). The prominent drilling-induced fractures seen in the televiewer log are believed to have been caused by excess downhole pressures applied during drilling the hole. Many throughgoing fractures are also seen in the televiewer log; most of these are high angle, stringking N 10° E to N 40° E. These fractures show a general decrease in angle of dip with depth. Stress-induced wellbore breakouts are seen at depths below 1050 m. The average N 60° W azimuth of these breakouts agrees very closely with the N 60° W to N 65° W direction of least horizontal principal stress inferred from the drilling-induced hydrofracs.
Additional Information
© 1984 USGS. Prepared in cooperation with the Nevada Operations Office, U. S. Department of Energy (Interagency Agreement DE-AI08-78ET44802).Attached Files
Published - OFR_84-172.pdf
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Additional details
- Eprint ID
- 50931
- Resolver ID
- CaltechAUTHORS:20141028-110414859
- DE-AI08-78ET44802
- Department of Energy (DOE)
- Created
-
2014-10-28Created from EPrint's datestamp field
- Updated
-
2019-10-03Created from EPrint's last_modified field
- Caltech groups
- Seismological Laboratory, Division of Geological and Planetary Sciences
- Series Name
- U.S. Geological Survey open-file report
- Series Volume or Issue Number
- 84-172