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Report on televiewer log and stress measurements in core hole USW G-2, Nevada Test Site, October-November, 1982

Stock, J. M. and Healy, J. H. and Hickman, S. H. (1984) Report on televiewer log and stress measurements in core hole USW G-2, Nevada Test Site, October-November, 1982. U.S. Geological Survey open-file report, 84-172. United States Geological Survey , Reston, VA.

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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.

Item Type:Report or Paper (Report)
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URLURL TypeDescription
Stock, J. M.0000-0003-4816-7865
Additional Information:© 1984 USGS. Prepared in cooperation with the Nevada Operations Office, U. S. Department of Energy (Interagency Agreement DE-AI08-78ET44802).
Group:Seismological Laboratory
Funding AgencyGrant Number
Department of Energy (DOE)DE-AI08-78ET44802
Series Name:U.S. Geological Survey open-file report
Issue or Number:84-172
Record Number:CaltechAUTHORS:20141028-110414859
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50931
Deposited By: Tony Diaz
Deposited On:28 Oct 2014 20:23
Last Modified:03 Oct 2019 07:28

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