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

Technical Report · Mon Dec 31 04:00:00 EST 1984

OSTI ID:59678

Stock, J M; Healy, J H; Hickman, S H

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 ad 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{sup 0} W to N 65{sup 0} 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{sup 0} E to N 30{sup 0} E and dipping 60{sup 0} to 67{sup 0}). 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, stringing N 10{sup 0} E to N 40{sup 0} 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{sup 0} W azimuth of these breakouts agrees very closely with the N 60{sup 0} W to N 65{sup 0} W direction of least horizontal principal stress inferred from the drilling-induced hydrofracs. 19 references, 13 figures, 3 tables.

• Research Organization: Geological Survey, Menlo Park, CA (United States)
• DOE Contract Number: AI08-78ET44802
• OSTI ID: 59678
• Report Number(s): USGS-OFR--84-172; ON: DE84009620
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
58 GEOSCIENCES
GEOLOGIC FAULTS
HIGH-LEVEL RADIOACTIVE WASTES
HYDRAULIC FRACTURING
STRESSES
TUFF
YUCCA MOUNTAIN
Yucca Mountain Project