The San Andreas fault zone drilling project: Scientific objectives and technological challenges

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:93060

Hickman, S ^[1]; Younker, L ^[2]; Zobeck, M ^[3]; Cooper, G ^[4]

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1. Geological Survey, Menlo Park, CA (United States)
2. Lawrence Livermore National Lab., CA (United States). Earth Science Division
3. Stanford Univ., CA (United States). Dept. of Geophysics
4. Univ. of California, Berkeley, CA (United States). Dept. of Material Science and Mineral Engineering

The authors are leading a new international initiative to conduct scientific drilling within the San Andreas fault zone at depths of up to 10 km. This project is motivated by the need to understand the physical and chemical processes operating within the fault zone and to answer fundamental questions about earthquake generation along major plate-boundary faults. Through an integrated program of coring, fluid sampling, in-situ and laboratory experimentation and long-term monitoring, the authors hope to provide fundamental constraints on the structure, composition, mechanical behavior and physical state of the San Andreas fault system at depths comparable to the nucleation zones of great earthquakes. The drilling, sampling and observational requirements needed to ensure the success of this project are stringent. These include: (1) drilling stable vertical holes to depths of about 9 km in fractured rock at temperatures of up to 300 C; (2) continuous coring of inclined holes branched off these vertical boreholes to intersect the fault at depths of 3, 6 and 9 km; (3) conducting sophisticated borehole geophysical measurements and fluid/rock sampling at high temperatures and pressures; and (4) instrumenting some or all of these inclined core holes for continuous monitoring of seismicity and a broad range of physical and chemical properties over periods of up to several decades. For all of these tasks, because of the overpressured clay-rich formations anticipated within the fault zone at depth, the authors expect to encounter difficult drilling, coring and hole-completion conditions in the regions of greatest scientific interest.

• OSTI ID: 93060
• Report Number(s): CONF-940113--; ISBN 0-7918-1182-4
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
58 GEOSCIENCES
BOREHOLES
CALIFORNIA
DESIGN
DRILLING EQUIPMENT
ENGINEERING
GEOLOGIC FAULTS
RESEARCH PROGRAMS
TECHNOLOGY UTILIZATION
WELL COMPLETION