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San Andreas fault zone drilling project: scientific objectives and technological challenges

Journal of Energy Resources Technology

By:
, , and
DOI: 10.1115/1.2835422

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Abstract

We 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 a comprehensive program of coring, fluid sampling, downhole measurements, laboratory experimentation, and long-term monitoring, we hope to obtain critical information 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 and completion 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 earthquake activity, fluid pressure, deformation and other parameters for 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, we expect to encounter difficult drilling, coring and hole-completion conditions in the region of greatest scientific interest.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
San Andreas fault zone drilling project: scientific objectives and technological challenges
Series title:
Journal of Energy Resources Technology
DOI:
10.1115/1.2835422
Volume
117
Issue:
4
Year Published:
1995
Language:
English
Publisher:
ASME
Publisher location:
New York, NY
Contributing office(s):
Earthquake Science Center
Description:
8 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Energy Resources Technology
First page:
263
Last page:
270
Country:
United States
State:
California
Other Geospatial:
San Andreas Fault