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Laboratory measurements of reservoir rock from the Geysers geothermal field, California

International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts

By:
, , ,
DOI: 10.1016/0148-9062(82)91632-1

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Abstract

Rock samples taken from two outcrops, as well as rare cores from three well bores at the Geysers geothermal field, California, were tested at temperatures and pressures similar to those found in the geothermal field. Both intact and 30?? sawcut cylinders were deformed at confining pressures of 200-1000 bars, pore pressure of 30 bars and temperatures of 150?? and 240??C. Thin-section and X-ray analysis revealed that some borehole samples had undergone extensive alteration and recrystallization. Constant strain rate tests of 10-4 and 10-6 per sec gave a coefficient of friction of 0.68. Due to the highly fractured nature of the rocks taken from the production zone, intact samples were rarely 50% stronger than the frictional strength. This result suggests that the Geysers reservoir can support shear stresses only as large as its frictional shear strength. Velocity of p-waves (6.2 km/sec) was measured on one sample. Acoustic emission and sliding on a sawcut were related to changes in pore pressure. b-values computed from the acoustic emissions generated during fluid injection were typically about 0.55. An unusually high b-value (approximately 1.3) observed during sudden injection of water into the sample may have been related to thermal cracking. ?? 1982.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Laboratory measurements of reservoir rock from the Geysers geothermal field, California
Series title:
International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts
DOI:
10.1016/0148-9062(82)91632-1
Volume
19
Issue:
2
Year Published:
1982
Language:
English
Publisher:
Elsevier
Description:
p.65-80
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts
First page:
65
Last page:
80
Number of Pages:
16