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Hydraulic fracturing in granite under geothermal conditions

International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts

By:
, ,
DOI: 10.1016/0148-9062(80)90003-0

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Abstract

The experimental hydraulic fracturing of granite under geothermal conditions produces tensile fracture at rapid fluid injection rates and shear fracture at slow injection rates and elevated differential stress levels. A sudden burst of acoustic emission activity accompanies tensile fracture formation whereas the acoustic emission rate increases exponentially prior to shear fracture. Temperature does not significantly affect the failure mechanism, and the experimental results have not demonstrated the occurrence of thermal fracturing. A critical result of these experiments is that fluid injection at intermediate rates and elevated differential stress levels increases permeability by more than an order of magnitude without producing macroscopic fractures, and low-level acoustic emission activity occurs simultaneously near the borehole and propagates outward into the specimen with time. Permeability measurements conducted at atmospheric pressure both before and after these experiments show that increased permeability is produced by permanent structural changes in the rock. Although results of this study have not demonstrated the occurrence of thermal fracturing, they suggest that fluid injection at certain rates in situ may markedly increase local permeability. This could prove critical to increasing the efficiency of heat exchange for geothermal energy extraction from hot dry rock. ?? 1980.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Hydraulic fracturing in granite under geothermal conditions
Series title:
International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts
DOI:
10.1016/0148-9062(80)90003-0
Volume
17
Issue:
1
Year Published:
1980
Language:
English
Publisher:
Elsevier
Description:
p.25-33
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
25
Last page:
33
Number of Pages:
9