Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation
Natural electrical potential signals have been recorded from numerous seismically active areas around the world and therefore have been proposed as a potential earthquake prediction tool. The streaming potential is being used to locate sub-surface water reservoirs, to monitor steam fronts during enh...
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ftucl:oai:eprints.ucl.ac.uk.OAI2:10112490 2023-12-24T10:17:59+01:00 Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation Clint, Oswald Conan 2000 text https://discovery.ucl.ac.uk/id/eprint/10112490/1/out.pdf https://discovery.ucl.ac.uk/id/eprint/10112490/ eng eng UCL (University College London) https://discovery.ucl.ac.uk/id/eprint/10112490/1/out.pdf https://discovery.ucl.ac.uk/id/eprint/10112490/ open UNSPECIFIED thesis, UCL (University College London). Earth sciences Acoustic emissions Thesis 2000 ftucl 2023-11-27T13:07:28Z Natural electrical potential signals have been recorded from numerous seismically active areas around the world and therefore have been proposed as a potential earthquake prediction tool. The streaming potential is being used to locate sub-surface water reservoirs, to monitor steam fronts during enhanced oil recovery techniques, and to delineate the anisotropy of fractures in geothermal and oil reservoirs. The generating mechanism for these signals is still unclear although plausible theories include: - Piezoelectric fields produced through stress changes on piezoelectric materials, such as quartz, found in many rocks. - Electrokinetic currents induced through a pressure gradient and caused by electrical charge transport within a moving fluid. - Less well-established theories for instance involving current carrying mobile O' charges. To investigate the relative significance of these mechanisms, I have measured the direct current electrical potential and acoustic emissions during constant strain rate rock deformation under simulated crustal conditions of pressure and pore fluid pressure. Some sixty-one experiments were done on rock samples of quartz rich Darley Dale and Bentheim sandstone and quartz free basalt from Iceland. A computer and servo-controlled conventional triaxial cell was used to deform dry, water-saturated and brine-saturated rock samples at confining pressures between 20 and 200MPa, pore fluid pressures between 10 and 50MPa and strain rates from 10-4 s-1 to 10-6 s-1 I identify the primary sources of the electrical potential signals as being generated by (i) piezoelectricity in dry sandstone experiments and (ii) electrokinetic effect in saturated basalt experiments. I show that electrical potential signals from the other proposed methods are not detectable above the background noise level. It can therefore be argued that the electrokinetic effect is the main electrical potential generating mechanism within the upper crust.Both precursory and coseismic signals to dynamic rupture exist for pure ... Thesis Iceland University College London: UCL Discovery |
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University College London: UCL Discovery |
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ftucl |
language |
English |
topic |
Earth sciences Acoustic emissions |
spellingShingle |
Earth sciences Acoustic emissions Clint, Oswald Conan Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation |
topic_facet |
Earth sciences Acoustic emissions |
description |
Natural electrical potential signals have been recorded from numerous seismically active areas around the world and therefore have been proposed as a potential earthquake prediction tool. The streaming potential is being used to locate sub-surface water reservoirs, to monitor steam fronts during enhanced oil recovery techniques, and to delineate the anisotropy of fractures in geothermal and oil reservoirs. The generating mechanism for these signals is still unclear although plausible theories include: - Piezoelectric fields produced through stress changes on piezoelectric materials, such as quartz, found in many rocks. - Electrokinetic currents induced through a pressure gradient and caused by electrical charge transport within a moving fluid. - Less well-established theories for instance involving current carrying mobile O' charges. To investigate the relative significance of these mechanisms, I have measured the direct current electrical potential and acoustic emissions during constant strain rate rock deformation under simulated crustal conditions of pressure and pore fluid pressure. Some sixty-one experiments were done on rock samples of quartz rich Darley Dale and Bentheim sandstone and quartz free basalt from Iceland. A computer and servo-controlled conventional triaxial cell was used to deform dry, water-saturated and brine-saturated rock samples at confining pressures between 20 and 200MPa, pore fluid pressures between 10 and 50MPa and strain rates from 10-4 s-1 to 10-6 s-1 I identify the primary sources of the electrical potential signals as being generated by (i) piezoelectricity in dry sandstone experiments and (ii) electrokinetic effect in saturated basalt experiments. I show that electrical potential signals from the other proposed methods are not detectable above the background noise level. It can therefore be argued that the electrokinetic effect is the main electrical potential generating mechanism within the upper crust.Both precursory and coseismic signals to dynamic rupture exist for pure ... |
format |
Thesis |
author |
Clint, Oswald Conan |
author_facet |
Clint, Oswald Conan |
author_sort |
Clint, Oswald Conan |
title |
Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation |
title_short |
Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation |
title_full |
Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation |
title_fullStr |
Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation |
title_full_unstemmed |
Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation |
title_sort |
electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation |
publisher |
UCL (University College London) |
publishDate |
2000 |
url |
https://discovery.ucl.ac.uk/id/eprint/10112490/1/out.pdf https://discovery.ucl.ac.uk/id/eprint/10112490/ |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
UNSPECIFIED thesis, UCL (University College London). |
op_relation |
https://discovery.ucl.ac.uk/id/eprint/10112490/1/out.pdf https://discovery.ucl.ac.uk/id/eprint/10112490/ |
op_rights |
open |
_version_ |
1786206462212571136 |