HR: 0800h
AN: V41A-0396    [Abstracts]
TI: Towards an Automatic, Real-time Detection of Subsurface Cracks in Geothermal Fields Using Shear-wave Splitting
AU: Tang, C
EM: chuanhaitang@gmail.com
AF: Geological Sciences Department, Mitchell Hall CB#3315, Chapel Hill, nc 27599, United States
AU: * Rial, J A
EM: jar@email.unc.edu
AF: Geological Sciences Department, Mitchell Hall CB#3315, Chapel Hill, nc 27599, United States
AU: Zhao, Y
EM: yangzhao@email.unc.edu
AF: Geological Sciences Department, Mitchell Hall CB#3315, Chapel Hill, nc 27599, United States
AB: We have developed, borrowed and consolidated a number of algorithms that can in principle reduce production costs in geothermal plants by simplifying the monitoring of the field's subsurface crack system, during exploration and into production. The data gatherer is an array of seismic sensors, and the data consists of shear-wave splitting parameters, obtained from natural or induced local seismic events. The operation starts with a portable seismic array of 20-25 three-component geophones telemetering to a computerized portable station that will display in real time the natural and induced seismicity, detect crack geometry and intensity of fracturing as the seismic data streams into the array. The display will progressively show an emerging cloud of seismic events, followed by images of the crack geometry and distribution, as newly data becomes available and the inversion of the measured SWS parameters stabilizes. The computer contains data from previously detected crack systems at the site and so before-and-after-injection comparisons can be readily done. As the data accumulate, tomographic images of the surrounding rock volume slowly become available. Changes in fluid motion, in crack orientation, in temperature will result in identifiable changes in the tomographic computer display. Since a real-time shear wave splitting monitoring system that performs as described here is unprecedented, it presents a number of important challenges - as well as opportunities - to advance geothermal science and technology. Some of these challenges and opportunities will be discussed.
DE: 1034 Hydrothermal systems (0450, 3017, 3616, 4832, 8135, 8424)
DE: 7280 Volcano seismology (8419)
DE: 8400 VOLCANOLOGY
DE: 8424 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8135)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting