HR: 0800h
AN: S41B-0964    [Abstracts]
TI: AE analysis in developing the Hot Fractured Rock geothermal power in Australia
AU: * Aoyagi, Y
EM: y-aoyagi@criepi.denken.or.jp
AF: Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi, Chiba-ken, Abiko, 270-1194 Japan
AU: Kaieda, H
EM: kaieda@criepi.denken.or.jp
AF: Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi, Chiba-ken, Abiko, 270-1194 Japan
AU: Asanuma, H
EM: asanuma@ni2.kankyo.tohoku.ac.jp
AF: Tohoku University, 6-6-20 Aoba, Aramaki-aza, Aoba-ku, Sendai-shi, Miyagi-ken, Sendai, 980-8579 Japan
AU: Wyborn, D
EM: dwyborn@geodynamics.com.au
AF: Geodynamics Co.Ltd., Level 2 349 Coronation Drive MILTON QLD 4064, Brisbane, 4064 Australia
AB: The hot fractured rock (HFR) geothermal power is being developed in Cooper Basin, South Australia since 2002. HFR geothermal power is one of natural energy acquiring systems, in which water is pumped into hot, crystalline rock via an injection well, becomes superheated as it flows through open joints in the hot rock reservoir, and is returned through production wells. At the surface, the useful heat is extracted by conventional processes, and the same water is re-circulated to mine more heat. Such hot granites are buried beneath 3.7 km of insulating sedimentary rocks at the site. The temperature of the granites reaches 250_E#381; or more. The first injection well Habanero#1 was drilled 720m into the granite, and a reservoir was made by the hydraulic fracturing in the vicinity of the well bottom (4421m in depth) in 2003. During the hydraulic fracturing many acoustic emissions (AE) were generated. We observed the AE activity using seismic network deployed in 8 wells around Habanero#1 to evaluate the reservoir. Total of 12000 or more AE were observed during the fracturing period from November to December, 2003. Although the AE hypocenters were located in the south side of the well at the initial stage, they finally distributed N-S to NE-SW direction at about 3km in diameter. The magnitude of the AE ranges M-2 to M1 for most events, but several felt earthquakes as maximum size of M3.7 were also generated. The hypocenters of the larger 12 events (> M2.5) were located by the seismic network of Geoscience Australia. The mechanism solution of these large events is basically E-W compression type, and it almost agrees to the regional stress estimated by borehole breakout in wells in the area. The AE generation property will help to understand earthquake dynamics and mechanics since it is controlled by hydraulic pressure. We will mainly discuss the relation between the generated regional energy and the mechanism solution of the events.
DE: 7230 Seismicity and seismotectonics
DE: 7200 SEISMOLOGY
DE: 7209 Earthquake dynamics and mechanics
SC: Seismology [S]
MN: 2004 AGU Fall Meeting