Micro-earthquake monitoring and tri-axial drill-bit VSP in NEDO {open_quotes}Deep-seated geothermal reservoir survey{close_quotes} in Kakkonda, Japan
- Japan Metals and Chemicals Co., Ltd., Iwate (Japan); and others
New Energy and Industrial Technology Development Organization has been drilling well WD-1 and employing micro-earthquake monitoring and tri-axial drill-bit VSP as the exploration techniques for the deep geothermal reservoir in the Kakkonda geothermal field, Japan. The results of them are as follows: (1) More than 1000 micro-earthquakes were observed from December 23, 1994 to July 1, 1995 in the Kakkonda geothermal field. Epicenters are distributed NW-SE from a macroscopic viewpoint; they distribute almost in the same areas as the fractured zone in the Kakkonda shallow reservoir as pointed out by Doi et al. (1988). They include three groups trending NE-SW. Depths of hypocenters range from the ground surface to about -2.5 km Sea level; they seem to be deeper in the western part. (2) Well WD-1 drilled into a swarm of micro-earthquakes at depths 1200 to 2200 m and encountered many lost circulations in those depths. However, these earthquakes occurred before well WD-1 reached those depths. (3) The bottom boundary of micro-earthquake distribution has a very similar shape to that of the top of the Kakkonda granite, though all of the micro-earthquakes are plotted 300 m shallower than the top of the granite. (4) The TAD VSP shows a possibility of existence of seismic reflectors at sea levels around -2.0, -2.2 and -2.6 km. These reflectors seem to correspond to the top of the Pre-Tertiary formation, the top of the Kakkonda granite and reflectors within the Kakkonda granite.
- OSTI ID:
- 175651
- Report Number(s):
- CONF-951037-; TRN: 95:008065-0063
- Resource Relation:
- Conference: Annual meeting of the Geothermal Resources Council, Reno, NV (United States), 8-11 Oct 1995; Other Information: PBD: 1995; Related Information: Is Part Of Accomplishments of the past and challenges of the future. Transactions, Volume 19; PB: 604 p.
- Country of Publication:
- United States
- Language:
- English
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