FLUID INCLUSION MICROTHERMOMETRY AND GAS CHEMISTRY IN GEOTHERMAL SYSTEM, JAPAN AND ITS APPLICATION FOR THE STUDY OF FLUID EVOLUTION - Energy Research Developments: Tidal Energy, Energy Efficiency and Solar Energy - page 159

Table 1. Underground temperature profile type of each well
in the Geothermal Development Promotion Survey fields
and of the geothermal fields established the power plant in Japan

Geothermal
Power Plant

Promoting Geothermal Development

Pattern

Conduction type
well name

Convection type
well name

Numbers
of wells*

Field name

Pattern (a)
(Minimmum
Th￿RT)

KK-2, TH-7, IB-7,
NB-1, NB-2, NB-4,
YK-2, YK-7, MK-1,
YD-1, MS-1, MS-2,
MS-7, FS-1, FS-2,
FS-3, FS-4, HK-3,
HK-4

NB-3, MS-5, UZ-2,
UZ-5, HK-2, HK-5,
HK-7, ID-1

27 (36)

Pattern (b)
(Minimmum
Th￿RT)

KK-1, NB-6, YK-5,
MK-4, MK-5, MK-
7, SK-5, DZ-6, KJ-
5, KJ-7

TH-1, TH-3, TH-5,
IB-6, OU-8, YD-2,
YD-3, OB-1, UZ-1,
UZ-3, UZ-4, UZ-7,
KT-1, KT-8, HK-6,
ID-3, ID-5, ID-6

28 (37) Mori,

Kakkonda,
Uenotai,
Takigami,
Otake,
Hatchobaru,
Kirishima

Pattern (c)
(Mean
Th￿RT)

YK-4, YK-6, MK-3,
YD-5, OB-2, OB-3,
DZ-4, MS-6, IN-1

TH-2, TH4, MK-2,
MK-6, SK-6, HT-2,
MS-3, KT-5

17 (22) Sumikawa,

Okuaizu

Pattern (d)
(Maximum
Th=RT)

DZ-3, DZ-5 TH-6, KT-7 4 ( 5) Sumikawa,

Okuaizu
Uenotai

Total 40 36 76 (100)
* Number in parenthesis shows percentage. For example of well name, well KK-2 shows a well drilled for
the second times at the Kamikawa field. Abbreviation: KK, Kamikawa; TH, Toyoha; NB, Noboribetsu;
IB, Iburi; YK, Yakumo; MK ,Minami Kayabe; SK, Shimokita; OU, Okiura; HT, Hachimantai Tobu;
YD, Yuda; MS, Minase; OB, Obanazawa Tobu; DZ, Dozangawa; IN, Inawashiro; KJ, Kuju; UZ, Unzen
Seibu; FS, Fukuejima Seibu; HK, Hishikari; KT ,Kurino-Tearai; ID, Ikedako Shuhen.

Through a long history of exploration of geothermal systems in Japan, there are now
seventeen geothermal power plants and total geothermal generated capacity exceeds 500
MWe. As pattern (b) is recognized in most geothermal fields where the power plant was
constructed in Japan (table 1), such as Mori (Muramatsu et al., 1997), Kakkonda (Muramatsu,
1984), Takigami (Takenaka and Furuya, 1991), Otake and Hachobaru (Fujino and Yamazaki,
1985: Taguchi and Nakamura, 1991), Kirishima (Taguchi et al., 1984￿Kodama and
Nakajima, 1988), the minimum Th is useful to know the present reservoir temperature in
almost Japanese geothermal fields. As an example, figure 3 shows distributions of Th values
of liquid-rich inclusions in the analyzed samples with Tb profile for well ND-6 at the Mori
geothermal field (Muramatsu et al., 1997). The Tb value obtained after a long period (13
days) of thermal recovery reflects a true pre-drilling underground temperature. The minimum
Th value is in general agreement with the Tb value, suggesting that the inclusion which has a
minimum Th value was trapped at the recent stage of geothermal activity. The similar feature
is recognized in the shallow reservoir ( ≦ 1400 m depth; Muramatsu,1984; Muramatsu et al.,
1996) and the deep reservoir (>1400 m depth) at the Kakkonda geothermal field (Komatsu