TY - JOUR
T1 - Temperature and chemical changes in the fluids of the Obama geothermal field (SW Japan) in response to field utilization
AU - Saibi, Hakim
AU - Ehara, Sachio
N1 - Funding Information:
The authors would like to thank Dr. Jun Nishijima, Dr. Yasuhiro Fujimitsu and the students of the Laboratory of Geothermics, Department of Earth Resources Engineering, Kyushu University for their help and assistance. The authors greatly appreciate the constructive and thoughtful comments of Drs. Greg Bignall, Patrick Dobson, Sabodh Garg and Marcelo Lippmann (members of the journal's “Editorial Team”) for their careful reading of our manuscript and numerous constructive suggestions that helped improve this paper. We thank Ms. Katie Kovac (Schlumberger, USA) for suggesting a number of improvements to this manuscript. The authors greatly appreciate the constructive and thoughtful comments of Dr. R.M. Barragán (Instituto de Investigaciones Eléctricas, Mexico). We also thank Dr. Shinji Ohsawa (Kyoto University, Japan) and Dr. Masaya Yasuhara (AIST, Japan) for their help. The first author gratefully acknowledges the financial support of the Japan Society for the Promotion of Science (JSPS). This study was supported by KAKENHI (Grant-in-Aid for Exploratory Research) .
PY - 2010/9
Y1 - 2010/9
N2 - Thermal waters from Quaternary volcanic rocks (predominantly andesites) discharge along faults in the Obama geothermal field of southwestern Japan. The chemistry of more than 100 thermal and ground water samples collected between 1936 and 2005 indicate that the Na-Cl hot spring waters are a mixture of " andesitic" magmatic, sea and meteoric waters. Mixing models and silica and cation geothermometry were used to estimate the SiO2 and Cl composition and the temperature (∼200°C) of the reservoir fluids deep in the geothermal system. The isotopic data (18O and D) are consistent with a mixed origin interpretation of the waters feeding the Obama hot springs, i.e. a large proportion of meteoric and sea waters, and a small magmatic component. Temperatures and chemical concentrations of the thermal waters were affected by the 1944-1959 salt production operations, but have recovered after closure of the salt factories; now they are similar to their pre-1940 values. In the future, the Obama geothermal field may be suitable for electric power generation, although heat and fluid extraction will require careful management to prevent or minimize reservoir cooling.
AB - Thermal waters from Quaternary volcanic rocks (predominantly andesites) discharge along faults in the Obama geothermal field of southwestern Japan. The chemistry of more than 100 thermal and ground water samples collected between 1936 and 2005 indicate that the Na-Cl hot spring waters are a mixture of " andesitic" magmatic, sea and meteoric waters. Mixing models and silica and cation geothermometry were used to estimate the SiO2 and Cl composition and the temperature (∼200°C) of the reservoir fluids deep in the geothermal system. The isotopic data (18O and D) are consistent with a mixed origin interpretation of the waters feeding the Obama hot springs, i.e. a large proportion of meteoric and sea waters, and a small magmatic component. Temperatures and chemical concentrations of the thermal waters were affected by the 1944-1959 salt production operations, but have recovered after closure of the salt factories; now they are similar to their pre-1940 values. In the future, the Obama geothermal field may be suitable for electric power generation, although heat and fluid extraction will require careful management to prevent or minimize reservoir cooling.
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U2 - 10.1016/j.geothermics.2010.06.005
DO - 10.1016/j.geothermics.2010.06.005
M3 - Article
AN - SCOPUS:77955846285
SN - 0375-6505
VL - 39
SP - 228
EP - 241
JO - Geothermics
JF - Geothermics
IS - 3
ER -
