Development of a method to estimate residence time of geothermal fluid using multiple environmental tracers

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05348
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: Kyoto University
• Principal Investigator: Kashiwaya Koki 京都大学, 工学研究科, 准教授 (40447074)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 地熱流体 / 温泉水 / 滞留時間 / 環境トレーサー / 放射性塩素同位体 / 多変量解析

Outline of Final Research Achievements

A method to estimate the origins of waters constituting a geothermal fluid and residence times of the waters whose origins are different through analyses of geochemical indices was developed. Hot spring water and other water samples were collected in four geothermal areas around the Bandung Basin, Indonesia, and concentrations of dissolved components and isotopic features were analyzed. The mixing ratios of waters originating from meteoric water, seawater, and magmatic water were calculated based on the analytical results. The residence time of the seawater could be estimated successfully.

Free Research Field

水理地質学，地球化学，資源工学

Academic Significance and Societal Importance of the Research Achievements

地熱流体の循環状態を把握することができれば，地熱発電を行う際に貯留層の圧力低下を防ぎ，再生可能エネルギーの一種である地熱エネルギーを持続的に利用する上で役立つ。本研究では，地熱流体の循環の活発さを反映した定量的指標として地熱流体の滞留時間に注目し，地熱流体を構成する起源の異なる水の滞留時間を推定する方法について検討した。その結果，地熱流体に含まれる海水起源の水の滞留時間を推定することに成功した。