| Title | Regional geothermal exploration and potential assessment in the Taitung Hongye area, Eastern Taiwan |
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| Authors | P. Hsieh, T. Guo, L. Tong, W. Lin, E. Yeh, H. Wen, S. Huang, C. Lin, C. Chung, C. Chen, M. Chen, Z. Su |
| Year | 2023 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | 3D geothermal conceptual model, magnetotellurics, geochemistry, discrete fracture network analysis, geothermal potential assessment |
| Abstract | This study compiles various geothermal exploration reports and academic papers since the 1980s, and conducts supplementary geological, geochemical, and magnetotelluric surveys and geothermal potential assessment. The threedimensional geothermal conceptual model of the Taitung Hongye area shows that under plate compression, the rock uplift resulting in a high geothermal gradient may act as the heat source of the geothermal system. A deep circulation of meteoric water accompanied by some deep crustal hot water forms a bicarbonate-type hot water with temperatures possibly exceeding 150°C. It migrates upward from the fracture zones and after being blocked by a relatively intact rock mass in the shallow depth, the hot water then migrates laterally along the fracture zone. Some of it infiltrates through river channels to form hot springs. The geothermal resource is the phenomenon of hightemperature and high-salinity hot water stored in fractured rock masses, which often shows that the resistivity is more than a hundred times lower than that of the intact rocks. In the three-dimensional resistivity model, a low-resistivity structures resembling mushroom shapes is recognized, with the hot water up-flow zone as the stem and the out-flow zone as the cap. The up-flow zone has the highest temperature and is ideal for the geothermal production wells. Based on these characteristics, this study has identified six potential geothermal structures. An 800-meter deep geological borehole commissioned by the Central Geological Survey was completed in the out-flow zone. The significant hot water feed zones are between 300-400 meters deep, with a maximum measured temperature of 142°C, which corresponds well to the interpreted depth range of the lowresistivity geothermal structure obtained from the magnetotelluric survey. A high correlation between the lowresistivity structure and the geothermal structure is confirmed. Preliminary estimation of the potential generating capacity using the Monte Carlo stored heat method ranges from 51 to 181 MWe. |