(Special session) Resource exploration and big-data processing

[2K0201-07-04] [Student presentation: Doctoral course] Three-dimensional imaging of caldera-hosted geothermal system in the Karurusu geothermal field, Japan using numerical simulation

○Heru Berian Pratama¹, Katsuaki Koike¹, Tada-nori Goto², Taiki Kubo¹ (1. Kyoto University, 2. University of Hyogo)

Chairperson : Akihisa Kizaki (Akita University)

Keywords:Geothermal system, Liquid-dominated reservoir, Reservoir simulation, Numerical modeling, TOUGH2

Accurate imaging of caldera-hosted geothermal systems from the earth's surface to considerable depths is a multidisciplinary challenge to effective and large utilization of geothermal resources. To realize this issue, a three-dimensional numerical simulation of the Karurusu geothermal field in Hokkaido, Japan is undertaken to clarify the system and temperature distribution in the reservoir. The model was built around the caldera with 27.5 km² and roughly 4.0 km thickness using a single-porosity model with equation of state for pure water (EOS1) module from the TOUGH2 simulator. The model was used for an optimization analysis to calibrate the model parameters with six exploration wells to obtain the steady-state condition. The simulation results reveal that the temperature reservoir is about 290 °C at the upflow zone in the elevation around -1000 meter above sea level (masl) with a heat source at 345 °C deeply seated at -3300 masl. The pressure output from the numerical model indicated that the Karurusu geothermal system is liquid-dominated, because the pressures follow almost the hydrostatic condition.