EGU21-8561
https://doi.org/10.5194/egusphere-egu21-8561
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Flow-induced microfracturing of granite in superhot geothermal environments

Ryota Goto1, Noriaki Watanabe1, Kiyotoshi Sakaguchi1, Youqing Chen2, Takuya Ishibashi3, Eko Pramudyo1, Francesco Parisio4, Keita Yoshioka5, Kengo Nakamura1, Takeshi Komai1, and Noriyoshi Tsuchiya1
Ryota Goto et al.
  • 1Tohoku, Graduate School of Environmental Studies, Department of Environmental Studies for Advanced Society, Japan (ryouta.gotou.q1@dc.tohoku.ac.jp)
  • 2Department of Energy Science and Technology, Graduate School of Energy Science, Kyoto University
  • 3Fukushima Renewable Energy Institute, National Institute of Advanced Industrial Science and Technology
  • 4Chair of Soil Mechanics and Foundation Engineering, Technische Universitaet Bergakademie Freiberg, Freiberg
  • 5Department of Environmental Informatics, Helmholtz Centre for Environmental Research–UFZ

Superhot geothermal environments with temperatures of approximately 400-500C at depth of approximately 2-4 km are expected as a new geothermal energy frontier. In order to efficiently exploit the superhot geothermal resources, fracture systems are necessary as flow path of working fluid. Hydraulic fracturing is a promising technique because it is able to create a new fracture system or enhance the permeability of preexisting fracture system. Laboratory-scale hydraulic fracturing experiments of granite have demonstrated the formation of densely distributed network of permeable fractures throughout the entire rock body at or near the supercritical temperature for water. Though the process has been presumed to involve continuous infiltration of low-viscosity water into preexisting microfractures followed by creation and merger of the subsequent fractures, plausible criterion for the fracturing is yet to be clarified. The possibility that the Griffith failure criterion is available to predict the occurrence of fracturing was shown by hydraulic fracturing experiments with acoustic emission measurements of granite at 400C under true triaxial stress. The present study provides a theoretical basis required to establish the procedure for hydraulic fracturing in superhot geothermal environment.

How to cite: Goto, R., Watanabe, N., Sakaguchi, K., Chen, Y., Ishibashi, T., Pramudyo, E., Parisio, F., Yoshioka, K., Nakamura, K., Komai, T., and Tsuchiya, N.: Flow-induced microfracturing of granite in superhot geothermal environments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8561, https://doi.org/10.5194/egusphere-egu21-8561, 2021.

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