DFG-JSPS Project HIGHER
Experiments proved the possibility of exploiting supercritical geothermal resources in the ductile crust, demonstrating that fractures in crystalline rock are still sufficiently permeable and and that permeability enhancement through hydraulic stimulation is possible (Watanabe et al. 2017a, Watanabe et al. 2017b). At high temperature, hydrofracture network morphology changes from planar to dendritic patterns: adequate conceptual frameworks that describe these phenomena are the objective of “HIGHER”. Models for the brittle-ductile transition of rocks (Parisio et al. 2019) have been successfully employed to describe high-temperature rheology. A successful extension to describe the above mentioned experimental phenomena requires addressing several open questions relating fluid and rock rheology to fracture morphology and permeability evolution. Experiments will be conducted at Tohoku University, and, based on the experimental results, models of hydraulic fracture propagation will be developed and implemented into the open-source multi-physics finite elements code OpenGeoSys (www.opengeosys.org). The explanatory capabilities of the newly developed concepts towards intricate dynamical processes in the earth’s crust will be assessed in simulations of selected large-scale scenarios to be conducted by the German-Japanese team utilizing High Performance Computing (HPC) capabilities. This study will unravel the complex mechanisms behind fluid driven fracture formation beyond the brittle condition in the earth crust.
Dr. Francesco Parisio (TU Bergakademie Freiberg) and Prof. Noriaki Watanabe (Tohoku University)
Dr. Keita Yoshioka (Helmholtz Centre for Environmental Research GmbH – UFZ, Leipzig) and Prof. Kiyotoshi Sakaguchi (Tohoku University)
Parisio, F., Vinciguerra, S., Kolditz, O., & Nagel, T. (2019). The brittle-ductile transition in active volcanoes. Scientific reports, 9(1), 143.
Watanabe, N., Numakura, T., Sakaguchi, K., Saishu, H., Okamoto, A., Ingebritsen, S. E., & Tsuchiya, N. (2017a). Potentially exploitable supercritical geothermal resources in the ductile crust. Nature Geoscience, 10(2), 140.
Watanabe, N., Egawa, M., Sakaguchi, K., Ishibashi, T., & Tsuchiya, N. (2017b). Hydraulic fracturing and permeability enhancement in granite from subcritical/brittle to supercritical/ductile conditions. Geophysical Research Letters.