TY - JOUR
T1 - Cloud-fracture networks as a means of accessing superhot geothermal energy
AU - Watanabe, Noriaki
AU - Sakaguchi, Kiyotoshi
AU - Goto, Ryota
AU - Miura, Takahiro
AU - Yamane, Kota
AU - Ishibashi, Takuya
AU - Chen, Youqing
AU - Komai, Takeshi
AU - Tsuchiya, Noriyoshi
N1 - Funding Information:
The present study was supported in part by the Japan Society for the Promotion of Science (JSPS) through Grants-in-Aid for Specially Promoted Research (No. 25000009), Scientific Research (B) (No. 17H03504) and Challenging Research (Exploratory) (No. 18K19039) and by the Arai Science and Technology Foundation through a Grant-in-Aid for General Scientific Research. In addition, some results reported herein were obtained under a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). The authors would like to thank the Toei Scientific Industrial Co., Ltd. for manufacturing the experimental system with the true triaxial cell.
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Superhot geothermal environments (above ca. 400 °C) represent a new geothermal energy frontier. However, the networks of permeable fractures capable of storing and transmitting fluids are likely to be absent in the continental granitic crust. Here we report the first-ever experimental results for well stimulation involving the application of low-viscosity water to granite at temperatures ≥400 °C under true triaxial stress. This work demonstrates the formation of a network of permeable microfractures densely distributed throughout the entire rock body, representing a so-called cloud-fracture network. Fracturing was found to be initiated at a relatively low injection pressure between the intermediate and minimum principal stresses and propagated in accordance with the distribution of preexisting microfractures, independent of the directions of the principal stresses. This study confirms the possibility of well stimulation to create excellent fracture patterns that should allow the effective extraction of thermal energy.
AB - Superhot geothermal environments (above ca. 400 °C) represent a new geothermal energy frontier. However, the networks of permeable fractures capable of storing and transmitting fluids are likely to be absent in the continental granitic crust. Here we report the first-ever experimental results for well stimulation involving the application of low-viscosity water to granite at temperatures ≥400 °C under true triaxial stress. This work demonstrates the formation of a network of permeable microfractures densely distributed throughout the entire rock body, representing a so-called cloud-fracture network. Fracturing was found to be initiated at a relatively low injection pressure between the intermediate and minimum principal stresses and propagated in accordance with the distribution of preexisting microfractures, independent of the directions of the principal stresses. This study confirms the possibility of well stimulation to create excellent fracture patterns that should allow the effective extraction of thermal energy.
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U2 - 10.1038/s41598-018-37634-z
DO - 10.1038/s41598-018-37634-z
M3 - Article
C2 - 30700779
AN - SCOPUS:85060941597
VL - 9
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 939
ER -