Development of rock fracturing simulator that combines damage theory and THMC coupling and its application to geothermal development

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01869
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: Kyoto University
• Principal Investigator: Kishida Kiyoshi 京都大学, 工学研究科, 教授 (20243066)
• Co-Investigator(Kenkyū-buntansha): 緒方 奨 大阪大学, 大学院工学研究科, 助教 (50868388) ; 中島 伸一郎 山口大学, 大学院創成科学研究科, 准教授 (70346089) ; 安原 英明 京都大学, 工学研究科, 教授 (70432797) ; 三好 貴子 京都大学, 工学研究科, 特定助教 (30982318)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 水圧破砕 / 損傷理論 / THMC連成解析 / 透水試験 / 地熱開発

Outline of Final Research Achievements

The proposed method, which takes into account the mineral distribution of the rock and the mechanical properties of the mineral boundary, succeeds in reproducing the basic mechanical properties in a crushing tensile test. It was also confirmed that when a fracture occurs prior to the surrounding surface, such as at a mineral interface, tensile stress concentrates at both ends of the fracture and the crack propagates, and that these cracks connect to form a macroscopic fracture.
To investigate the permeability of single cracks in granite, a combination of permeability tests and X-ray computed tomography (CT) studies were conducted. Heat-induced irreversible behavior of the crack contact state was observed, indicating a tendency for the aperture to close. Long-term tests revealed that the pressure and temperature environment had an influence on the permeability.

Free Research Field

岩盤工学

Academic Significance and Societal Importance of the Research Achievements

水圧破砕による熱・圧力の影響を考慮した亀裂進展過程を精緻に説明できるシミュレータの開発は，安定的な地熱増産システムの開発につながる．また，熱・圧力環境下でき裂の構造が変化し，透過率を変化するメカニズムを捉えることは，長期間の安定的な地熱開発に寄与するものである．
これらの技術は，長期間，岩盤に物質を安定的にこていする技術にも援用可能であり，エネルギー生成後の副産物（CO2や高レベル放射性廃棄物）の処分事業に援用できる技術である．