Effect of distance between drilled well and pre-existing fault on induced earthquakes

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14579
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Kitamura Manami 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 研究員 (40795960)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 誘発地震 / 注水 / 応力降下

Outline of Final Research Achievements

It is known that the induced earthquakes occur with the fluid injection. Therefore, it is important to investigate fault slip characteristics associated with fluid injection from laboratory fluid injection tests. In this study, we conducted laboratory fluid injection tests focusing on the distance between the drilled well (or injection point) and the existing fault, and other parameters related to the fluid injection such as permeability of host rock, injection rate, and effective pressure. As a result, the rapid stress drop is observed regardless of the fluid injection rate when the permeability to the fault surface is enough high, and a rapid stress drop is observed at higher effective pressure, while a gentle stress drop tends to occur at lower effective pressure.

Free Research Field

実験岩石力学

Academic Significance and Societal Importance of the Research Achievements

注水、つまり間隙水圧の上昇によって断層運動がおこることはよく知られていたが、どのような注水、間隙水圧の上昇方法が、どのような断層すべり特性（急激な応力降下やゆっくりとした応力降下か、など）を示すかはこれまであまり調べられていなかった。本研究によって、様々なパラメータが断層すべり特性に寄与していることが明らかになった。また注水誘発地震は、様々な地圏の地活用事業において問題視されているため、発生メカニズムの解明は地圏の地活用事業の促進に貢献できる。