| Project/Area Number |
18360429
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Earth system and resources enginnering
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| Research Institution | Tohoku University |
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Principal Investigator |
ITO Takatoshi Tohoku University, Institute of Fluid Science, Associate Professor (00184664)
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| Co-Investigator(Kenkyū-buntansha) |
SEKINE Kotaro Tohoku University, Institute of Fluid Science, Assistant Professor (70361194)
ITO Hisao Center for Deep Earth Exploration, Japan Agency for Marine Science and Technology, Principal Research Scientist (10356470)
OMURA Kentaro Earthquake Research Department, National Research Institute for Earth Science and Disaster Prevention, Senior Researcher (90399361)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥17,820,000 (Direct Cost: ¥15,000,000、Indirect Cost: ¥2,820,000)
Fiscal Year 2007: ¥12,220,000 (Direct Cost: ¥9,400,000、Indirect Cost: ¥2,820,000)
Fiscal Year 2006: ¥5,600,000 (Direct Cost: ¥5,600,000)
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| Keywords | Hydraulic fracturing / In-situ stress / In-situ measurement / Reopening pressure / High stiffness / Deep depth / Over coring / BABHY / BABHT |
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| Research Abstract |
Hydraulic fracturing is suitable in principle for in-situ stress measurements at deep depths. However, as has been pointed out recently, its current testing systems and procedure involve essential problems which have to be solved before putting the principle into practice. The most serious problem is associated with the hydraulic compliance of fracturing systems. For measuring the reopening pressure, it is necessary to use the fracturing system with sufficiently small compliance. If not, there is no way to estimate the maximum horizontal stress from the reopening pressure assuming a vertical borehole, even though the maximum horizontal stress is the greatest concern in the stress measurement. This limitation makes it difficult to apply hydraulic fracturing for the stress measurement, because the compliance of the conventional system is so large. Taking into account of these facts, we have proposed recently a new method which will allow us to measure both of the maximum and minimum stresses by in-situ tests of hydraulic fracturing at a depth greater than a few km. We have proceeded to test and verify the method step by step so far through laboratory and field experiments using a borehole of 80 m in depth drilled from the ground surface at Matsushiro. Finally, we succeeded to apply the method to an in-situ test of hydraulic fracturing at a depth of 811 m in a vertical borehole drilled from the ground surface at Tazawako.
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