2005 Fiscal Year Final Research Report Summary
Development of measurement method for high permeable fracture system by the multiplet-clustering analysis.
| Project/Area Number |
16560710
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 |
MORIYA Hirokazu Tohoku University, Graduate School of Engineering, Lecturer, 大学院・工学研究科, 講師 (60261591)
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| Co-Investigator(Kenkyū-buntansha) |
NIITSUMA Hiroaki Tohoku University, Graduate School of Environmental Studies, Professor, 大学院・環境科学研究科, 教授 (90108473)
ASANUMA Hiroshi Tohoku University, Graduate School of Environmental Studies, Associate Professor, 大学院・環境科学研究科, 助教授 (50250717)
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| Project Period (FY) |
2004 – 2005
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| Keywords | AE / Microearthquakes / Geothermal / Fracture / Permeability / Multiplet / Fault / Shear slip |
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| Research Abstract |
In this research, we have examined the parameters for estimation of high permeable fracture by using induced AE multiplet, where the field data were analyzed and model experiment using granite rock specimen was also carried out in order to study the relation between the induced AE events and the permeable fractures. The relationships among AE occurrence, shear slip, flow rate and pressure in fracture has been investigated through the model experiments, where the shear slip was artificially induced using split rock specimen under the parameter controlled high stiffness system. On the other hand, the induced AE at Coper Basin in Australia and Soultz in France was analyzed and the relationships among the injection pressure, flow rate and AE occurrence were examined. The distribution of the critical pore-pressure for shear slip of fracture has been estimated at Soultz, and the pore-pressure propagation and the formation process of permeable fracture system has been examined. It has been revealed that the permeable fracture system in the reservoir is developed by the linkage of preexisting permeable fractures due to the shear slip of fractures which favorably oriented to the principal stress direction and easily caused shear slip. In addition, it has also been revealed that the pore-pressure spreads in few hundred meters in the reservoir without pressure drop and the pore-pressure exponentially declines as a function of distance from the outlet point in the injection well. On the basis of the above mentioned studies, we have proposed a measurement method for estimation of permeable fractures in reservoir by using the induced AE multiplets.
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