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1999 Fiscal Year Final Research Report Summary

Dynamic Response of a Fluid-filled 3-D Crack and its Application to Characterization of Geothermal Reservoir Cracks

Research Project

Project/Area Number 10650070
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Materials/Mechanics of materials
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

HAYASHI Kazuo  Institute of Fluid Science, Tohoku University, Professor, 流体科学研究科, 教授 (30111256)

Co-Investigator(Kenkyū-buntansha) NAGAO Koji  Faculty of Engineering, Muroran Institute of Technology, Research Associate, 工学部, 助手 (90212109)
NIITSUMA Hiroaki  Graduate School of Engineering, Tohoku University, Professor, 工学研究科, 教授 (90108473)
Project Period (FY) 1998 – 1999
KeywordsGeothermal Energy / HDR / Geothermal Reservoir Crack / Crack Characterization / AE / Elastic Wave
Research Abstract

The dynamic response of a fluid-filled penny shaped crack, which was a typical example of 3-D cracks, was analyzed in detail in the framework of the theory of elasto-dynamics. It was revealed that the response was divided into tree types (Type I, II and III). Type I is the group that does not have any clear peaks in the power spectrum of the oscillation of the crack surface, and Type III is the group that has very clear peaks of fundamental modes in the power spectrum. Type II is in between Type I and Type III. Type III appears under the condition that attenuation of the wave traveling along the crack surfaces is weak and thus standing wave can be easily formed due to the reflection of the elastic wave at the crack periphery. Since Type III is far more informative than the other two and thus is preferable for the estimation of the crack parameters, it can be recommended that the reservoir pressure should be kept as higher as possible during the field experiments of active acoustic techniques.
A new method is proposed for estimating the crack size, aperture and interfacial stiffness which is caused due to the asperity contact between the two crack surfaces. The method compares the frequencies of the fundamental modes of the standing wave, that are theoretically determined by the analyses just mentioned above, with the peak frequencies of the elastic waves observed during the field experiments such as hydraulic fracturing. The method was successfully applied to the field data obtained during hydraulic fracturing conducted in Hijiori and Ogachi HDR/HWR fields. Crack size and aperture in Hijiori field were estimated to be 5-11m and 1-44mm, respectively. Those in the Ogachi field are 4-28n and 10-22mm.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] 伊藤伸: "地下き裂の振動特性におよぼすき裂面接触剛性の影響"日本機械学会論文集(A). 64. 91-96 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] S.Ito: "Effect of Fluid Viscosity, Permeability of Rock and Crack Interfacial Stiffness on Dynamic Response of a Penny Shaped Geothermal Reservoir Crack -Further Details-"Geothermal Resources Council Transaction. 22. 203-210 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 林一夫: "地下き裂の振動特性におよぼすき裂面上の接触位置の影響"日本機械学会東北支部地方講演会講演論文集. 981. 29-30 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Nagano: "Crack-Wave Dispersion at a Fluid-Filled Fracture with Low Velocity Layers"Geophysical Journal International. 134. 903-910 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] S.Ito: "Fracture Characterization from Microcosmic Events at Hijiori and Ogachi Fields in Japan"Geothermal Resources Council Transaction. 23. 265-270 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 多田祥明: "地下き裂に発生する定在波を用いたき裂評価に関する研究―き裂先端から流体のもれがある場合―"第6回地下と土木のAE国内総合コンファレンス論文集. 112-116 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] S. Ito: "Effect of Fluid Viscosity, Permeability of Rock and Crack Interfacial Stiffness on Dynamic Response of a Geothermal Reservoir Crack (Penny Shaped Crack Model)"Trans. JSME Ser.A. 624-64. 91-96 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] S. Ito: "Effect of Fluid Viscosity, Permeability of Rock and Crack Interfacial Stiffness on Dynamic Response of a Penny Shaped Geothermal Reservoir Crack - Further Details -"Geothermal Resources Council Transaction. 22. 203-210 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Hayashi: "Dynamics of Geothermal Reservoirs Cracks - Effect of Position of Contact between Crack Surface -"Proc. JSME Conf. Tohoku Branch. 981. 29-30 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Nagano: "Crack-Wave Dispersion at a Fluid-Filled Fracture with Low Velocity Layers"Geophysical Journal International. 134. 903-910 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] S. Ito: "Fracture Characterization from Microseimic Events at Hijiori and Ogachi Fields in Japan"Geothermal Resources Council Transaction. 23. 265-270 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Y. Tada: "Characterization of Subsurface Cracks Based on Standing Waves - Effect of Fluid Leakage at the Crack Tips -"Proc. 6th Domestic Conf. AE in Subsurface and Civil Engng.. 112-116 (1999)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2001-10-23  

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