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1990 Fiscal Year Final Research Report Summary

Transient, Dynamic Response of a Reservoir Crack Against an Artificial Hydraulic Stimulation

Research Project

Project/Area Number 01550064
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 材料力学
Research InstitutionTohoku University

Principal Investigator

HAYASHI Kazuo  Tohoku Univ., Inst. Fluid Sci., Prof., 流体科学研究所, 教授 (30111256)

Co-Investigator(Kenkyū-buntansha) NIITSUMA Hiroaki  Tohoku Univ., Dept. Min. Miner. Eng., Prof., 工学部, 教授 (90108473)
Project Period (FY) 1989 – 1990
KeywordsFracture / Geothermal Energy / HDR / Crack Characterization / Subsurface Crack / Elastic Wave / Inverse Problem / Subsurface Structure
Research Abstract

Transient, elastic, dynamic response was analyzed for a subsurface reservoir crack subjected to an artificial hydraulic stimulation, based on linear theory of dynamic elasticity and linear fracture mechanics. In the image spaces of Laplace and Fourier transforms, the problem was found to be reduced to solving a singular integral equation with a dominant term defined by finite part integral, where the singular integral equation was coupled with a motion of fluid trapped in the crack. Based on the analysis, characterization of a subsurface crack by the triaxial hodogram method using acoustic emission was examined in detail. The conclusion are summarized as follows :
1. For a attenuating medium, the tri-axial hodogram method maps an AE source as a point inside inside the crack periphery or one of the crack tips, depending on the location of the observation station relative to the reservoir crack.
2. The peak frequency which appears in the spectrum of the circumferential displacement corresponds to the natural frequency of the lowest, symmetric mode of the oscillation of the crack surface it self. Therefore, the value of the peak frequency depends only on the crack size and the crack stiffness and independent of the observation station and the intensity of attenuation of the medium.
3. The energy of the elastic waves due to a tensile mode crack was found out to numerically to be significantly smaller than that due to a shear mode crack. This is due to the fact that the failure of asperities caused by rubbing between the two crack surfaces is primary cause of the elastic waves from a shear mode crack, not the fracture toughness. This theoretical evidence was verified by the examination, using the so-called grid method, of the experimental AE data obtained during hydraulic fracturing conducted in a huge, rock specimen (10mx10mx10mx).

  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] 林 一夫, 飯村 正彦: "三軸ホドグラム法による地下き裂位置標定に対する弾性波の減衰の影響" 日本機械学会材料力学構演会講演概要集. 890ー59. 80-81 (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 林 一夫, 茂木 周二: "円板状地下き裂からの弾性波により誘起される粒子運動と地下き裂位置標定" 日本機械学会論文集(A). 56. 817-824 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 宮本 剛寿, 林 一夫, 阿部 博之: "AE波による岩体内き裂モ-ドの判別の可能性ー超大型岩石試験片の水圧破砕時の弾性波エネルギ-の検討ー" 資源・素材学会,地下き裂のキャラクタリゼ-ションワ-クショップ論文集. 60-64 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Hayashi,M.Iimura: "Elastic Waves Radiating from a Penny Shaped Reservoir Crack in a Rock with Attenuation and Mapping of a Reservoir Crack" Progress in Acoustic Emission,Jpn.Sec.NDI. V. 203-210 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Hayashi: "A BIEM Approach to the Problem of a Dynamically Excited Crack with Applications to the Characterization of a Hydraulically Stimulated Geothermal Reservoir Crack" Proc.of Fith Conf.AE/MS Activity in Geologic Struc.Mater.(1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K. Hayashi and M. Iimura: "Effect of Attenuation on the Characterization Reservoir Crack by the Tri-Axial Hodogram Method (in Japanese)" Proc. Conf. Strength Mater. JSME,. 890-59. 80-81 (1989)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Hayashi and S. Motegi: "Particle Motion Induced by Elastic Waves Radiating from Subsurface, Penny-Shaped Cracks and Mapping of Subsurface Cracks (in Japanese)" Bull. JSME (Ser. E),. 56-524. 817-824 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T. Miyamoto, K. Hayashi and H. Abe: "Feasibility for Distinguishing the Deformation Mode of a Crack in Rock Masses by AE - Consideration on A during Hydrofracs in a Huge Rock Specimen - (in Japanese)" Proc. Wrksp. Charact. Subsurf. Cracks,. 60-64 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Hayashi and M. Iimura: "Elastic Waves Radiating from a Penny Shaped Reservoir Crack in a Rock with Attenuation Mapping of a Reservoir Crack" Progress in Acoustic Emission. V. 203-210 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Hayashi: "A BIEM Approach to the Problem of a Hydraulically Excited Crack, with Applications to the Characterization of a Hydraulically Stimulated Geothermal Reservoir Crack" Proc. 5th Conf. AE/MS Activity in Geol. Strus. Mater.(1991)

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

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Published: 1993-08-12  

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