Detection of traveltime delay caused by inflation of a single artificial fracture

Katsuro Tanaka, Hirokazu Moriya, Hiroshi Asanuma, Hiroaki Niitsuma, Kazuo Hayashi

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

We observed traveltime delays of transmitted waves during pressurization of a subsurface artificial fracture at Higashi Hachimantai geothermal field, Iwate Prefecture, Japan. The transmitted waves generated by a downhole air gun were observed by the downhole triaxial seismic detector during pressurization. Traveltime delay was detected by the cross-spectrum method with a resolution of 0.01 ms. There is a strong correlation between the wellhead pressure and traveltime of P- and S-waves. The P- and S- wave traveltime delays of about 0.2 ms to 0.3 ms maximum were observed when the fracture was pressurized up to 3.4 MPa. We discuss the mechanism of this phenomenon using a model of a fracture with micro-cracks in the vicinity of the main fracture which are hydraulically connected with each other.

Original languageEnglish
Pages (from-to)181-200
Number of pages20
JournalGeothermal Science and Technology
Volume6
Issue number1-4
Publication statusPublished - 1999 Jan 1

Keywords

  • Artificial fracture
  • Cross-spectrum analysis
  • Crosshole seismic measurement
  • HDR
  • Process zone
  • Subsurface
  • Traveltime delay

ASJC Scopus subject areas

  • Water Science and Technology
  • Ocean Engineering
  • Management of Technology and Innovation

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