Coupled flow-deformation analysis of hot dry rock stimulation

J. Vychytil, H. Horii, Kazuo Hayashi

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The mechanical response of rock masses to hydrofracturing injections applied during Hot Dry Rock (HDR) stimulations is studied. A coupled flow-deformation model is formulated by combining the governing equation for the mechanical behaviour with that for the flow of water in joints. A micromechanical-based continuum model for jointed rock masses under hydrofracturing is employed. Sliding of natural joints assisted by the action of water pressure is assumed for the governing mechanism of hydrofracturing. Coupled FEM analysis is then carried out with input parameters from two HDR project test sites. With the time history of injection flow rate as an input, the analysis allows prediction of the size, shape and permeability of the fractured zone, and injection water pressure in time. The analysis reproduces the phenomenon observed in experiments: with increasing injection flow rate due to expansion of joints and enhancement of permeability, water pressure does not increase after a certain critical pressure is attained. Predicted permeability distributions also agree with the spatial distribution of acoustic emission source locations recorded during both HDR stimulation tests.

Original languageEnglish
Pages (from-to)259-279
Number of pages21
JournalGeothermal Science and Technology
Volume6
Issue number1-4
Publication statusPublished - 1999 Jan 1

Keywords

  • Flow deformation
  • Hot dry rock
  • Mechanical response
  • Rock mechanics

ASJC Scopus subject areas

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

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