Relationship between rate of aperture reduction and contact pressure of fracture in granite under hydrothermal condition

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A coupled experimental and numerical analysis was performed on artificial fractures of granite in order to evaluate a relationship between a rate of aperture reduction and a contact pressure under hydrothermal conditions. In the experimental work, distilled water was injected into the fractures of 150 °C at the different effective confining pressures of 16 and 25 MPa during several tens of hours. At both the effective confining pressures, the fracture permeabilities decreased non-monotonically with time. Since Si concentrations of effluents were far from saturation over the range of experiments, the predominant reaction within the fractures was dissolution of rock-forming minerals. In addition, the surface mapping did not show significant changes in the fracture surface roughness between before and after the experiment, suggesting that the permeability reductions originated mainly from the aperture reductions by pressure solution of contacting asperities. The rates of aperture reduction were therefore evaluated on the basis of the numerical modeling of the aperture structures during the experiment. The numerically determined changes in the aperture reduction and the contact pressure of the fractures provided the rates of aperture reduction of 1.0-6.4 μm/hour for the contact pressures of 35-54 MPa. Although the relationship between the aperture reduction and the contact pressure was far from one-to-one, the rate of aperture reduction seemed to grow exponentially with an increase of contact pressure.

Original languageEnglish
Title of host publicationGeothermal Resources Council Annual Meeting 2008
Subtitle of host publication"Geothermal - Gaining Steam"
Pages416-421
Number of pages6
Publication statusPublished - 2008 Dec 1
EventGeothermal Resources Council Annual Meeting 2008: "Geothermal - Gaining Steam" - Reno, NV, United States
Duration: 2008 Oct 52008 Oct 8

Publication series

NameTransactions - Geothermal Resources Council
Volume32
ISSN (Print)0193-5933

Other

OtherGeothermal Resources Council Annual Meeting 2008: "Geothermal - Gaining Steam"
CountryUnited States
CityReno, NV
Period08/10/508/10/8

Keywords

  • Aperture reduction
  • Contact pressure
  • ECS
  • Granite fracture
  • Hydrothermal condition

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Geophysics

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