Permeability reduction of a natural fracture under net dissolution by hydrothermal fluids

A. Polak, D. Elsworth, H. Yasuhara, A. S. Grader, P. M. Halleck

Research output: Contribution to journalArticle

130 Scopus citations

Abstract

Flow-through tests are completed on a natural fracture in novaculite at temperatures of 20°C, 80°C, 120°C, and 150°C. Measurements of fluid and dissolved mass fluxes, and concurrent X-ray CT imaging, are used to constrain the progress of mineral dissolution and its effect on transport properties. Under constant effective stress, fracture permeability decreases monotonically with an increase in temperature. Increases in temperature cause closure of the fracture, although each increment in temperature causes a successively smaller effect. The initial differential fluid pressure-drop across the fracture increases by two orders of magnitude through the 900 h duration of the test, consistent with a reduction of an equivalent hydraulic aperture by a factor of five. Both the magnitude and rate of aperture reduction is consistent with the dissolution of stressed asperities in contact, as confirmed by the hydraulic and mass efflux data. These observations are confirmed by CT imaging, resolved to 35 microns, and define the potentially substantial influence that benign changes in environmental conditions of stress, temperature, and chemistry may exert on transport properties.

Original languageEnglish (US)
Pages (from-to)SDE 1-1 - SDE 1-4
JournalGeophysical Research Letters
Volume30
Issue number20
DOIs
StatePublished - Oct 15 2003

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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