Short-timescale chemo-mechanical effects and their influence on the transport properties of fractured rock

Derek Elsworth, Hideaki Yasuhara

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Anomalous changes in permeability are reported in fractures circulated by fluids undersaturated with respect to the mineral host. Under net dissolution and net removal of mineral mass, fractures may alternately gape or seal, depending on the prevailing mechanical and chemical conditions. The influence on transport properties is observed to be large, rapid, and irreversible: Permeabilities may change by two orders of magnitude in a month, and the direction of permeability change may switch spontaneously, for no apparent change in environmental forcing. These behaviors are apparent in continuous circulation experiments conducted on fractures in novaculite and limestone, intermittently imaged by X-ray CT. In novaculite, permeability reduces by two orders of magnitude as silica is net removed from the sample. Surprisingly, these changes can occur at modest temperatures (∼80°C) and stresses (∼3.5 MPa), where compaction progresses as temperatures are incremented. Isothermal (∼20°C) circulation tests in limestone show similar compaction driven by pressure solution. Where circulation remains undersaturated in Ca, the change in permeability spontaneously switches from net reduction to net increase as a wormhole forms. The surprising magnitude and rapidity of these changes are investigated in the context of the competition between stress- and chemistry-mediated effects.

Original languageEnglish (US)
Pages (from-to)2051-2070
Number of pages20
JournalPure and Applied Geophysics
Volume163
Issue number10
DOIs
StatePublished - Oct 1 2006

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Transport properties
permeability
Calcium Carbonate
transport properties
Rocks
rocks
timescale
Minerals
Compaction
Switches
rock
limestone
compaction
Silicon Dioxide
Seals
minerals
Dissolution
pressure solution
X rays
mineral

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Cite this

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Short-timescale chemo-mechanical effects and their influence on the transport properties of fractured rock. / Elsworth, Derek; Yasuhara, Hideaki.

In: Pure and Applied Geophysics, Vol. 163, No. 10, 01.10.2006, p. 2051-2070.

Research output: Contribution to journalArticle

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