Reactive transport under stress: Permeability evolution in deformable porous media

R. Roded, X. Paredes, R. Holtzman

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We study reactive transport in a stressed porous media, where dissolution of the solid matrix causes two simultaneous, competing effects: pore enlargement due to chemical deformation, and pore compaction due to mechanical weakening. We use a novel, mechanistic pore-scale model to simulate flooding of a sample under fixed confining stress. Our simulations show that increasing the stress inhibits the permeability enhancement, increasing the injected volume required to reach a certain permeability, in agreement with recent experiments. We explain this behavior by stress concentration downstream, in the less dissolved (hence stiffer) outlet region. As this region is also less conductive, even its small compaction has a strong bottleneck effect that curbs the permeability. Our results also elucidate that the impact of stress depends on the dissolution regime. Under wormholing conditions (slow injection, i.e. high Damkohler number, Da), the development of a sharp dissolution front and high porosity contrast accentuates the bottleneck effect. This reduces transport heterogeneity, promoting wormhole competition. Once the outlet starts eroding, the extreme focusing of transport and hence dissolution—characteristic of wormholing—becomes dominant, diminishing the bottleneck effect and hence the impact of stress at breakthrough. In contrast, at high flow rates (low Da), incomplete reaction upstream allows some of the reactant to traverse the sample, causing a more uniform dissolution. The continuous dissolution and its partial counteraction by compaction at the outlet provides a steady, gradual increase in the effect of stress. Consequently, the impact of stress is more pronounced at high Da during early stages (low permeability), and at low Da close breakthrough. Our work promotes understanding of the interplay between dissolution and compaction and its effect on the hydromechanical property evolution, with important implications for processes ranging from diagenesis and weathering of rocks, to well stimulation and carbon sequestration.

Original languageEnglish
Pages (from-to)198-207
Number of pages10
JournalEarth and Planetary Science Letters
Volume493
Early online date3 May 2018
DOIs
Publication statusPublished - 1 Jul 2018
Externally publishedYes

Fingerprint

reactive transport
Porous materials
porous medium
permeability
dissolving
Dissolution
dissolution
Compaction
outlets
compaction
porosity
Well stimulation
Damkohler number
Curbs
stress concentration
weathering
scale models
Weathering
stimulation
confining

Keywords

  • hydro-chemo-mechanical coupling
  • mechanical compaction
  • mineral dissolution
  • permeability evolution
  • pore-scale simulations
  • wormholing

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Reactive transport under stress : Permeability evolution in deformable porous media. / Roded, R.; Paredes, X.; Holtzman, R.

In: Earth and Planetary Science Letters, Vol. 493, 01.07.2018, p. 198-207.

Research output: Contribution to journalArticle

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