Shear-induced permeability enhancement

Kyungjae Im, Derek Elsworth, Yi Fang

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

Abstract

Shear induced permeability evolution is a crucial mechanism in understanding changes in the subsurface hydraulic system driven by natural seismic events and in the stimulation for subsurface energy recovery. We investigate permeability response during aseismic-through-seismic shear deformation on saw-cut fractures of varying low-order roughness. We report shear-instability-permeability direct shear experiments on Westerly granite in a triaxial pressure cell that concurrently and continuously measures friction and permeability during multiple sequential slide and hold events. We observe two clearly different responses in permeability evolution representing end-of-spectrum behaviors. These are (i) shear induced permeability reduction which is dominant in the initial stage of shear slip to a shear offset of several millimeters and (ii) gradual permeability enhancement with further shear offset. When the sample is static (experimental hold period), permeability continuously decreases and follows a power law decay with time. We observe that, with a given (~1mm) shear displacement, the normalized permeability enhancement Δq/qinitial is greater after a longer hold period. This observation implies that the permeability of natural pre-existing faults that are locked over long durations can be significantly enhanced by shear deformations. The result suggests that permeability can be engineered in reservoirs by reactivated shear deformation and also suggests that the well-documented seismicity-associated permeability increase in natural hydraulic systems (e.g., Elkhoury et. al., 2006) may also be contributed to by systematic shear deformations.

Original languageEnglish (US)
Title of host publication4th ISRM Young Scholars Symposium on Rock Mechanics, YSS 2017
PublisherInternational Society for Rock Mechanics
Pages383-385
Number of pages3
ISBN (Electronic)9791156103158
StatePublished - Jan 1 2017
Event4th ISRM Young Scholars Symposium on Rock Mechanics, YSS 2017 - Jeju, Korea, Republic of
Duration: May 10 2017May 13 2017

Publication series

Name4th ISRM Young Scholars Symposium on Rock Mechanics, YSS 2017
Volume2017-May

Other

Other4th ISRM Young Scholars Symposium on Rock Mechanics, YSS 2017
CountryKorea, Republic of
CityJeju
Period5/10/175/13/17

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All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology
  • Geophysics

Cite this

Im, K., Elsworth, D., & Fang, Y. (2017). Shear-induced permeability enhancement. In 4th ISRM Young Scholars Symposium on Rock Mechanics, YSS 2017 (pp. 383-385). (4th ISRM Young Scholars Symposium on Rock Mechanics, YSS 2017; Vol. 2017-May). International Society for Rock Mechanics.