Influence of fracture roughness on shear strength, slip stability and permeability: A micro mechanistic analysis by 3D digital rock physics

Chaoyi Wang, Derek Elsworth, Yi Fang, Fengshou Zhang

Research output: Contribution to conferencePaper

Abstract

Subsurface fluid injection can disturb the effective stress regime by elevating pore pressure and potentially reactivate faults and fractures. Laboratory studies indicate that fracture rheology and permeability in such reactivation events are linked to the roughness of the fracture surfaces. We construct discrete element method (DEM) models to explore the influence of fracture surface roughness on the shear strength, slip stability, and permeability evolution during such slip events. For each simulation, a pair of analog rock coupons (3D bonded quartz-particle analogs) representing a mated fracture are sheared under a velocity-stepping scheme. The roughness of the fracture is defined in terms of asperity height and asperity wavelength. Results show that (1) samples with larger asperity heights (rougher), when sheared, exhibit a higher peak strength which quickly devolves to a residual strength after a threshold shear displacement; (2) these rougher samples also exhibit greater slip stability due to a high degree of asperity wear and resultant production of wear products; (3) long-term suppression of permeability is observed with rougher fractures, which is plausibly due to the removal of asperities and redistribution of wear products, which locally reduces porosity in the dilating fracture. This study provides insights into the understanding of the mechanisms of frictional and rheological evolution of rough fractures anticipated during reactivation events.

Original languageEnglish (US)
StatePublished - Jan 1 2019
Event53rd U.S. Rock Mechanics/Geomechanics Symposium - Brooklyn, United States
Duration: Jun 23 2019Jun 26 2019

Conference

Conference53rd U.S. Rock Mechanics/Geomechanics Symposium
CountryUnited States
CityBrooklyn
Period6/23/196/26/19

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

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    Wang, C., Elsworth, D., Fang, Y., & Zhang, F. (2019). Influence of fracture roughness on shear strength, slip stability and permeability: A micro mechanistic analysis by 3D digital rock physics. Paper presented at 53rd U.S. Rock Mechanics/Geomechanics Symposium, Brooklyn, United States.