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

Fingerprint

shear strength
microanalysis
Shear strength
roughness
permeability
slip
physics
Physics
Surface roughness
Rocks
rocks
asperity
rock
Wear of materials
reactivation
residual strength
fluid injection
analogs
porosity
analysis

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

Cite this

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.
Wang, Chaoyi ; Elsworth, Derek ; Fang, Yi ; Zhang, Fengshou. / 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.
@conference{b8cc34f61aba4d6a9b59a8971eea40ad,
title = "Influence of fracture roughness on shear strength, slip stability and permeability: A micro mechanistic analysis by 3D digital rock physics",
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.",
author = "Chaoyi Wang and Derek Elsworth and Yi Fang and Fengshou Zhang",
year = "2019",
month = "1",
day = "1",
language = "English (US)",
note = "53rd U.S. Rock Mechanics/Geomechanics Symposium ; Conference date: 23-06-2019 Through 26-06-2019",

}

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, 6/23/19 - 6/26/19.

Influence of fracture roughness on shear strength, slip stability and permeability : A micro mechanistic analysis by 3D digital rock physics. / Wang, Chaoyi; Elsworth, Derek; Fang, Yi; Zhang, Fengshou.

2019. Paper presented at 53rd U.S. Rock Mechanics/Geomechanics Symposium, Brooklyn, United States.

Research output: Contribution to conferencePaper

TY - CONF

T1 - Influence of fracture roughness on shear strength, slip stability and permeability

T2 - A micro mechanistic analysis by 3D digital rock physics

AU - Wang, Chaoyi

AU - Elsworth, Derek

AU - Fang, Yi

AU - Zhang, Fengshou

PY - 2019/1/1

Y1 - 2019/1/1

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85074065107&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85074065107&partnerID=8YFLogxK

M3 - Paper

AN - SCOPUS:85074065107

ER -

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