Title: Permeability Evolution and Frictional Stability of Fabricated Fractures With Specified Roughness

Abstract

Roughness is widely observed on natural fractures, and its impact on the potential for induced seismicity and associated fluid migration in the subsurface remains unclear. Here we perform fracture shearing and fluid flow experiments on artificially fabricated fractures with specified roughness to investigate the role of fracture roughness on frictional properties and permeability evolution. Given the experimental conditions, we observe that rough fractures show high roughness ratio S _q/L _w and return higher frictional strength due to the presence of cohesive interlocking asperities. Rough fracture surfaces show velocity strengthening behavior in the initial shearing stage, which may evolve to velocity neutral and velocity weakening at greater displacements—suggesting a dynamic weakening that rough fractures become less stable with shearing. The surface roughness exerts a dominant control on permeability evolution over the entire shearing history. Permeability declines monotonically by about 2 orders of magnitude for smooth fractures. For high roughness fractures, the permeabilities evolve episodically due to cycled compaction and dilation during shearing. With a slip distance of 6 to 8 mm, permeability of the rough surface may enhance up to an order of magnitude, but significant permeability reduction may also occur for rough samples when asperities are highly worn with gougemore » clogging flow paths. However, there is no obvious correlation between permeability evolution and frictional behavior for rough fracture samples when fractures are subject to sudden sliding velocity changes.« less

Authors:

Fang, Yi  ^[1];

• Search DOE PAGES for author "Fang, Yi"
• Search DOE PAGES for ORCID "0000-0003-3837-6794"

Elsworth, Derek  ^[2];

• Search DOE PAGES for author "Elsworth, Derek"
• Search DOE PAGES for ORCID "0000-0002-4942-1151"

Ishibashi, Takuya  ^[3];

• Search DOE PAGES for author "Ishibashi, Takuya"
• Search DOE PAGES for ORCID "0000-0002-7998-0595"

Zhang, Fengshou  ^[4]

• Search DOE PAGES for author "Zhang, Fengshou"
• Search DOE PAGES for ORCID "0000-0002-4998-6259"

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+ Show Author Affiliations

1. Univ. of Texas, Austin, TX (United States). Inst. for Geophysics; Pennsylvania State Univ., University Park, PA (United States). EMS Energy Inst., and G3 Center
2. Pennsylvania State Univ., University Park, PA (United States). EMS Energy Inst., and G3 Center
3. Pennsylvania State Univ., University Park, PA (United States). EMS Energy Inst., and G3 Center; National Inst. of Advanced Industrial Science and Technology, Koriyama (Japan). Fukushima Renewable Energy Inst.
4. Tongji Univ., Shanghai (China)

Publication Date:

Thu Oct 04 00:00:00 EDT 2018

Research Org.:

Pennsylvania State Univ., University Park, PA (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE)

OSTI Identifier:

1614208

Alternate Identifier(s):

OSTI ID: 1480903

Grant/Contract Number:  

FE0023354

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Solid Earth

Additional Journal Information:

Journal Volume: 123; Journal Issue: 11; Journal ID: ISSN 2169-9313

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Geochemistry & Geophysics; friction; permeability; fabricated fractures; specified roughness