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Title: MINERALOGICAL AND TEXTURAL CONTROLS ON SHEAR STRENGTH, SLIP STABILITY AND PERMEABILITY OF FAULTS

Abstract

Induced seismicity resulting from fluid injection into the subsurface related to water and CO2 disposal, hydraulic fracturing and the stimulation of geothermal reservoirs present an important societal concern. These human activities involve the injection of large volumes of pressurized fluid into the subsurface, potentially at high rates, raising local pore pressures and disturbing the pristine local stress regime by lowering effective normal stress on pre-existing faults and fractures. The reduction of effective normal stress may trigger fault/fracture reactivation and in some cases result in hazardous seismic ruptures. Effective management and engineering of anthropogenic seismic events requires substantial understanding in the mechanisms, especially for the controlling factors on coupled rheological and transport response, including fault shear strength, slip stability, and permeability evolution during such events. In this study, we explore the coupled rheological and transport response of faults and fractures during reactivation as controlled by two fundamental controlling properties, viz., mineralogy and textural features. We approach this problem through shear experiments on analog faults and fractures via laboratory and numerical experiments. Specifically, we investigate: (1) the influence of frictionally weak minerals (talc) in mixtures of mineral analogs featuring contrasting frictional properties, (2) the influence of iron oxide grain coatings on quartzmore » aggregates, and (3) the influence of fracture roughness in mated fractures on the ensemble shear strength, slip stability, and permeability evolution during reactivation events. We address the following questions in this study: (1) how much and what distribution of frictionally weak minerals is required to induce significant weakening in faults consisting of a matrix of frictionally strong minerals, (2) how does a pre-imposed weak mineral layer influence the rheological and transport behavior of faults, (3) what is the influence of a trace amount of grain coating materials introduce on the coupled behavior of faults, and finally (4) how do asperity height and wave length control the ensemble behavior of faults. These questions are explicitly answered in the following.« less

Authors:
Publication Date:
Research Org.:
Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
Contributing Org.:
Pennsylvania State University
OSTI Identifier:
1646026
DOE Contract Number:  
FE0023354
Resource Type:
Other
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Permeability, Seismicity, Stability.

Citation Formats

Wang, Chaoyi. MINERALOGICAL AND TEXTURAL CONTROLS ON SHEAR STRENGTH, SLIP STABILITY AND PERMEABILITY OF FAULTS. United States: N. p., 2019. Web.
Wang, Chaoyi. MINERALOGICAL AND TEXTURAL CONTROLS ON SHEAR STRENGTH, SLIP STABILITY AND PERMEABILITY OF FAULTS. United States.
Wang, Chaoyi. Wed . "MINERALOGICAL AND TEXTURAL CONTROLS ON SHEAR STRENGTH, SLIP STABILITY AND PERMEABILITY OF FAULTS". United States. https://www.osti.gov/servlets/purl/1646026.
@article{osti_1646026,
title = {MINERALOGICAL AND TEXTURAL CONTROLS ON SHEAR STRENGTH, SLIP STABILITY AND PERMEABILITY OF FAULTS},
author = {Wang, Chaoyi},
abstractNote = {Induced seismicity resulting from fluid injection into the subsurface related to water and CO2 disposal, hydraulic fracturing and the stimulation of geothermal reservoirs present an important societal concern. These human activities involve the injection of large volumes of pressurized fluid into the subsurface, potentially at high rates, raising local pore pressures and disturbing the pristine local stress regime by lowering effective normal stress on pre-existing faults and fractures. The reduction of effective normal stress may trigger fault/fracture reactivation and in some cases result in hazardous seismic ruptures. Effective management and engineering of anthropogenic seismic events requires substantial understanding in the mechanisms, especially for the controlling factors on coupled rheological and transport response, including fault shear strength, slip stability, and permeability evolution during such events. In this study, we explore the coupled rheological and transport response of faults and fractures during reactivation as controlled by two fundamental controlling properties, viz., mineralogy and textural features. We approach this problem through shear experiments on analog faults and fractures via laboratory and numerical experiments. Specifically, we investigate: (1) the influence of frictionally weak minerals (talc) in mixtures of mineral analogs featuring contrasting frictional properties, (2) the influence of iron oxide grain coatings on quartz aggregates, and (3) the influence of fracture roughness in mated fractures on the ensemble shear strength, slip stability, and permeability evolution during reactivation events. We address the following questions in this study: (1) how much and what distribution of frictionally weak minerals is required to induce significant weakening in faults consisting of a matrix of frictionally strong minerals, (2) how does a pre-imposed weak mineral layer influence the rheological and transport behavior of faults, (3) what is the influence of a trace amount of grain coating materials introduce on the coupled behavior of faults, and finally (4) how do asperity height and wave length control the ensemble behavior of faults. These questions are explicitly answered in the following.},
doi = {},
url = {https://www.osti.gov/biblio/1646026}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {5}
}