TY - JOUR
T1 - The influence of CO2-transformed iron oxide grain coatings on the frictional stability and transport properties of simulated faults in sandstones
AU - Wang, Chaoyi
AU - Elsworth, Derek
N1 - Funding Information:
This work is a partial result of the support provided by DOE Grant DE-FE0023354 and NSF Grant EAR-1552211. This support is gratefully acknowledged. Especially appreciated is the support of Dr. Peter Heaney and Si Athena Chen in the production of the iron oxides used in the experiments.
Publisher Copyright:
© 2020, Springer Nature Switzerland AG.
PY - 2020/12/1
Y1 - 2020/12/1
N2 - Carbon sequestration involves long-term containment of CO2 in ideally sealed reservoirs. However, CO2 migration can weaken rocks and faults by geochemical alteration, elevate risks of seismic hazards, and loss of inventory. Recent studies show that CO2 bleaching can alter the iron oxide grain coating of sand-sized quartz in sandstones, which may impose a significant influence on frictional stability and permeability evolution of faults in sandstones. This study investigates the influence of iron oxide grain coatings via coupled shear-flow experiments on uncoated, hematite-coated, and CO2-transformed goethite-coated synthetic sand gouge. Shear strength, frictional stability, healing/relaxation, and shear-parallel permeability are measured in velocity-stepping and slide-hold-slide loading modes. Hematite-coated sand exhibits the highest shear strength, followed by goethite-coated and uncoated sand. All samples, both coated and uncoated, show similar residual shear strength. Frictional stability measurements suggest hematite-coated sand may undergo potential seismic slip (negative (a − b) values); goethite-coated sand is aseismic (positive (a − b) values) but features higher frictional healing and relaxation. Shear-parallel permeability enhances during initial shear in all samples, followed by a sharp decline after the peak strength, except for goethite-coated sand, for which permeability reduction is moderate. SEM characterizations pre- and post-shear suggest that the competitive liberation, transport, and clogging of coating particles and shear-produced wear products can be an important mechanism in permeability evolution.
AB - Carbon sequestration involves long-term containment of CO2 in ideally sealed reservoirs. However, CO2 migration can weaken rocks and faults by geochemical alteration, elevate risks of seismic hazards, and loss of inventory. Recent studies show that CO2 bleaching can alter the iron oxide grain coating of sand-sized quartz in sandstones, which may impose a significant influence on frictional stability and permeability evolution of faults in sandstones. This study investigates the influence of iron oxide grain coatings via coupled shear-flow experiments on uncoated, hematite-coated, and CO2-transformed goethite-coated synthetic sand gouge. Shear strength, frictional stability, healing/relaxation, and shear-parallel permeability are measured in velocity-stepping and slide-hold-slide loading modes. Hematite-coated sand exhibits the highest shear strength, followed by goethite-coated and uncoated sand. All samples, both coated and uncoated, show similar residual shear strength. Frictional stability measurements suggest hematite-coated sand may undergo potential seismic slip (negative (a − b) values); goethite-coated sand is aseismic (positive (a − b) values) but features higher frictional healing and relaxation. Shear-parallel permeability enhances during initial shear in all samples, followed by a sharp decline after the peak strength, except for goethite-coated sand, for which permeability reduction is moderate. SEM characterizations pre- and post-shear suggest that the competitive liberation, transport, and clogging of coating particles and shear-produced wear products can be an important mechanism in permeability evolution.
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U2 - 10.1007/s40948-020-00192-8
DO - 10.1007/s40948-020-00192-8
M3 - Article
AN - SCOPUS:85094187569
VL - 6
JO - Geomechanics and Geophysics for Geo-Energy and Geo-Resources
JF - Geomechanics and Geophysics for Geo-Energy and Geo-Resources
SN - 2363-8419
IS - 4
M1 - 65
ER -