Damage and permeability around faults: Implications for mineralization

Sheldon, Heather A.; Micklethwaite, Steven

doi:10.1130/g23860a.1

Cited by 53 publications

(31 citation statements)

References 21 publications

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“…The simulated tensional stepovers show damage patterns consistent with intense tensile fracturing and dilation, and therefore are expected to exhibit long-lived enhanced permeability. Such damage patterns are consistent with recent structural evolution models for dilational stepovers (DE PAOLA et al, 2007), and with mineral exploration studies that relate hydrothermal ore deposits to long-lasting extensive damage and increased permeability within fault stepovers (MICKLETHWAITE and COX, 2004;SHELDON and MICKLETHWAITE, 2007). The permanent damage zones our models predict should be detectable with detailed seismic and geodetic imaging studies.…”

Section: Discussionsupporting

confidence: 66%

Structural Properties and Deformation Patterns of Evolving Strike-slip Faults: Numerical Simulations Incorporating Damage Rheology

Finzi

Hearn

Ben‐Zion

et al. 2009

Mechanics, Structure and Evolution of Fault Zones

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Abstract-We present results on evolving geometrical and material properties of large strike-slip fault zones and associated deformation fields, using 3-D numerical simulations in a rheologically-layered model with a seismogenic upper crust governed by a continuum brittle damage framework over a viscoelastic substrate. The damage healing parameters we employ are constrained using results of test models and geophysical observations of healing along active faults. The model simulations exhibit several results that are likely to have general applicability. The fault zones form initially as complex segmented structures and evolve overall with continuing deformation toward contiguous, simpler structures. Along relatively-straight mature segments, the models produce flower structures with depth consisting of a broad damage zone in the top few kilometers of the crust and highly localized damage at depth. The flower structures form during an early evolutionary stage of the fault system (before a total offset of about 0.05 to 0.1 km has accumulated), and persist as continued deformation localizes further along narrow slip zones. The tectonic strain at seismogenic depths is concentrated along the highly damaged cores of the main fault zones, although at shallow depths a small portion of the strain is accommodated over a broader region. This broader domain corresponds to shallow damage (or compliant) zones which have been identified in several seismic and geodetic studies of active faults. The models produce releasing stepovers between fault zone segments that are locations of ongoing interseismic deformation. Material within the fault stepovers remains damaged during the entire earthquake cycle (with significantly reduced rigidity and shearwave velocity) to depths of 10 to 15 km. These persistent damage zones should be detectable by geophysical imaging studies and could have important implications for earthquake dynamics and seismic hazard.

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Section: Discussionsupporting

confidence: 66%

Structural Properties and Deformation Patterns of Evolving Strike-slip Faults: Numerical Simulations Incorporating Damage Rheology

Finzi

Hearn

Ben‐Zion

et al. 2009

Mechanics, Structure and Evolution of Fault Zones

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“…Step-overs and relays are likely to have a rate-limiting impact on the integrity of any CO 2 storage (e.g., Micklethwaite & Cox, 2004;Sheldon & Micklethwaite, 2007).…”

Section: Discussionmentioning

confidence: 99%

Geomechanical effects on CO2 leakage through fault zones during large-scale underground injection

Rinaldi

Rutqvist

Cappa

2014

International Journal of Greenhouse Gas Control

151

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The importance of geomechanics-including the potential for faults to reactivate during largescale geologic carbon sequestration operations-has recently become more widely recognized.However, notwithstanding the potential for triggering notable (felt) seismic events, the potential for buoyancy-driven CO 2 to reach potable groundwater and the ground surface is actually more important from public safety and storage-efficiency perspectives. In this context, this work extends the previous studies on the geomechanical modeling of fault responses during underground carbon dioxide injection, focusing on the short-term integrity of the sealing caprock, and hence on the potential for leakage of either brine or CO 2 to reach the shallow groundwater aquifers during active injection. We consider stress/strain-dependent permeability and study the leakage through the fault zone as its permeability changes during a reactivation, also causing seismicity. We analyze several scenarios related to the volume of CO 2 injected (and hence as a function of the overpressure), involving both minor and major faults, and analyze the profile risks of leakage for different stress/strain-permeability coupling functions. We conclude that whereas it is very difficult to predict how much fault permeability could change upon reactivation, this process can have a significant impact on the leakage rate. Moreover, our analysis shows that induced seismicity associated with fault reactivation may not necessarily open up a new flow path for leakage. Results show a poor correlation between magnitude and amount of fluid leakage, meaning that a single event is generally not enough to substantially change the permeability along the entire fault length. Consequently, even if some changes in permeability occur, this does not mean that the CO 2 will migrate up along the entire fault, breaking through the caprock to enter the overlying aquifer.3

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“…The orientation, spacing, aperture, persistence, and type of mechanical discontinuities are all important factors controlling both the magnitude and anisotropy of rock permeability (Watts, 1983;Tsang, 1984;Narr and Suppe, 1991;Antonellini and Aydin, 1995;Caine et al, 1996;Agarwal et al, 1997;Child et al, 1997;Dholakia et al, 1998;Bell et al, 1999;Odling et al, 1999;Aydin, 2000;Eichhubl and Boles, 2000;Cello et al, 2001;Doolin and Mauldon, 2001;M.Fisher and Knipe, 2001;Labaume et al, 2001;Rawling et al, 2001;Bailey et al, 2002;Gale, 2002;Laubach, 2003;Davatzes et al, 2005;Géraud et al, 2006;Fossen et al, 2007;Sheldon and Micklethwaite, 2007;Ortega et al, 2009). Owing to the wide variety of kinematic pathways that are associated with the growth of salt-related structures (e.g.…”

Section: Introductionmentioning

confidence: 97%

Sub-seismic scale fracture pattern and in situ permeability data in the chalk atop of the Krempe salt ridge at Lägerdorf, NW Germany: Inferences on synfolding stress field evolution and its impact on fracture connectivity

Storti¹,

Balsamo²,

Cappanera³

et al. 2011

Marine and Petroleum Geology

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Damage and permeability around faults: Implications for mineralization

Cited by 53 publications

References 21 publications

Structural Properties and Deformation Patterns of Evolving Strike-slip Faults: Numerical Simulations Incorporating Damage Rheology

Structural Properties and Deformation Patterns of Evolving Strike-slip Faults: Numerical Simulations Incorporating Damage Rheology

Geomechanical effects on CO2 leakage through fault zones during large-scale underground injection

Sub-seismic scale fracture pattern and in situ permeability data in the chalk atop of the Krempe salt ridge at Lägerdorf, NW Germany: Inferences on synfolding stress field evolution and its impact on fracture connectivity

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