Permeability changes in simulated granite faults during and after frictional sliding

Tanikawa, Wataru; Tadai, Osamu; Mukoyoshi, Hideki

doi:10.1111/gfl.12091

Cited by 16 publications

(7 citation statements)

References 42 publications

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“…This strength contrast possibly influences the development process of the décollement itself. Fluid permeability perpendicular to the fault plane tends to decrease with the slip displacement and the fault may act as a barrier (Faulkner et al 2010;Tanikawa et al 2014;Yamashita and Tsutsumi 2018). Generated or advected fluids thus flow beneath the décollement plane.…”

Section: Resultsmentioning

confidence: 99%

In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough

Hamada

Hirose

Ijiri

et al. 2018

Prog Earth Planet Sci

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The study investigates the in-situ strength of sediments across a plate boundary décollement using drilling parameters recorded when a 1180-m-deep borehole was established during International Ocean Discovery Program (IODP) Expedition 370, Temperature-Limit of the Deep Biosphere off Muroto (T-Limit). Information of the in-situ strength of the shallow portion in/around a plate boundary fault zone is critical for understanding the development of accretionary prisms and of the décollement itself. Studies using seismic reflection surveys and scientific ocean drillings have recently revealed the existence of high pore pressure zones around frontal accretionary prisms, which may reduce the effective strength of the sediments. A direct measurement of in-situ strength by experiments, however, has not been executed due to the difficulty in estimating in-situ stress conditions. In this study, we derived a depth profile for the in-situ strength of a frontal accretionary prism across a décollement from drilling parameters using the recently established equivalent strength (EST) method. At site C0023, the toe of the accretionary prism area off Cape Muroto, Japan, the EST gradually increases with depth but undergoes a sudden change at~800 mbsf, corresponding to the top of the subducting sediment. At this depth, directly below the décollement zone, the EST decreases from~10 to 2 MPa, with a change in the baseline. This mechanically weak zone in the subducting sediments extends over 250 m (~800-1050 mbsf), corresponding to the zone where the fluid influx was discovered, and high-fluid pressure was suggested by previous seismic imaging observations. Although the origin of the fluids or absolute values of the strength remain unclear, our investigations support previous studies suggesting that elevated pore pressure beneath the décollement weakens the subducting sediments.

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Section: Resultsmentioning

confidence: 99%

In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough

Hamada

Hirose

Ijiri

et al. 2018

Prog Earth Planet Sci

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“…In particular, the peak friction coefficients are all at ~0.7, similar to the dry results, while the steady state values are lower than the dry results and show a decreasing trend with increasing normal stress. Higher normal stress implies that more frictional heating can be generated, while the gouge layer is expected to be less permeable [ Tanikawa et al ., ]. In general, this will result in more efficient fluid pressurization, giving rise to a lower effective normal stress and therefore faster slip‐weakening (smaller D w ) and lower apparent dynamic friction (smaller μ ss ).…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Water vaporization promotes coseismic fluid pressurization and buffers temperature rise

Chen

Niemeijer

Yao

et al. 2017

Geophysical Research Letters

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We investigated the frictional properties of carbonate‐rich gouge layers at a slip rate of 1.3 m/s, under dry and water‐saturated conditions, while monitoring temperature at different locations on one of the gouge‐host rock interfaces. All experiments showed a peak frictional strength of 0.4–0.7, followed by strong slip weakening to steady state values of 0.1–0.3. Experiments which used a pore fluid with a constant drainage path to the atmosphere showed the development of a temperature plateau beyond 100°C, contemporaneous with the dynamic slip weakening and consistent with thermodynamic considerations of ongoing vaporization of pore water. Upon pore fluid vaporization, the pore pressure increases, while the temperature is buffered endothermically, such that the pore water moves along the liquid‐vapor transition curve in a pressure‐temperature phase diagram. Pore fluid phase transitions of this kind are expected to occur in natural earthquakes at relatively shallow crustal levels, enhancing fluid pressurization while impeding the achievement of high temperatures. Therefore, the operation of vaporization may help explain the low downhole temperature anomalies obtained shortly after large earthquakes.

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“…However, for reliable extrapolation to deeper GCS fields, we need a microphysical model accommodating the effects of temperature and effective normal stress. The applied experimental loading velocity (10 0 µm/s to 10 1 µm/s) does not purport to cover the full spectrum of possible seismic or aseismic transient slip velocities but represents a narrow range where contrasting responses of different mineralogies may be explored, with velocity as a control parameter. As the sliding velocity in these experiments is approximately 2 orders of magnitude lower than similar experiments, no thermal pressurization effect is considered [ Rice , ; Tanikawa et al ., , ].…”

Section: Experimental Methodsmentioning

confidence: 99%

Frictional stability‐permeability relationships for fractures in shales

et al. 2017

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There is wide concern that fluid injection in the subsurface, such as for the stimulation of shale reservoirs or for geological CO2 sequestration (GCS), has the potential to induce seismicity that may change reservoir permeability due to fault slip. However, the impact of induced seismicity on fracture permeability evolution remains unclear due to the spectrum of modes of fault reactivation (e.g., stable versus unstable). As seismicity is controlled by the frictional response of fractures, we explore friction‐stability‐permeability relationships through the concurrent measurement of frictional and hydraulic properties of artificial fractures in Green River shale (GRS) and Opalinus shale (OPS). We observe that carbonate‐rich GRS shows higher frictional strength but weak neutral frictional stability. The GRS fracture permeability declines during shearing while an increased sliding velocity reduces the rate of permeability decline. By comparison, the phyllosilicate‐rich OPS has lower friction and strong stability while the fracture permeability is reduced due to the swelling behavior that dominates over the shearing induced permeability reduction. Hence, we conclude that the friction‐stability‐permeability relationship of a fracture is largely controlled by mineral composition and that shale mineral compositions with strong frictional stability may be particularly subject to permanent permeability reduction during fluid infiltration.

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Permeability changes in simulated granite faults during and after frictional sliding

Cited by 16 publications

References 42 publications

In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough

In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough

Water vaporization promotes coseismic fluid pressurization and buffers temperature rise

Frictional stability‐permeability relationships for fractures in shales

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