Hydraulic-mechanical properties of microfaults in granitic rock using the Punch-Through Shear test

Kluge, Christian; Blöcher, Guido; Barnhoorn, Auke; Bruhn, David

doi:10.1016/j.ijrmms.2020.104393

Cited by 16 publications

(30 citation statements)

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“…2a). This distance corresponds to the maximum pressure difference, p f , along the micro-fault (Kluge et al 2020):…”

Section: Methodsmentioning

confidence: 99%

“…The pore fluid pressure was estimated by the outflow pressure, p p,out , and the difference in fluid pressures, p p,in − p p,out , divided by two (Eq. 4), assuming a linear pressure distribution (Kluge et al 2020):…”

Section: Methodsmentioning

confidence: 99%

“…2a. A full description of the experimental testing procedure can be found in Kluge et al (2020). Four tests were performed and are listed with their respective dimensions and testing conditions in Table 2.…”

Section: Sample Geometry and Experimental Set-upmentioning

confidence: 99%

“…Such simplified surface geometries allow us to investigate specific physical processes that control, for example, frictional properties or permeability during shearing. However, they cannot depict the variety of structural features commonly found in a natural shear zone (Kluge et al 2020;Ye and Ghassemi 2019).…”

Section: Introductionmentioning

confidence: 99%

“…The Punch-Through Shear (PTS) test was originally developed to obtain the mode II fracture toughness of rocks (Backers and Stephansson 2012). This testing set-up has been adapted to quantify the permeability evolution during fault generation under saturated conditions with a rate or pressure controlled fluid flow (Kluge et al 2020). In our experiments, we relate the evolution of hydraulic properties, such as permeability, to microstructural observations in shear zones on a laboratory scale (microfault).…”

Section: Introductionmentioning

confidence: 99%

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Permeability Evolution During Shear Zone Initiation in Low-Porosity Rocks

et al. 2021

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Using an innovative experimental set-up (Punch-Through Shear test), we initiated a shear zone (microfault) in Flechtingen sandstone and Odenwald granite under in situ reservoir conditions while monitoring permeability and fracture dilation evolution. The shear zone, which has a cylindrical geometry, is produced by a self-designed piston assembly that punches down the inner part of the sample. Permeability and fracture dilation were measured for the entire duration of the experiment. After the shear zone generation, the imposed shear displacement was increased to 1.2 mm and pore pressure changes of $$\pm 5$$ ± 5 or $$\pm 10$$ ± 10 MPa were applied cyclically to simulate injection and production scenarios. Thin sections and image analysis tools were used to identify microstructural features of the shear zone. The geometry of the shear zone is shown to follow a self-affine scaling invariance, similar to the fracture surface roughness. The permeability evolution related to the onset of the fracture zone is different for both rocks: almost no enhancement for the Flechtingen sandstone and an increase of more than 2 orders of magnitude for the Odenwald granite. Further shear displacement resulted in a slight increase in permeability. A fault compaction is observed after shear relaxation which is associated to a permeability decrease by a factor more than 3. Permeability changes during pressure cycling are reversible when varying the effective pressure. The difference in permeability enhancement between the sandstone and the granite is related to the larger width of the shear zones.

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“…2a). This distance corresponds to the maximum pressure difference, p f , along the micro-fault (Kluge et al 2020):…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Sample Geometry and Experimental Set-upmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%