Experimental and Numerical Investigations of the Dynamic Permeability Evolution of a Fracture in Granite During Shearing Under Different Normal Stress Conditions

Special Issue “Observations of Coupled Processes in Fractured Geological Media at Various Space and Time”

“…The Special Issue covers recent developments in the understanding of permeability evolution of fractured rock during hydro-shearing (Kakurina et al 2020;Shen et al 2020), fracturing mechanisms of fractured rock (Zhuang et al 2020;Pan et al 2020;Li et al 2020;Zhou et al 2020), effect of high and low temperature on various rock properties (Yang et al 2020;Weng et al 2020) and characterization of transport and mechanical characteristics of rock under different conditions (Suzuki et al 2020;Zhang et al 2020). Kakurina et al (2020) investigate the orientation of injection-induced fault reactivation in two in situ experiments, one performed in carbonate rock at the Rustrel Low Noise Underground Laboratory (LSBB URL), France, and another in shale rock at the Mont Terri Rock laboratory, Switzerland.…”

“…The distinct two phases identified in the current study from the underground research laboratories have potential to be further used in various applications requiring fluid injection. Shen et al (2020) investigate the dynamic permeability evolution in the direction parallel with shear slip of six rough granite fractures under different effective normal stress. As shear slip accumulates, permeability first increases due to dilatancy, but subsequently decreases at effective normal stress lower than 5 MPa.…”

Experimental Investigation of Hydraulic Fracturing and Stress Sensitivity of Fracture Permeability Under Changing Polyaxial Stress Conditions

“…Guo et al, 2016;McDermott et al, 2015), non-linear flow (Konzuk & Kueper, 2004;Zhang & Nemcik, 2013;Zhou et al, 2015), non-linear relationships between fracture normal stress and effective hydraulic aperture (e.g. Bandis et al, 1983;Barton et al, 1985;Pyrak-Nolte et al, 1987;Witherspoon et al, 1980;Zimmerman & Main, 2003), and potential effective hydraulic aperture change when displacement juxtaposes fracture surface asperities (Chen et al, 2000;Lee & Cho, 2002;Shen et al, 2020;Vogler et al, 2016).…”

“…Shear dilation refers to the increase in effective hydraulic aperture as a result of juxtaposing asperities on each side of the fracture being forced past each other by displacement of the fracture. Experimental investigations of this phenomenon include static fracture offset tests (Chen et al, 2000;Hofmann et al, 2016;Zhou et al, 2015), direct shear tests at constant shear displacement rates (Shen et al, 2020), increasing shear stress (Rutter & Mecklenburgh, 2018), and hydraulically induced dynamic shear tests (Ye & Ghassemi, 2018). Kamali & Ghassemi (2018) and Ye & Ghassemi (2019) also provide mechanisms and evidence of fracture displacement leading to enhanced permeability through increased fracture tip stresses and the coalescence of nearby fractures during shear displacement, as opposed to the enhancement of permeability of each individual fractures through shear dilation.…”

“…However, fractures are not simply planar parallel plates, and many authors have shown that taking the mean mechanical aperture (determined from fracture surface characteristics and used to represent the aperture between parallel plates) will not result in an accurate prediction of fluid flow (Kulatilake et al, 2008; Renshaw, 1995). The topography of fracture surfaces leads to significantly more complex behaviors, such as channelization (e.g., Guo et al, 2016; McDermott et al, 2015), nonlinear flow (Konzuk & Kueper, 2004; Zhang & Nemcik, 2013; Zhou et al, 2015), nonlinear relationships between fracture normal stress and effective hydraulic aperture (e.g., Bandis et al, 1983; Barton et al, 1985; Pyrak‐Nolte et al, 1987; Witherspoon et al, 1980; Zimmerman & Main, 2003), and potential effective hydraulic aperture change when displacement juxtaposes fracture surface asperities (Chen et al, 2000; Lee & Cho, 2002; Shen et al, 2020; Vogler et al, 2016).…”