Influence of wall roughness on the geometrical, mechanical and transport properties of single fractures

Abstract

This article reviews the main features of the transport properties of single fractures. A particular attention paid to fractures in geological materials which often display a roughness covering a broad range of length scales. Because of the small distance separating the fracture walls, the surface roughness is a key parameter influencing the structure of the void space. Studies devoted to the characterization of the surface roughness are presented as well as works aimed at characterizing the void space geometry. The correlation of the free space is found to be crucially function of the failure mechanism (brittle, quasi brittle or plastic...) but also of possible shear displacements during the failure. The influence of the surface roughness on the mechanical behavior of fractures under a normal load and a shear stress is also described. Finally, experimental, numerical and theoretical works devoted to the study of the influence of the fracture void geometry on the permeability and on the hydrodynamic dispersion of a dissolved species are discussed.

Critical Reynolds number for nonlinear flow through rough-walled fractures: The role of shear processes

“…Since the flow occurs over a few tortuous channels, the hydraulic behavior of fracture would be controlled by the small apertures and constrictions [ Tsang and Tsang , ; Neuzil and Tracy , ]. The structure of the aperture field is strongly related to the relative position of the fracture surfaces together with the statistical distribution of the asperities [ Auradou , ]. Due to the roughness of the fracture surfaces, the shear displacement is accompanied with two main features including dilation and lateral mismatching of surfaces [ Esaki et al ., ].…”

Emergence of anomalous transport in stressed rough fractures

“…Geologic fractures, however, are always under significant overburden stress. While confining stress has been shown to impact fluid flow through rough-walled fractures in a fundamental way (e.g., Unger & Mase, 1993;Olsson & Brown, 1993;Pyrak-Nolte & Morris, 2000;Watanabe et al, 2008;Auradou, 2009;Nemoto et al, 2009;Watanabe et al, 2013;Ishibashi et al, 2015;Pyrak-Nolte & Nolte, 2016), studies of anomalous transport at the scale of individual fractures have so far either ignored the potential role of confining stress (Måløy et al, 1988;Detwiler et al, 2000;Auradou et al, 2001;Bodin et al, 2003a;Drazer et al, 2004;Talon et al, 2012;Wang & Cardenas, 2014), relied on nonmechanistic models (Tsang & Tsang, 1987), or focused on the role of shear stress (Koyama et al, 2008;Vilarrasa et al, 2011;Jing et al, 2013). As a result, the mechanistic underpinning and theoretical modeling for the emergence of anomalous transport in rough fractures under normal stress remains unexplored.…”

Influence of wettability on interfacial area during immiscible liquid invasion into a 3D self-affine rough fracture: Lattice Boltzmann simulations

“…Although the roughness in natural fractures is extremely complex, many experimental studies [23,24] have shown that the roughness surface in natural fractures follows self-affine fractal statistics. Due to the flexibility for solving problems with geometrically complex boundaries, the LBM is naturally suitable for simulating the fluid flow in a self-affine fracture [25].…”