Diversity of channeling flow in heterogeneous aperture distribution inferred from integrated experimental‐numerical analysis on flow through shear fracture in granite

Watanabe, Noriaki; Hirano, Nobuo; Tsuchiya, Noriyoshi

doi:10.1029/2008jb005959

Cited by 98 publications

(118 citation statements)

References 70 publications

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“…Except the study by Watanabe et al (2008), who highlight qualitative insights into the flow structures, all other studies in Table 1 quantify and intend to validate simulated fracture flow. In a subsequent study which is not listed in Table 1, Watanabe et al (2009) applied a similar (non-quantitative) procedure for other fracture types. By contrast, quantification of fracture flow was performed by Indraratna et al (2015), who performed CFD simulations based on initial laser-scanning measurements, where the flow model is coupled with a deformation criteria simulating fracture closing.…”

Section: Introductionmentioning

confidence: 99%

“…By contrast, quantification of fracture flow was performed by Indraratna et al (2015), who performed CFD simulations based on initial laser-scanning measurements, where the flow model is coupled with a deformation criteria simulating fracture closing. Similar, but more simplified, deformation procedures were performed for statistically derived aperture distributions (Pyrak-Nolte and Morris, 2000), profilometer measurements (Kim et al, 2003), laser-scan data (Nemoto et al, 2009;Watanabe et al, 2008Watanabe et al, , 2009) and a conceptual 2-D model (Liu et al, 2010). Furthermore, Dicman et al (2004) described changes in aperture distribution by combining laboratory data and stochastic approaches.…”

Section: Introductionmentioning

confidence: 99%

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Simulating stress-dependent fluid flow in a fractured core sample using real-time X-ray CT data

et al. 2016

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Abstract. Various geoscientific applications require a fast prediction of fracture permeability for an optimal workflow. Hence, the objective of the current study is to introduce and validate a practical method to characterize and approximate single flow in fractures under different stress conditions by using a core-flooding apparatus, in situ X-ray computed tomography (CT) scans and a finite-volume method solving the Navier-Stokes-Brinkman equations. The permeability of the fractured sandstone sample was measured stepwise during a loading-unloading cycle (0.7 to 22.1 MPa and back) to validate the numerical results. Simultaneously, the pressurized core sample was imaged with a medical X-ray CT scanner with a voxel dimension of 0.5 × 0.5 × 1.0 mm 3 . Fracture geometries were obtained by CT images based on a modification of the simplified missing attenuation (MSMA) approach. Simulation results revealed both qualitative plausibility and a quantitative approximation of the experimentally derived permeabilities. The qualitative results indicate flow channeling along several preferential flow paths with less pronounced tortuosity. Significant changes in permeability can be assigned to temporal and permanent changes within the fracture due to applied stresses. The deviations of the quantitative results appear to be mainly caused by both local underestimation of hydraulic properties due to compositional matrix heterogeneities and the low CT resolution affecting the accurate capturing of sub-grid-scale features. Both affect the proper reproduction of the actual connectivity and therefore also the depiction of the expected permeability hysteresis. Furthermore, the threshold value CT mat (1862.6 HU) depicting the matrix material represents the most sensitive input parameter of the simulations. Small variations of CT mat can cause enormous changes in simulated permeability by up to a factor of 2.6 ± 0.1 and, thus, have to be defined with caution. Nevertheless, comparison with further CT-based flow simulations indicates that the proposed method represents a valuable method to approximate actual permeabilities, particularly for smooth fractures (< 35 µm). However, further systematic investigations concerning the applicability of the method are essential for future studies. Thus, some recommendations are compiled by also including suggestions of comparable studies.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulating stress-dependent fluid flow in a fractured core sample using real-time X-ray CT data

et al. 2016

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“…The geological realism of multi-Gaussian structures has been questioned [Gomez-Hernandez and Wen, 1998], and alternatives that emphasize connectivity and channeling, have been considered for fractures [Tsang and Doughty, 2003;Tsang et al, 2008]. Many studies have indeed emphasized the significance of channeling in fractures [e.g., Tsang and Tsang, 1989;Tsang and Neretnieks, 1998;Watanabe et al, 2009], which in general will be a consequence of both large variability in T [Tsang and Tsang, 1989] and its correlation structure [Cvetkovic and Shapiro, 1989;Tsang and Doughty, 2003]. To capture this combined effect, a generic model for non-multi-Gaussian structures will be used.…”

Section: Transmissivity Statisticsmentioning

confidence: 99%

Flow‐dependence of matrix diffusion in highly heterogeneous rock fractures

Cvetković

Gotovac

2013

Water Resources Research

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[1] Diffusive mass transfer in rock fractures is strongly affected by fluid flow in addition to material properties. The flow-dependence of matrix diffusion is quantified by a random variable (''transport resistance'') denoted as b [T/L] and computed from the flow field by following advection trajectories. The numerical methodology for simulating fluid flow is mesh-free, using Fup basis functions. A generic statistical model is used for the transmissivity field, featuring three correlation structures: (i) highly connected non-multiGaussian; (ii) poorly connected (or disconnected) non-multi-Gaussian ; and (iii) multiGaussian. The moments of b are shown to be linear with distance, irrespective of the structure, after approximately 10 integral scales of ln T. Percentiles of b are found to be linear with the mean b when considering all three structures. Taking advantage of this property, a potentially useful relationship is presented between b percentiles and the fracture mean water residence time that integrates all structures with high variability; it can be used in discrete fracture network simulations where T statistical data on individual fractures are not available.Citation: Cvetkovic, V., and H. Gotovac (2013), Flow-dependence of matrix diffusion in highly heterogeneous rock fractures, Water Resour. Res., 49,[7587][7588][7589][7590][7591][7592][7593][7594][7595][7596][7597]

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“…Research has been performed regarding the actual flow speed of groundwater inside such fractures, and regarding the hydraulic characteristics of rock by focusing on the network of fractures. As the hydraulic characteristics of rock are the accumulation of the hydraulic characteristics of each fracture, it is necessary to develop a hydraulic model of a single fracture to predict a large-scale hydraulic behavior (e.g., Raven and Gale 1985;Yeo et al 1998;Chen et al 2000;Olsson and Barton 2001;Kim and Inoue 2003;Watanabe et al 2008;Chen et al 2009;Watanabe et al 2009). When a shear displacement takes place in a rock fracture having rough surfaces, it may cause significant changes in the pore structure (e.g., Mitsui et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Mechanical and hydraulic behavior of a rock fracture under shear deformation

et al. 2014

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With regard to crystalline rock that constitutes deep geology, attempts have been made to explore its hydraulic characteristics by focusing on the network of numerous fractures within. As the hydraulic characteristics of a rock are the accumulation of hydraulic characteristics of each fracture, it is necessary to develop the hydraulic model of a single fracture to predict the large-scale hydraulic behavior. To this end, a simultaneous permeability and shear test device is developed, and shear-flow coupling tests are conducted on specimens having fractures with varied levels of surface roughness in the constant normal stiffness conditions. The results show that the permeability characteristics in the relation between shear displacement and transmissivity change greatly at the point where the stress path reaches the Mohr-Coulomb failure curve. It is also found that there exists a range in which transmissivity is not proportional to the cube of mechanical aperture width, which seems to be because of the occurrence of channeling phenomenon at small mechanical aperture widths. This channeling flow disappears with increasing shear and is transformed into a uniform flow. We develop a simulation technique to evaluate the macroscopic permeability characteristics by the lattice gas cellular automaton method, considering the microstructure of fracture, namely the fracture surface roughness. With this technique, it is shown that the formation of the Hagen-Poiseuille flow is affected by the fracture microstructure under shear, which as a result determines the relationship between the mechanical aperture width and transmissivity.

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Diversity of channeling flow in heterogeneous aperture distribution inferred from integrated experimental‐numerical analysis on flow through shear fracture in granite

Cited by 98 publications

References 70 publications

Simulating stress-dependent fluid flow in a fractured core sample using real-time X-ray CT data

Simulating stress-dependent fluid flow in a fractured core sample using real-time X-ray CT data

Flow‐dependence of matrix diffusion in highly heterogeneous rock fractures

Mechanical and hydraulic behavior of a rock fracture under shear deformation

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