Review: The state-of-art of sparse channel models and their applicability to performance assessment of radioactive waste repositories in fractured crystalline formations

Figueiredo, Bruno; Tsang, Chin‐Fu; Niemi, Auli; Lindgren, Georg

doi:10.1007/s10040-016-1415-x

Cited by 36 publications

(22 citation statements)

References 50 publications

(14 reference statements)

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“…Many factors can affect the magnitude of permeability of fractured rock masses, including fracture length [28][29][30][31], aperture [32][33][34], surface roughness [35,36], dead-end [37], number of intersections [38,39], hydraulic gradient [40], boundary stress [41,42], anisotropy [43][44][45][46], scale [47][48][49][50], stiffness [51], coupled thermo-hydro-mechanical-chemical (HTMC) processes [52][53][54][55], and precipitation-dissolution and biogeochemistry [56]. The discrete fracture network (DFN) model, which can consider most of the above parameters, has been increasingly utilized to simulate fluid flow in the complex 2 Geofluids fractured rock masses [57][58][59][60], although it cannot model the aperture heterogeneity of each fracture [61][62][63]. In the numerical simulations and/or analytical analysis, the linear governing equation such as the cubic law is solved to simulate fluid flow in fractures by applying constant hydraulic gradients ( ) on the two opposing boundaries, such as = 1 [57,[64][65][66][67][68]], = 0.1 …”

Section: Introductionmentioning

confidence: 99%

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Jiang

2017

Geofluids

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Selecting appropriate governing equations for fluid flow in fractured rock masses is of special importance for estimating the permeability of rock fracture networks. When the flow velocity is small, the flow is in the linear regime and obeys the cubic law, whereas when the flow velocity is large, the flow is in the nonlinear regime and should be simulated by solving the complex NavierStokes equations. The critical conditions such as critical Reynolds number and critical hydraulic gradient are commonly defined in the previous works to quantify the onset of nonlinear fluid flow. This study reviews the simplifications of governing equations from the Navier-Stokes equations, Stokes equation, and Reynold equation to the cubic law and reviews the evolutions of critical Reynolds number and critical hydraulic gradient for fluid flow in rock fractures and fracture networks, considering the influences of shear displacement, normal stress and/or confining pressure, fracture surface roughness, aperture, and number of intersections. This review provides a reference for the engineers and hydrogeologists especially the beginners to thoroughly understand the nonlinear flow regimes/mechanisms within complex fractured rock masses.

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Section: Introductionmentioning

confidence: 99%

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Jiang

2017

Geofluids

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“…There are generally three conceptual models to simulate fluid flow and transport in fractured porous media, including stochastic continuum model, channel network model and discrete fracture network model (Selroos et al, 2002;Figueiredo et al, 2016). The stochastic continuum model can represent the fractured systems as equivalent homogenous media, in which the anisotropy of permeability cannot be considered (Tsang et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…The stochastic continuum model can represent the fractured systems as equivalent homogenous media, in which the anisotropy of permeability cannot be considered (Tsang et al, 1996). The channel network model can simulate flow properties of fractures that are tortuous and exhibit preferential pathways, which is more realistic than the stochastic continuum model (Neretnieks, 1987;Figueiredo et al, 2016). However, when the aperture heterogeneity of each fracture in complex fracture networks is considered, it is a timeconsuming and even unavailable task for calculations.…”

Section: Introductionmentioning

confidence: 99%

Geometrical, fractal and hydraulic properties of fractured reservoirs: A mini-review

Wei

Xia

2017

Adv. Geo-Energ. Res.

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Fractures and fracture networks play an important role in fluid flow and transport properties of oil and gas reservoirs. Accurate estimation of geometrical characteristics of fracture networks and their hydraulic properties are two key research directions in the fields of fluids flow in fractured porous media. Recent works focusing on the geometrical, fractal and hydraulic properties of fractured reservoirs are reviewed and summarized in this mini-review. The effects of several important parameters that significantly influences hydraulic properties are specifically discussed and analyzed, including fracture length distribution, aperture distribution, boundary stress and anisotropy. The methods for predicting fractal dimension of fractures and models for fracture networks and fractured porous media based on fractal-based approaches are addressed. Some comments and suggestions are also given on the future research directions and fractal fracture networks as well as fractured porous media.

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“…It is widely acknowledged that groundwater flow occurs within a limited proportion of a fracture's surface (Figueiredo et al 2016). Bourke (1987) (Fig.…”

Section: Channel Widthmentioning

confidence: 99%

An alternative approach to understanding groundwater flow in sparse channel networks supported by evidence from ‘background’ fractured crystalline rocks

Black¹,

Barker

2018

Hydrogeol J

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Size and shape of individual flow-features, and not their 'organization' in sets of predominant orientation, are the major influences on the ability of groundwater to percolate through sparse channel networks. Measurements in background fractured crystalline rocks proposed for nuclear waste repositories provide useful insight. Flow-features are observed as locations of increased transmissivity during packer or flow testing in boreholes. They are conceived here as channels on fracture surfaces. Findings are based on numerical modelling and a general formula by Barker (2018) for the percolation of two-dimensional (2D) objects in 3D space. Equidimensional shapes are found to be the least efficient at forming percolating networks. As discs are evolved into highly eccentric ellipses, percolation thresholds for number, area and intersection density decrease. At the same time, the percentage of features forming the active flow path declines from about 10% for discs to a few per cent for 50:1 ellipses.

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Review: The state-of-art of sparse channel models and their applicability to performance assessment of radioactive waste repositories in fractured crystalline formations

Abstract: Review: The state-of-art of sparse channel models and their applicability to performance assessment of radioactive waste repositories in fractured crystalline formations.Hydrogeology Journal, 24 (7)

Cited by 36 publications

References 50 publications

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Geometrical, fractal and hydraulic properties of fractured reservoirs: A mini-review

An alternative approach to understanding groundwater flow in sparse channel networks supported by evidence from ‘background’ fractured crystalline rocks

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