Dimensional Threshold for Fracture Linkage and Hooking

Lamarche, Juliette; Chabani, Arezki; Gauthier, B.

doi:10.3997/2214-4609.201800039

Cited by 2 publications

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“…Curved paths suggest that remote stresses are nearly isotropic relative to the stresses induced by fractures. Furthermore, the onset of fracture connectivity has significant implications for the hydraulic properties of rock [9]. Fracture mechanics seeks to describe the physical processes taking place at each step of fracture extension, but analytical approaches are limited to specific geometries [10].…”

Section: Introductionmentioning

confidence: 99%

“…Fracture analysis benefits greatly from visualising fully three-dimensional fracture surfaces, where multiple cut-plane traces can be sampled to understand how the fracture would appear in experiments or outcrops.The modified two step Paris-type law captures the variation in extension between different fractures and fracture tips within a growing network. Fractures must have grown concurrently in order to create the patterns that are observed in outcrops, and to create curvature that arises during stress field re-orientation caused by fracture interaction[7][8][9]. Higher values of β n and β f generate fracture patterns where growth is more concentrated on the most energetic fractures and fracture tips (see Figures7 and 8).…”

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confidence: 99%

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Growth of three-dimensional fractures, arrays, and networks in brittle rocks under tension and compression

Thomas

Paluszny

Zimmerman

2020

Computers and Geotechnics

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Concurrent growth of multiple fractures in brittle rock is a complex process due to mechanical interaction effects. Fractures can amplify or shield stress on other fracture tips, and stress field perturbations change continuously during fracture growth. A three-dimensional, finite-element based, quasi-static growth algorithm is validated for mixed mode fracture growth in linear elastic media, and is used to investigate concurrent fracture growth in arrays and networks.Growth is governed by fracture tip stress intensity factors, which quantify the energy contributing to fracture extension, and are validated against analytical solutions for fractures under compression and tension, demonstrating that growth is accurate even in coarsely meshed domains. Isolated fracture geometries are compared to wing cracks grown in experiments on brittle media. A novel formulation of a Paris-type extension criterion is introduced to handle concurrent fracture growth. Fracture and volume-based growth rate exponents are shown to modify fracture interaction patterns. A geomechanical discrete fracture network is generated and examined during its growth, whose properties are the direct result of the imposed anisotropic stress field and mutual fracture interaction. Two-dimensional cut-plane views of the network demonstrate how fractures would appear in outcrops, and show the variability in fracture traces arising during interaction and growth.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Growth of three-dimensional fractures, arrays, and networks in brittle rocks under tension and compression

Thomas

Paluszny

Zimmerman

2020

Computers and Geotechnics

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“…The use of the modified two‐step Paris‐type law is instrumental for growing geomechanical networks, for several reasons. In many brittle geological materials (e.g., in outcrops, reservoirs, and deep crystalline rock), fractures are found to have grown together in populations under the same stress conditions (Segall, ; Lamarche et al, ). A standard Paris‐type law in three dimensions focuses growth on only the most stressed tips, leading to the activation of relatively few fractures in the network, unless very low values of the growth exponent are used.…”

Section: Methodsmentioning

confidence: 99%

Permeability of Three‐Dimensional Numerically Grown Geomechanical Discrete Fracture Networks With Evolving Geometry and Mechanical Apertures

2020

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Fracture networks significantly alter the mechanical and hydraulic properties of subsurface rocks. The mechanics of fracture propagation and interaction control network development. However, mechanical processes are not routinely incorporated into discrete fracture network (DFN) models. A finite element, linear elastic fracture mechanics-based method is applied to the generation of three-dimensional geomechanical discrete fracture networks (GDFNs). These networks grow quasi-statically from a set of initial flaws in response to a remote uniaxial tensile stress. Fracture growth is handled using a stress intensity factor-based approach, where extension is determined by the local variations in the three stress intensity factor modes along fracture tips. Mechanical interaction between fractures modifies growth patterns, resulting in nonuniform and nonplanar growth in dense networks. When fractures are close, stress concentration results in the reactivation of fractures that were initially inactive. Therefore, GDFNs provide realistic representations of subsurface networks that honor the physical process of concurrent fracture growth. Hydraulic properties of the grown networks are quantified by computing their equivalent permeability tensors at each growth step. Compared to two sets of stochastic DFNs, GDFNs with uniform fracture apertures are strongly anisotropic and have relatively higher permeabilities at high fracture intensities. In GDFN models, where fracture apertures are based on mechanical principles, fluid flow becomes strongly channeled along distinct flow paths. Fracture orientations and interactions significantly modify apertures, and in turn, the hydraulic properties of the network. GDFNs provide a new way of understanding subsurface networks, where fracture mechanics is the primary influence on their geometric and hydraulic properties.

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Dimensional Threshold for Fracture Linkage and Hooking

Cited by 2 publications

References 0 publications

Growth of three-dimensional fractures, arrays, and networks in brittle rocks under tension and compression

Growth of three-dimensional fractures, arrays, and networks in brittle rocks under tension and compression

Permeability of Three‐Dimensional Numerically Grown Geomechanical Discrete Fracture Networks With Evolving Geometry and Mechanical Apertures

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