Variation of the energy release rate as a crack approaches and passes through an elastic inclusion

Li, Rongshun; Chudnovsky, A.

doi:10.1007/bf00034570

Cited by 29 publications

(2 citation statements)

References 2 publications

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“…For glutenite reservoirs, strong heterogeneity is induced by embedded gravel, and this causes the initiation and propagation of hydraulic fractures to be more complicated. It was reported that a substantial "shielding" effect on near fracture can be produced by embedded gravel, and this would result in a reduction in the energy release rate [28,29]. Therefore, the stress near the interfaces between gravel and matrix quickly increases as hydraulic fractures approach the gravel, and this change subsequently causes local failures, which gradually attract the propagating hydraulic fractures.…”

Section: Discussionmentioning

confidence: 99%

Investigation on the Propagation Mechanisms of a Hydraulic Fracture in Glutenite Reservoirs Using DEM

Tang¹,

Liu²,

Zhang³

2022

Energies

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The geometry heterogeneity induced by embedded gravel can cause severe stress heterogeneity and strength heterogeneity in glutenite reservoirs, and subsequently affect the initiation and propagation of hydraulic fractures. Since the discrete element method (DEM) can accurately describe the inter-particle interactions, the macromechanical behavior of glutenite specimen can be preciously represented by DEM. Therefore, the initiation and propagation mechanisms of hydraulic fractures were investigated using a coupling seepage-DEM approach, the terminal fracture morphologies of hydraulic fractures were determined, and the effects of stress differences, permeability, and gravel strength were studied. The results show that the initiation and propagation of hydraulic fractures are significantly influenced by embedded gravel. In addition, the stress heterogeneity and strength heterogeneity induced by the gravel embedded near the wellbore increase local initiation points, causing a complicated fracture network nearby. Moreover, due to the effect of local stress heterogeneity, gravel strength, and energy concentration near the fracture tip, four interactions of attraction, deflection, penetration, and termination between propagating fractures and encountering gravel were observed.

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Section: Discussionmentioning

confidence: 99%

Investigation on the Propagation Mechanisms of a Hydraulic Fracture in Glutenite Reservoirs Using DEM

Tang¹,

Liu²,

Zhang³

2022

Energies

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“…These propagation morphology characteristics of the HF are consistent with those proposed by Ma (Figures 5(a) and 5(b)) and consistent with the simulation results of Li et al [38,39], Rui et al [44], Zhang et al [45], and others. Previous studies have shown that the embedded gravel will have a substantial "shielding" effect on the HF propagation, resulting in slower energy release, which is a manifestation of the stress intensity factor and toughness locally [56]. When HF propagates to the vicinity of the gravel, the stress close by 11 Geofluids the matrix-gravel interface increases rapidly, causing failures at the interface; thus, HF is easily attracted to the interface (Figure 4), which is consistent with the results from a physical experiment, as shown in Figure 5(d).…”

Section: Model Verification and Comparisonmentioning

confidence: 99%

Numerical Investigation of Hydraulic Fracture Propagation Morphology in the Conglomerate Reservoir

Liu

Liang

2022

Geofluids

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The random distribution of gravels makes the conglomerate reservoir highly heterogeneous. A stress concentration occurs at the gravel-matrix interfaces owing to the embedded gravel and affects the local mechanical response significantly, making it difficult to control and predict hydraulic fracture (HF) propagation. The mechanism of HF propagation in conglomerate reservoirs remains unclear; thus, it is difficult to effectively design and treat hydraulic fracturing. Based on the global pore-pressure cohesive zone element (GPPCZ) model method, a two-dimensional (2D) fracture propagation model with flow-stress-damage (FSD) coupling was established to investigate HF nucleation, propagation, and coalescence in conglomerate reservoirs. This model was experimentally verified, and fractal theory was introduced to quantify the complexity of fracture morphology. The microscale interactions of the gravel, matrix, and interface have been taken into consideration during simulating HF propagation accurately in macroscale. The influence of the mechanical properties of gravel, matrix, matrix-gravel interface, and reservoir stress distribution state, on HF morphology (HF length, stimulated reservoir square, and HF complexity morphology), was investigated. Finally, the main factors affecting fracture propagation were analyzed. It was revealed that the difference between the mechanical properties of the gravel and the matrix in the conglomerate rock will affect the geometry of HF to varying degrees. The local behavior of fracture propagation is obviously dominated by the elastic modulus, tensile strength, and the strength for the matrix-gravel interface. However, the propagation of HF at the whole scale is mainly dominated by the horizontal stress state, including the minimum horizontal stress and horizontal stress difference. In addition, the difference in horizontal stress significantly affects the fracturing patterns (deflection, bifurcation, and penetration) when HF encounters gravel. In this study, a simulation method of HF propagation in conglomerate reservoirs is introduced, and the results provide theoretical support for the prediction of HF propagation morphology and plan design of hydraulic fracturing in conglomerate reservoirs.

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Three-dimensional interaction between a crack front and particles

Haddi

Weichert

1998

Int. J. Numer. Meth. Engng.

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The three-dimensional interaction of a crack front with particles is investigated under mode-I loading. The J-integral is applied to characterize the crack-inclusion interactions. Numerical examples are presented, using 20 node, isoparametric finite elements, for the compact tension specimen and elastic materials. The J-integral is calculated for various moduli of the particles, distances of the crack from the interface and particle size. The problem of the crack penetrating a cluster of particles is discussed.1998 John Wiley & Sons, Ltd.

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Variation of the energy release rate as a crack approaches and passes through an elastic inclusion

Cited by 29 publications

References 2 publications

Investigation on the Propagation Mechanisms of a Hydraulic Fracture in Glutenite Reservoirs Using DEM

Investigation on the Propagation Mechanisms of a Hydraulic Fracture in Glutenite Reservoirs Using DEM

Numerical Investigation of Hydraulic Fracture Propagation Morphology in the Conglomerate Reservoir

Three-dimensional interaction between a crack front and particles

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