Contributions of non-tectonic micro-fractures to hydraulic fracturing—A numerical investigation based on FSD model

Wang, Yu; Li, Xiao; Zhao, Ziyan; Zhou, Ru; Zhang, Bo; Li, Guanfang

doi:10.1007/s11430-015-5232-1

Cited by 14 publications

(12 citation statements)

References 13 publications

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“…Stress ratio also plays an important role in the generation of fracturing networks, as it controls the geometry of fracturing network. Wang et al [25] studied the influence of non-tectonic micro-fractures on hydraulic fracturing, but for their studies, thesilty laminae structure is not introduced into the modeling. Under different stress ratio, two different morphology of fracturing network are observed.…”

Section: Discussionmentioning

confidence: 99%

“…They are often small scale and the majority present in the form of microfractures [23,24]. The non-tectonic microfractures are small, high-aspect-ratio cracks in shale formations that result from differential stresses [22,23,25]. A detailed discussion of random non-tectonic microfracture generation and how it influences the hydraulic fracturing effectiveness has been presented by Wang et al [25]; in addition, the effect of silty lamined have been studied using physical modeling experiments, but the effects of natural fractures on hydraulic fracturing have not been introduced in their studied cement models [26].…”

Section: Introductionmentioning

confidence: 99%

“…In the core specimens, medium-angle slip fractures and horizontal bedding cracks were the most common types of fractures, whereas vertical and high-angle fractures and horizontal bedding cracks were under developed. In the thin sections, microfractures arising in organic matter laminations or at their edges as well as those of tectonic origin were the predominant type of fractures, and they were mainly short, narrow, and open [23][24][25]. As a result, considering the non-tectonic fractures in silty laminated model is important to grasp the mechanical properties of hydraulic fracturing, and the associate fracability predication in the continental shale formation.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Fracturing Network Propagation in Random Naturally Fractured and Laminated Block Experiments

Wang

et al. 2016

Energies

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Abstract:Researchers have recently realized thatsilty laminas are very developed in naturally fractured continentalsedimentary formations in the Ordos Basin(China). Studies have shown that silty laminas are significant to improve the physical properties and gas storage capacity, and the natural fractures interact with the hydraulic fractures to maximize the fracture network during hydraulic fracturing. However, the influence of silty laminas withrandom fractures on the created hydraulic fracture networkis not well understood. Laboratory experiments are proposed to investigate the evolution of fracture networks in naturally fractured formations with model blocks that contain laminas and random fractures. The influence of dominating factors was studied and analyzed, with an emphasis on stress ratio, injection rate, and laminae strength. Macroscopic failure morphology descriptions combined with meso 3-D laser scanning techniques are both used to reveal the evolution of fracture networks. It is suggested that high injection rate, medium laminae strength, and low stress ratio tend to increase the stimulated reservoir volume (SRV). The interactions between the silty laminae and random natural fractures affect the effect of hydraulic fracturing effectiveness. This work strongly links the production technology and fracability evaluation in the continental shale formation. It can aid in the understanding and optimization of hydraulic fracturing simulations in silty laminae shale reservoirs.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of Fracturing Network Propagation in Random Naturally Fractured and Laminated Block Experiments

Wang

et al. 2016

Energies

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“…The four-node isoparametric element is applied as the basic element mesh. This coupled flow, stress, and damage (FSD) model in RFPA 2D -Flow has been validated in previous publications [18,35,40,41]. The progressive failure process of a quasibrittle material such as rock subjected to gradually increasing static loading can be simulated.…”

Section: Numerical Approaches Of Rfpa 2d -Flowmentioning

confidence: 90%

“…When the element is under uniaxial compression, the constitutive law is as shown in Figure 1(b). An element is considered to have failed in the shear mode when the compressive or shear stress has satisfied the Mohr-Coulomb failure criterion which is chosen as the second damage criterion [11,35,40,41,44]:…”

Section: Numerical Approaches Of Rfpa 2d -Flowmentioning

confidence: 99%

The Influence of Bedding Planes and Permeability Coefficient on Fracture Propagation of Horizontal Wells in Stratification Shale Reservoirs

et al. 2020

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The complexity of hydraulic fractures (HF) significantly affects the success of reservoir reconstruction. The existence of a bedding plane (BP) in shale impacts the extension of a fracture. For shale reservoirs, in order to investigate the interaction mechanisms of HF and BPs under the action of coupled stress-flow, we simulate the processes of hydraulic fracturing under different conditions, such as the stress difference, permeability coefficients, BP angles, BP spacing, and BP mechanical properties using the rock failure process analysis code (RFPA2D-Flow). Simulation results showed that HF spread outward around the borehole, while the permeability coefficient is uniformly distributed at the model without a BP or stress difference. The HF of the formation without a BP presented a pinnate distribution pattern, and the main direction of the extension is affected by both the ground stress and the permeability coefficient. When there is no stress difference in the model, the fracture extends along the direction of the larger permeability coefficient. In this study, the in situ stress has a greater influence on the extension direction of the main fracture when using the model with stress differences of 6 MPa. As the BP angle increases, the propagation of fractures gradually deviates from the BP direction. The initiation pressure and total breakdown pressure of the models at low permeability coefficients are higher than those under high permeability coefficients. In addition, the initiation pressure and total breakdown pressure of the models are also different. The larger the BP spacing, the higher the compressive strength of the BP, and a larger reduction ratio (the ratio of the strength parameters of the BP to the strength parameters of the matrix) leads to a smaller impact of the BP on fracture initiation and propagation. The elastic modulus has no effect on the failure mode of the model. When HF make contact with the BP, they tend to extend along the BP. Under the same in situ stress condition, the presence of a BP makes the morphology of HF more complex during the process of propagation, which makes it easier to achieve the purpose of stimulated reservoir volume (SRV) fracturing and increased production.

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Investigation of the Effect of Cemented Fractures on Fracturing Network Propagation in Model Block with Discrete Orthogonal Fractures

Wang

2017

Rock Mech Rock Eng

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Contributions of non-tectonic micro-fractures to hydraulic fracturing—A numerical investigation based on FSD model

Cited by 14 publications

References 13 publications

Investigation of Fracturing Network Propagation in Random Naturally Fractured and Laminated Block Experiments

Investigation of Fracturing Network Propagation in Random Naturally Fractured and Laminated Block Experiments

The Influence of Bedding Planes and Permeability Coefficient on Fracture Propagation of Horizontal Wells in Stratification Shale Reservoirs

Investigation of the Effect of Cemented Fractures on Fracturing Network Propagation in Model Block with Discrete Orthogonal Fractures

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