Numerical Investigation on the Hydraulic Fracture Evolution of Jointed Shale

Men, Xiaoxi; Jin, Jiaxu

doi:10.1155/2021/5538243

Cited by 3 publications

(3 citation statements)

References 29 publications

(29 reference statements)

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“…The numerical simulation of the interaction between the HF and the BP can be divided into three parts. The first part refers to the experiment in [32] for verifying the reliability of the RFPA-Flow code [9,10,[33][34][35]. The second part refers to the verification of the above prediction criterion.…”

Section: Model Setmentioning

confidence: 99%

“…The existence of bedding planes (BP) affects the stress distribution, thus affecting the fracture propagation trajectory [7]. Many studies have shown that the existence of bedding promotes the formation of fracture networks in shale reservoirs [8][9][10][11][12][13], thus promoting shale reservoir permeability and oil and gas production [14][15][16]. Since 1947, the year of the first experimental hydraulic fracturing treatment in the United States in the Hugoton gas field in Grant County, Kansas [17], hydraulic fracturing treatments have become an essential part in gas and oilfield development [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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Prediction criterion and numerical validation for the interaction between hydraulic fractures and bedding planes

Men,

Han

2023

PLoS ONE

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Shale is a kind of sedimentary rock with an obvious bedding structure. The effect of the bedding plane on hydraulic fracture initiation, propagation, and complex fracture network formation is remarkable and a major problem in hydraulic fracturing and shale oil and gas development. In this study, a criterion is established to predict the evolution behavior of hydraulic fractures (HF) under different confining pressure differences and intersection angles. This criterion is intended to predict the types of interaction between HFs and bedding planes (BPs): penetrating, slipping, or dilating. The dependence of crossing on the intersection angle and the principal stress difference is quantitatively presented using the criterion. Meanwhile, 20 simulations with principal stress differences of 2, 4, 6, and 8 MPa and intersection angles of 30°, 45°, 60°, 75°, and 90° were simulated using the RFPA2D-Flow code. Simulation results exhibit good agreement with the criterion results for a wide range of angles. The investigation showed that HFs tend to penetrate BPs under high confining pressure differences and intersection angles and open BPs under low confining pressure differences and intersection angles. In addition to the above two forms, HFs slip due to shear. The criterion can provide relevant reference about the formation of complex fracture networks in shale layers.

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Section: Model Setmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prediction criterion and numerical validation for the interaction between hydraulic fractures and bedding planes

Men,

Han

2023

PLoS ONE

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“…It was found that the mechanical properties of the joint primarily determine whether a hydraulic fracture penetrates or is deflected at the joint. Men and Jin [12] studied the hydraulic fracture evolution of jointed shale specimens under different confining pressures and the results indicated that the fracture evolution was predominantly affected by the maximum principal stress when the confining pressure is high whereas it was significantly influenced by the joint plane if the confining pressure is low. e oriented perforation is a common technique in hydraulic fracturing.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Hydraulic Fracture Network Formation of Jointed Shale with Oriented Perforation

Men

Wang

2022

Mathematical Problems in Engineering

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This paper aims at exploring the fracture evolution as well as capturing the fracture network formation of jointed shale during hydraulic fracturing process by numerical simulation using the Rock Failure Process Analysis System of Flow (RFPA—Flow). The simulations were successfully completed following two stages. In the first stage, a series of simulations are performed to investigate the influence of different angle-oriented perforations on fracture initiation and propagation. The simulation results agreed well with the experimental results confirming the validity of the RFPA-Flow code in the application. In the second stage, extensive hydraulic fracturing simulations on jointed shale with different angled-joint planes and different angle-oriented perforations were performed. The simulation results demonstrated that the fracture evolution changes significantly as the magnitude of α (the angle between perforation and the joint plane) increased. It was found that a large α value could lead to a larger the tensile stress region around the fracture tip resulting in more joint planes pulled apart. It could also induce more secondary fractures and hence a more complex fracture could be formed. As a result, the α value of 60° to 90° were found to aid in the fracture network generation. On the other hand, the angle β being the angle between the parallel joints and the maximum stress direction was another important factor in fracture evolution. Its influence on fracturing performance was similar to angle α. It was found that the initiation and breakdown pressure of jointed shale were in proportional to the magnitude of angle β. Therefore, this paper introduced an efficient approach to promote the formation of a complex fracture network in jointed shale with the presence of oriented perforation, which could offer valuable guidance for the design of unconventional reservoir reconstruction.

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Study on the influence of vertical stress difference coefficient on fracture characteristics of shale under high stress

Chang,

Qiu,

et al. 2024

Energy Science & Engineering

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To study the effect of vertical stress difference coefficient on fracture characteristics of shale fracturing, high stress true triaxial hydraulic fracturing test was carried out. By analyzing the profile after fracturing, it was found that the area of hydraulic fracture increased with the increase of vertical stress difference coefficient, and the probability of shear fracture will increase when the stress difference coefficient was high. A high vertical stress differential coefficient exerts a strong control over the direction of crack propagation, while a low vertical stress difference coefficient is beneficial to improve the roughness of hydraulic fracture surface and promote the formation of complex fracture network. By analyzing the pump pressure curves of different tests, it was found that with the increase of vertical stress difference coefficient, the formation and expansion of hydraulic fractures were more difficult. The surface characteristics of hydraulic fractures were quantified based on three‐dimensional topography scanning technology, combined with fractal dimension and fracture area calculation method, the results showed that with the increase of vertical stress difference coefficient, the fractal dimension and fracture area decreased. Since shale is stratified, and the transformation of reservoir is mainly reflected in the enhancement of fracture complexity through tensile failure, Xsite discrete grid method was used to study the influence of fracture propagation behavior with different bedding strengths. The results showed that when the bedding tensile strength was high, hydraulic fractures were easy to pass through the bedding, and when the bedding tensile strength was low, hydraulic fractures were easy to be captured by natural fractures. In addition, tensile cracks were easy to form when the tensile strength of bedding was low, shear cracks were easy to form when the strength of bedding was high, and the fracture volume was larger when the strength of bedding was low. This study provides a theoretical basis for hydraulic fracturing in engineering.

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Numerical Investigation on the Hydraulic Fracture Evolution of Jointed Shale

Cited by 3 publications

References 29 publications

Prediction criterion and numerical validation for the interaction between hydraulic fractures and bedding planes

Prediction criterion and numerical validation for the interaction between hydraulic fractures and bedding planes

Numerical Investigation of Hydraulic Fracture Network Formation of Jointed Shale with Oriented Perforation

Study on the influence of vertical stress difference coefficient on fracture characteristics of shale under high stress

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