Numerical simulation of hydraulic fracture propagation in naturally fractured formations using the cohesive zone model

Taleghani, Arash Dahi; Gonzalez-Chavez, Miguel Alejandro; Yu, Haibin; Asala, Hope

doi:10.1016/j.petrol.2018.01.063

Cited by 164 publications

(59 citation statements)

References 26 publications

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“…Bilinear traction-separation law is simple to implement because it only requires the determination of tensile/shear strength, critical fracture energy, Young's modulus and Poisson's ratio. Other more sophisticated traction-separation law is also available, but requires laboratory data from well-designed experiments, such as three points bending test (Lee et al 2010), semi-circular bending test (Dahi-Taleghani et al 2018). The coulomb friction law is applied to the failed but contacting surfaces, where the shear slippage occurs when…”

Section: Global Cohesive Zone Modelmentioning

confidence: 99%

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Wang

2019

Journal of Natural Gas Science and Engineering

138

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All reservoirs are fractured to some degree. Depending on the density, dimension, orientation and the cementation of natural fractures and the location where the hydraulic fracturing is done, pre-existing natural fractures can impact hydraulic fracture propagation and the associated flow capacity. Understanding the interactions between hydraulic fracture and natural fractures is crucial in estimating fracture complexity, stimulated reservoir volume (SRV), drained reservoir volume (DRV) and completion efficiency. However, what hydraulic fracture looks like in the subsurface, especially in unconventional reservoirs, remain elusive, and many times, field observations contradict our common beliefs. In this study, a global cohesive zone model is presented to investigate hydraulic propagation in naturally fractured reservoirs, along with a comprehensive discussion on hydraulic fracture propagation behaviors in naturally fractured reservoirs. The results indicate that in naturally fractured reservoirs, hydraulic fracture can turn, kink, branch and coalesce, and the fracture propagation path is quite complex, but it does not necessarily mean that fracture networks can be created, even under low horizontal stress difference, because of strong stress shadow effect and flow-resistance dependent fluid distribution. Perhaps, 'complex fracture', rather than 'fracture networks', is the norm in most unconventional reservoirs.

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Section: Global Cohesive Zone Modelmentioning

confidence: 99%

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Wang

2019

Journal of Natural Gas Science and Engineering

138

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“…The width of fractures decreases away from the wellbore. For each segment, the width of the segment can be set with an average value based on experience or hydraulic fracturing simulation results [13][14][15]. To model fracture closure more accurately, understanding of fracture properties is of great importance.…”

Section: Fractal Fracture Network and Fracture Discretizationmentioning

confidence: 99%

Semi-Analytical Model for Two-Phase Flowback in Complex Fracture Networks in Shale Oil Reservoirs

Cai

Taleghani

2019

Energies

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Flowback data is the earliest available data for estimating fracture geometries and the assessment of different fracturing techniques. Considerable attention has been paid recently to analyze flowback data quantitively in order to obtain fracture properties such as effective half-length and effective conductivity by simply assuming fractures having bi-wing planar geometries and constant fracture compressibility. However, this simplifying assumption ignores the complexity of fracture networks. To overcome this limitation, we proposed a semi-analytical method, which can be used as a direct model for fast inverse analysis to characterize complex fracture networks generated during hydraulic fracturing. A two-phase oil-water flowback model with a matrix oil influx for wells with bi-wing planar fractures is also presented to identify limitations of the former solution.Since most available flowback studies use constant fracture properties and the assumption of planar fractures, considering variable fracture properties and complex fracture geometries gives this model more robustness for modeling fracture flow during flowback, more realistically. The proposed models have been validated by numerical simulations. The presented procedure provides a simple way for modeling early flowback in complex fracture networks and it can be used for inverse analysis.

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“…In this study, a fully seepage-stress coupling model based on XFEM was developed to model the diverting fractures in the refracturing process. The accuracy of this model was verified by using the commercial software ABAQUS and experiments [24][25][26]. An improved model with initial fracture was introduced to analyze the influence of geological data and hydraulic fracturing treatment, including the perforation azimuth angle, perforation depth, injection rate, fluid viscosity, horizontal stress difference, and far-field location of fracture initiation.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation on Deflecting Hydraulic Fracture with Refracturing Using Extended Finite Element Method

Dong

Hua

et al. 2019

Energies

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Refracturing is a key technology in enhancing the conductivity of fractures from hydraulically-fractured wells. However, the deflecting mechanism of the diverting fracture is still unclear. In this paper, a fully coupled seepage-stress model based on the extended finite element method (XFEM) was developed to realize the deflection mechanism of the refracturing fractures. The modified construction of refracturing was then verified by laboratory experiments. Furthermore, two new deflection angles considering the influence area along initial fracture length were introduced to evaluate the refracturing. The numerical results demonstrated that: (1) lower stress difference, larger perforation angle and longer perforation depth can lead to a higher deflection angle, thereby a more curving propagation path of the diverting fracture; (2) increasing injection rate or fluid viscosity can significantly enhance the diverting behavior; and (3) an initial location near the root of the initial fracture results in a larger value of the deflection angle, which is preferred for far-field refracturing. The conclusions in this study can be a systematic guide for the parameter optimization in refracturing treatment.

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Numerical simulation of hydraulic fracture propagation in naturally fractured formations using the cohesive zone model

Cited by 164 publications

References 26 publications

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Semi-Analytical Model for Two-Phase Flowback in Complex Fracture Networks in Shale Oil Reservoirs

Numerical Simulation on Deflecting Hydraulic Fracture with Refracturing Using Extended Finite Element Method

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