Optimisation of hydraulic fracturing parameters based on cohesive zone method in oil shale reservoir with random distribution of weak planes

Zhai, Lianghao; Zhang, Han; Pan, Dong; Zhu, Ying; Zhu, Jiang; Zhang, Ying; Chen, Chen

doi:10.1016/j.jngse.2019.103130

Cited by 30 publications

(10 citation statements)

References 47 publications

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“…To ensure that the numerical calculation can more closely simulate the real physical experiment, the actual physical parameters of the experimental sample are adopted in the numerical simulation as much as possible. 4 Geofluids…”

Section: 2mentioning

confidence: 99%

“…In recent years, hydraulic fracturing has been widely used in the engineering practices of petroleum, natural gas, shale gas, and coal mining [1][2][3][4][5]. The propagation of hydraulic fractures plays a key role in the optimisation of hydraulic fracture design and represents a challenging problem corresponding to the theoretical study of hydraulic fractures [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of the Influence of Natural Fractures on Hydraulic Fracture Propagation

Song

et al. 2020

Geofluids

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According to the theory of plane mechanics involving the interaction of hydraulic and natural fractures, the law of hydraulic fracture propagation under the influence of natural fractures is verified using theoretical analysis and RFPA2D-Flow numerical simulation approaches. The shear and tensile failure mechanisms of rock are simultaneously considered. Furthermore, the effects of the approach angle, principal stress difference, tensile strength and length of the natural fracture, and elastic modulus and Poisson’s ratio of the reservoir on the propagation law of a hydraulic fracture are investigated. The following results are obtained: (1) The numerical results agree with the experimental data, indicating that the RFPA2D-Flow software can be used to examine the hydraulic fracture propagation process under the action of natural fractures. (2) In the case of a low principal stress difference and low approach angle, the hydraulic fracture likely causes shear failure along the tip of the natural fracture. However, under a high stress difference and high approach angle, the hydraulic fracture spreads directly through the natural fracture along the original direction. (3) When natural fractures with a low tensile strength encounter hydraulic fractures, the hydraulic fractures likely deviate and expand along the natural fractures. However, in the case of natural fractures with a high tensile strength, the natural fracture surface is closed, and the hydraulic fracture directly passes through the natural fracture, propagating along the direction of the maximum principal stress. (4) Under the same principal stress difference, a longer natural fracture corresponds to the easier initiation and expansion of a hydraulic fracture from the tip of the natural fracture. However, when the size of the natural fracture is small, the hydraulic fracture tends to propagate directly through the natural fracture. (5) A smaller elastic modulus and larger Poisson’s ratio of the reservoir result in a larger fracture initiation pressure. The presented findings can provide theoretical guidance regarding the hydraulic fracturing of reservoirs with natural fractures.

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Section: 2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Influence of Natural Fractures on Hydraulic Fracture Propagation

Song

et al. 2020

Geofluids

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“…The effect of parameters of the CZM on fracture propagation is tested in detail 57,59–61 . The cohesive element is further used to model the more realistic and complex fluid‐driven fracture, such as the hydraulic fracturing in reservoirs with natural fractures and weak planes 62–69 …”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal constraints of the cohesive modeling: A unified criterion for fluid‐driven fracture

Wang

et al. 2023

Numerical Meth Engineering

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We present a unified criterion for cohesive modeling of fluid-driven fracture based on the dimensional analysis to simultaneously provide the constraint for cohesive element and time step sizes. Complicated by the nonlinear interaction between solid deformation and fluid flow, the underlying correlation between discretization and physical parameters of fluid-driven fracture is still unclear. This work studies this correlation through the dimensionless process of the governing equations that associate the cohesive element and time step sizes in a discrete regime. Three characteristic parameters (i.e., related to crack opening, fluid pressure, and fracture length) are introduced in the derivation, and two dimensionless parameters are proposed to construct the unified criterion. The criterion is validated by numerical tests of toughness-dominated fracture with various conditions including the modulus of solid, injection rate of fluid, fracture energy, and in-situ stress. The proposed criterion determines the spatial and temporal constraints of the cohesive zone model for modeling fluid-driven fracture, which is often treated empirically in previous practices.

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“…In these cases, the operation parameters have an important role in enhancing the reservoir stimulation effect. Therefore, on the basis of understanding geological parameters, an exploration of the influence of construction parameters (such as injection rate and fluid viscosity) on fracture network propagation and fracture properties has more practical significance (Zhai et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Shale Reservoir Fluid-Driven Fracture Network Morphology Based on Global CZM

Yang

Jiao

et al. 2021

Front. Earth Sci.

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There are a large number of natural fractures in shale reservoirs, which create great challenges to hydraulic fracturing. Activating the natural fractures in reservoirs can form a complex fracture network, enhance fracturing effects, and increase shale gas production. Reservoir geological conditions (low in situ stress, natural fracture distribution, and cement strength) and operation parameters (fracturing fluid viscosity and injection rate) have an important influence on fracture network propagation. In this article, a two-dimensional hydraulic fracturing fluid-mechanic coupling numerical model for shale reservoirs with natural fractures was established. Based on the global cohesive zone model, the influence of geological conditions and operation parameters on the propagation of the hydraulic fracture network and fracturing process is investigated. The numerical simulation results show that when the horizontal in situ stress difference, approach angle, and cement strength are low, it is easier to form a complex fracture network. Research on the construction parameters indicated that when the viscosity of the fracturing fluid is low, it is easier to form a complex network of fractures, but the length of the fractures is shorter; in contrast, the fractures are straight and long. In addition, increasing the injection rate is beneficial for increasing the complexity of the fracture network while increasing the initiation pressure and width of the principal fracture reduces the risk of sand plugging. This article also proposes an optimization solution for hydraulic fracturing operations based on numerical simulation results.

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Optimisation of hydraulic fracturing parameters based on cohesive zone method in oil shale reservoir with random distribution of weak planes

Cited by 30 publications

References 47 publications

Numerical Simulation of the Influence of Natural Fractures on Hydraulic Fracture Propagation

Numerical Simulation of the Influence of Natural Fractures on Hydraulic Fracture Propagation

Spatial and temporal constraints of the cohesive modeling: A unified criterion for fluid‐driven fracture

Numerical Simulation of Shale Reservoir Fluid-Driven Fracture Network Morphology Based on Global CZM

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