Numerical and Experimental Investigations of the Interactions between Hydraulic and Natural Fractures in Shale Formations

Chang, Xin; Guo, Yintong; Zhou, Jianting; Song, Xuehang; Yang, Chunhe

doi:10.3390/en11102541

Cited by 9 publications

(4 citation statements)

References 70 publications

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“…Rocks are complex in multiscale with heterogeneous structures, which makes prediction models for geomechanical properties challenging [1][2][3][4][5][6]. An emerging necessity to link microscale to macroscale properties has led researchers to take efforts to propose multiscale models of poromechanical behaviors, for different rock types [7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Geomechanical Upscaling Methods: Comparison and Verification via 3D Printing

et al. 2019

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Understanding geomechanical properties of rocks at multiple scales is critical and relevant in various disciplines including civil, mining, petroleum and geological engineering. Several upscaling frameworks were proposed to model elastic properties of common rock types from micro to macroscale, considering the heterogeneity and anisotropy in the samples. However, direct comparison of the results from different upscaling methods remains limited, which can question their accuracy in laboratory experiments. Extreme heterogeneity of natural rocks that arises from various existing components in them adds complexity to verifying the accuracy of these upscaling methods. Therefore, experimental validation of various upscaling methods is performed by creating simple component materials, which is, in this study, examining the predicted macroscale geomechanical properties of 3D printed rocks. Nanoindentation data were first captured from 3D printed gypsum powder and binder rock fragments followed by, triaxial compression tests on similar cylindrical core plugs to acquire modulus values in micro and macroscale respectively. Mori-Tanaka (MT) scheme, Self-Consistent Scheme (SCS) method and Differential Effective Medium (DEM) theory were used to estimate Young’s modulus in macroscale based on the results of nanoindentation experiments. The comparison demonstrated that M-T and SCS methods would provide us with more comparable results than DEM method. In addition, the potential applications of 3D printed rocks were also discussed regarding rock physics and the geomechanics area in petroleum engineering and geosciences.

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Section: Introductionmentioning

confidence: 99%

Geomechanical Upscaling Methods: Comparison and Verification via 3D Printing

et al. 2019

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“…Natural fractures play a significant role in the creation of fracture networks [24]. Hydraulic fracture growth depends on the shear slip of natural fractures or Processes 2022, 10, 2604 2 of 18 bedding planes with different cement strengths, which is documented by both numerical results and tri-axial hydraulic fracturing experiments [25,26]. A study demonstrates that after intersecting hydraulic fractures, failure modes within cemented natural fractures may change from tensile regime to mixed-mode or shear regime in heterogeneous reservoirs [27].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Fracture Morphology Characteristics in Heterogeneous Reservoirs

Cao

Liu

2022

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Highly heterogeneous glutenite reservoirs with large amounts of gravel and weak interfaces pose a great challenge to predicting the trajectory of hydraulic fractures during the fracturing process. Based on the phase field method, a fully coupled numerical model of hydraulic fracturing is established. This paper is devoted to investigating the variation in the overall expansion pattern of hydraulic fractures in reservoirs considering randomly distributed gravel and weak interfaces. The numerical results demonstrate that the existence of gravel and a weak interface could alter the extending paths of the hydraulic fractures as well as the value of critical bifurcation injection rate. As the fracture energy of the weak interface is large enough, the hydraulic fracture tends to cross the gravel and the weak interface between the rock matrix and the gravel, forming a planar fracture. Deflection and branching of the hydraulic fracture are more likely to occur in reservoirs containing large gravels. The presented results extend the understanding of fractures propagating in heterogeneous reservoirs.

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“…Based on the displacement discontinuity method (DDM), a two-dimensional numerical model has been developed and used to investigate the interaction between hydraulic and pre-existing natural fractures. Research has shown that the cemented strength of the NF has an important influence on the interaction mechanism [7]. In the fracturing experiment, the anisotropy of shale plays an important role in the mechanical behavior and fracture propagation.…”

Section: Introductionmentioning

confidence: 99%

Study on Fracture Morphological Characteristics of Refracturing for Longmaxi Shale Formation

et al. 2020

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Refracturing technology has become an important means for the regeneration of old wells reconstruction. It is of great significance to understand the formation mechanism of hydraulic fracturing fracture for the design of hydraulic fracturing. In order to accurately evaluate and improve fracturing volume after refracturing, it is necessary to understand the mechanism of refracturing fracture in shale formation. In this paper, a true triaxial refracturing test method was established. A series of large-scale true triaxial fracturing experiments were carried out to characterize the refracturing fracture initiation and propagation. The results show that for shale reservoirs with weak bedding planes and natural fractures, hydraulic fracturing can not only form the main fracturing fracture, which is perpendicular to horizontal minimum principal stress, but it can also open weak bedding plane or natural fractures. The characteristics of fracturing pump curve indicated that the evolution of fracturing fractures, including initiation and propagation and communication of multiple fractures. The violent fluctuation of fracturing pump pressure curve indicates that the sample has undergone multiple fracturing fractures. The result of refracturing shows that initial fracturing fracture channels can be effectively closed by temporary plugging. The refracturing breakdown pressure is generally slightly higher than that of initial fracturing. After temporary plugging, under the influence of stress induced by the initial fracturing fracture, the propagation path of the refracturing fracture is deviated. When the new fracturing fracture communicates with the initial fracturing fracture, the original fracturing fracture can continue to expand and extend, increasing the range of the fracturing modifications. The refracturing test results was shown that for shale reservoir with simple initial fracturing fractures, the complexity fracturing fracture can be increased by refracturing after temporary plugging initial fractures. The effect of refracturing is not obvious for the reservoir with complex initial fracturing fractures. This research results can provide a reliable basis for optimizing refracturing design in shale gas reservoir.

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Numerical and Experimental Investigations of the Interactions between Hydraulic and Natural Fractures in Shale Formations

Cited by 9 publications

References 70 publications

Geomechanical Upscaling Methods: Comparison and Verification via 3D Printing

Geomechanical Upscaling Methods: Comparison and Verification via 3D Printing

Numerical Investigation of Fracture Morphology Characteristics in Heterogeneous Reservoirs

Study on Fracture Morphological Characteristics of Refracturing for Longmaxi Shale Formation

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