Combined influences of shear displacement, roughness, and pressure gradient on nonlinear flow in self-affine fractures

Zhang, Yao; Jaturapitakkul, Chai; Cheng, Chao; Shang, Tao

doi:10.1016/j.petrol.2020.108229

Cited by 28 publications

(10 citation statements)

References 46 publications

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“…As the Reynolds number increases, the value of e h /e m decreases gradually, suggesting that as the Reynolds number increases, the characteristics of nonlinearity in the fracture seepage increase. is is consistent with the research results of Zhang et al [48]. Qin et al [49] found that the modified cubic law can be well adopted in the test when the hydraulic pressure is 0.1 MPa, but R 2 of the fitting lines decreases with the increase of hydraulic pressure.…”

Section: Evolution Of Equivalent Hydraulicsupporting

confidence: 91%

“…In order to reflect the effect of fracture roughness and nonlinear seepage on the water conductivity of fracture, the equivalent hydraulic aperture is normalized (the ratio of the equivalent hydraulic aperture e h to the average mechanical aperture e m ). Li and Jiang [46], Qian et al [47], and Zhang et al [48] have established the relationship between e m /e h , roughness, and Reynolds number Re. Besides, under the same roughness, e m /e h will increase with the increase of Re.…”

Section: Evolution Of Equivalent Hydraulicmentioning

confidence: 99%

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Discrepancy between Forward and Reverse Seepage Characteristics in a Single Rough Fracture

Niu

Wang

Sun

et al. 2021

Advances in Civil Engineering

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Under the uniform seepage boundary condition, the forward and reverse seepage flow rates will vary widely. In response to this phenomenon, this paper studies the mechanism of the difference in seepage characteristics between the forward and reverse directions from the fracture profile’s roughness, Darcy and non-Darcy seepage, and distribution of eddy currents. First of all, wavelet transform was used to decompose and reconstruct the single rough fracture for 8 times, and then 9 fracture models with various roughness degrees were constructed. Then, Finite Volume Method was used to simulate the seepage in the original and approximate models of the Reynolds number varying from 0.001 to 1000. The results show that the nonlinear seepage is necessary for the difference between the forward and reverse seepage characteristics of the single rough fracture. The mechanism of the discrepancy between forward and reverse nonlinear seepages is the diverse shapes and distribution of the eddy current generated by the forward and reverse seepage. The secondary roughness provides space for the existence and development of the eddy current. The secondary roughness is the geometric basis of the discrepancy between the forward and reverse seepage characteristics.

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Section: Evolution Of Equivalent Hydraulicsupporting

confidence: 91%

Section: Evolution Of Equivalent Hydraulicmentioning

confidence: 99%

Discrepancy between Forward and Reverse Seepage Characteristics in a Single Rough Fracture

Niu

Wang

Sun

et al. 2021

Advances in Civil Engineering

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“…In addition, shear induces expansion of rock fractures and surface mismatch, resulting in changes in contact characteristics and flow channels, thus affecting the flow behaviors in fractures. In recent years, scholars have studied the changes in fluid flow behavior during fracture shearing, mainly using the numerical simulations and experimental studies (Xie et al 2015;Zou et al 2017;Zhou et al 2018;Li et al 2020;Zhang et al 2017Zhang et al , 2021 and experimental studies (Rong et al 2016;Yin et al 2017;Wang et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Assessment of nonlinear flow behaviors through real rough rock fractures during shearing

Zhu

Yin

Huang

et al. 2022

Geomech. Geophys. Geo-energ. Geo-resour.

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of fractures. The transmissivity decreased with the increase in confining pressure, while it increased with the increase in shear displacement. In addition, during the shearing process, the change of transmissivity with Reynolds number can be characterized by a fifth-order polynomial function. The Forchheimer coefficient (β) increased by 71.05-153.15% with the applied confining pressure, while it decreased by 42.72-69.52% with the increase in shear displacement. Variations in the equivalent permeability coefficient with the hydraulic gradient can be divided into three stages of being constant, gentle decrease and significant decrease, and corresponded to linear Darcy flow, weak inertia and strong flow nonlinearity, respectively. Article highlights• An engraving technique was adopted to copy 3D self-affine fracture surfaces. • Hydro tests with perpendicular flow to shear direction were conducted. • Nonlinear flow responses of rough fractures during shearing were revealed.

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“…The calculation model of the fluid flow in fracture networks established by this study can help in the analysis of experimental or numerical simulation results and in the calculation of the proppant distribution in fracture networks. However, the leak‐off of the fracturing fluid, the effect of the suspended proppant and sand bank on the fluid flow, and the surface morphology and roughness of the fracture wall 29,30 were not considered. Additionally, owing to the influence of the reservoir properties and in situ stress, the fluid flow during an actual slickwater hydraulic fracturing may be more complex.…”

Section: Discussionmentioning

confidence: 99%

Numerical investigation of fluid flow in fracture junctions with consideration to effect of fracture morphology

Liu

Zhang

2021

Energy Science & Engineering

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Because the fracturing fluid flow at fracture junctions directly affects the proppant distribution in fracture networks, it is very important to quantitatively investigate the fluid flow in fracture junctions. In this study, the fluid flow in a laboratory‐size fracture junction was investigated, and equations for calculating the fluid split ratio were established. The correlations between the pressure loss coefficients and the width ratio, approaching angle, and fluid split ratio were obtained by simulation. Using a custom‐made Visual Basic program, the fluid split ratios in an actual‐size fracture or complex fracture networks with several secondary or tertiary fractures were calculated. The results reveal that the fluid split ratio is significantly affected by the approaching angle and width ratio in laboratory‐size fractures. In contrast, in an actual‐size fracture junction, the fluid split ratio is mainly affected by the length of the fracture channel and the width ratio. The split ratios in laboratory‐size and real‐size fracture networks with several secondary or tertiary fractures are quite different, which indicates that the split ratio should be quantitatively estimated when investigating the proppant distribution by experiment or simulation. The findings of this study can be useful in the quantitative investigation of the proppant distribution in fracture networks.

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Combined influences of shear displacement, roughness, and pressure gradient on nonlinear flow in self-affine fractures

Cited by 28 publications

References 46 publications

Discrepancy between Forward and Reverse Seepage Characteristics in a Single Rough Fracture

Discrepancy between Forward and Reverse Seepage Characteristics in a Single Rough Fracture

Assessment of nonlinear flow behaviors through real rough rock fractures during shearing

Numerical investigation of fluid flow in fracture junctions with consideration to effect of fracture morphology

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