Connectivity evaluation of fracture networks considering the correlation between trace length and aperture

Fan, Hongwei; Yao, Chi; Yang, Jianhua; He, Chen; Shao, Yulong; Zhou, Chuangbing

doi:10.1016/j.apm.2020.07.011

Cited by 13 publications

(8 citation statements)

References 28 publications

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“…The power law correlation between fracture aperture and length was proposed by previous studies. − The fracture length characteristic for DFN is generated by the aperture and eq in this study where A is the fracture aperture, L is the fracture length, a and β are constants. The value of the constant is the same as the previous study …”

Section: Samples and Methodsmentioning

confidence: 99%

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Characteristics of a Multi-scale Fracture Network and Its Contributions to Flow Properties in Anthracite

Han

Shen

et al. 2021

Energy Fuels

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Fractures are the main flow channels in the coal and play a significant role in coalbed methane (CBM) production. For a comprehensive understanding of the importance of multi-scale fractures in coal, an integrated approach of laboratory experiments and numerical simulation was used to analyze the characteristics of coal fracture networks in the samples collected from the southern Qinshui Basin, China. X-ray micro-computed tomography (micro-CT) was conducted to study the geometrical and topological parameters of multi-scale fractures in samples of different sizes. The fracture parameters, including fracture equivalent diameter, angle, orientation, spacing, fracture porosity, fractal dimension, and intersection point density, were quantitatively measured from micro-CT images of the coal samples. These micro-CT data were used to generate the multi-scale discrete fracture networks (DFNs), followed by the simulation of the gas flow behavior in coal fractures using COMSOL modeling software. The results show that the fracture equivalent diameter, fracture porosity, fractal dimension, and intersection point density are higher in the bright coal lithotype, indicating the heterogeneity distribution of the fractures in different coal lithotypes. The results depict a decline in the fracture equivalent diameter, fracture angle, fracture spacing, fracture porosity, and fractal dimension with the decrease in the sample size. However, the intersection point density of fractures shows the opposite trend. According to the fracture parameters, the fracture network development degree decreases, while the relation between different fractures (connectively) increases with the decrease of the fracture scale. The DFN simulation illustrates that the permeability increases from semi-dull coal (0.02 mD) to bright coal (0.025 mD). The long fractures contribute to the fracture connectivity network by connecting to smaller fractures and might show high-flow velocity in coal seams. Overall, the results indicate that the semi-bright coal and bright coal are beneficial to the production of CBM for the development of fractures. The findings of this study can help for a better understanding of the distribution of fractures in different coal lithotypes and will be favorable for enhancing CBM production.

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Section: Samples and Methodsmentioning

confidence: 99%

“…The value of the constant is the same as the previous study. 40 The number of fractures was measured by multiplying the fracture density by the simulation region area. The fracture center point was uniformly distributed in the simulation region.…”

Section: Lithotype Band Partitionmentioning

confidence: 99%

Characteristics of a Multi-scale Fracture Network and Its Contributions to Flow Properties in Anthracite

Han

Shen

et al. 2021

Energy Fuels

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“…In the consequent bedded rock, the fracture aperture decreased with the increase of the height and the decrease of the inclination angle and changed little. In addition, other research has shown that there is a certain correlation between the crack length and the fracture aperture in the tensile deformation cracking characteristics of different materials [37]; the quantitative relationship between the crack opening and the theoretical development length has been established as:…”

Section: Calculation Pressure Length Of Explosive Gas On a Rock Layermentioning

confidence: 99%

Failure Mechanism of Back-Break in Bench Blasting of Thin Terrane

Dong

Chen

et al. 2021

Applied Sciences

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The shape of a free surface is an important factor that determines the effect of bench blasting. The structural dynamics theory was applied to establish a structural failure model of the layered rock considering the impact of a blasting gas intrusion. Combined with the continuous-discontinuous element method (CDEM), the influence of rock strata on the failure mechanism of back-break was analyzed. The results show that structural failure characteristics of stratum with different dip angles are different. The bending failure characteristics of dipping-in-face stratum are stronger than that in dipping-out-of-face stratum. With the increase of the dip angle and height of rock stratum, the bending failure length of dipping-in-face stratum increases and the maximum value reaches 5.24 m. The trend of failure along the stratum surface towards the bottom increases, which is an important reason for the formation of an unfavorable shape of free surface. However, the failure depth of the gently dipping stratum and dipping-out-of-face stratum is relatively uniform; the average value is about 0.5 m. Finally, combined with the results of the bench blasting field test of the Changjiu (Shenshan) limestone mine, which is the largest in the production of sand and gravel aggregates, we verify the correctness of the theoretical analysis results. Relevant research results can provide a theoretical basis and technical support for controlling the bench blasting effect.

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“…In order to understand the influence of multiphase flow behavior in fractured media on implementation with these applications, numerical simulations have been applied in fractured media using a continuum method [6,7] or a discrete fracture network model [8,9]. In contrast to the macroscale continuum model, the flow behavior in the fractured rock is mainly governed by the presence of fracture, which can highly improve the permeability of rock masses [10][11][12]. For the fracture-dominated flow, the relative permeability of a single fracture is one of the key parameters to describe the multiphase flow behavior that controls the accuracy of modeling results during numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

A Fractal Model for Predicting the Relative Permeability of Rough‐Walled Fractures

Luo

Huang

Chen

et al. 2021

Advances in Civil Engineering

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The relative permeability and saturation relationships through fractures are fundamental for modeling multiphase flow in underground geological fractured formations. In contrast to the traditional straight capillary model from porous media, the realistic flow paths in rough-walled fractures are tortuous. In this study, a fractal relationship between relative permeability and saturation of rough-walled fractures is proposed associated with the fractal characteristics of tortuous parallel capillary plates, which can be generalized to several existing models. Based on the consideration that the aperture distribution of rough-walled fracture can be represented by Gaussian and lognormal distributions, aperture-based expressions between relative permeability and saturation are explicitly derived. The developed relationships are validated by the experimental observations on Gaussian distributed fractures and numerical results on lognormal distributed fractures, respectively.

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Connectivity evaluation of fracture networks considering the correlation between trace length and aperture

Cited by 13 publications

References 28 publications

Characteristics of a Multi-scale Fracture Network and Its Contributions to Flow Properties in Anthracite

Characteristics of a Multi-scale Fracture Network and Its Contributions to Flow Properties in Anthracite

Failure Mechanism of Back-Break in Bench Blasting of Thin Terrane

A Fractal Model for Predicting the Relative Permeability of Rough‐Walled Fractures

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