Gas transport behaviors in shale nanopores based on multiple mechanisms and macroscale modeling

Zhang, Qi; Wang, Wendong; Wang, Wendong; Lu, Mingjing; Sheng, Guanglong

doi:10.1016/j.ijheatmasstransfer.2018.04.129

Cited by 55 publications

(32 citation statements)

References 34 publications

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“…If V∕ V L = , the effective pore radius as shown in Fig. 4 can be expressed as (detailed derivation presented in our previous work (Zhang et al 2018)):…”

Section: Slip Flowmentioning

confidence: 99%

“…Different from the previous work (Zhang et al 2018), we modified a unified AGP model and focused on the comparison of different characterizations for the gas transport mechanisms, and more influences of various parameters on gas transport behavior are analyzed in this work. Viscous-slip flow, Knudsen diffusion, monolayer and multilayer gas adsorption, surface diffusion, the weighting coefficients of viscous-slip flow and Knudsen diffusion, and stress dependence are included in nanopores.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of gas transport behavior in organic and inorganic nanopores based on a unified apparent gas permeability model

Zhang

Wang

Kade³

et al. 2019

Pet. Sci.

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Different from the conventional gas reservoirs, gas transport in nanoporous shales is complicated due to multiple transport mechanisms and reservoir characteristics. In this work, we presented a unified apparent gas permeability model for real gas transport in organic and inorganic nanopores, considering real gas effect, organic matter (OM) porosity, Knudsen diffusion, surface diffusion, and stress dependence. Meanwhile, the effects of monolayer and multilayer adsorption on gas transport are included. Then, we validated the model by experimental results. The influences of pore radius, pore pressure, OM porosity, temperature, and stress dependence on gas transport behavior and their contributions to the total apparent gas permeability (AGP) were analyzed. The results show that the adsorption effect causes Kn(OM) > Kn(IM) when the pore pressure is larger than 1 MPa and the pore radius is less than 100 nm. The ratio of the AGP over the intrinsic permeability decreases with an increase in pore radius or pore pressure. For nanopores with a radius of less than 10 nm, the effects of the OM porosity, surface diffusion coefficient, and temperature on gas transport cannot be negligible. Moreover, the surface diffusion almost dominates in nanopores with a radius less than 2 nm under high OM porosity conditions. For the small-radius and low-pressure conditions, gas transport is governed by the Knudsen diffusion in nanopores. This study focuses on revealing gas transport behavior in nanoporous shales.

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“…If V∕ V L = , the effective pore radius as shown in Fig. 4 can be expressed as (detailed derivation presented in our previous work (Zhang et al 2018)):…”

Section: Slip Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of gas transport behavior in organic and inorganic nanopores based on a unified apparent gas permeability model

Zhang

Wang

Kade³

et al. 2019

Pet. Sci.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Physically, under actual reservoir condition, the fractured rock medium may be subjected to multiple stress and strain boundary conditions [1][2][3][4][5]. In general, the fixedstress boundary condition and the constant-volume (fixed displacement) boundary condition are the most important two boundary conditions, which have been widely studied in scientific and engineering fields, such as physics, hydraulics, chemistry, petroleum, and engineering [6][7][8][9][10][11][12][13]. Physically, during the process of reservoir development, with an increase in effective stress, physical properties (e.g., porosity and permeability) of the rock will change.…”

Section: Introductionmentioning

confidence: 99%

Study on Stress-Dependent Permeability of Fracture Networks in Fractured Porous Media

2021

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In order to investigate the stress-sensitive characteristics of fracture networks under reservoir actual stress condition and its influence on the seepage in fractured porous media, we carried out permeability tests on experimental models with fracture networks under constant-volume boundary condition. In addition, a novel analytical stress-dependent permeability model of fracture networks in different directions was derived. Based on the test results and the proposed analytical model, the effects of various parameters (e.g., initial fracture aperture, fluid pressure, rock elastic modulus, effective-stress coefficient, and fracture dip) on deformation characteristics of fracture networks and the corresponding permeability tensor of fracture networks were studied. The research results show that, for a fractured porous media with a single group of fractures, the principal value of permeability is always parallel to the fracture-development direction. With increasing effective stress, the principal value of permeability decreases; however, the principal value direction remains unchanged. Moreover, for the fractured porous media with multiple sets of fractures, the principal direction of equivalent permeability will be inclined to the fractures with larger fracture aperture. Specifically, for the fractured porous media with two sets of intersecting fractures, the principal direction of equivalent permeability is parallel to the angular bisector of these two sets of intersecting fractures. Furthermore, the greater the difference of the fracture aperture change rate under effective stress, the more obvious the deviation of the permeability principal direction. The derived analytical model is of great theoretical and scientific significance to deepen the understanding of the stress-sensitive permeability of fractured reservoirs.

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“…Fluid flow under stress through fractured media has drawn considerable attention in many engineering fields, including physics [1,2], hydraulics [3,4], chemistry [5], petroleum, and engineering [6][7][8][9][10]. The permeability of a reservoir decreases as effective stress increases during reservoir development [11].…”

Section: Introductionmentioning

confidence: 99%

Stress-Dependent Permeability of Fractures in Tight Reservoirs

et al. 2018

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Permeability is one of the key factors involved in the optimization of oil and gas production in fractured porous media. Understanding the loss in permeability influenced by the fracture system due to the increasing effective stress aids to improve recovery in tight reservoirs. Specifically, the impacts on permeability loss caused by different fracture parameters are not yet clearly understood. The principal aim of this paper is to develop a reasonable and meaningful quantitative model that manifests the controls on the permeability of fracture systems with different extents of fracture penetration. The stress-dependent permeability of a fracture system was studied through physical tests and numerical simulation with the finite element method (FEM). In addition, to extend capability beyond the existing model, a theoretical stress-dependent permeability model is proposed with fracture penetration extent as an influencing factor. The results presented include (1) a friendly agreement between the predicted permeability reduction under different stress conditions and the practical experimental data; (2) rock permeability of cores with fractures first reduces dramatically due to the closure of the fractures, then the permeability decreases gradually with the increase in effective stress; and (3) fracture penetration extent is one of the main factors in permeability stress sensitivity. The sensitivity is more influenced by fracture systems with a larger fracture penetration extent, whereas matrix compaction is the leading influencing factor in permeability stress sensitivity for fracture systems with smaller fracture penetration extents.

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Gas transport behaviors in shale nanopores based on multiple mechanisms and macroscale modeling

Cited by 55 publications

References 34 publications

Analysis of gas transport behavior in organic and inorganic nanopores based on a unified apparent gas permeability model

Analysis of gas transport behavior in organic and inorganic nanopores based on a unified apparent gas permeability model

Study on Stress-Dependent Permeability of Fracture Networks in Fractured Porous Media

Stress-Dependent Permeability of Fractures in Tight Reservoirs

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