An analytical model for gas transport through elliptical nanopores

Sun, Zheng; Shi, Juntai; Wu, Keliu; Tao, Zhang; Feng, Dong; Huang, Liang; Shi, Yongbo; Ramachandran, Hariharan; Li, Xiangfang

doi:10.1016/j.ces.2019.01.013

Cited by 36 publications

(22 citation statements)

References 83 publications

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“…The first approach attempts to utilize a subtle function or formula to describe the concrete distribution of the physical property within nanoscale pores. [45][46][47][48] However, due to the complexity of this issue, all the corresponding functions or formulas based on the first approach inevitably have complicated expressions and hard to be solved. Furthermore, the high accuracy of the first approach is challenging to remain when it is applied to pore surfaces with a wide range of wettability.…”

Section: Water Viscosity In the Elliptical Nanoporesmentioning

confidence: 99%

Effect of pore geometry on nanoconfined water transport behavior

Sun

Shi

et al. 2019

AIChE Journal

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Different pore shapes correspond to different interaction strengths between pore surface and molecules, which will result in discrepancy of nanoconfined water transport capacity. In this article, complex nanoscale pore shapes are represented by ellipses, which possess an excellent shape-variation physical property, that is, ellipses can gradually transition from circles to slit-like cross-sections by manipulating aspect ratio from 1 to maxima. Moreover, capturing water slip phenomenon and spatially variation of water viscosity, an analytical model for water transport capacity through elliptical nanopores is developed. Results show that (a) water slip effect plays a limited positive role at hydrophilic environment and a strong positive role at hydrophobic environment;(b) nanopores with more flat geometry feature will possess smaller enhance factor at hydrophilic environment; (c) spatially viscosity distribution is a negative factor when contact angle is lower than about 130 and turns to a positive factor when contact angle is higher than about 130 . K E Y W O R D Snanoconfined water flow, various pore shapes, water slip phenomenon, water viscosity

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Section: Water Viscosity In the Elliptical Nanoporesmentioning

confidence: 99%

Effect of pore geometry on nanoconfined water transport behavior

Sun

Shi

et al. 2019

AIChE Journal

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“…We use the pore‐scale numerical simulation method to analyze the viscous dissipation and validate different apparent permeability calculation models for gas flow in nanoporous media. There are different types of microscale simulation methods, including molecular dynamics method (Bird & Brady, ; Sun et al, ), direct simulation Monte Carlo method (Nie et al, ), and LBM. Even with modern computers, the molecular dynamics method and direct simulation Monte Carlo method are too computationally expensive to be adopted to simulate gas flow in nanoporous media.…”

Section: Introductionmentioning

confidence: 99%

Viscous Dissipation and Apparent Permeability of Gas Flow in Nanoporous Media

Zhao

Kang

Youping³

et al. 2020

JGR Solid Earth

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The nanopore confinement effect can increase the mobility for gas flow in shale rocks, and the apparent permeability is usually adopted to account for this effect. However, most of the apparent permeability calculation models are derived based on straight channels (capillaries) and neglect the influence of end effect. The end effect is caused by the bending of streamlines which yields more viscous dissipation and additional flow resistance for gas flow in nanoporous media. In this paper, for the first time the viscous dissipation for gas flow in nanoporous media is analyzed. In addition, an improved apparent permeability calculation model is proposed based on the Beskok‐Karniadakis (B‐K) model by introducing the influence of end effect, which is characterized by the ratio of the length to the width of a short channel (L/H). The accuracy of this model is validated by lattice Boltzmann simulations of gas flow in three different geometries: an infinite‐length straight channel, a finite‐length straight channel, and nanoporous media. For the infinite‐length straight channel, there is no end effect therefore both the B‐K model and the improved model can well predict the apparent permeability. However, for the finite‐length straight channel and nanoporous media, the original B‐K model overestimates the gas apparent permeability as it neglects the influence of end effect, while the improved model can still well predict the gas apparent permeability. In summary, the improved apparent permeability calculation model is more reasonable in predicting gas mobility in nanoporous media.

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“…Due to the random distribution of pore size in the shale matrix and different storage mechanisms (including viscous flow, free gas slip flow, transition flow and surface diffusion generated by adsorption Energies 2019, 12, 3381 5 of 18 and desorption) [25,40,41], there are multiple gas migration mechanisms in the shale reservoir, as shown in Figure 2.…”

Section: Shale Gas Multi-scale Flow Modelmentioning

confidence: 99%

“…According to Hagen-Poiseuille law, the mass flux of mass flow through a single circular pipe cross section is [19,41,42] ( )…”

Section: Slip Flowmentioning

confidence: 99%

“…Through Equations (39)- (41), the relationship between slip apparent permeability, Knudsen diffusion apparent permeability, surface diffusion apparent permeability and geometric fractal parameters is established, and the relationship between matrix apparent permeability of shale gas reservoir and three flow mechanisms and geometric fractal theory is also established through Equation (38).…”

Section: Apparent Shale Gas Permeabilitymentioning

confidence: 99%

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Multiscale Apparent Permeability Model of Shale Nanopores Based on Fractal Theory

Wang

Zhao

et al. 2019

Energies

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Based on fractal geometry theory, the Hagen–Poiseuille law, and the Langmuir adsorption law, this paper established a mathematical model of gas flow in nano-pores of shale, and deduced a new shale apparent permeability model. This model considers such flow mechanisms as pore size distribution, tortuosity, slippage effect, Knudsen diffusion, and surface extension of shale matrix. This model is closely related to the pore structure and size parameters of shale, and can better reflect the distribution characteristics of nano-pores in shale. The correctness of the model is verified by comparison with the classical experimental data. Finally, the influences of pressure, temperature, integral shape dimension of pore surface and tortuous fractal dimension on apparent permeability, slip flow, Knudsen diffusion and surface diffusion of shale gas transport mechanism on shale gas transport capacity are analyzed, and gas transport behaviors and rules in multi-scale shale pores are revealed. The proposed model is conducive to a more profound and clear understanding of the flow mechanism of shale gas nanopores.

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An analytical model for gas transport through elliptical nanopores

Cited by 36 publications

References 83 publications

Effect of pore geometry on nanoconfined water transport behavior

Effect of pore geometry on nanoconfined water transport behavior

Viscous Dissipation and Apparent Permeability of Gas Flow in Nanoporous Media

Multiscale Apparent Permeability Model of Shale Nanopores Based on Fractal Theory

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