Two-Phase Transport Characteristic of Shale Gas and Water through Hydrophilic and Hydrophobic Nanopores

Xu, HengYu; Yu, Hao; Fan, JingCun; Zhu, YinBo; Wang, Fengchao; Wu, HengAn

doi:10.1021/acs.energyfuels.0c00212

Cited by 57 publications

(38 citation statements)

References 85 publications

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“…In contrast, current research, regarding water transport through cylindrical nanopores, involves both hydrophilic and hydrophobic scenarios. 32,56,57 excellent match in Figure 3 proves the capacity of the proposed mathematic model, covering a wide range of surface wettability. Also, in light of the urgent shortage regarding hydrophilic effect on nanocone transport capacity, the research in this article can bridge the knowledge gap.…”

Section: Model Validationsupporting

confidence: 55%

“…In the case of investigations toward nanocone opening angle, carbon‐based surface with perfect slip boundary is assumed, possessing the hydrophobic property. In contrast, current research, regarding water transport through cylindrical nanopores, involves both hydrophilic and hydrophobic scenarios 32,56,57 . Therefore, excellent match in Figure 3 proves the capacity of the proposed mathematic model, covering a wide range of surface wettability.…”

Section: Model Validationmentioning

confidence: 72%

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Optimal nanocone geometry for water flow

Sun

Wang²,

Xiong

et al. 2021

AIChE Journal

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The pursuit, toward transport efficiency, is significantly necessary for energy conversion, water filtration. However, structure design, aiming at further enhancing nanoconfined water flow, is still lacking. With the motivation to bridge the knowledge gap, a simple yet practical model regarding the nanocone structure design is established. This research demonstrates that nanocone, with desirable opening angle and length, possesses the capacity to achieve the optimal flow behavior. Flow resistance occurring inside nanocones, and that at cone entrance, exit, are considered. Optimal nanocone geometry can be determined based on the minimization of total resistance. Results show that (a) suitable opening angle spans from 10 to 30 over a wide range of nanocone geometry; (b) evident decline tendency of the suitable opening angle toward the increasing surface wettability is captured; and (c) water transport capacity inside optimal nanocone is 4-50 times that within cylindrical nanopores. This article forms a theoretical framework for nanocone design.

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Section: Model Validationsupporting

confidence: 55%

Section: Model Validationmentioning

confidence: 72%

Optimal nanocone geometry for water flow

Sun

Wang²,

Xiong

et al. 2021

AIChE Journal

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“…The number of water molecules decreases while gas molecules increase (indicated by the shaded part). Combined with the analysis of 1D and 2D density distribution of gas-water molecules, water and gas molecules form interfacial regions with the 1-99 thickness (1%-99% of bulk gas density) around 0.3 nm [23,26], and we call the interfacial regions as the miscible zone (zone 2). In zone 3, the water molecule number of zone 3 becomes less and is about five or six times less than that in zone 2, but the number of gas molecules reaches its maximum.…”

Section: Model Establishmentmentioning

confidence: 99%

“…Molecular dynamics simulation plays an important role in studying the mechanism of gas-water flow in pores. Xu et al [23] performed a comprehensive study on the two-phase transport characteristics of shale gas and water through hydrophilic and hydrophobic nanopores combined with molecular dynamics (MD) simulation and analysis model. Hao et al [24] used nonequilibrium molecular dynamics to simulate the mixed flow behavior of water and methane gas in shale pores.…”

Section: Introductionmentioning

confidence: 99%

Gas Transport in Shale Nanopores with Miscible Zone

Hao

et al. 2020

Geofluids

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Based on the results of molecular dynamics simulation, in a gas-water miscible zone, the velocity profiles of the flowing water film do not increase monotonously but increase first and then decrease, which is due to the interaction between water and gas molecules. This exhibits a new physical mechanism. In this paper, we firstly propose a gas-water flow model that takes into account the new physical phenomena and describes the distribution of gas-water velocity in the whole pore more accurately. In this model, a decreasing factor for water film in the gas-water miscible zone is used to describe the decrease of water velocity in the gas-water miscible zone, which leads to the gas velocity decrease correspondingly. The new flow model considers the interaction among gas and water molecules in the miscible zone and can provide more accurate velocity profiles compared with the flow models not considering the miscible region. Comparison calculation shows that the previous model overestimates the flow velocity, and the overestimation increases with the decrease of the pore radius. Based on the new gas-water flow model, a new permeability correction factor is deduced to consider the interaction among gas and water molecules.

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“…Furthermore, to have an accurate understanding of gas transport characteristics in nanoporous/microporous media, the molecular dynamic (MD) simulation is also widely applied to understand the gas flow behaviors, as summarized and depicted in one recent review by Yu et al [39,40]. The nanochannels are generally used to mimic the fluids flow confined in shale nanoporous media in these MD simulations [22,41,42]. Since the shale organic matter is mainly composed of carbon atoms and the pore wall is hydrophobic; thus, the graphene sheets, carbon nanotubes, and arrayed carbons are abstracted as organic pore wall materials in numerous previous work [39].…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Type on the Flow Characteristics in Shale Nanopores

Zhan

et al. 2021

Geofluids

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The underlying mechanism of shale gas migration behavior is of great importance to understanding the flow behavior and the prediction of shale gas flux. The slippage of the methane molecules on the surface is generally emphasized in nanopores in most predicted methods currently. In this work, we use molecular dynamic (MD) simulations to study the methane flow behavior in organic (graphene) and inorganic (quartz) nanopores with various pore size. It is observed that the slippage is obvious only on the graphene nanopores and disappeared on the quartz surface. Compared with the traditional Navier-Stokes equation combined with the no-slip boundary, the enhancement of the gas flux is nonnegligible in the graphene nanopores and could be neglected in the quartz nanopores. In addition, the flux contribution ratios of the adsorption layer, Knudsen layer, and the bulk gas are analyzed. In quartz nanopores, the contributions of the adsorption layer and the Knudsen layer are slight when the pore size is larger than 10 nm. It is also noted that even if the Knudsen number is the same, the flow mode may be various with the effect of the pore surface type. Our work should give molecular insights into gas migration mechanisms in organic and inorganic nanopores and provide important reference to the prediction of the gas flow in various types of shale nanopores.

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Two-Phase Transport Characteristic of Shale Gas and Water through Hydrophilic and Hydrophobic Nanopores

Cited by 57 publications

References 85 publications

Optimal nanocone geometry for water flow

Optimal nanocone geometry for water flow

Gas Transport in Shale Nanopores with Miscible Zone

Effect of Surface Type on the Flow Characteristics in Shale Nanopores

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