Molecular dynamics simulations of two-phase flow of n-alkanes with water in quartz nanopores

Xu, Jianhong; Zhan, Shiyuan; Wang, Wendong; Su, Yuliang; Wang, Han

doi:10.1016/j.cej.2021.132800

Cited by 42 publications

(14 citation statements)

References 70 publications

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“…The long-range Coulomb electrostatic interactions are computed by particle−particle particle-mesh (PPPM) solver. 53,54 After initial model construction, energy minimization is conducted to optimize the system with two static silica sheets filled with fluid molecules. Then, an external force along the Z-direction is applied to the top silica sheet while keeping the bottom one static to achieve the target normal pressure (20 MPa) at 323 K. External forces are applied on each atom in the top silica sheet.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Effects of Interfacial Molecular Structures on Pressure-Driven Brine Flow in Silica Mesopores

Duan,

Zhang,

Nan

et al. 2023

Langmuir

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In this work, we conduct molecular dynamics simulations to investigate pressure-driven brine flow in silica mesopores under typical reservoir conditions (323 K and 20 MPa). While surface counterions accumulate strongly in the vicinity of fully deprotonated silica surfaces, water forms multilayer structures due to hydrogen bonding, counterion hydration, and excluded-volume effect. Brine flow behaviors exhibit adsorption, transition, and bulk-like regions in fully deprotonated silica mesopores, while the transition region is negligible in fully protonated ones. In the adsorption region, strong surface hydrogen bonding and a high degree of counterion hydration collectively hinder water mobility. Even without surface hydrogen bonding, persistent ion hydration impedes water flow, leading to the transition region in fully deprotonated silica mesopores and higher viscosity of brine (with 10 wt % NaCl) in the bulk region. This work elucidates the collective effects of surface chemistry and interfacial water structures on brine flow behaviors in silica mesopores from molecular perspectives.

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Section: ■ Materials and Methodsmentioning

confidence: 99%

Effects of Interfacial Molecular Structures on Pressure-Driven Brine Flow in Silica Mesopores

Duan,

Zhang,

Nan

et al. 2023

Langmuir

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“…The bond lengths were constrained by the LINCS algorithm . The bulk density (density in the middle of the slit) of the fluid was calculated to identify the bulk phase pressure ,− according to the National Institute of Standards and Technology (NIST) database; details are given in the Supporting Information (SI).…”

Section: Model and Methodologymentioning

confidence: 99%

Adsorption Behaviors of Different Components of Shale Oil in Quartz Slits Studied by Molecular Simulation

Xue

Cheng

et al. 2022

ACS Omega

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Understanding the adsorption state and molecular behavior of the diverse components of shale oil in shale slits is of critical importance for exploring novel enhanced shale oil recovery techniques, but it is hard to be achieved by experimental measurements. In this paper, molecular dynamics (MD) simulations are performed to quantitatively describe the microbehavior of shale oil mixtures containing different kinds of hydrocarbon components, including asphaltene, in quartz slits. The spatial distributions of all the presenting components are given, the interaction energy between the components and quartz is analyzed, and the diffusion coefficients of all the components are calculated. It was found that asphaltene molecules play a vitally important role in restricting the detachment and diffusion movement of all hydrocarbon components, which is actually a key problem limiting the recovery efficiency of shale oil. The effects of temperature, slit aperture, and the appearance of CO2 on the adsorption behavior of the different shale oil components are examined; the results suggest that the light and medium components are the fractions with the most potential in thermal exploitation, while injection of CO2 is beneficial for the extraction of all the components, especially the medium components. This work gives insights into the effect of asphaltene on shale oil recovery in quartz slits and might provide guidance on the utilization of thermal and CO2-enhanced enhanced oil recovery (EOR) techniques in shale oil production.

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“…Thus, in comparison to conventional gas reservoirs with a fairly large pore size, the methane amount will increase under the impact of nanopore existence, rendering shale gas reservoirs as a favorable energy resource. , However, the accurate characterization of the methane adsorption amount is still challenging, although multiple approaches have been applied. On one hand, shale rock is inherently a complex porous media, composed of organic matter with various thermal maturities , as well as inorganic matter, including clay, and several kinds of minerals. , The total organic carbon (TOC) of shale, , indicating the weight fraction of organic matter, generally spans from 2 to 19.7%. Thus, the solid phase of the nanopore in shale can be organic matter, inorganic matter, or organic–inorganic mixed matter.…”

Section: Introductionmentioning

confidence: 99%

“…5,6 However, the accurate characterization of the methane adsorption amount is still challenging, although multiple approaches have been applied. On one hand, shale rock is inherently a complex porous media, composed of organic matter with various thermal maturities 7,8 as well as inorganic matter, including clay, and several kinds of minerals. 9,10 The total organic carbon (TOC) of shale, 11,12 indicating the weight fraction of organic matter, generally spans from 2 to 19.7%.…”

Section: Introductionmentioning

confidence: 99%

“…On one hand, shale rock is inherently a complex porous media, composed of organic matter with various thermal maturities 7,8 as well as inorganic matter, including clay, and several kinds of minerals. 9,10 The total organic carbon (TOC) of shale, 11,12 indicating the weight fraction of organic matter, generally spans from 2 to 19.7%. Thus, the solid phase of the nanopore in shale can be organic matter, inorganic matter, or organic−inorganic mixed matter.…”

Section: Introductionmentioning

confidence: 99%

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Wettability Impact on Nanoconfined Methane Adsorption Behavior: A Simplified Local Density Investigation

Luo

Fang³

et al. 2022

Energy Fuels

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The key to unlock huge economic benefits from shale gas reservoirs is to reveal the methane adsorption behavior in nanopores. A clear understanding of nanoconfined methane adsorption behavior will dramatically mitigate the imbalance between energy supply and demand over the world, which remains a challenge and entails in-depth investigation. To the current knowledge, specific materials, like graphene layers, quartz, and feldspar, are utilized to mimic an organic or inorganic solid phase in shale, while the shale physical composition is complex and evidently cannot be represented by one or several identified compositions. In this paper, to bridge the knowledge gap, the wettability effect, embodied by the surface contact angle, is correlated to the nanoconfined methane adsorption behavior for the first time. Because the solid-phase composition variation will result in alteration of the contact angle regarding the solid−methane system, the incorporation of the surface contact angle enables this research to cover a wide range of solid composition variations. First, the relationship between solid−fluid interactions and the surface contact angle is revealed. Then, the simplified local density method is proposed by coupling the relationship upon the surface contact angle, and also the shift of methane critical properties induced by the nanoconfinement effect is considered. Results show that (a) the ratio of bulk methane to nanoconfined average density ranges from 0.55 to 0.71 with increasing pressure, (b) adsorption peak density can enhance up to 3 times by manipulating the solid-phase wettability effect, and (c) the adsorption capacity in organic-rich shale is 1.72 times that in inorganic-rich shale. The research provides a profound theoretical framework to elucidate the methane adsorption mechanism in nanopores and serves as a robust tool to reproduce and predict the methane adsorption behavior.

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Molecular dynamics simulations of two-phase flow of n-alkanes with water in quartz nanopores

Cited by 42 publications

References 70 publications

Effects of Interfacial Molecular Structures on Pressure-Driven Brine Flow in Silica Mesopores

Effects of Interfacial Molecular Structures on Pressure-Driven Brine Flow in Silica Mesopores

Adsorption Behaviors of Different Components of Shale Oil in Quartz Slits Studied by Molecular Simulation

Wettability Impact on Nanoconfined Methane Adsorption Behavior: A Simplified Local Density Investigation

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