Molecular Dynamics Simulation of Diffusion of Shale Oils in Montmorillonite

Wang, Hui; Wang, Xiaoqi; Xu, Jinkai; Cao, Dapeng

doi:10.1021/acs.jpcc.6b01660

Cited by 71 publications

(43 citation statements)

References 34 publications

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“…While we primarily focus on applications in heterogeneous catalysis and adsorption based separations, the fundamental concepts of molecular diffusion have broader application to membrane science [12], chromatography [13], gas exploration [14], environmental remediation [15], etc. Greater cross-community collaborations can help provide new insights into diffusion processes that are valuable across disciplines.…”

Section: Introductionmentioning

confidence: 99%

Connecting theory and simulation with experiment for the study of diffusion in nanoporous solids

et al. 2021

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Nanoporous solids are ubiquitous in chemical, energy, and environmental processes, where controlled transport of molecules through the pores plays a crucial role. They are used as sorbents, chromatographic or membrane materials for separations, and as catalysts and catalyst supports. Defined as materials where confinement effects lead to substantial deviations from bulk diffusion, nanoporous materials include crystalline microporous zeotypes and metal–organic frameworks (MOFs), and a number of semi-crystalline and amorphous mesoporous solids, as well as hierarchically structured materials, containing both nanopores and wider meso- or macropores to facilitate transport over macroscopic distances. The ranges of pore sizes, shapes, and topologies spanned by these materials represent a considerable challenge for predicting molecular diffusivities, but fundamental understanding also provides an opportunity to guide the design of new nanoporous materials to increase the performance of transport limited processes. Remarkable progress in synthesis increasingly allows these designs to be put into practice. Molecular simulation techniques have been used in conjunction with experimental measurements to examine in detail the fundamental diffusion processes within nanoporous solids, to provide insight into the free energy landscape navigated by adsorbates, and to better understand nano-confinement effects. Pore network models, discrete particle models and synthesis-mimicking atomistic models allow to tackle diffusion in mesoporous and hierarchically structured porous materials, where multiscale approaches benefit from ever cheaper parallel computing and higher resolution imaging. Here, we discuss synergistic combinations of simulation and experiment to showcase theoretical progress and computational techniques that have been successful in predicting guest diffusion and providing insights. We also outline where new fundamental developments and experimental techniques are needed to enable more accurate predictions for complex systems.

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Section: Introductionmentioning

confidence: 99%

Connecting theory and simulation with experiment for the study of diffusion in nanoporous solids

et al. 2021

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“…(Anovitz et al, 2015;Clarkson et al, 2013;Gu et al, 2015;Swift et al, 2014) Measured pore size distributions are needed for accurate models of hydrocarbon transport in shales. (Collell et al, 2015;Wang et al, 2016) Nanopores in organic matter were first documented in the Barnett Shale, (Loucks et al, 2009)but have since been reported in most of the major gas producing shales worldwide, including the Eagle Ford and the Marcellus. (Anovitz et al, 2015;Bernard and Horsfield, 2014) This porosity may, in fact, form the interconnected three-dimensional network of pores required for extracting hydrocarbons.…”

Section: Introductionmentioning

confidence: 99%

Extraction of organic compounds from representative shales and the effect on porosity

DiStefano

McFarlane

Anovitz

et al. 2016

Journal of Natural Gas Science and Engineering

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As the location and accessibility of hydrocarbons is key to understanding and improving the extractability of hydrocarbons in hydraulic fracturing, this study is an attempt to understand how native organics are distributed with respect to pore size to determine the relationship between hydrocarbon chemistry and pore structure in shales.First, selected shale cores from the Eagle Ford and Marcellus formations were subjected to pyrolysis gas chromatography (GC),thermogravimetric analysis, and organic solvent extraction with the resulting effluent analyzed by GC-mass spectrometry (MS). Organics representing the oil and gas fraction (0.1 to 1 wt. %) were observed by GC-MS. For most of the samples, the amount of native organic extracted directly related to the percentage of clay in the shale. The porosity and pore size distribution (0.95 nm to 1.35µm)in the Eagle Ford and Marcellus shales was measured before and after solvent extraction using small angle neutron scattering (SANS). An unconventional method was used to quantify the background from incoherent scattering as the Porod transformation obscures the Bragg peak from the clay minerals. The change in porosity from SANS is indicative of the extraction or breakdown of higher molecular weight bitumen with high

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“…In addition to the chemistry of the solid interface, the pore size had a strong influence on the diffusivity of fluids. For example, octane diffusion was found to increase rapidly with the size of the montmorillonite interlayer pore (Wang H. et al, 2016). The decrease in the density of octane as it migrates from the nanopore to mesopore enhances the diffusivity which aids hydrocarbon recovery from the subsurface (Wang H. et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…With more than 80% of our energy needs being met by the subsurface environments (BP Global, 2015), there is a significant interest in environmentally benign approaches to recover and store fluids in complex materials characterized by chemical and morphological heterogeneity and nano-scale porosity. Various studies have shown that the properties and transport of confined fluids such as water (Bonnaud et al, 2010;Ho and Striolo, 2015;Hu et al, 2015;Chakraborty et al, 2017), gases such as CO 2 (Chialvo et al, 2012;Striolo and Cole, 2017;Simoes Santos et al, 2018), and hydrocarbons (Cole et al, 2013;Le et al, 2015a,b;Wu et al, 2015;Le T. T. B. et al, 2017;Herdes et al, 2018;Obliger et al, 2018;Simoes Santos et al, 2018) in nanoporous environments differs from bulk behaviors due to changes in the structure and affinity of confined liquids (Wang H. et al, 2016;Johnston, 2017) and gases (Yuan et al, 2015;Sun et al, 2016aSun et al, ,b, 2017Wang S. et al, 2016a,b) for the solid interfaces. With increasing interest in enhanced gas recovery coupled with subsurface CO 2 storage, a fundamental understanding of the changes in the structure of CO 2 and CH 4 and transport properties of these gases through water-bearing nanoporous environments provides a scientific basis for the observed fate and transport of these gases at the field scale (Glezakou and McGrail, 2013;Gadikota et al, 2017;Gadikota, 2018;Gadikota and Allen, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…For example, octane diffusion was found to increase rapidly with the size of the montmorillonite interlayer pore (Wang H. et al, 2016). The decrease in the density of octane as it migrates from the nanopore to mesopore enhances the diffusivity which aids hydrocarbon recovery from the subsurface (Wang H. et al, 2016). In this work, MD simulations were performed to investigate the structure and transport behavior of confined CO 2 and CH 4 in calcite slit shaped nanopore with varying levels of hydration to mimic water-bearing nanopores in the subsurface environments.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Effect of Hydration on the Structure and Transport Properties of Confined Carbon Dioxide and Methane in Calcite Nanopores

Mohammed

Gadikota

2018

Front. Energy Res.

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With increasing interest in using or displacing confined water for CH 4 recovery or CO 2 storage in nanoporous environments, understanding the organization and diffusion of gases is confined water environments is essential. In this study, the effect of hydration on the structure and diffusivity of confined carbon dioxide (CO 2) and methane (CH 4) in 2 nm slit-shaped calcite nanopore was studied using classical molecular dynamics simulations. The absence of confined water and the effect of different water concentrations including one layer of confined water composed of 150 water molecules, 500 water molecules, and 1,296 water molecules that correspond to the density of bulk water of 1 g/cm 3 on the structural arrangement and diffusivity of confined CO 2 and CH 4 were investigated. Water molecules were found to influence the anisotropic distribution and mobility of confined CO 2 and CH 4 significantly by altering the structures of the adsorbed gas layers onto the calcite surfaces. The preferential adsorption of water on calcite surface over CO 2 and CH 4 resulted in the displacement of the adsorbed gas molecules toward the center of the pore. This water-induced displacement impacts the diffusivity of the confined gases by enabling transport through the center of the pore where there are fewer intermolecular collisions and less steric hindrance for transporting the molecules. Therefore, the diffusivity of CO 2 and CH 4 is higher in the presence of a single water layer as opposed to in pores without water. Energetic calculations showed that van der Waals and electrostatic interactions contributed to the affinity of CO 2 for calcite surfaces, while van der Waals interactions dominate CH 4 interactions with calcite and the surrounding water molecules. The anisotropic variations in the diffusivities of confined fluids emerge from changes in the organization of confined fluids and potential differences in the free energy distributions as a function of the orientation of the calcite surface. These findings suggest that any efforts to potentially engineer the nano-scale pore environment in calcite for enhanced gas recovery or storage will require us to consider the organization and anisotropic transport behaviors of confined fluids.

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Molecular Dynamics Simulation of Diffusion of Shale Oils in Montmorillonite

Cited by 71 publications

References 34 publications

Connecting theory and simulation with experiment for the study of diffusion in nanoporous solids

Connecting theory and simulation with experiment for the study of diffusion in nanoporous solids

Extraction of organic compounds from representative shales and the effect on porosity

The Effect of Hydration on the Structure and Transport Properties of Confined Carbon Dioxide and Methane in Calcite Nanopores

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