Novel molecular simulation process design of adsorption in realistic shale kerogen spherical pores

Zhou, Bo; Xu, Ruina; Jiang, Pei-Xue

doi:10.1016/j.fuel.2016.04.096

Cited by 73 publications

(48 citation statements)

References 33 publications

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“…The pore is essentially modified by water to have a higher preference to CO 2 . An increase in CO 2 selectivity is also reported by other researchers for modeled coal, 26 kerogen, 18,22 and clays. 85 It was also shown that water is preferentially absorbed in the kerogen matrix rather than being adsorbed on the pore surface.…”

Section: ■ Methodssupporting

confidence: 84%

“…Kerogen molecules are fixed, and the matrix swelling effect is not directly simulated. To take into account the hierarchical pore size distribution, simulations are expanded in length scale, and meso- and micropores can be constructed by using blocks of kerogen matrix − to form slit pores or creating spherical pores inside the kerogen matrix by dummy particle insertion or cutter atom insertion . Despite the advancement in molecular simulation models, it should be noted that the results from simulations can only represent the localized phenomena in the real shale matrix because the pore connectivity from subnanoscale to macroscale and the distribution of organics in inorganics have not been rigorously considered yet.…”

Section: Introductionmentioning

confidence: 99%

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Competitive Sorption of CO₂ with Gas Mixtures in Nanoporous Shale for Enhanced Gas Recovery from Density Functional Theory

Liu

Chapman

2019

Langmuir

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CO 2 competitive sorption with shale gas under various conditions from simple to complex pore characteristics is studied using a molecular density functional theory (DFT) that reduces to perturbed chain-statistical associating fluid theory in the bulk fluid region. The DFT model is first verified by grand canonical Monte Carlo simulation in graphite slit pores for pure and binary component systems at different temperatures, pressures, pore sizes, and bulk gas compositions for methane/ethane with CO 2 . Then, the model is utilized in multicomponent systems that include CH 4 , C 2 H 6 , and C3+ components of different compositions. It is shown that the selectivity of CO 2 decreases with increases in temperature, pressure, nanopore size, and average molecular weight of shale gas. Extending the model to more realistic situations, we consider the impact of water present in the pore and consider the effect of permeation of fluid molecules into the kerogen that forms the pore walls. The water−graphite interaction is calibrated with contact angle from molecular simulation data from the literature. The kerogen pore model prediction of gas absolute sorption is compared with experimental and molecular simulation values in the literature. It is shown that the presence of water reduces the CO 2 adsorption but improves the CO 2 selectivity. The dissolution of gases into the kerogen matrix also leads to the increase in CO 2 selectivity. The effect of kerogen type and maturity on the gas sorption amount and CO 2 selectivity is also studied. The associated mechanisms are discussed to provide fundamental understanding for gas recovery by CO 2 .

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Section: ■ Methodssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Competitive Sorption of CO₂ with Gas Mixtures in Nanoporous Shale for Enhanced Gas Recovery from Density Functional Theory

Liu

Chapman

2019

Langmuir

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“…2(d), the pores size distribution is not changed dramatically, but the micropores increase with the porosity when the pore size smaller than 1 nm. Using these dummy particles is more likely to create small pores, which has been discussed and verified in other paper [14]. Large pores are main from the anisotropy of the kerogen composition and molecular structure.…”

Section: Pore Size Distributionsupporting

confidence: 55%

Evaluation of the diffusive tortuosity by analyzing the molecular thermal motion displacement

Wang

Hou

et al. 2019

THERM SCI

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Molecular thermal motion is a very meaningful process. Plenty of useful information can be extracted from molecular travel displacement. In this paper, a kerogen model with a random and complex pore network is constructed. Based on the molecular thermal motion process, the diffusive tortuosity caused by the confined pore network is investigated by the molecular dynamics simulations. The influence of thermodynamic parameters on the diffusive tortuosity is carefully studied. The results showed that the diffusive tortuosity ranges from 1.57 to 2.70 depending on the pressure. However, with the variation of temperature and porosity, the diffusive tortuosity has a little change, mainly distributed from 1.79 to 1.95. The thermal diffusive tortuosity of the complex pore network is successfully calculated by analyzing molecular thermal motion property.

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“…7,[46][47][48]50 In another method, the kerogen macromolecules are placed in a box with specific molecules. 39,42,45,54,55,63,64 In a third method, a hybrid reverse Monte Carlo reconstruction technique is used. 37,38,40,51 MD simulations are used for the creation of the initial kerogen structure in the studies mentioned below.…”

Section: ■ Introductionmentioning

confidence: 99%

Deformation and Swelling of Kerogen Matrix in Light Hydrocarbons and Carbon Dioxide

Tesson

Firoozabadi

2019

J. Phys. Chem. C

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Shale gas has become an attractive alternative to conventional fossil fuels due to its clean-burning characteristics. Fluid molecules reside in micropores and mesopores in shale formations. Molecular simulations provide insights into the kerogen structures, adsorption of hydrocarbons and carbon dioxide, and kerogen swelling. In this work, a new approach is introduced to create atomistic configurations of kerogen matrix with specific porosity. A dummy particle is used to control the porosity. Once the kerogen matrix is created, the dummy particle is removed and a limited number of nails are placed on the periphery of the pores to prevent the kerogen matrix from collapsing and to keep its basic structure intact. The hybrid Molecular Dynamics-Grand Canonical Monte Carlo (MD-GCMC) simulations are performed to investigate the adsorption and kerogen swelling of five hydrocarbon gases (methane, ethane, propane, n-butane, and i-butane at 393.15 K and various pressures), n-pentane liquid (at 298.15 K and 1 atm), and supercritical carbon dioxide (at 393.15 K to a pressure of 400 atm). The kerogen matrix is flexible. Our simulation results show that there is a coupling between adsorbate molecular size and shape and deformation of the kerogen matrix structure. The flexibility of the kerogen matrix affects swelling. The kerogen matrix deformation allows small adsorbate molecules to dissolve in the matrix. Our simulations results show that kerogen swelling decreases with the increase of the molecular size of the adsorbate (CO 2 > CH 4 > C 2 H 6 > C 3 H 8 ). The deformation and increase in swelling by n-pentane is much more pronounced than by methane and other light hydrocarbon gases. Our work is based on type II-A kerogen macromolecules. The methodology can be applied to other types of kerogen molecules.

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Novel molecular simulation process design of adsorption in realistic shale kerogen spherical pores

Cited by 73 publications

References 33 publications

Competitive Sorption of CO₂ with Gas Mixtures in Nanoporous Shale for Enhanced Gas Recovery from Density Functional Theory

Competitive Sorption of CO₂ with Gas Mixtures in Nanoporous Shale for Enhanced Gas Recovery from Density Functional Theory

Evaluation of the diffusive tortuosity by analyzing the molecular thermal motion displacement

Deformation and Swelling of Kerogen Matrix in Light Hydrocarbons and Carbon Dioxide

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Novel molecular simulation process design of adsorption in realistic shale kerogen spherical pores

Cited by 73 publications

References 33 publications

Competitive Sorption of CO2 with Gas Mixtures in Nanoporous Shale for Enhanced Gas Recovery from Density Functional Theory

Competitive Sorption of CO2 with Gas Mixtures in Nanoporous Shale for Enhanced Gas Recovery from Density Functional Theory

Evaluation of the diffusive tortuosity by analyzing the molecular thermal motion displacement

Deformation and Swelling of Kerogen Matrix in Light Hydrocarbons and Carbon Dioxide

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Competitive Sorption of CO₂ with Gas Mixtures in Nanoporous Shale for Enhanced Gas Recovery from Density Functional Theory

Competitive Sorption of CO₂ with Gas Mixtures in Nanoporous Shale for Enhanced Gas Recovery from Density Functional Theory