Molecular simulation of the adsorption-induced deformation during CO2 sequestration in shale and coal carbon slit pores

Zhang, Hongyang; Diao, Rui; Chan, Hing Hao; Mostofi, Masood; Evans, Brian

doi:10.1016/j.fuel.2020.117693

Cited by 19 publications

(12 citation statements)

References 49 publications

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“…Then, as the adsorption pressure continues to increase to 2.5 MPa, the nanopores inside two coal samples show a trend of a continuous increase in each pore diameter segment. It is because the CO 2 adsorption for pore size variation almost follows the same pattern, that the variation sharply increases at low pressures below 1.5 MPa but then changes not obviously at higher pressures (from 2.0 to 2.5 MPa), and this trend is not obvious in the pore range of 15.73–33.86 nm. This may indicate that the time influence on the pore range from 15.73 to 33.86 nm is not significant in the process of adsorption during the same pressure.…”

Section: Resultsmentioning

confidence: 83%

Pore Distribution and Variation Rules of the Coal Sample with CO₂ Adsorption at Different Pressures Based on Small-Angle X-ray Scattering

et al. 2021

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Micropores play an important role in gas adsorption and migration. To reveal the variation rule of coal structural parameters in nanosize at different CO2 adsorption pressures, a CO2 adsorption in situ small-angle X-ray scattering test is performed in this work. The results show that the adsorption at different pressures somewhat influences the pore diameter distribution. The nanopores (2.13–33.86 nm) inside the coal samples shrink at low pressures (from 0.5 to 1.0 MPa) and swell at higher pressures (1.5 and 2.0 MPa). Regardless of shrinkage or swelling, the deformation increases with the decrease of the pore size. D s of the samples depends upon the capillary force. The variation of D s during 600 min (each adsorption pressure adsorbed 120 min) at five different pressures is divided into three stages. For these lower metamorphism samples (V daf lower than 55%), the micropores are abundant and distributed unevenly, which also leads to relatively high heterogeneity on the pore surface. The variation trend of the pore size distribution with time under different adsorption pressures is correlated with the variation of D s to some extent. This work enables us to better understand the variation of the pore size and surface fractal dimension during the process of adsorption in multi-points of pressure.

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Section: Resultsmentioning

confidence: 83%

Pore Distribution and Variation Rules of the Coal Sample with CO₂ Adsorption at Different Pressures Based on Small-Angle X-ray Scattering

et al. 2021

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“…Not surprisingly, each mineral exhibits a unique adsorption behavior. Fortunately, molecular simulation studies have investigated the adsorption characteristics of different gases over various mineral surfaces. , For instance, the adsorption characteristics of both methane and CO 2 in montmorillonite pores were studied by Jin and Firoozabadi, in quartz pores by Xiong et al, and in Illite pores by Chen et al…”

Section: Atomistic Simulationmentioning

confidence: 99%

Molecular Modeling of Subsurface Phenomena Related to Petroleum Engineering

et al. 2021

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Experiments are always the go-to approach to reveal mysterious observations and verify new theories. However, scientific research has shifted to areas that are difficult to probe experimentally. Fortunately, computational approaches, such as molecular simulation, became available. With a rigorous theoretical foundation and microscopic insights, molecular simulation could explore unknown territories in physics and validate macroscopic theories. Grand challenges in petroleum engineering require knowledge at the molecular scale more than ever, such as the behavior of confined fluids in shale nanopores. Although it is widely used in materials science, biophysics, and biochemistry, molecular simulation has been underutilized in subsurface modeling. However, the complexity of the subsurface systems and the heterogeneity of reservoir fluids, which currently challenge both our continuum modeling approaches and experimental techniques, could benefit from molecular insights. In this Review, we briefly present the basics of molecular simulation and a few applications addressing current petroleum engineering challenges. These applications include (1) phase equilibria, where molecular simulation handles inaccessible experimental conditions such as high pressure, high temperature, or a toxic environment; (2) asphaltene aggregation, where molecular simulation enables the synthesis and evaluation of the solvent performance; (3) low-salinity water flooding, where molecular simulation reveals the key mechanisms; and (4) shale reservoirs, where molecular simulation derives the new physics controlling the transport phenomena in these reservoirs. Our goal is to demonstrate that the molecular models can shed some light on numerous subsurface applications, moving toward more predictive physics-based models to optimize and control subsurface systems.

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“…All electron double-numerical atomic orbitals augmented by d-polarization functions were chosen as the basis set with a basis file of 3.5, and the orbital cut-off quality was set at “fine”. The adsorption energy (Δ E ) is defined as follows for single adsorption systems where E adsorbent+adsorbate is the total energy of the adsorption system, E adsorbent is the molecular energy of the VFG molecule, and E adsorbate is the energy of CO 2 or CH 4 .…”

Section: Simulation Detailsmentioning

confidence: 99%

Effects of Pore Parameters and Functional Groups in Coal on CO₂/CH₄ Adsorption

Dong

Zhai²,

Guo

2021

ACS Omega

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The mechanisms of CO 2 /CH 4 adsorption in coal are the theoretical foundation for CO 2 sequestration in coal seams targeted for enhanced coalbed methane recovery. Herein, by changing the model (low rank coal: WMC, middle rank coal: XM and high rank coal: CZ) with plenty of side aliphatic chains and functional groups established in the literature, the influence and mechanism of pore parameters and functional groups(−CH 3 , − OH, −C 2 O, −C=O) on the adsorption of CO 2 and CH 4 in different rank coals are systematically studied. Using the Connolly surface algorithm to calculate the pore volume (V F ) and the specific surface area (S SA ) of coal with different functional groups, it can be seen that the influence of the functional group change on the pore structure is related to the coal rank. Changing the various functional groups in the original coal structure to a unified functional group (−CH 3 , −OH, −C 2 O, or −CO) will increase the accessible pore volume (V F ) and the specific surface area (S SA ), except in low-rank and middle-rank coal, where the ordered arrangement of −CO will decrease V F and S SA . The adsorption capacities of different pore parameters and functional groups were calculated by Grand Canonical Monte Carlo simulation and density functional theory. On pure adsorption, the pore parameters exert greater influence than the functional groups. By comparing the adsorption energy of the original pore structure containing functional groups and that of modified pores without functional groups, the contributions of the pore structure and original functional groups on CO 2 /CH 4 adsorption are 71 and 29% and 83 and 17%, respectively. Small-diameter pores and −C 2 O have a strong adsorption capacity. In terms of competitive adsorption, the −C O functional groups and pore diameters ranging from 1.0 to 2.0 nm can significantly enhance the selectivity of CO 2 over CH 4 . The CH 4 and CO 2 adsorption does not occur via rigorous monolayer adsorption; multilayer adsorption can occur for CH 4 and CO 2 with pore diameters of 1.0−2.0 and 1.0−2.2 nm, respectively, thus causing micropore filling. These quantitative results establish a foundation for the development of adsorption theory for CO 2 /CH 4 in coal.

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Molecular simulation of the adsorption-induced deformation during CO2 sequestration in shale and coal carbon slit pores

Cited by 19 publications

References 49 publications

Pore Distribution and Variation Rules of the Coal Sample with CO₂ Adsorption at Different Pressures Based on Small-Angle X-ray Scattering

Pore Distribution and Variation Rules of the Coal Sample with CO₂ Adsorption at Different Pressures Based on Small-Angle X-ray Scattering

Molecular Modeling of Subsurface Phenomena Related to Petroleum Engineering

Effects of Pore Parameters and Functional Groups in Coal on CO₂/CH₄ Adsorption

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Molecular simulation of the adsorption-induced deformation during CO2 sequestration in shale and coal carbon slit pores

Cited by 19 publications

References 49 publications

Pore Distribution and Variation Rules of the Coal Sample with CO2 Adsorption at Different Pressures Based on Small-Angle X-ray Scattering

Pore Distribution and Variation Rules of the Coal Sample with CO2 Adsorption at Different Pressures Based on Small-Angle X-ray Scattering

Molecular Modeling of Subsurface Phenomena Related to Petroleum Engineering

Effects of Pore Parameters and Functional Groups in Coal on CO2/CH4 Adsorption

Contact Info

Product

Resources

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Pore Distribution and Variation Rules of the Coal Sample with CO₂ Adsorption at Different Pressures Based on Small-Angle X-ray Scattering

Pore Distribution and Variation Rules of the Coal Sample with CO₂ Adsorption at Different Pressures Based on Small-Angle X-ray Scattering

Effects of Pore Parameters and Functional Groups in Coal on CO₂/CH₄ Adsorption