Coupling Effects of Supercritical CO<sub>2</sub> Sequestration in Deep Coal Seam

Zhang, Beining; Liang, Weiguo; Ranjith, P.G.; Li, Zhigang; Li, Chang; Hou, Dongsheng

doi:10.1021/acs.energyfuels.8b03151

Cited by 29 publications

(11 citation statements)

References 79 publications

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“…The aliphatic hydrocarbon chain length (L = A 2925 /A 2950 ) showed irregular changes. Zhang et al found that aliphatic hydrocarbons in coal are more easily extracted by Sc-CO 2 than aromatic hydrocarbons [54]. Because of the low content of aliphatic hydrocarbons in the shale, the aliphatic hydrocarbons peaks in the FTIR spectrum were, at best, subtle and the peak fitting results obtained were not very good.…”

Section: (A) Changes In Hydroxyl Structuresmentioning

confidence: 99%

Effects of Supercritical CO2 Treatment Temperatures on Mineral Composition, Pore Structure and Functional Groups of Shale: Implications for CO2 Sequestration

Cheng

Zeng

et al. 2020

Sustainability

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Research on the physicochemical reactions between supercritical carbon dioxide (Sc-CO2) and shale at different temperature is essential for geological CO2 sequestration. In this paper, shale from the Longmaxi formation in Sichuan basin of China was collected to study the changes in mineral composition, pore structure, and organic functional groups treated with Sc-CO2 at fixed pressure 8 MPa and temperatures 40 °C to 80 °C. Samples were analyzed with x-ray diffraction, CO2/N2 gas adsorption, and Fourier transform infrared spectroscopy. The results show that the dissolution of clay minerals by Sc-CO2 first declined, but then increased when the temperature increased; dissolution reached a minimum at 60 °C. The specific surface area, total pore volume, predominant pore type (mesopores), and fractal dimension of the shale pore structure first increases and then decreases with increasing temperature. The destruction of hydroxyl structures by Sc-CO2 is related to the destruction of OH–N and ring hydroxyls. As the temperature increases, the hydroxyl destruction first increases and then decreases. The aromatic hydrocarbons are mainly dominated by 3H and 2H, and their abundances increase significantly as temperature increases, whereas the 4H shows a decreasing trend; the 1H abundance does not change appreciably. The relative abundances of aromatic and aliphatic hydrocarbons decrease linearly as the temperature increases. These research results provide theoretical support for the geological storage of Sc-CO2 in shale at different temperatures.

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Section: (A) Changes In Hydroxyl Structuresmentioning

confidence: 99%

Effects of Supercritical CO2 Treatment Temperatures on Mineral Composition, Pore Structure and Functional Groups of Shale: Implications for CO2 Sequestration

Cheng

Zeng

et al. 2020

Sustainability

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“…the swelling ratio of the coal matrix decreases with increasing R o,max (Majewska et al., 2010; Yu et al., 2003). Furthermore, the extraction effect and mineral dissolution and precipitation effects have been found to depend upon the volatile matter yield and ash content, respectively (Zhang et al., 2013a, 2019a). Based on this, the changing amplitude of the micropore surface area (| f S mic |) and micropore volume (| f V mic |) were plotted against R o,max .…”

Section: Effects Of Scco2 On the Pore Morphology Of Coalsmentioning

confidence: 99%

Influences of supercritical carbon dioxide fluid on pore morphology of various rank coals: A review

Zhang

Wang

et al. 2020

Energy Exploration & Exploitation

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Supercritical carbon dioxide is known to change the pore structure of coals and thus affect their carbon dioxide sequestration capacity. In this study, supercritical carbon dioxide dependence of pore morphology of coals was reviewed. Results indicated that the micropore surface area and volume of dry coals varied between –20% and 20% after exposure to supercritical carbon dioxide. Changes in the micropore size distribution of dry coals after supercritical carbon dioxide exposure were not found to be significant; however, the change in meso- and macropores with diameter of 2–8 nm was observed to be significant. Supercritical carbon dioxide and H2O exposure mainly influenced pores with diameters of 0.4–0.7, 0.7–0.9 and 2–8 nm. The variation in the pore fractal dimensions of the coals ranged from –0.5% to 0.5% after supercritical carbon dioxide exposure. Furthermore, the dependence of supercritical carbon dioxide on the pore structure of coals relies on the coal rank. The change in the pore structure of the coals after supercritical carbon dioxide exposure was observed to be related to the following aspects. First, supercritical carbon dioxide induced swelling in coal matrix, thus reducing the pore surface area and volume of the coal matrix and compressing the cleat system. Next, the extraction of supercritical carbon dioxide mobilised the small organic molecules dispersed in the coal matrix; this increased the pore volume, particularly of micropores. Finally, the mineral dissolution/precipitation also changed the pore structure of the coals. To further examine supercritical carbon dioxide dependence of coal pore morphology, the following studies should be performed. The characterisation of the chemical and pore structure of coals should be combined with existing coal structure models to account for the mechanism of supercritical carbon dioxide changing the pore structure of coals. Combination of physical experiments and numerical simulations is recommended to predict the changes in porosity and permeability of coals due to long-term carbon dioxide sequestration.

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“…Jiang et al [50] found that crystal water was released from clay minerals after ScCO 2 treatment. Previous studies have shown that some carbonate minerals are dissolved and some hydrocarbons are extracted and washed away by the gas or water after ScCO 2 treatment [23,26]. The chemical reactions are listed in Equations (4) and (5).…”

Section: Ir Indexmentioning

confidence: 99%

“…These continuous pores are conducive to CH 4 desorption and flow. Therefore, CO 2 could enhance coalbed methane recovery and can be stored in the coal seam [26].…”

Section: Ir Indexmentioning

confidence: 99%

“…Fourier transform infra-red spectroscopy (FTIR) is a non-destructive method of detecting macromolecular structure of the coal, especially organic functional groups [24]. Zhang et al [25,26] found that the functional group intensities of coal weakened significantly after ScCO 2 treatment, indicating that ScCO 2 extraction occurred. These studies qualitatively judge the weakening of the functional group intensities.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Supercritical CO2 Treatment Temperature on Functional Groups and Pore Structure of Coals

Zeng

Cheng

et al. 2019

Sustainability

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The buried depth of a coal seam determines the temperature at which CO2 and coal interact. To better understand CO2 sequestration, the pore structure and organic functional groups of coal treated with different ScCO2 temperatures were studied. In this study, three different rank coals were treated with ScCO2 at different temperatures under 8 MPa for 96 h in a geochemical reactor. The changes in pore structure and chemical structure of coal after ScCO2 treatment were analyzed using mercury intrusion porosimetry, attenuated total reflection Fourier transform infra-red spectroscopy, fractal theory, and curve fitting. The results show that the enhancement effect of ScCO2 on pore structure of coal becomes less significant as the increase of buried depth. In most of the treated coal samples, the variation proportion of mesopores decreased and the variation proportion of macropores increased. In the relatively higher rank coals, the degree of condensation (DOC) of aromatic rings decreased after treatment with ScCO2. The DOC values showed a U-shape relationship with temperature, and the aromaticity showed a downward trend with increasing temperature. The chemical structural changes in the relatively lower rank coal sample were complex. These findings will provide an understanding of mechanisms relevant to CO2 sequestration with enhanced coalbed methane recovery under different geothermal gradients and for different ranks of coal.

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Coupling Effects of Supercritical CO₂ Sequestration in Deep Coal Seam

Cited by 29 publications

References 79 publications

Effects of Supercritical CO2 Treatment Temperatures on Mineral Composition, Pore Structure and Functional Groups of Shale: Implications for CO2 Sequestration

Effects of Supercritical CO2 Treatment Temperatures on Mineral Composition, Pore Structure and Functional Groups of Shale: Implications for CO2 Sequestration

Influences of supercritical carbon dioxide fluid on pore morphology of various rank coals: A review

Effects of Supercritical CO2 Treatment Temperature on Functional Groups and Pore Structure of Coals

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Coupling Effects of Supercritical CO2 Sequestration in Deep Coal Seam

Cited by 29 publications

References 79 publications

Effects of Supercritical CO2 Treatment Temperatures on Mineral Composition, Pore Structure and Functional Groups of Shale: Implications for CO2 Sequestration

Effects of Supercritical CO2 Treatment Temperatures on Mineral Composition, Pore Structure and Functional Groups of Shale: Implications for CO2 Sequestration

Influences of supercritical carbon dioxide fluid on pore morphology of various rank coals: A review

Effects of Supercritical CO2 Treatment Temperature on Functional Groups and Pore Structure of Coals

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Coupling Effects of Supercritical CO₂ Sequestration in Deep Coal Seam