Mechanical strength and porosity changes of bituminous coal induced by supercritical CO2 interactions: Influence of saturation pressure

Liu, Xianfeng; Jia, Xueqi; Liu, Wei; Nie, Baisheng; Zhang, Chengpeng; Song, Dazhao

doi:10.1016/j.geoen.2023.211691

Cited by 24 publications

(8 citation statements)

References 86 publications

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“…With the increase of adsorption amount, the multi-molecular layer adsorption was produced because of the stronger adsorption of CO 2 . So, the effect of inhibiting wettability of coal by CO 2 far exceeded the effect of N 2 atmosphere. , In summary, when the aqueous solution wets the coal sample containing gas adsorption, the water molecules will compete with the gas molecules for adsorption. Thus, resulting in fewer water molecule adsorption sites, lower adsorption, and weaker wettability.…”

Section: Results and Analysismentioning

confidence: 99%

Study on Coal Wettability under Different Gas Environments Based on the Adsorption Energy

Ding

Wei

et al. 2023

ACS Omega

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Coal seam water injection is a kind of comprehensive prevention and control measure to avoid gas outburst and coal dust disasters. However, the gas adsorbed in the coal seriously influence the coal-water wetting effect. With the deepening of coal seam mining, the gas pressure also gradually increases, but there is still a lack of in-depth understanding of the coal-water wetting characteristics under the high-pressure adsorbed gas environment. Therefore, the mechanism of coal-water contact angle under different gas environments was experimentally investigated. The coal-water adsorption mechanism in pre-absorbed gas environment was analyzed by molecular dynamics simulation combined with FTIR, XRD, and 13C NMR. The results showed that the contact angle in the CO2 environment increased most significantly, with the contact angle increasing by 17.62° from 63.29° to 80.91°, followed by the contact angle increasing by 10.21° in the N2 environment. The increase of coal-water contact angle in the He environment is the smallest, which is 8.89°. At the same time, the adsorption capacity of water molecules decreases gradually with increasing gas pressure, and the total system energy decreases after the coal adsorbs gas molecules, leading to a decrease in the coal surface free energy. Therefore, the coal surface structure tends to be stable with rising gas pressure. With the increase in environmental pressure, the interaction between coal and gas molecules enhances. In addition, the adsorptive gas will be adsorbed in the pores of coal in advance, occupying the primary adsorption sites and thus competing with the subsequent water molecules, resulting in a decline of coal wettability. Moreover, the stronger the adsorption capacity of gas, the more obvious the competitive adsorption of gas and liquid, which further weakens the wetting capacity of coal. The research results can provide a theoretical support for improving the wetting effect in coal seam water injection.

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Section: Results and Analysismentioning

confidence: 99%

Study on Coal Wettability under Different Gas Environments Based on the Adsorption Energy

Ding

Wei

et al. 2023

ACS Omega

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“…Particularly, supercritical CO 2 is a special fluid, which is provided with competitive diffusivity of gas and dissolving capability of liquid . Moreover, the supercritical CO 2 fluid is characterized by low viscosity and surface tension . Therefore, supercritical CO 2 can easily enter heavy oil to dissolve and extract light components.…”

Section: Resultsmentioning

confidence: 99%

Diffusion and Dissolution Behaviors of CO₂, CH₄, and N₂ in Heavy Oil under High-Temperature and -Pressure Conditions: Insights into Heavy Oil Production via Multithermal Fluid Stimulation

Su,

Wang,

et al. 2023

Energy Fuels

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To comprehend heavy oil production well via the multithermal fluid stimulation technology, the diffusion and dissolution processes of CO2, CH4, and N2 in heavy oil were conducted under a temperature range of 308.15–423.15 K and bulk pressures up to 20 MPa. Accordingly, the diffusion coefficients and solubilities of CO2, CH4, and N2 were measured. Results indicated that the diffusion coefficients of CO2, CH4, and N2 in heavy oil increase with rising temperature and decrease with rising pressure. The diffusion capability of these fluids in heavy oil conforms to the order CH4 > CO2 > N2. Moreover, the solubility of CO2, CH4, and N2 in heavy oil is negatively related to temperature and positively related to pressure. The solubility of various fluids in heavy oil decreases in the sequence of CO2 > CH4 > N2. The diffusion and dissolution of CO2, CH4, and N2 could induce volume expansion, colloidal structure damage, intermolecular force alteration, gap filling, and light component extraction toward heavy oil, thereby promoting its quality and recovery. Overall, heavy oil production via the multithermal fluid stimulation technology is recommended to be implemented under high-temperature and -pressure conditions.

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“…It is known that the Ordos Basin has abundant CBM resources, and the gas resources are estimated to be approximately 9 × 10 12 m 3 at the burial depths above 1500 m just in the eastern margin of this basin. − For a better comparison, three samples with different coal ranks were collected from the Daliuta (DLT) mine in the northeast, Hujiahe (HJH) mine in the south, and Baijigou mine in the west of the Ordos Basin, as depicted in Figure . All the fresh samples were directly acquired from the working faces.…”

Section: Sample Preparation and Methodsmentioning

confidence: 99%

Quantitative Evaluation of the Influence of Injected Water on Methane Desorption Behaviors of Coal in the Ordos Basin

Zou,

Liu,

Nie

et al. 2023

Energy Fuels

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Hydraulic fracturing technology is widely utilized to enhance gas drainage efficiency in underground coal mines. Water plays a crucial role in gas migration within coal after water is injected into the coal seams. In this study, methane desorption behaviors of coal were quantitatively evaluated under the influence of the injected water content. X-ray photoelectron spectroscopy (XPS), mercury intrusion porosimetry (MIP), and methane desorption experiments were combined to reveal the influencing mechanism. XPS results show that sample DLT also has the greatest content of the total oxygen-containing groups, which is 99.67% and 176.55% higher than those of samples HJH and BJG, respectively. MIP results indicate that sample DLT has the smallest pore volume (0.0315 cm3/g) and pore surface area (2.79 m2/g), while sample BJG shows the largest pore parameters. It is confirmed that the pore structures of anthracite are more complex than those of bituminous coals. Methane desorption characteristics of anthracite and bituminous coal are affected by injected water to varying degrees. Gas desorption in bituminous B is the most sensitive to the injected water content, and only 6% of the water content triggers a 46.83% reduction of the methane desorption capacity, which is attributed to the less accessible pore space and more hydrophilic oxygen-containing groups. Due to the highly developed pore networks and less oxygen-containing groups, CH4 molecules are replaced by H2O molecules in anthracite at the lower injected water content (<6%), resulting in the increase of the desorption capacity. The higher water content (>6%) accounts for the pore-blocking effect, resulting in the abrupt reduction of the gas desorption capacity.

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Mechanical strength and porosity changes of bituminous coal induced by supercritical CO2 interactions: Influence of saturation pressure

Cited by 24 publications

References 86 publications

Study on Coal Wettability under Different Gas Environments Based on the Adsorption Energy

Study on Coal Wettability under Different Gas Environments Based on the Adsorption Energy

Diffusion and Dissolution Behaviors of CO₂, CH₄, and N₂ in Heavy Oil under High-Temperature and -Pressure Conditions: Insights into Heavy Oil Production via Multithermal Fluid Stimulation

Quantitative Evaluation of the Influence of Injected Water on Methane Desorption Behaviors of Coal in the Ordos Basin

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Mechanical strength and porosity changes of bituminous coal induced by supercritical CO2 interactions: Influence of saturation pressure

Cited by 24 publications

References 86 publications

Study on Coal Wettability under Different Gas Environments Based on the Adsorption Energy

Study on Coal Wettability under Different Gas Environments Based on the Adsorption Energy

Diffusion and Dissolution Behaviors of CO2, CH4, and N2 in Heavy Oil under High-Temperature and -Pressure Conditions: Insights into Heavy Oil Production via Multithermal Fluid Stimulation

Quantitative Evaluation of the Influence of Injected Water on Methane Desorption Behaviors of Coal in the Ordos Basin

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Diffusion and Dissolution Behaviors of CO₂, CH₄, and N₂ in Heavy Oil under High-Temperature and -Pressure Conditions: Insights into Heavy Oil Production via Multithermal Fluid Stimulation