Permeability of micro-scale structure in coal: Insights from μ-CT image and pore network modelling

Liu, Peng; Nie, Baisheng; Zhao, Zhengduo; Li, Jiajun; Yang, Hengquan; Qin, Chaozhong

doi:10.1016/j.jgsce.2023.204931

Cited by 13 publications

(11 citation statements)

References 47 publications

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“…Creating a three-dimensional pore network model shows the pros and cons of assessing soil connectedness. The quantitative study of pores, throats, and ligand count can reveal soil connection details (Chun et al 2023;Liu et al 2023). Euler number and tortuosity both characterize pores' complexity.…”

Section: Resultsmentioning

confidence: 99%

Effects of microplastics on the porosity and connectivity with different soil textures: Based on CT scanning

Wang,

Li,

et al. 2023

Preprint

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Microplastics-contaminated soils exhibit disordered pore architecture. However, research on soil pores' morphological features and connectivity under microplastics endowment needs to be more extensive. This research used computed tomography and three-dimensional visualization tools to quantitatively analyze the micropore structure of sandy soils, sandy loam, and loamy soils after microplastics endowment, and we also built a pore network model. The findings revealed that microplastics deposition considerably altered the spatial structure of the pores and reduced soil porosity. The effects of microplastics accumulation on soil pore morphology and connectivity varied greatly between soil textures, with connected pores in sandy soils and sandy loams partially or completely disappearing and connected pores in loamy soils changing from a complex spatial structure to a monolayer sheet. Furthermore, as the abundance of microplastics increases, the soil pore network model becomes more straightforward, and the Euler number and tortuosity increase, which leads to the hydraulic conductivity declines. Finally, the microplastics endowment caused significant damage to the soil's connectivity and reduced its infiltration ability.

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Section: Resultsmentioning

confidence: 99%

Effects of microplastics on the porosity and connectivity with different soil textures: Based on CT scanning

Wang,

Li,

et al. 2023

Preprint

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“…The equivalent sphere diameter can be used to quantitatively analyze the variation of fractures on different scales. The equivalent sphere diameter expressed as , D normale normalq = 6 V P / π 3 where D eq is the equivalent spherical diameter of the fracture, μm, and V P is the fracture volume of CT, μm 3 .…”

Section: Methodsmentioning

confidence: 99%

“…The equivalent sphere diameter can be used to quantitatively analyze the variation of fractures on different scales. The equivalent sphere diameter expressed as 47,48…”

Section: Microfractures Were Characterized By Ct and Fesemmentioning

confidence: 99%

Experimental Study on Permeability Enhancement of Anthracite by High Pressure Nitrogen Injection and Soaking

Shi,

Cao,

et al. 2024

Energy Fuels

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Nitrogen treatment is a widely used coalbed methane (CBM) recovery technique for low permeability CBM reservoirs. We conducted a series of experiments to investigate the nitrogen injection and soaking (NI-n-S) induced coal structure alteration and, thus, the permeability variations. Two sets of experimental variations were investigated, which are the treatment pressure and the treatment duration. The experiments were carried out with nitrogen pressures of 6, 9, 12, and 15 MPa for 2, 12, 24, and 36 h, respectively. The core-scale permeability was employed as an indication of the gas flow enhancement capability and effectiveness. Both X-ray CT and field emission scanning electron microscopy (FESEM) were used for the imaging analyses for cross-comparison before and after NI-n-S treatments. The permeability of the coal samples after NI-n-S has shown a significant increase by 13.6−524.1%, with an average of 98.5%. The permeability increase ratio positively correlates with nitrogen treatment pressure; high-pressure nitrogen produced six types of damage modes on microfractures. The main mode is improving the microfracture opening width, and it increased by 4.4−166.7% (mean 45.1%) of the coal specimen with NI-n-S.

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“…The surface porosity is the ratio of the pore area to the overall area in the picture (eq ). The study of the surface porosity of the sample helps us understand the change in the local pore structure of the coal …”

Section: Materials and Preparationmentioning

confidence: 99%

Comprehensive Analysis of Connectivity and Permeability of a Pore-Fracture Structure in Low Permeability Seam of Huainan–Huaibei Coalfield

Wang,

Fang,

Sang

et al. 2024

ACS Omega

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The connectivity and permeability of the coal seam pore structures control the occurrence and migration of coalbed methane. Coal samples were used from Huainan−Huaibei to reconstruct three-dimensional models of the pores and an equivalent pore network model, Statistical pore structure characteristic parameters. The pore structure of the coal reservoir was analyzed from the direction of multidimensional and multiangle. It shows that based on quantitative analysis, the representative Elementary volume of 500 × 500 × 500 was the most suitable experimental volume. The Y-axis direction of the Renlou sample had poor pore connectivity compared to that of other samples. Large volume connected pores dominated their pore systems. In terms of coal sample pore connectivity, the coal samples from the Liuzhuang and Qidong regions had pore connectivity better than those from the other regions. The pore connectivity of the Liuzhuang coal samples was the best. In terms of coal permeability, the Liuzhuang sample had better permeability than the other three samples, and the permeability was the best in the Y-axis direction. For all the combinations of the different types of throats, the shorter the throat, the greater the equivalent radius and the better the permeability. Conversely, the worse the permeability. During gas injection production, the closer the gas injection area was to the gas injection well, the poorer the connectivity and the lower the permeability over time. Near the production area, where the CO 2 did not reach the production area, the fracture porosity and effective connected porosity of the coal reservoir increased over time. When CO 2 reached the production area, the change in its connected pore structure was consistent with the change in the connected pores in the gas injection area. With this study, the coal seam pore structure on a microscale was characterized. A comprehensive analysis of the coal reservoir pore connectivity and permeability was completed. The study results are significant for the exploration and development of coalbed methane in the Huainan−Huaibei coalfield.

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Permeability of micro-scale structure in coal: Insights from μ-CT image and pore network modelling

Cited by 13 publications

References 47 publications

Effects of microplastics on the porosity and connectivity with different soil textures: Based on CT scanning

Effects of microplastics on the porosity and connectivity with different soil textures: Based on CT scanning

Experimental Study on Permeability Enhancement of Anthracite by High Pressure Nitrogen Injection and Soaking

Comprehensive Analysis of Connectivity and Permeability of a Pore-Fracture Structure in Low Permeability Seam of Huainan–Huaibei Coalfield

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