Effect of Particle Size on Pore Structure and Fractal Characteristics of Deep Siliceous Shales in Southern Sichuan, China, Measured Using Small-Angle Neutron Scattering and Low-Pressure Nitrogen Adsorption

Granular samples are often used to characterize the pore structure of shale. To systematically analyze the influence of particle size on pore characteristics, case studies were performed on two groups of organic-rich deep shale samples. Multiple methods, including small-angle neutron scattering (SAN...

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Main Authors: Hongming Zhan, Xizhe Li, Zhiming Hu, Liqing Chen, Weijun Shen, Wei Guo, Weikang He, Yuhang Zhou
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Fractal and Fractional
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Online Access:https://www.mdpi.com/2504-3110/9/3/165
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author Hongming Zhan
Xizhe Li
Zhiming Hu
Liqing Chen
Weijun Shen
Wei Guo
Weikang He
Yuhang Zhou
author_facet Hongming Zhan
Xizhe Li
Zhiming Hu
Liqing Chen
Weijun Shen
Wei Guo
Weikang He
Yuhang Zhou
author_sort Hongming Zhan
collection DOAJ
description Granular samples are often used to characterize the pore structure of shale. To systematically analyze the influence of particle size on pore characteristics, case studies were performed on two groups of organic-rich deep shale samples. Multiple methods, including small-angle neutron scattering (SANS), low-pressure nitrogen gas adsorption (LP-N<sub>2</sub>GA), low-pressure carbon dioxide gas adsorption (LP-CO<sub>2</sub>GA), and XRD analysis, were adopted to investigate how the crushing process would affect pore structure parameters and the fractal features of deep shale samples. The research indicates that with the decrease in particle size, the measurements from nitrogen adsorption and SANS experiments significantly increase, with relative effects reaching 95.09% and 51.27%, respectively. However, the impact on carbon dioxide adsorption measurements is minor, with a maximum of only 8.97%. This suggests that the comminution process primarily alters the macropore structure, with limited influence on the micropores. Since micropores contribute the majority of the specific surface area in deep shale, the effect of particle size variation on the specific surface area is negligible, averaging only 16.52%. Shales exhibit dual-fractal characteristics. The distribution range of the mass fractal dimension of the experimental samples is 2.658–2.961, which increases as the particle size decreases. The distribution range of the surface fractal dimension is 2.777–2.834, which decreases with the decrease in particle size.
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spelling doaj-art-7c60a4891c4648d5b742e87265a6b8972025-08-20T03:43:27ZengMDPI AGFractal and Fractional2504-31102025-03-019316510.3390/fractalfract9030165Effect of Particle Size on Pore Structure and Fractal Characteristics of Deep Siliceous Shales in Southern Sichuan, China, Measured Using Small-Angle Neutron Scattering and Low-Pressure Nitrogen AdsorptionHongming Zhan0Xizhe Li1Zhiming Hu2Liqing Chen3Weijun Shen4Wei Guo5Weikang He6Yuhang Zhou7Research Institute of Petroleum Exploration & Development, Beijing 100083, ChinaSchool of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, ChinaResearch Institute of Petroleum Exploration & Development, Beijing 100083, ChinaShale Gas Research Institute, PetroChina Southwest Oil & Gas Field Company, Chengdu 610051, ChinaInstitute of Mechanics, Chinese Academy of Sciences, Beijing 100190, ChinaResearch Institute of Petroleum Exploration & Development, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Development, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Development, Beijing 100083, ChinaGranular samples are often used to characterize the pore structure of shale. To systematically analyze the influence of particle size on pore characteristics, case studies were performed on two groups of organic-rich deep shale samples. Multiple methods, including small-angle neutron scattering (SANS), low-pressure nitrogen gas adsorption (LP-N<sub>2</sub>GA), low-pressure carbon dioxide gas adsorption (LP-CO<sub>2</sub>GA), and XRD analysis, were adopted to investigate how the crushing process would affect pore structure parameters and the fractal features of deep shale samples. The research indicates that with the decrease in particle size, the measurements from nitrogen adsorption and SANS experiments significantly increase, with relative effects reaching 95.09% and 51.27%, respectively. However, the impact on carbon dioxide adsorption measurements is minor, with a maximum of only 8.97%. This suggests that the comminution process primarily alters the macropore structure, with limited influence on the micropores. Since micropores contribute the majority of the specific surface area in deep shale, the effect of particle size variation on the specific surface area is negligible, averaging only 16.52%. Shales exhibit dual-fractal characteristics. The distribution range of the mass fractal dimension of the experimental samples is 2.658–2.961, which increases as the particle size decreases. The distribution range of the surface fractal dimension is 2.777–2.834, which decreases with the decrease in particle size.https://www.mdpi.com/2504-3110/9/3/165fractal dimensionshale gassmall-angle neutron scatteringpore structureparticle size
spellingShingle Hongming Zhan
Xizhe Li
Zhiming Hu
Liqing Chen
Weijun Shen
Wei Guo
Weikang He
Yuhang Zhou
Effect of Particle Size on Pore Structure and Fractal Characteristics of Deep Siliceous Shales in Southern Sichuan, China, Measured Using Small-Angle Neutron Scattering and Low-Pressure Nitrogen Adsorption
Fractal and Fractional
fractal dimension
shale gas
small-angle neutron scattering
pore structure
particle size
title Effect of Particle Size on Pore Structure and Fractal Characteristics of Deep Siliceous Shales in Southern Sichuan, China, Measured Using Small-Angle Neutron Scattering and Low-Pressure Nitrogen Adsorption
title_full Effect of Particle Size on Pore Structure and Fractal Characteristics of Deep Siliceous Shales in Southern Sichuan, China, Measured Using Small-Angle Neutron Scattering and Low-Pressure Nitrogen Adsorption
title_fullStr Effect of Particle Size on Pore Structure and Fractal Characteristics of Deep Siliceous Shales in Southern Sichuan, China, Measured Using Small-Angle Neutron Scattering and Low-Pressure Nitrogen Adsorption
title_full_unstemmed Effect of Particle Size on Pore Structure and Fractal Characteristics of Deep Siliceous Shales in Southern Sichuan, China, Measured Using Small-Angle Neutron Scattering and Low-Pressure Nitrogen Adsorption
title_short Effect of Particle Size on Pore Structure and Fractal Characteristics of Deep Siliceous Shales in Southern Sichuan, China, Measured Using Small-Angle Neutron Scattering and Low-Pressure Nitrogen Adsorption
title_sort effect of particle size on pore structure and fractal characteristics of deep siliceous shales in southern sichuan china measured using small angle neutron scattering and low pressure nitrogen adsorption
topic fractal dimension
shale gas
small-angle neutron scattering
pore structure
particle size
url https://www.mdpi.com/2504-3110/9/3/165
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