Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos Basin

Marine–continental transitional shale is a promising unconventional gas reservoir, playing an increasingly important role in China’s energy portfolio. However, compared to marine shale, research on marine–continental transitional shale’s fractal characteristics of pore structure and complete pore si...

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Main Authors: Jiao Zhang, Wei Dang, Qin Zhang, Xiaofeng Wang, Guichao Du, Changan Shan, Yunze Lei, Lindong Shangguan, Yankai Xue, Xin Zhang
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Energies
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Online Access:https://www.mdpi.com/1996-1073/18/15/4013
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author Jiao Zhang
Wei Dang
Qin Zhang
Xiaofeng Wang
Guichao Du
Changan Shan
Yunze Lei
Lindong Shangguan
Yankai Xue
Xin Zhang
author_facet Jiao Zhang
Wei Dang
Qin Zhang
Xiaofeng Wang
Guichao Du
Changan Shan
Yunze Lei
Lindong Shangguan
Yankai Xue
Xin Zhang
author_sort Jiao Zhang
collection DOAJ
description Marine–continental transitional shale is a promising unconventional gas reservoir, playing an increasingly important role in China’s energy portfolio. However, compared to marine shale, research on marine–continental transitional shale’s fractal characteristics of pore structure and complete pore size distribution remains limited. In this work, high-pressure mercury intrusion, N<sub>2</sub> adsorption, and CO<sub>2</sub> adsorption techniques, combined with fractal geometry modeling, were employed to characterize the pore structure of the Shanxi Formation marine–continental transitional shale. The shale exhibits generally high TOC content and abundant clay minerals, indicating strong hydrocarbon-generation potential. The pore size distribution is multi-modal: micropores and mesopores dominate, contributing the majority of the specific surface area and pore volume, whereas macropores display a single-peak distribution. Fractal analysis reveals that micropores have high fractal dimensions and structural regularity, mesopores exhibit dual-fractal characteristics, and macropores show large variations in fractal dimension. Characteristics of pore structure is primarily controlled by TOC content and mineral composition. These findings provide a quantitative basis for evaluating shale reservoir quality, understanding gas storage mechanisms, and optimizing strategies for sustainable of oil and gas development in marine–continental transitional shales.
format Article
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institution Kabale University
issn 1996-1073
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publisher MDPI AG
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spelling doaj-art-150a90232ff940b28a1919f9ac978f982025-08-20T04:00:50ZengMDPI AGEnergies1996-10732025-07-011815401310.3390/en18154013Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos BasinJiao Zhang0Wei Dang1Qin Zhang2Xiaofeng Wang3Guichao Du4Changan Shan5Yunze Lei6Lindong Shangguan7Yankai Xue8Xin Zhang9School of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, ChinaSchool of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, ChinaResearch Institute of Petroleum Exploration and Development, Beijing 100083, ChinaNo. 12 Oil Production Plant, PetroChina Changqing Oilfield Company, Qingyang 745000, ChinaSchool of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, ChinaSchool of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, ChinaSchool of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, ChinaSchool of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, ChinaSchool of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, ChinaSchool of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, ChinaMarine–continental transitional shale is a promising unconventional gas reservoir, playing an increasingly important role in China’s energy portfolio. However, compared to marine shale, research on marine–continental transitional shale’s fractal characteristics of pore structure and complete pore size distribution remains limited. In this work, high-pressure mercury intrusion, N<sub>2</sub> adsorption, and CO<sub>2</sub> adsorption techniques, combined with fractal geometry modeling, were employed to characterize the pore structure of the Shanxi Formation marine–continental transitional shale. The shale exhibits generally high TOC content and abundant clay minerals, indicating strong hydrocarbon-generation potential. The pore size distribution is multi-modal: micropores and mesopores dominate, contributing the majority of the specific surface area and pore volume, whereas macropores display a single-peak distribution. Fractal analysis reveals that micropores have high fractal dimensions and structural regularity, mesopores exhibit dual-fractal characteristics, and macropores show large variations in fractal dimension. Characteristics of pore structure is primarily controlled by TOC content and mineral composition. These findings provide a quantitative basis for evaluating shale reservoir quality, understanding gas storage mechanisms, and optimizing strategies for sustainable of oil and gas development in marine–continental transitional shales.https://www.mdpi.com/1996-1073/18/15/4013marine–continental transitional shaleshale gasgas adsorptionpore structurefractal properties
spellingShingle Jiao Zhang
Wei Dang
Qin Zhang
Xiaofeng Wang
Guichao Du
Changan Shan
Yunze Lei
Lindong Shangguan
Yankai Xue
Xin Zhang
Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos Basin
Energies
marine–continental transitional shale
shale gas
gas adsorption
pore structure
fractal properties
title Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos Basin
title_full Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos Basin
title_fullStr Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos Basin
title_full_unstemmed Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos Basin
title_short Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos Basin
title_sort fractal characterization of pore structures in marine continental transitional shale gas reservoirs a case study of the shanxi formation in the ordos basin
topic marine–continental transitional shale
shale gas
gas adsorption
pore structure
fractal properties
url https://www.mdpi.com/1996-1073/18/15/4013
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