Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern Guizhou

The microfracture and pore structure characteristics of coal reservoirs are crucial for coalbed methane (CBM) development. This study examines the evolution of pore and fracture structures at the microscopic level and their fractal characteristics, elucidating their impact on CBM development in the...

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Main Authors: Haiying Ren, Zhijun Guo, Honggao Xie, Sijie Han, Xiaozhi Zhou, Lingyun Zhao, Yuanlong Wei, Wenci Qiu
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Energies
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Online Access:https://www.mdpi.com/1996-1073/18/1/5
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author Haiying Ren
Zhijun Guo
Honggao Xie
Sijie Han
Xiaozhi Zhou
Lingyun Zhao
Yuanlong Wei
Wenci Qiu
author_facet Haiying Ren
Zhijun Guo
Honggao Xie
Sijie Han
Xiaozhi Zhou
Lingyun Zhao
Yuanlong Wei
Wenci Qiu
author_sort Haiying Ren
collection DOAJ
description The microfracture and pore structure characteristics of coal reservoirs are crucial for coalbed methane (CBM) development. This study examines the evolution of pore and fracture structures at the microscopic level and their fractal characteristics, elucidating their impact on CBM development in the northern Guizhou coal reservoirs. The results indicate that the pores and fractures in the coal reservoirs are relatively well-developed, which facilitates the adsorption of CBM. The density of primary fractures ranges from 5.8 to 14.4 pcs/cm, while the density of secondary fractures ranges from 3.6 to 11.8 pcs/cm. As the metamorphic degree of coal increases, the density of primary fractures initially increases and then decreases, whereas the density of secondary fractures decreases with increasing metamorphic degree. With increasing vitrinite reflectance, the specific surface area and pore volume of the coal samples first decrease and then increase. The fractal dimension ranges from 2.3761 to 2.8361; as the vitrinite reflectance of the coal samples increases, the fractal dimension <i>D</i><sub>1</sub> decreases initially and then increases, while <i>D</i><sub>2</sub> decreases. In the northern Guizhou region, CBM is characterized by an enrichment model of “anticline dominance + fault-hydrogeological dual sealing” along with geological controlling factors of” burial depth controlling gas content and permeability + local fault controlling accumulation”. The research findings provide a theoretical basis for the occurrence and extraction of CBM in northern Guizhou.
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spelling doaj-art-deb2d6e5b996479da168b2df862a7a892025-01-10T13:16:48ZengMDPI AGEnergies1996-10732024-12-01181510.3390/en18010005Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern GuizhouHaiying Ren0Zhijun Guo1Honggao Xie2Sijie Han3Xiaozhi Zhou4Lingyun Zhao5Yuanlong Wei6Wenci Qiu7Key Laboratory of Unconventional Natural Gas Evaluation and Development in Complex Tectonic Areas, Ministry of Natural Resources, Guiyang 550081, ChinaKey Laboratory of Unconventional Natural Gas Evaluation and Development in Complex Tectonic Areas, Ministry of Natural Resources, Guiyang 550081, ChinaSchool of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, ChinaJiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization, China University of Mining and Technology, Xuzhou 221008, ChinaSchool of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, ChinaKey Laboratory of Unconventional Natural Gas Evaluation and Development in Complex Tectonic Areas, Ministry of Natural Resources, Guiyang 550081, ChinaKey Laboratory of Unconventional Natural Gas Evaluation and Development in Complex Tectonic Areas, Ministry of Natural Resources, Guiyang 550081, ChinaSchool of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, ChinaThe microfracture and pore structure characteristics of coal reservoirs are crucial for coalbed methane (CBM) development. This study examines the evolution of pore and fracture structures at the microscopic level and their fractal characteristics, elucidating their impact on CBM development in the northern Guizhou coal reservoirs. The results indicate that the pores and fractures in the coal reservoirs are relatively well-developed, which facilitates the adsorption of CBM. The density of primary fractures ranges from 5.8 to 14.4 pcs/cm, while the density of secondary fractures ranges from 3.6 to 11.8 pcs/cm. As the metamorphic degree of coal increases, the density of primary fractures initially increases and then decreases, whereas the density of secondary fractures decreases with increasing metamorphic degree. With increasing vitrinite reflectance, the specific surface area and pore volume of the coal samples first decrease and then increase. The fractal dimension ranges from 2.3761 to 2.8361; as the vitrinite reflectance of the coal samples increases, the fractal dimension <i>D</i><sub>1</sub> decreases initially and then increases, while <i>D</i><sub>2</sub> decreases. In the northern Guizhou region, CBM is characterized by an enrichment model of “anticline dominance + fault-hydrogeological dual sealing” along with geological controlling factors of” burial depth controlling gas content and permeability + local fault controlling accumulation”. The research findings provide a theoretical basis for the occurrence and extraction of CBM in northern Guizhou.https://www.mdpi.com/1996-1073/18/1/5CBM developmentmiddle- and high-rank coalmicrofracturesfractal characteristicsfracture density
spellingShingle Haiying Ren
Zhijun Guo
Honggao Xie
Sijie Han
Xiaozhi Zhou
Lingyun Zhao
Yuanlong Wei
Wenci Qiu
Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern Guizhou
Energies
CBM development
middle- and high-rank coal
microfractures
fractal characteristics
fracture density
title Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern Guizhou
title_full Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern Guizhou
title_fullStr Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern Guizhou
title_full_unstemmed Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern Guizhou
title_short Characteristics of the Microfracture and Pore Structure of Middle- and High-Rank Coal and Their Implications for CBM Exploration and Development in Northern Guizhou
title_sort characteristics of the microfracture and pore structure of middle and high rank coal and their implications for cbm exploration and development in northern guizhou
topic CBM development
middle- and high-rank coal
microfractures
fractal characteristics
fracture density
url https://www.mdpi.com/1996-1073/18/1/5
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