Accumulation models for coalbed methane in medium- to high-rank coals: examples from the southern Qinshui Basin and southeastern Ordos Basin

Song, Yan; Liu, S.; Ma, Xingzhi; Ju, Yi‐Hsu; Hong, Feng; Jiang, Lin

doi:10.1080/08120099.2018.1430065

Cited by 3 publications

(4 citation statements)

References 37 publications

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“…The results, detailed in Table 2 and Figure 3, reveal the presence of aromatic carbon (f a ′) ranging from 38. 40 4, where two peaks are distinctly observed within the Raman shift range of 1000− 2000 cm −1 . These peaks correspond to the D1 peak (Raman shift: 1250−1400 cm −1 ) and the G peak (Raman shift: 1500− 1700 cm −1 ).…”

Section: C Nmr Spectroscopy Figure 2 Illustrates Thementioning

confidence: 97%

“…The eastern margin of the Ordos Basin is currently one of successful CBM development bases in China, − located in the eastern segment of the Weibei Uplift, which forms part of the western segment of the Jinxi Fold (Figure ). The tectonics of this region are relatively simple and stable, characterized by a large monocline gently dipping toward the west and northwest.…”

Section: Samples and Experimentsmentioning

confidence: 99%

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Unraveling the Nanopores Evolution: Chemical Structure Control in Coal during Coalification

Feng,

Li,

Tang

et al. 2024

Energy Fuels

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Nanopores play a crucial role in the storage, desorption, and diffusion of coalbed methane within the coal. This study aims to clarify the evolution mechanism of nanopores controlled by the chemical structure of coal during coalification. By conducting lowpressure CO 2 and N 2 adsorption experiments, the nanopore structure of six distinct coal samples with varying ranks was identified. Additionally, the chemical structure of coal was characterized through 13 C nuclear magnetic resonance and Raman spectroscopies. Through comprehensive analysis, the evolution mechanism of nanopores influenced by the chemical structure of coal was thoroughly investigated. The results show that during coalification (R o range 0.6−3.0%), the aliphatic content in coal gradually decreases, while the aromatic content relatively increases. The aromatic structures become more ordered, and condensation leads to an increase in the size of aromatic rings. Due to the influence of the chemical structure, the evolution of nanopores in coal can be divided into three stages. In the first stage (0.6% < R o < 1.5%), the cleavage of aliphatic side chains and the adjustment of chemical structure orientation lead to the transformation of micropores to mesopores in coal. In the second stage (1.5% < R o < 2.0%), the strengthened condensation of aromatic rings leads to the transformation of mesopores to micropores in coal. In the third stage (2.0% < R o < 3.0%), most oriented aromatic rings undergo significant condensation, leading to the formation of many micropores in coal. These findings can help understand the control mechanism of the chemical structure on the nanopores in coal and provide valuable theoretical insights for enhancing coalbed methane extraction efficiency.

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Section: C Nmr Spectroscopy Figure 2 Illustrates Thementioning

confidence: 97%

Section: Samples and Experimentsmentioning

confidence: 99%

Unraveling the Nanopores Evolution: Chemical Structure Control in Coal during Coalification

Feng,

Li,

Tang

et al. 2024

Energy Fuels

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“…China has abundant reserves of high-rank CBM, accounting for one-third of the total resources, and the production of high-rank CBM has accounted for over 90% of the total production . The Qinshui Basin is China’s major high-rank CBM resource area .…”

Section: Introductionmentioning

confidence: 99%

“…China has abundant reserves of high-rank CBM, accounting for one-third of the total resources, and the production of high-rank CBM has accounted for over 90% of the total production. 9 The Qinshui Basin is China’s major high-rank CBM resource area. 10 The Fanzhuang block, the main development area in the Basin, has been in large-scale development since 2006.…”

Section: Introductionmentioning

confidence: 99%

Geological Characteristics of Low-Yield and Low-Efficiency CBM Wells and Practical Measures for Production Increase in the Qinshui Basin

Zhang,

Ren,

Zhao

et al. 2023

ACS Omega

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Many low-production and low-efficiency wells in the Zhengzhuang, Fanzhuang, Lu’an, and Yangquan blocks of the Qinshui Basin seriously hinder the development of coalbed methane in China. Through in-depth research on the geological conditions and development technology of coalbed methane, it was found that the main reasons for the existence of a large number of low-production and low-efficiency wells are the fragmentation of coal structure, poor adaptability of vertical well types, sizable well spacing, and mismatched stimulation measures. On this basis, it is proposed to adopt an L-shaped horizontal well and staged Fracking technology in the block with a complete coal structure but low permeability. For stress–concentration areas, the first fracturing of a vertical well has a single crack and a small coverage area; After a period of drainage and production, the use of repeated fracturing technology can increase the complexity of fractures and increase gas production; For the fractured area of coal structure, the use of roof fracturing technology effectively solves the problem of coal fragmentation. In natural fracture development areas, new fractures are formed using fracture turning technology to achieve the effect of increasing production. The above technologies have achieved good results in the Qinshui Basin engineering experiment. Therefore, in-depth research on the geological conditions of coalbed methane and matching related development technologies are the main ways to solve low-efficiency and low-production wells in coalbed methane development blocks.

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Characteristics and Origins of the Difference between the Middle and High Rank Coal in Guizhou and Their Implication for the CBM Exploration and Development Strategy: A Case Study from Dahebian and Dafang Block

et al. 2022

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The coalbed methane (CBM) geology in Guizhou is characterized by a high gas content, pressure and resource abundance, indicating superior CBM resource potential. However, there are also many unfavorable factors, such as complex structure geology, significant regional differences in CBM geology, the widespread development of tectonically deformed coal, and the unclear understanding of the configuration of geological factors for CBM enrichment and high yield, which restrict the increase in CBM production and a large-scale development. Taking the Dahebian Block in Liupanshui coal field and the Dafang Block in Qianbei coal field as examples, this study presented the CBM geological differences between middle- and high-rank coals; their origins were analyzed and the effect of depth on gas content and permeability was discussed. A CBM enrichment and high-yield model was illustrated, and the geologic fitness-related exploration and development methods for Guizhou CBM were finally proposed. The results show that (1) significant differences between the middle- and high-rank coals occur in coal occurrence and distribution, coal qualities, and coal reservoir properties. Compared to Dahebian coal, Dafang coal has a higher coal rank, vitrinite content, and gas content, but a lower number of coal layers and permeability. (2) The sedimentary–tectonic evolution of the Longtan coal-bearing sequence is the fundamental reason for CBM geological differences between the Dadebian Block and Dafang Block, consisting of coal occurrence, qualities, maceral, rank, structure, and their associated reservoir properties. (3) The coordinated variation of gas content and permeability contributes to a greater depth for CBM enrichment and a high yield of the middle-rank coal. It is suggested that the best depths for CBM enrichment and high yield in Guizhou are 600–800 m for the middle-rank coal and 500 m for the high-rank coal, respectively. (4) Considering the bottleneck of inefficient CBM development in Guizhou, we proposed three CBM assessment and development technologies, including the CBM optimization of the classification–hierarchical optimization–analytical hierarchy, multiple coal seams commingling production with the pressure relief of tectonically deformed coal, and surface–underground CBM three-dimensional drainage development. The aim of this study was to provide new insights into the efficient exploration and development of CBM in Guizhou.

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Accumulation models for coalbed methane in medium- to high-rank coals: examples from the southern Qinshui Basin and southeastern Ordos Basin

Cited by 3 publications

References 37 publications

Unraveling the Nanopores Evolution: Chemical Structure Control in Coal during Coalification

Unraveling the Nanopores Evolution: Chemical Structure Control in Coal during Coalification

Geological Characteristics of Low-Yield and Low-Efficiency CBM Wells and Practical Measures for Production Increase in the Qinshui Basin

Characteristics and Origins of the Difference between the Middle and High Rank Coal in Guizhou and Their Implication for the CBM Exploration and Development Strategy: A Case Study from Dahebian and Dafang Block

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