Key Takeaways & Executive Findings
- •• The boundary of the gas transport zone is located in the region of fracture separation, while the gas storage area boundary is in the abrupt penetration zone. • Fracture rate and fracture entropy, based on information theory, determine the state of gas transport and storage areas. • A mathematical model representing the dip effect on gas transport and storage areas was established, providing criteria for regional location. • The cross-fusion evolution process of the dip effect was revealed, offering guidance for directional and accurate gas extraction.
Abstract
In this study, to better decide the effect of coal seam dip angle upon the dynamic change of the cross-fusion in gas transport and storage areas during the progress of working face in the high gas thick coal seam, a two-dimensional physical simulation experiment regarded as the theoretical research was conducted to properly explore the variation law of overburden fracture. The results demonstrated that the boundary of the gas transport zone was located in the region of fracture separation. The boundary of the gas storage area was located in the abrupt penetration zone. Also, according to the information theory, the state of the gas transport and storage areas was determined by the changing trend of the fracture rate and fracture entropy. The mathematical representation model of the dip effect in gas transport and storage areas was established. The criteria upon which the regional location of the gas transport area and gas storage area can be based were put forward. The cross-fusion evolution process of the dip effect in gas transport and storage areas was revealed as well. The research results could provide guidance for realising directional and accurate gas extraction.
1. Introduction
In the early 21st century, owing to China's high-intensity mining of coal resources, proven coal reserves are declining expeditiously. As a result, the recoverable reserves in eastern China are facing exhaustion, and the development of coal resources is gradually shifting to western China. Xinjiang is one of China's 1.4 billion tonnes of coal bases. The area is abundant in exploitable coal resources, and so there are an immense number of inclined coal seams. Xinjiang is not only a crucial coal resource continuation area but also a strategic reserve area in China [1–3]. Because of the effect of coal seam dip angle during mining, the overlying rock caving in coal seam with dip angle has sliding characteristics. This feature is different from that of the horizontal coal seam mining. Inclined coal seam mining can disturb a gigantic range of overlying rock, cause the total amount of coal extracted to break readily, and augment pressure relief gas emission intensity. These inherent problems make it difficult to quantify the boundary of the gas transport and storage areas. Also, the pressure relief gas extraction effect is not ideal, and this not only results in the increased possibility of gas accidents but also seriously affects the efficiency of coal mining [4–6]. Accordingly, to make the fracture change law and regional evolution characteristics of pressure relief gas under inclined coal seam mining conditions further accurate is essential. The gas extraction efficiency should be further improved.
To date, domestic and foreign scholars have delved into the evolution law of mining fracture through physical analogue simulation [7,8], numerical simulation [9–11], theoretical analysis, and field tests [12–14]. Ju et al. [15] utilised computer scanning technology to capture the images of the fracture network of pressurised rock mass. The fractal dimension of the fracture network of rock mass decreases first and then rises during the rock stress change.
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Pengxiang Zhao, Zechen Chang, Shugang Li, Risheng Zhuo, Yongyong Jia, Qiudong Shao, Wen Lei (2024). Study and application of the influence of inclination angle on the cross-fusion mechanism of high gas thick coal seam. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2024.12.003
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Frequently Asked Questions
What is the main objective of the study?
The main objective is to determine the effect of coal seam dip angle on the dynamic change of cross-fusion in gas transport and storage areas during working face advancement in high gas thick coal seams, using physical simulation and theoretical analysis.
How were the boundaries of gas transport and storage areas identified?
The boundary of the gas transport zone was located in the region of fracture separation, while the boundary of the gas storage area was located in the abrupt penetration zone, as revealed by the physical simulation experiments.
What role do fracture rate and fracture entropy play in the study?
Based on information theory, the state of gas transport and storage areas is determined by the changing trend of fracture rate and fracture entropy, which serve as indicators for the evolution of these zones.
What practical applications do the research findings have?
The research results provide guidance for realizing directional and accurate gas extraction in inclined coal seams, improving gas extraction efficiency and reducing gas accident risks.
What methods were used in the study?
The study employed a two-dimensional physical simulation experiment, along with theoretical analysis and information theory, to explore the variation law of overburden fracture and the cross-fusion mechanism.
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