Under the context of intelligent coal mine development, this study reviews the research progress in optimizing the performance of gas extraction pipeline network and intelligent control for promoting efficient and intelligent gas extraction. Specifically, a composition framework for gas extraction pipeline network was established, and the fluid flow laws within the pipeline network were elucidated. A "static-dynamic" two-dimensional framework was established based on the existing performance optimization technologies for gas extraction pipelines. The static optimization technologies can enhance the system's inherent performance through pipe material selection, structural redesign, and fault diagnosis, while the dynamic optimization technologies can dynamically adjust pump and valve parameters based on multi-source data sensing and intelligent evaluation to ensure real-time optimal operation of the pipeline network system. The present performance optimization and intelligent control technologies face such limitations as the lack of a universal model for pipeline network topology design, insufficient visualization and verification of abnormal conditions, and weak coordination among intelligent algorithms. To address these challenges, this study proposed to determine optimal combinations of parameters such as pipe diameter and slope by combining orthogonal experiments with the Analytic Hierarchy Process; develop a testing platform for simulating abnormal operations and control of mine gas extraction pipeline to replicate operating conditions such as leaks, blockages, and deformation; integrate various data mining and neural network algorithms to establish more effective intelligent control models. This study can provide guidance and reference for promoting intelligent and efficient coalbed methane extraction and ensuring the safe and sustainable development of coal mines.

Mechanical reaming technology can significantly improve the permeability of coal seams, thus promoting gas extraction from low-permeability coal seams, and is an effective measure to reduce the risk of gas dynamic disasters. To elucidate the mechanism by which mechanical reaming affects gas extraction, this study employed a gas-solid coupling model and numerical simulation to investigate the evolution of coal seam permeability before and after reaming, thereby deriving analytical solutions for gas extraction. Subsequently, field tests were conducted at the Yangquan mining area to validate the findings. The results of the study show that coal seam gas pressure under reaming stress disturbance decreases continuously with the increase of extraction time. The pattern of change in the rate of decline can be divided into two types of laws: gradually decreasing with pumping time (Type Ⅰ) and unchanged (Type Ⅱ). The gas pressure of the reamed coal seam is significantly lower than that of the normal borehole coal seam. As the distance from the center of the borehole increases, the permeability of the coal seam gradually decreases. The permeability of the coal seam increases with time. The permeability of the reamed coal seam is significantly higher than that of the normal borehole coal seam. Compared with normal boreholes, the gas seepage rate of reamed boreholes increases by about 8 times, and the effective extraction radius is enlarged by 1.70~1.78 times. The gas extraction density and purity of the coal seam in the mechanically reamed face were improved by 6.2 times and 12.6 times, and the content of residing gas was reduced by 19 %. Reaming significantly improves the coal seam permeability and gas extraction effect. The reliability of the coupled model solution and the effectiveness of the mechanical reaming technique were verified.

In the process of deep coal seam mining, multiple factors affect the coal body damage-permeability characteristics.In order to reveal the evolution law of coal mining damage-permeability characteristics, the coal damage-permeability experiments under three mechanical paths of fixed confining pressure and increased axial pressure (path 1), fixed axial pressure and decreased confining pressure (path 2), increased axial pressure and decreased confining pressure (path 3) were carried out under different engineering conditions.Then the influence of factors such as loading and unloading methods, axial pressure loading rate, confining pressure unloading rate, and confining pressure on coal damage-permeability characteristics were analyzed.The results show that the different loading and unloading methods significantly affect the degree of sample damage, whose order is: path 1 < path 2 < path 3.The compressive strength of samples is easier to achieve with an increased rate of loading and unloading, but the extent of damage and permeability increase along with it.With the increase of confining pressure, the time response of damage becomes slow and the ultimate recovery degree of permeability decreases.The damage and permeability characteristics of coal have significant confining pressure effects.The cumulative amount of energy changes with time in an exponential function, and the relative permeability k/k₀ after damage expansion is in a power function.