To further enhance the intelligent technology, platformisation, and systematisation of coalbed methane extraction sealing technology, this paper analyses the research progress of theories, technologies, and sealing materials related to coalbed methane extraction sealing and systematically summarises the latest achievements of the basic theories, key technologies, and sealing materials of coalbed methane extraction. Considering the increasing mining depth, advancements in intelligent technology, and the evolving landscape of coalbed methane development, it is particularly important to establish a more comprehensive coalbed methane extraction borehole sealing system. Based on this, future development trends and research prospects are proposed: In terms of coalbed-methane-extraction-related theories, there should be a stronger focus on fundamental research such as on gas flow within the coal matrix. For coalbed methane extraction borehole sealing technologies and devices, efforts should be made to enhance research on intelligent, platform-based, and systematic approaches, while adapting to the application of directional long borehole sealing processes. In terms of coalbed methane extraction borehole leakage detection, non-contact measurement and non-destructive monitoring methods should be employed to achieve dynamic monitoring and early warning of methane leaks, integrating these technologies into coalbed methane extraction system platforms. For coalbed methane extraction borehole sealing materials, further development is needed for liquid sealing materials that address borehole creep and the development of fractures in surrounding rock, as well as solid sealing materials with Poisson’s ratios similar to that of the surrounding rock mass.
Pre-pumping of coal seam gas by gas extraction borehole is an effective measure to manage gas. The existing study concluded that the pressure relief zone of the roadway is difficult to seal, and thus the sealing depth of the gas extraction borehole should generally exceed the pressure relief zone of the roadway. Based on the relationship between roughness and GSI, a numerical simulation was carried out with the engineering background of the 22200 machine tunnel of the E8 coal seam of the Sixth Mine of Pingdingshan Tianan Coal Industry Company Limited. The results of numerical simulation and field experiments show that: (1) the quantitative standard of whether the borehole has “air leakage” or whether the surrounding rock cracks around the borehole are connected to the free surface can be characterized by permeability; (2) the variation rate of relative permeability has an inflection point at 2–4 m from the free surface of the roadway wall; (3) the dividing point of whether the surrounding rock cracks around the borehole are connected to the free surface can be set at 6 m, which is located in the pressure relief zone. (4) when the sealing depth of the coal roadway is 6 m and the sealing depth of the rock roadway is 5 m, there is no gas leakage in the borehole, that is, there is an area where a crack is not connected with the free surface of the roadway in the pressure relief zone.