Influence of Gas Extraction Process Elements on the Gas Migration Law in High-Gas Goaf Areas.

Gas gush in goaf leads to gas accumulation in local areas, which not only easily leads to excessive gas concentration in the corner of the working surface but also may induce gas explosion, which seriously threatens the safety of mine production. In order to study the influence of gas extraction technology on gas migration in gobs, a gob model is established based on experimental parameters, and the application effect of buried pipe extraction and high level borehole extraction technology in high gas gobs is analyzed by numerical simulation software (Fluent). The results show that (1) buried pipe extraction will cause the gas concentration in the gob to increase along the strike and dip direction, and the negative pressure at the extraction mouth will reduce the gas concentration at the pipe mouth and the gas concentration near the upper corner. (2) The best technical parameters of buried pipe extraction are buried pipe length 30 m, pipe diameter 0.3 m, and extraction flow rate 80 m³/min. (3) When the vertical distance of the upper borehole is 18.5 m, the horizontal distance is 10 m, and the spacing of the borehole is 8 m. the gas extraction effect is the best, but the gas concentration in the upper corner still reaches 1.42%, which does not meet the safety production requirements, so it needs to be combined with the gas extraction in the upper corner. The research in this paper provides a theoretical basis for the selection and optimization of gas extraction technology in high gas goaf.