Characteristics of Pressure Relief Gas Extraction in the Protected Layer by Surface Drilling in Huainan

Table 1

Surface gas extraction wells of different structural types in the Huainan mining area.

Type	Structural representation	Coal mines featuring successful application	Result
I		Panyi coal mine, Xieqiao coal mine, and Pansan coal mine	The maximum single-well gas extraction volume is close to 1,000,000 m^3
II		Dingji coal mine	The cumulative gas output of a single well is close to 1,000,000 m^3
III		Guqiao coal mine, as well as other coal mines in the Huainan mining area	The gas output of a single well is more than 1,000,000 m^3, which solves the problem of gas extraction and pressure relief by rapidly advancing surface gas extraction drilling in complex geological and hydrogeological environments
IV		Pansan coal mine, as well as other coal mines in the Huainan mining area	The maximum single well gas extraction volume reached 7,500,000 m^3