Research And Application On The Hole-sealing And Hole-connecting Pipe Diameter Optimization Of Coal Seam Gas Extraction In Xinyuan Coal Mine

Coal-bed gas pre-drainage through borehole is the most effective way to eliminate the coal and gas outburst disaster. Borehole-sealing and borehole-connecting are two key points of coal seam gas drainage. Selecting and matching the borehole-sealing pipe diameter and borehole-connecting pipe diameter is one of the key point of the borehole’s sealing-and-connecting technology.The matched pipe diameter between borehole-sealing pipe and boreholeconnecting pipe of Xinyuan coal mine was researched. Firstly the reasonable borehole-sealing depth was determined. And then the gas emission from the coal seam borehole was analyzed and computed by theory. The mixed gas emission and gas density was tested by field measurement simultaneously. The mixed gas emission value was determined. The optimized pipe diameter was gained through theoretically analyzing the borehole-sealing pipe diameter’s effect on the actual borehole subpressure,economical cost contrast, pipeline flow velocity calculation and so on. It concluded that the reasonable diameter of the borehole-sealing pipe was fifty millimeters, and the borehole-connecting pipe diameter was sixty-three millimeters. Finally, the optimized borehole-sealing and borehole-connecting pipe was put to good use in borehole-sealing and borehole-connecting industrial experiment. The test result made it clear that the gas density and pure gas flow quantity of the optimized borehole’s sealing-and-connecting system was higher than that of borehole’s sealing-and-connecting system of Xinyuan coal mine. It turned out that the optimized borehole-sealing and borehole-connecting system was superior to Xinyuan coal mine’s system.