Analysis of radius impact of coal seam gas drainage drill-hole in 13-1 coal seam of Kouzidong coal mine

摘要

In order to accurately determine the effective drainage radius of 13-1 coal seam gas in Kouzidong coal mine, we established the flow equation of pre-drainage gas from drill-holes, which was based on negative exponential decay laws of drilling gas flow and deduced the calculation formula of drill-hole spacing, selecting extraction rate as an indicator.By field measurement, the effective drainage radius was analyzed in different times.With the time of pre-pumping being prolonged,the effective radius of gas extraction drilling holes increased gradually, until the limit radius of extraction.According to a reasonable seam gas pre-pumping rate range of 20％ ～40％, we know that the effective drainage radius of a drilling hole with a diameter of 94 mm is about 4.5～9.0 m.According to the actual status of gas drainage results in Kouzidong coal mine, the optimal distance between bores of drainage gas in coal seams is 7.5 m.This provides a reliable theoretical basis for drainage work in gas mines and has important implications for the protection of safe and efficient exploitation of the mine.