Strip Gas Pre-pumping Technology in Horizontal Well of Broken Soft and Low Permeability Coal Seam Roof

Gas extraction from the broken soft and low permeable coal seam is difficult with low safety in underground coal mine in Mining area of Western Guizhou Province. The advanced technology of ground extraction will be used for coal mine gas control, and the research on strip pre-pumping technology of horizontal well of broken soft and low permeability coal seam roof is carried out. Taking Duijiangnan Coal Mine as an example, through the study of technological process of optimizing well location, well trajectory design, directional perforation and staged fracturing, the coal seam gas in the working face and driving strip is extracted, and the reservoir numerical simulation and compilation of residual gas content distribution map were used to describe the extraction effect. The predicted results show that the influence range of horizontal sublevel fracturing wells on the roof is distributed in a strip, and expands to both sides with the borehole as the pumping time continues, and the pumping intensity decreases with the increase of the distance from the borehole. Continuous extraction for 5 years, the comprehensive extraction rate can reach 32%, and gas content in tunneling strip can be reduced to 8 m³/t.