Technical method for rapid gas extraction standard reaching in broken soft, low-permeability and outburst coal seam by replacing roadways with holes

Abstract

The invention provides a technical method for rapid gas extraction standard reaching in broken soft, low-permeability and outburst coal seam by replacing roadways with holes. The method comprises thefollowing steps that S10, a large-diameter super-long directional drilling hole is constructed on the basic top layer of a coal seam roof or the old bottom layer of a coal seam floor; S20, the spacingd of small-curvature-radius branch drilling holes arranged in a penetrating mode in the coal seam to be excavated and the number n of the small-curvature-radius branch drilling holes are determined according to the drilling hole gas extraction influence radius r of coal seam to be excavated and extraction standard reaching time; S30, a retreat branch method is used for constructing the small-curvature-radius branch drilling holes; S40, a special permeability improvement device for underground coal mine is used for performing gas phase fracturing permeability improvement or combination of hydraulic fracturing and gas phase fracturing permeability improvement on the small-curvature-radius branch drilling holes until a plurality of sections of three-dimensional fissures are formed; and S50,connecting pipelines extracts the gas in the coal seam until the gas content of the coal seam meets extraction standard reaching. The construction method can achieve low-cost, long-distance, dense, controllable, high-efficiency extraction of the gas from the coal seam.

Description

technical field [0001] The invention belongs to the technical field of underground safety in coal mines, in particular to the field of gas control in broken, soft and outburst coal seams, and specifically relates to a technical method for quickly extracting gas from broken, soft and low-permeability outburst coal seams to meet the standard by using Kongdai Lane. Background technique [0002] China's geology has experienced multi-stage tectonic movements and basin compound superposition, and the coal seam structure has undergone intense deformation. Activities such as uplifts, depressions, folds, and fractures occurred in many mining areas. Under the action of structural extrusion and shear stress, the original structure of the coal seam was destroyed, showing bedding disorder, and the coal quality was soft (the firmness coefficient is generally 0.1- 0.5), poor coal seam permeability (coal seam permeability is less than 1.0×10-3μm 2 ), this type of coal seam is called broken...

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Problems solved by technology

[0004] Therefore, some people propose to use directional drilling rigs to construct comb-shaped long holes on the roof and floor for pre-pumping of coal roadways in broken, soft and low-permeability outburst coal seams to be excavated. However, this is limited to the existing directional drilling equipment and technical conditions, and the curvature radius of branch openings is large (above 150m). , the branch distance is long (50-80m), and the number of branch drainage drilling holes is limited, resulting in blind spots, blind sections, and even blind spots in the drainage area, which is difficult to meet the standard requirements of excavation and drainage

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