The invention discloses a
coal mine underground
coal seam long
drill hole staged fracturing permeability increase and gas extraction method. The
coal mine underground coal seam long
drill hole stagedfracturing permeability increase and gas extraction method comprises the steps that a long
drill hole with the length more than 100m are drilled into a coal seam using a
underground tunnel drilling
machine for a coal mine or a kilometer drilling
machine; a rigid casing with an one-way valve is lowered into to protect the hole directly using the
underground tunnel drilling
machine or the kilometerdrilling machine, and casing centralizers are installed at regular intervals; after the casing is lowered, preset volumetric
cement paste is injected into an annular space between the outer wall of the casing and a
drill hole wall to carry out blocking and sealing; a rigid fracturing
pipe with two or multiple packers is lowered into the casing to carry out coal seam staged fracturing step by stepor multistage staged fracturing; and the fracturing
pipe and the packers are removed after staged fracturing permeability increase, the casing of coal seam long
drill hole opening is accessed with a gas extraction pipeline after drainage finishes to carry out efficient extraction of gas. The
engineering amount of a tunnel and hole-drilling can be greatly reduced, the coal seam gas extraction efficiency is improved, and the coal mine underground gas treatment cost is reduced.