Directional fracturing permeability improvement outburst elimination method in coal mine and device thereof.

Abstract

The invention relates to a directional fracturing method in the coal mine and a fracturing permeability improvement outburst elimination device to ensure the coal-bed gas to release rapidly and continually in the coal mine. The method comprises the following steps: fracturing and drilling a bore on a preparing working face along the dip direction and strike direction of a coal bed, fixing a fracturing hole packer with an outer diameter matching with the pore diameter of a fracturing drilling bore into the fracturing drilling bore; connecting a fluid reservoir with a sand mixing machine, connecting the sand mixing machine with a fracturing pump package, and then connecting the fracturing pump package with the fracturing drilling bore; pumping formation fracturing fluid and proppant into the fracturing drilling bore to fracture the formation and sealing the fracturing drilling at above formation fracturing pressure, and completing directional fracturing permeability improvement outburst elimination in the coal mine, thus ensuring that the coal-bed gas discharges rapidly and continually relatively and solving the problems that drainage in low air permeability coal bed can only influence a limited range and the drainage attenuation period is short, improving the drainage rate by over 50% on primary base, decreasing the coal body dynamic phenomenon after fracturing and reginal stress influenced by fracturing, and having a significant effect for eliminating outburst.

Description

technical field [0001] The invention relates to an underground coal mine directional fracturing method and a fracturing anti-burst reduction device for ensuring rapid and sustained release of coal bed gas (coal mine gas) underground in a coal mine. technical background [0002] For a long time, coal mine gas disasters have been an important factor restricting the safe and efficient production of coal enterprises. Judging from the development status of my country's high gas and outburst mine gas drainage and coalbed methane (coal mine gas) mining, improving the pre-pumping rate and shortening the pre-pumping period has always been an urgent problem to be solved. Coal-bearing strata in my country have generally experienced strong tectonic movements after coal formation, and the endogenous fracture system is often severely damaged, becoming a low-permeability and high-ductility structure, which is very different from foreign countries, and the permeability is lower by 2 ~3 orde...

AI Technical Summary

Problems solved by technology

These technical measures often carry out drainage at the cost of densely distributed holes and high engineering investment. There are generally problems such as insufficient overall pressure relief, large drainage blank zone, and complicated construction procedures.

When the coal seam is drilled for gas extraction, the range of the fracture zone formed around the borehole is about 2 to 3 times the radius of the borehole, and the maximum extraction radius is 3 to 5m, and there will be a relatively high extraction volume in the early stage of extraction. , but decayed quickly, and the free gas and analytical gas farther away could not be replenished into the borehole in time because the permeability of the original coal seam had not been improved, resulting in a rapid and sharp decline in the extraction volume and a small extraction rate

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