Gas drainage system and method for hyposmosis soft coal seams

Abstract

The invention discloses a gas drainage system for hyposmosis soft coal seams, which comprises a power device mechanism, a drilling-pressing-pumping integrated mechanism, and a metering mechanism. The power device mechanism comprises an air compressor and an air drilling machine; the drilling-pressing-pumping integrated mechanism comprises a rotary blowout preventer, a boosting pipeline, a drill pipe, a multiple-completion packer, an inner drill pipe connector, a power motor, an electromotor, and an auto-reducing and reaming triple-wing drill bit. The air compressor is sealed and communicated with the inner drill pipe through a high pressure hose; moreover, a control valve, a flowmeter and a pressure meter are arranged on the high pressure hose. The invention also discloses a method using the system to pump gas. The system not only can be used for drilling to make up the difficulty of inconvenient transformation of the gravitation of the soft coal seams, but also can timely implement pressing and cave forming on coal bodies to pump gas after drilling. The method integrates drilling with pressing and cave forming, and improves the ventilation property of the coal seams through cave forming. Integration of drilling, pressing and pumping effectively prevents the problem that transformation of a reservoir can not be continued due to collapse of coal holes to a certain extent.

Description

technical field [0001] The invention relates to a gas extraction system suitable for low-permeability and soft coal seams. Background technique [0002] Coal and gas outburst is a very serious natural disaster that seriously threatens the safety of coal mines. It not only threatens the personal safety of coal mine workers, but also is the main factor restricting the production efficiency of coal mines. my country is one of the most disaster-stricken countries in the world. In the past ten years, the average annual disaster loss is nearly 160 billion yuan, which is equivalent to 3.8% of the gross national product, which is more than ten times that of developed countries. The vast number of workers, cadres and scientific and technical personnel on the front line of my country's coal industry have accumulated relatively rich experience in the process of fighting against coal and gas outbursts. Everyone agrees that: coal and gas outbursts are caused by in-situ stress, gas It is...

AI Technical Summary

Problems solved by technology

However, for low-permeability and soft coal seams, the downhole only relies on the "drilling-sealing-negative pressure" drainage method for gas drainage, which not only requires a large amount of work, but also the drainage effect is not ideal; At present, the current hydraulic fracturing, nitrogen foam fracturing, and carbon dioxide foam fracturing technologies can hardly make the original fracture system more developed, and the drainage effect is very unsatisfactory.

[0004] How to explore an effective gas drainage device and corresponding drainage technology for lo

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