A method for stepwise construction of a preferential gas migration pathway at a stope in a coal seam. First, a gas migration pathway is preliminarily formed at a stope depending on a mining effect of mining in a first mined seam. construction and stabilization method of gob-side entry retaining in deep strata, and a method of manual-guided pre-fracturing boreholes are then used to perform active construction respectively in external space and the outside of coal-rock mass to form preferential gas migration pathways. Eventually, under the effect of mining-induced stress, a system of preferential gas migration pathways connected to each other at the stope is further formed.

A hole protection system and a method for coal seam slotting and fracturing combined drainage. The system includes a hydraulic slotting subsystem, a hydraulic fracturing subsystem and a flexible hole protection system. The hydraulic slotting subsystem includes an ultra-high pressure water jet generating module, a drill pipe drilling tool module, an orifice sealer, a gas slag separator and a drilling rig. The hydraulic fracturing system includes an emulsion pump station, a water tank, a hole sealing device, a fracturing string and a casing. The flexible hole protection system includes a front end fixing device, a water injection support pipe, a first flexible support and a water injection connecting section.

A hole protection system and a method for coal seam slotting and fracturing combined drainage. The system includes a hydraulic slotting subsystem, a hydraulic fracturing subsystem and a flexible hole protection system. The hydraulic slotting subsystem includes an ultra-high pressure water jet generating module, a drill pipe drilling tool module, an orifice sealer, a gas slag separator and a drilling rig. The hydraulic fracturing system includes an emulsion pump station, a water tank, a hole sealing device, a fracturing string and a casing. The flexible hole protection system includes a front end fixing device, a water injection support pipe, a first flexible support and a water injection connecting section.

The present invention discloses a closed circulation system for improving operating efficiency of a gas drainage pump. A liquid inlet of a pneumatic diaphragm pump is connected to a liquid outlet of a drag-reducing polymer solution tank, and a liquid outlet pipe of the pneumatic diaphragm pump leads to a circulation water pool. The drag-reducing polymer solution tank is provided with a pneumatic stirrer internally, and a charging hopper at the top. A liquid outlet of a submersible pump is connected to a liquid inlet of the drag-reducing polymer solution tank and a liquid inlet of a gas drainage pump respectively through a three way pipe, and a liquid discharge pipe of the gas drainage pump is connected to the circulation water pool. The pneumatic stirrer and the pneumatic diaphragm pump operate at high speeds.

The present invention discloses a closed circulation system for improving operating efficiency of a gas drainage pump. A liquid inlet of a pneumatic diaphragm pump is connected to a liquid outlet of a drag-reducing polymer solution tank, and a liquid outlet pipe of the pneumatic diaphragm pump leads to a circulation water pool. The drag-reducing polymer solution tank is provided with a pneumatic stirrer internally, and a charging hopper at the top. A liquid outlet of a submersible pump is connected to a liquid inlet of the drag-reducing polymer solution tank and a liquid inlet of a gas drainage pump respectively through a three way pipe, and a liquid discharge pipe of the gas drainage pump is connected to the circulation water pool. The pneumatic stirrer and the pneumatic diaphragm pump operate at high speeds.

A barrier assembly used in the protection of personnel at worksites and/or residential areas from escapes of gas. Such a barrier assembly controls the lateral and vertical spread of gas in the event of an escape of the gas, even more particularly toxic gas. The barrier assembly can be used at operating sites where gases are produced, and in particular where high concentrations of toxic gases (e.g. CO2, H2S, SO2, mercaptans etc.) are present. The barrier assembly can, optionally act as a safety system in the event of an accidental uncontrolled release of these toxic gases into the atmosphere.

A barrier assembly used in the protection of personnel at worksites and/or residential areas from escapes of gas. Such a barrier assembly controls the lateral and vertical spread of gas in the event of an escape of the gas, even more particularly toxic gas. The barrier assembly can be used at operating sites where gases are produced, and in particular where high concentrations of toxic gases (e.g. CO2, H2S, SO2, mercaptans etc.) are present. The barrier assembly can, optionally act as a safety system in the event of an accidental uncontrolled release of these toxic gases into the atmosphere.

A gas extraction method in which high energy gas fracturing technology is used to form a fracture network in a thermal injection borehole. Then high-pressure, cyclically temperature-changing steam is injected into the borehole using a spinning oscillating-pulse jet nozzle to form oscillating superheated steam, alternatingly impacting and heating the coal body. The high energy gas forms a fracture network that provides channels for passage of the superheated steam, while oscillating changes in steam temperature and pressure also promote crack propagation and perforation of the coal body; the combined effect of alternation of the two enhances gas desorption and extraction efficiency.

A gas extraction method in which high energy gas fracturing technology is used to form a fracture network in a thermal injection borehole. Then high-pressure, cyclically temperature-changing steam is injected into the borehole using a spinning oscillating-pulse jet nozzle to form oscillating superheated steam, alternatingly impacting and heating the coal body. The high energy gas forms a fracture network that provides channels for passage of the superheated steam, while oscillating changes in steam temperature and pressure also promote crack propagation and perforation of the coal body; the combined effect of alternation of the two enhances gas desorption and extraction efficiency.

A method for combining integrated drilling, flushing and slotting with thermal injection to enhance coalbed gas extraction, applicable to managing gas extraction from microporous, low-permeability, high-adsorption coalbed areas. A gas extraction borehole is drilled within a certain distance of a predetermined drilling, flushing and slotting borehole, and, once sealed, is used for gas extraction. An integrated drilling, flushing and slotting drill bit is used to sink the borehole, which is then sealed. Concentration variation in the gas extraction borehole is monitored in real time, and when concentration is below 30%, borehole is opened and high-temperature steam is injected by means of a steam generator, after which the borehole is again closed. Drilling a drilling, flushing and slotting borehole increases pressure relief space and the surface of exposed coal, relieves stress on the coal body, and increases gas permeability of the coalbed, while the injection of high-temperature steam promotes gas desorption in the coal body, promotes crack propagation around the borehole, and increases channels for gas flow, thus achieving highly efficient extraction of gas from the coalbed.