A simulation test method for gas extraction from a tectonically-deformed coal seam in-situ by depressurizing a horizontal well cavity. A coal series stratum structure reconstruction and similar material simulation subsystem simulates a tectonically-deformed coal reservoir. A horizontal well drilling and reaming simulation subsystem constructs a U-shaped well in which a horizontal well adjoins a vertical well, and performs a reaming process on a horizontal section thereof. A horizontal well hole-collapse cavity-construction depressurization excitation simulation subsystem performs pressure-pulse excitation and stress release on the horizontal well, and hydraulically displaces a coal-liquid-gas mixture such that the mixture is conveyed towards a vertical well section. A product lifting simulation subsystem further pulverizes the coal and lifts the mixture. A gas-liquid-solid separation simulation subsystem separates the coal, liquid and gas. A monitoring and control subsystem detects and controls the operation and the execution processes of equipment in real time.

A permeability enhancement method for coalbed methane wells by using electric pulse detonation fracturing technology is applicable to exploitation of coalbed methane wells in coal beds with low permeability. Firstly, a positive electrode coalbed methane wellbore and a negative electrode coalbed methane wellbore are constructed from the ground surface to a coal bed. A fixed platform installed with a positive electrode and a high-voltage pulse device are placed, by using a derrick, downwards to a predetermined permeability enhancement portion of the coal bed in the positive electrode coalbed methane wellbore, and another fixed platform installed with a negative electrode is placed, by using a derrick, downwards to a predetermined permeability enhancement portion of the coal bed in the negative electrode coalbed methane wellbore. The coal bed between the positive electrode and the negative electrode is broken down by using a high voltage, and coalbed methane extraction is carried out in the positive electrode coalbed methane wellbore and the negative electrode coalbed methane wellbore. A large amount of energy produced by high-voltage electric pulse directly acts on the coal reservoir to form a plasma channel in the coal bed between the positive electrode and the negative electrode. The large amount of energy instantly passes through the plasma channel, and the produced high-temperature thermal expansion force and shock waves act on the coal bed, such that the number of cracks in the coal bed is effectively increased and a favorable condition is created for flowing of coalbed methane.

Disclosed is a ground wellhole dedicated protective pipe for gas extraction of a mining-induced area. The ground wellhole dedicated protective pipe for gas extraction of a mining-induced area is disposed inside a ground wellhole for gas extraction of the mining-induced area and the ground wellhole dedicated protective pipe for gas extraction of a mining-induced area includes a casing and a chain that is disposed inside the casing and slidable relative to the casing, wherein the chain includes a plurality of chain drums and connecting pieces movably connecting the adjacent chain drums, and a plurality of air holes are opened in the chain drum along an axial direction of the chain drum. Beneficial effects include as follows: the ground wellhole dedicated protective pipe for gas extraction of a mining-induced area is capable of resisting a change and a failure of the casing caused by a shearing force, a squeezing force and a stretching force due to a displacement of a rock stratum simultaneously, and ensures the gas passes under any one or more forces no matter what displacement and forces occur to a protection region inside the ground wellhole for gas extraction of the mining-induced area, and thus the pipe has versatility, economy and applicability compared with traditional protection methods and apparatuses.

An integrated hole sealing, device includes a capsule plug, an outer capsule having a first hole site, an inner capsule having a second hole site, a capsule water injection pipe, a borehole water injection pipe and a tapered plug. Two ends of the outer capsule and the inner capsule are respectively fixed on the capsule plug and the tapered plug. The capsule plug, the tapered plug, the outer capsule and the inner capsule form a closed hollow cylindrical cavity. A middle part of the inner capsule is a hollow pipeline, and two ends thereof respectively correspond to the first and second hole sites. The borehole water injection pipe passes through the hollow cylindrical cavity. A part, located in the hollow cylindrical cavity, of the borehole water injection pipe is telescopically wound outside the inner capsule. The capsule water injection pipe passes through the capsule plug and extends into the hollow cylindrical cavity.

A multi-stage combustion impact wave coal mass cracking and heat injection alternating intensified gas extracting method is provided. A large amount of N.sub.2 or CO.sub.2 is injected into a drill hole by a heat injection and gas injection extracting pipe and by a high-pressure gas cylinder and a reducing valve, then a certain amount of methane and dry air are injected into a high-temperature and high-pressure combustion chamber by the high-pressure gas cylinder and the reducing valve, to be mixed and combusted to form high-temperature and high-pressure impact wave. High-temperature vapour is injected into the drill holes by the heat injection and gas injection extracting pipe to promote desorption of the coal masses.

A multi-stage combustion impact wave coal mass cracking and heat injection alternating intensified gas extracting method is provided. A large amount of N.sub.2 or CO.sub.2 is injected into a drill hole by a heat injection and gas injection extracting pipe and by a high-pressure gas cylinder and a reducing valve, then a certain amount of methane and dry air are injected into a high-temperature and high-pressure combustion chamber by the high-pressure gas cylinder and the reducing valve, to be mixed and combusted to form high-temperature and high-pressure impact wave. High-temperature vapour is injected into the drill holes by the heat injection and gas injection extracting pipe to promote desorption of the coal masses.

A portable monitor used to measure landfill gas and landfill well parameters. The portable monitor includes a control unit and a measuring unit that can communicate wirelessly with one another. The control unit and/or measuring unit can include a heating arrangement to increase the temperature of one or more components in the control unit and/or measuring unit in cold environments.

Closed circulation system for production of and continuously preparing a polymer solution, including a pneumatic stirrer inside and a charging hopper at a top of a drag-reducing polymer solution tank, a gas drainage pump, a submersible pump, and a compressed air pipe connected to a pneumatic diaphragm pump. A liquid inlet of the pneumatic diaphragm pump is connected to a liquid outlet of the drag-reducing polymer solution tank, and the gas drainage pump liquid discharge pipe and a liquid outlet pipe of the diaphragm pump leads to a circulation water pool; a liquid outlet of the submersible pump is connected to a liquid inlet of the drag-reducing polymer solution tank and a liquid inlet of the gas drainage pump respectively through a three way pipe. The pneumatic stirrer and pneumatic diaphragm pump operate at speeds, so the drag-reducing polymer solution is mixed uniformly and fed into the circulation water pool.

Closed circulation system for production of and continuously preparing a polymer solution, including a pneumatic stirrer inside and a charging hopper at a top of a drag-reducing polymer solution tank, a gas drainage pump, a submersible pump, and a compressed air pipe connected to a pneumatic diaphragm pump. A liquid inlet of the pneumatic diaphragm pump is connected to a liquid outlet of the drag-reducing polymer solution tank, and the gas drainage pump liquid discharge pipe and a liquid outlet pipe of the diaphragm pump leads to a circulation water pool; a liquid outlet of the submersible pump is connected to a liquid inlet of the drag-reducing polymer solution tank and a liquid inlet of the gas drainage pump respectively through a three way pipe. The pneumatic stirrer and pneumatic diaphragm pump operate at speeds, so the drag-reducing polymer solution is mixed uniformly and fed into the circulation water pool.

The present invention discloses a combined automatic anti-explosion method for a gas drainage pipeline, comprising specific steps of: preparation of an anti-explosion installation piping; connection of the installation piping and the gas drainage pipeline; assembly of a porous foam material and an automatic control valve; installation of an automatic powder-spraying device and a signal analyzer; installation of a temperature sensor and a pressure sensor; and signal processing and automatic anti-explosion. According to the present invention, the porous foam material is located in a bottom groove of an arched pipeline when no gas explosion occurs in the gas drainage pipeline, without affecting the extraction effect of the gas drainage pipeline. If a gas explosion occurs, the present invention blocks the pipeline with the porous foam material due to its fire resistance and pressure reduction performances, and the automatic powder-spraying device sprays a certain amount of a dry powder explosion suppressant to reduce the explosion overpressure generated in the gas explosion process and isolate the propagation of flame, so that the safety performance of the gas drainage pipeline is ensured, and thus the safety production of coal mines can be ensured.