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 and slotting with oscillating thermal injection to enhance coalbed gas extraction, applicable to managing gas extraction from microporous, low-permeability, high-adsorption coal seam areas. A number of slots are formed within a thermal injection/extraction borehole by means of integrated drilling and slotting technology; a steam generator, is then used to three high-pressure, cyclically temperature-changing steam into said borehole; the steam passing through a spinning, oscillating-pulse jet nozzle forms an oscillating superheated steam, heating the coal body. The present method overcomes the limitations of simple permeability-increasing techniques, the slotting by means of hydraulic. pressure significantly increasing the pressure relief range of a single borehole and forming a fracture network that provides channels for passage of the superheated steam, while oscillating variation in steam temperature and pressure also promote crack propagation and perforation of the coal body; the combined effect of the two enhances the efficiency of gas desorption and extraction.

Disclosed is a self-regenerative integrated device for the synergetic oxidation of low-concentration gas and ventilation gas in a coal mine. The integrated device comprises a metal shell (5). A honeycomb ceramic oxidation bed (13) is arranged within the metal shell (5) and divided into a regenerative section (40) and an oxidation section (41) by a heat exchange chamber (14). A first cavity between the regenerative section (40) and the inner wall of the metal shell (5) is divided into a first inlet chamber (6) and an exhaust chamber (8) by an inlet partition plate (7), a second cavity between the oxidation section (41) and the inner wall of the metal shell (5) is divided into a second inlet chamber (22) and a mixing chamber (20) by a partition plate (21) for averaging gas, and a plurality of gas nozzles (28) are provided on the partition plate (21) for averaging gas. An internal heat exchanger (35) is arranged within the heat exchange chamber (14), and a heat exchanger inlet (16) and a heat exchanger outlet (15) of the internal heat exchanger (35) are respectively connected with a boiler drum (18). The first inlet chamber (6) is connected with an inlet (1) of the ventilation gas through a proportional control valve (38), the second inlet chamber (22) is connected with an inlet (31) for extracting the low-concentration gas through a proportional mixer (33), and the proportional control valve (38) is connected with the proportional mixer (33) through a connecting pipeline (36). The two ends of an inlet preheating pipe (9) on the honeycomb ceramic oxidation bed (13) are respectively communicated with the first inlet chamber (6) and the mixing chamber (20).

Disclosed is a self-regenerative integrated device for the synergetic oxidation of low-concentration gas and ventilation gas in a coal mine. The integrated device comprises a metal shell (5). A honeycomb ceramic oxidation bed (13) is arranged within the metal shell (5) and divided into a regenerative section (40) and an oxidation section (41) by a heat exchange chamber (14). A first cavity between the regenerative section (40) and the inner wall of the metal shell (5) is divided into a first inlet chamber (6) and an exhaust chamber (8) by an inlet partition plate (7), a second cavity between the oxidation section (41) and the inner wall of the metal shell (5) is divided into a second inlet chamber (22) and a mixing chamber (20) by a partition plate (21) for averaging gas, and a plurality of gas nozzles (28) are provided on the partition plate (21) for averaging gas. An internal heat exchanger (35) is arranged within the heat exchange chamber (14), and a heat exchanger inlet (16) and a heat exchanger outlet (15) of the internal heat exchanger (35) are respectively connected with a boiler drum (18). The first inlet chamber (6) is connected with an inlet (1) of the ventilation gas through a proportional control valve (38), the second inlet chamber (22) is connected with an inlet (31) for extracting the low-concentration gas through a proportional mixer (33), and the proportional control valve (38) is connected with the proportional mixer (33) through a connecting pipeline (36). The two ends of an inlet preheating pipe (9) on the honeycomb ceramic oxidation bed (13) are respectively communicated with the first inlet chamber (6) and the mixing chamber (20).

A pumpable mine ventilation stopping wall structure comprised of a pumpable bag having spaced walls of generally parallel nonporous and flexible sheets with the sheets retained in spaced relationship with spaced flexible cross ties. The perimeter of the spaced walls may be closed off with a permeable mesh having a mesh size which will permit restricted flow of cementitious grout therethrough for sealing the wall structure to surrounding rough mine faces. The bag is provided with at least one grout fill port for filling the bag by pumping cementitious grout into the bag.

A pumpable mine ventilation stopping wall structure comprised of a pumpable bag having spaced walls of generally parallel nonporous and flexible sheets with the sheets retained in spaced relationship with spaced flexible cross ties. The perimeter of the spaced walls may be closed off with a permeable mesh having a mesh size which will permit restricted flow of cementitious grout therethrough for sealing the wall structure to surrounding rough mine faces. The bag is provided with at least one grout fill port for filling the bag by pumping cementitious grout into the bag.

A pumpable mine ventilation stopping wall structure comprised of a pumpable bag having spaced walls of generally parallel nonporous and flexible sheets with the sheets retained in spaced relationship with spaced flexible cross ties. The perimeter of the spaced walls may be closed off with a permeable mesh having a mesh size which will permit restricted flow of cementitious grout therethrough for sealing the wall structure to surrounding rough mine faces. The bag is provided with at least one grout fill port for filling the bag by pumping cementitious grout into the bag.

A pumpable mine ventilation stopping wall structure comprised of a pumpable bag having spaced walls of generally parallel nonporous and flexible sheets with the sheets retained in spaced relationship with spaced flexible cross ties. The perimeter of the spaced walls may be closed off with a permeable mesh having a mesh size which will permit restricted flow of cementitious grout therethrough for sealing the wall structure to surrounding rough mine faces. The bag is provided with at least one grout fill port for filling the bag by pumping cementitious grout into the bag.

A method for permeability improvement for a downhole coal seam by directional fracturing with pulsed detonation waves, which is applicable to gas control in coal seam areas with high gas concentration and low air permeability. The permeability improvement method is as follows: first, drilling a pulsed detonation borehole and pulsed detonation guide boreholes from a coal roadway to a coal seam respectively; then, pushing a positive electrode connected to a positive output side of an explosion-proof high-voltage electrical pulse generator to the bottom of the pulsed detonation borehole and pushing a negative electrode connected to a negative output side of the explosion-proof high-voltage electrical pulse generator to the bottom of the pulsed detonation guide borehole; connecting the pulsed detonation borehole and the pulsed detonation guide boreholes to an extraction pipeline for gas extraction, after electrical pulsed detonation fracturing for the coal seam is carried out. The method disclosed in the present invention utilizes the high instantaneous energy provided by electrical pulsed detonation waves to fracture a coal mass, so as to form a fissure network in the coal mass between the pulsed detonation borehole and the pulsed detonation guide boreholes; thus, the air permeability coefficient of the coal mass can be increased by 200-400 times, the effective influence scope of gas extraction of a single borehole for gas extraction can be enlarged by 3-4 times, the extracted gas volume from the borehole can be increased by 3-8 times, and the coal seam gas pre-extraction time can be shortened effectively.