Method for integrated drilling, flushing, slotting and thermal injection for coalbed gas extraction

    公开(公告)号:US10370942B2

    公开(公告)日:2019-08-06

    申请号:US15325506

    申请日:2015-12-21

    Abstract: 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.

    METHOD FOR INTEGRATED DRILLING, FLUSHING, SLOTTING AND THERMAL INJECTION FOR COALBED GAS EXTRACTION

    公开(公告)号:US20170145794A1

    公开(公告)日:2017-05-25

    申请号:US15325506

    申请日:2015-12-21

    CPC classification number: E21B43/006 E21B7/00 E21B43/24 E21B43/30 E21F7/00

    Abstract: 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.

    Method of sorting and utilizing coal and rock for coal and rock combined mining face

    公开(公告)号:US10413911B2

    公开(公告)日:2019-09-17

    申请号:US15549175

    申请日:2016-12-15

    Abstract: The present invention relates to a method for sorting and utilizing coal and rock for a coal and rock combined mining face, and is especially applicable to the sorting and utilization of coal and rock mined from a coal and rock combined mining face when an extremely thin coal seam is used as a protective layer in combined mining of multiple coal seams. Underground gangue transport, storage and filling systems are directly established underground to convey a large amount of coal and gangue mined from the coal and rock mining face to an underground sorting and washing chamber for efficient separation of the coal and the gangue, sorted gangue is crushed and then filled in a mined-out area of a protected layer, thus realizing the environment-friendly cut and fill mining of the protective layer while the gangue is not lifted, and effectively preventing the ground subsidence caused by combined mining of multiple coal seams; sorted middlings are conveyed to a gangue power plant on the ground for power generation through a main conveying system, so that the pressure on mine coal quality is alleviated when benefits are created in the power plant, and thus the average ash content of commercial coal is reduced, and the selling price is increased. The method provided by the invention realizes the efficient utilization of coal and rock while realizing the efficient separation of coal and gangue, and has remarkable economic and social benefits and excellent promotional value.

    Permeability enhancement method for coalbed methane wells by using electric pulse detonation fracturing technology

    公开(公告)号:US10858913B2

    公开(公告)日:2020-12-08

    申请号:US15767880

    申请日:2016-12-15

    Abstract: 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.

    Downhole coal seam pulse detonation wave directional fracturing permeability-increasing method

    公开(公告)号:US09951597B1

    公开(公告)日:2018-04-24

    申请号:US15325662

    申请日:2015-12-28

    CPC classification number: E21B43/26 E21B43/30

    Abstract: 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.

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