China University of Mining and Technology (CUMT)

Chuanjie Zhu

Baiquan Lin

Ting Liu

Hao Yao

Fazhi Yan

Quanle Zou

Chang Guo

Jia Kong

Yidu Hong

Yidou Hong

Xiangliang Zhang

Zishan Gao

Bai Quan Lin

Ximiao Lu

In a method, a gyroscope and an endoscopic camera are first used to investigate coal-seam strike trend, coal-seam dip trend, and coal-seam thickness data of a to-be-extracted area. According to gas extraction standard requirements of a to-be-extracted area, boreholes are then designed and constructed, and trajectories of boreholes are tracked to obtain a correspondence relationship between designed borehole parameters and actual borehole trajectory parameters. Next, drilling parameters are adjusted according to the correspondence relationship between the designed borehole parameters and the actual borehole parameters to construct boreholes at predetermined borehole locations. Subsequently, the boreholes are connected to an extraction pipeline, and gas extraction flow rates and gas extraction amounts per meter of the boreholes are observed. Eventually, other boreholes are designed and constructed according to the adjusted borehole construction parameters and extraction data. After being constructed, the boreholes are connected to perform gas extraction.

Method for precisely extracting coal-mine gas

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.

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

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.

Method for gas extraction alternating oscillating pulse high energy gas extraction with thermal injection

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

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.

Method for integrated drilling, slotting and oscillating thermal injection for coal seam gas extraction

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.

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

A method for thermal-displacement-type strengthened extraction in a drill hole, suitable for efficient gas extraction in a coal mine, the method comprising the following steps: arranging an extraction drill hole and a thermal displacement drill hole at intervals in a coal seam; continuously heating coal in the drill hole to form a stable temperature field by using a heat pipe; and significantly reducing gas adsorption potential by utilizing a heat effect, prompting gas desorption, and strengthening gas extraction. The method enlarges a range of effective pressure relief influence of a single hole, increases an extraction efficiency of gas in a coal seam by more than 40%, is safe, reliable and low-cost, and is easy to operate, saving both time and labor.

Growing community of inventors

Jiangsu, China

Chuanjie Zhu