Permeability enhancement device for coal-seam gas drainage

Abstract

A high-efficiency permeability enhancement device for coal-seam gas drainage, the device comprising: a high-pressure gas cylinder, the high-pressure gas cylinder being configured to store a gas medium; an air compressor, the air compressor being connected to a gas outlet of the high-pressure gas cylinder, and the air compressor being configured to pressurize the gas medium in the high-pressure gas cylinder; a drill pipe, a drill bit being provided at an end of the drill pipe; jet nozzles, the plurality of jet nozzles being evenly disposed in the circumferential direction of the drill pipe, and the jet nozzles being located below the drill bit, arranged outwards in the radial direction of the drill pipe, and in communication with the gas outlet of the high-pressure gas cylinder; and self-driven drill bits, the plurality of self-driven drill bits being evenly disposed in the circumferential direction of the drill pipe, the self-driven drill bits being located below the jet nozzles, a plurality of front spray holes being radially provided in the front end of each self-driven drill bit, and the self-driven drill bits being in communication with the gas outlet of the high-pressure gas cylinder. The device can significantly improve the gas drainage effect; and coal-seam gas drainage is controlled to be concentrated in a main borehole, such that the construction workload is small, and the gas drainage effect is good.

Description

A device for coal seam gas extraction and permeability enhancement Technical Field

[0001] The present invention belongs to the technical field of bottom drainage tunnel gas extraction, and in particular relates to a device for high-efficiency permeability enhancement for coal seam gas extraction. Background Art

[0002] Gas extraction is a key technical approach to coal seam gas control. Excavating bottom extraction tunnels for pre-extraction of coal seams, where conditions permit, is an effective method. In practice, the use of bottom extraction tunnel gas extraction drilling technology for gas extraction is characterized by large engineering workloads, further increasing the amount of drilling required and impacting the gas extraction construction cycle. Reducing the number of gas extraction holes in bottom extraction tunnels while achieving optimal gas extraction results is a bottleneck in improving the application of bottom extraction tunnel gas extraction technology.

[0003] Therefore, it is necessary to provide an improved technical solution to the above-mentioned deficiencies in the prior art.

[0004] Summary of the Invention

[0005] The object of the present invention is to provide a device for high-efficiency permeability enhancement in coal seam gas extraction, so as to at least solve the above-mentioned problems existing in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A device for high-efficiency permeability enhancement in coal seam gas extraction, comprising:

[0008] High-pressure gas cylinders, which are used to store gaseous media;

[0009] An air compressor connected to the gas outlet of the high-pressure gas cylinder and used to pressurize the gas medium in the high-pressure gas cylinder;

[0010] a drill rod, the end of which is provided with a drill bit;

[0011] Jet nozzles, multiple jet nozzles are evenly arranged around the drill pipe, and the jet nozzles are located below the drill bit. The jet nozzles are arranged radially outward along the drill pipe, and the jet nozzles are connected to the gas outlet of the high-pressure gas cylinder;

[0012] A self-driving drill bit, wherein multiple self-driving drill bits are evenly arranged around the drill pipe, the self-driving drill bits are located below the jet nozzle, the front end of the self-driving drill bit is radially provided with multiple front spray holes, and the self-driving drill bit is connected to the gas outlet of the high-pressure gas cylinder;

[0013] The gas outlet of the high-pressure gas cylinder is connected to a self-driven main pipe, and a self-driven gas supply valve is provided on the self-driven main pipe. The self-driven gas supply valve is used to control the on and off of the self-driven main pipe.

[0014] The self-driving main pipe is connected to a plurality of self-driving branch pipes, each of which is correspondingly connected to at least one self-driving drill bit, and air is supplied to the self-driving drill bit through the self-driving branch pipes;

[0015] The self-driving drill bit includes a high-pressure hose and a nozzle, one end of the high-pressure hose is connected to the self-driving branch pipe, and the other end is connected to the nozzle; a plurality of the front spray holes are radially arranged at the front end of the nozzle. Beneficial effects:

[0016] In the device for efficient permeability enhancement of coal seam gas extraction, a borehole can be drilled in the bottom extraction lane as the main borehole; high-pressure air or supercritical carbon dioxide is used to perform water-free pre-cutting on the borehole coal hole section formed by the main borehole; at the same time, air self-driven drilling is used to realize new drilling construction, and the coal seam cutting based on the new borehole is completed; multiple cutting and permeability enhancement of the coal seam is achieved, which greatly improves the gas extraction effect; at the same time, the entire process is driven or cut by a high-pressure gas medium, which reduces the influence of the presence of water on the desorption of gas in the coal seam, and can significantly improve the gas extraction effect; the controlled coal seam gas extraction is all concentrated in the main borehole, the construction workload is small, and the gas extraction effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a schematic structural diagram of a device for efficient permeability enhancement in coal seam gas extraction according to an embodiment of the present invention;

[0018] FIG2 is a flow chart of a method for efficient permeability enhancement in coal seam gas extraction according to an embodiment of the present invention;

[0019] Figure 3 is a cross-sectional view at point A in Figure 1;

[0020] FIG4 is a cross-sectional view at point B in FIG1 ;

[0021] FIG5 is a cross-sectional view at point C in FIG1 ;

[0022] FIG6 is a schematic structural diagram of a self-driving drill bit according to an embodiment of the present invention.

[0023] In the figure: 1. Drill bit; 2. Jet nozzle; 3. Self-propelled drill bit; 4. Lateral spray hole; 5. Drill rod; 6. Jet air supply valve; 7. Self-propelled air supply valve; 8. High-pressure gas cylinder; 9. Supercritical carbon dioxide generator; 10. Air compressor; 11. Jet branch pipe; 12. Self-propelled branch pipe; 13. High-pressure hose; 14. Rear spray hole; 15. Nozzle; 16. Front spray hole. DETAILED DESCRIPTION

[0024] As shown in Figures 1-6, the present invention provides a device for efficient permeability enhancement in coal seam gas extraction, comprising:

[0025] The high-pressure gas cylinder 8 is used to store gaseous medium.

[0026] The air compressor 10 is connected to the gas outlet of the high-pressure gas cylinder 8 and is used to pressurize the gas medium in the high-pressure gas cylinder 8.

[0027] A drill rod 5 is provided with a drill bit 1 at the end of the drill rod 5 .

[0028] Jet nozzles 2, multiple jet nozzles 2 are evenly arranged around the drill rod 5, and the jet nozzles 2 are located below the drill bit 1. The jet nozzles 2 are arranged radially outward along the drill rod 5, and the jet nozzles 2 are connected to the gas outlet of the high-pressure gas cylinder 8.

[0029] A self-propelled drill bit 3, multiple self-propelled drill bits 3 are evenly arranged on the circumference of the drill rod 5, the self-propelled drill bit 3 is located below the jet nozzle 2, the front end of the self-propelled drill bit 3 is radially provided with multiple front spray holes 16, and the self-propelled drill bit 3 is connected to the gas outlet of the high-pressure gas cylinder 8.

[0030] A main borehole is drilled into the coal seam in the bottom extraction lane, and the drill rod 5 of the device is extended into the main borehole. The jet nozzle 2 on the drill rod 5 sprays high-pressure air into the coal body to pre-cut the coal body without water. On this basis, a pre-spray hole 16 is set at the front end of the self-propelled drill bit 3 to continue to spray high-pressure air into the coal body, so that the self-propelled drill bit 3 can drill in a radial direction perpendicular to the main borehole, and then the circumference of the coal body with the main borehole as the center is enhanced by the drilling, so that the coal body achieves a better enhanced permeability effect; not only does it reduce the drilling construction volume, but it also maximizes the gas extraction efficiency.

[0031] The gas outlet of the high-pressure gas cylinder 8 is connected to a jet main pipe, and a jet gas supply valve 6 is provided on the jet main pipe. The jet gas supply valve 6 is used to control the on-off of the jet main pipe.

[0032] The jet main pipe is connected to a plurality of jet branch pipes 11 , each jet branch pipe 11 is correspondingly connected to a jet nozzle 2 , and air is supplied to the jet nozzle 2 through the jet branch pipe 11 .

[0033] There are eight jet nozzles 2 and eight jet branch pipes 11 , each of which is connected to one jet nozzle 2 . The direction of the airflow ejected from the jet nozzle 2 is perpendicular to the axial direction of the drill rod 5 .

[0034] The gas outlet of the high-pressure gas cylinder 8 is connected to a self-propelled main pipe, and a self-propelled gas supply valve 7 is provided on the self-propelled main pipe. The self-propelled gas supply valve 7 is used to control the on-off of the self-propelled main pipe.

[0035] The jet main pipe and the self-propelled main pipe are two gas supply branches on the gas outlet of the high-pressure gas cylinder 8. By setting a jet gas supply valve 6 on the jet main pipe and a self-propelled gas supply valve 7 on the self-propelled main pipe, the two gas supply branches can be used independently without affecting each other.

[0036] A plurality of self-driving branch pipes 12 are connected to the self-driving main pipe, and each self-driving branch pipe 12 is correspondingly connected to at least one self-driving drill bit 3 , and air is supplied to the self-driving drill bit 3 through the self-driving branch pipe 12 .

[0037] Three layers of self-driving drill bits 3 are provided on the drill rod 5, with eight self-driving drill bits 3 on each layer. Eight self-driving branch pipes 12 are provided, and each self-driving branch pipe 12 is connected to three self-driving drill bits 3 in the same axial direction, that is, each self-driving branch pipe 12 supplies air to three self-driving drill bits 3.

[0038] The jet branch pipe 11 and the self-driving branch pipe 12 are both located inside the drill pipe 5, and multiple self-driving branch pipes 12 are located outside the multiple jet branch pipes 11. Eight self-driving branch pipes 12 are located outside the eight jet branch pipes 11 to make the pipeline layout inside the drill pipe 5 more reasonable.

[0039] The self-driving drill bit 3 includes a high-pressure hose 13 and a nozzle 15 . One end of the high-pressure hose 13 is connected to the self-driving branch pipe 12 , and the other end is connected to the nozzle 15 . A plurality of front spray holes 16 are radially arranged at the front end of the nozzle 15 .

[0040] The high-pressure hose 13 can facilitate the free extension and retraction of the nozzle 15, so that the nozzle 15 can be close to the coal body, and the high-pressure gas ejected from the nozzle 15 can be close to the coal body for destruction, which greatly improves the coal breaking effect and makes it easier for the self-propelled drill bit 3 to form pores in the coal body; and the multiple front nozzle holes 16 are arranged in an outward radial shape, so that the high-pressure gas ejected from the nozzle 15 can be larger than the cross-sectional area of ​​the nozzle 15, and the diameter of the pore formed by the self-propelled drill bit 3 to break the coal is larger than the diameter of the nozzle 15, which makes it easier for the nozzle 15 to extend into the pore to break the coal.

[0041] A rear spray hole 14 is provided at the rear end of the nozzle 15, and the rear spray hole 14 is inclined toward the high-pressure hose 13; a lateral spray hole 4 is provided in the middle of the nozzle 15, and the lateral spray hole 4 is located between the front spray hole 16 and the rear spray hole 14, and the direction of the lateral spray hole 4 is perpendicular to the axis of the nozzle 15.

[0042] The rear nozzle hole 14 is inclined toward the high-pressure hose 13, that is, the rear nozzle hole 14 is inclined toward the rear of the nozzle head 15. With this arrangement, when the nozzle head 15 enters the pore formed by the self-propelled drill bit 3, the front nozzle hole 16 breaks the coal to produce coal dust. During the forward movement of the nozzle head 15, the rear nozzle hole 14 blows air toward the rear to blow out the coal dust in the pore as much as possible to avoid clogging of the pore; and the lateral nozzle hole 4 ejects high-pressure gas in the direction perpendicular to the extension of the pore, thereby forming cracks perpendicular to the pore in the pore, which can greatly increase the permeability of the coal body.

[0043] The device also includes a supercritical carbon dioxide generator 9, which is connected to the high-pressure gas cylinder 8 and is used to provide supercritical carbon dioxide gas to the high-pressure gas cylinder 8.

[0044] The supercritical carbon dioxide jet has a deep rock breaking depth and a large crushing range. In addition, the threshold pressure of supercritical carbon dioxide jet rock breaking is lower than that of water jet, which can achieve better rock breaking effect; it can also greatly save water resources.

[0045] The present application also provides a method for high-efficiency permeability enhancement in coal seam gas extraction, which uses the above-mentioned device for high-efficiency permeability enhancement in coal seam gas extraction and includes the following steps:

[0046] Step 1: Drill a large-diameter borehole into the coal seam from the bottom extraction tunnel as a main borehole;

[0047] Step 2: After the main borehole is drilled, the drill rod 5 and the drilling tool are withdrawn from the main borehole; then the drill rod 5 in the device is extended into the main borehole;

[0048] Step 3: When the jet nozzle 2 reaches the coal point, start the air compressor 10 and open the jet air supply valve 6; inject supercritical carbon dioxide into the coal body through the jet nozzle 2; cut the coal body to achieve preliminary permeability enhancement, providing a good foundation for subsequent drilling by the self-propelled drill bit 3; cut the coal body for 10 minutes at each location, and advance forward every 0.3m.

[0049] Step 4: When the drill rod 5 moves upward to the middle of the coal hole, the self-propelled air supply valve 7 is opened and the pressure parameters of the air compressor 10 are adjusted to allow the self-propelled drill bit 3 to drill into the coal seam;

[0050] When high-pressure gas medium is introduced into the self-propelled drill bit 3, the high-pressure hose 13 is straightened forward so that the nozzle 15 is pressed against the coal seam. The front nozzle hole 16 on the nozzle head 15 sprays supercritical carbon dioxide to break the coal and form a gap, so that the nozzle head 15 extends into the pore. At this time, the rear nozzle hole 14 sprays gas to eject the coal dust in the pore, and the lateral nozzle hole 4 ejects high-pressure gas in the direction perpendicular to the pore extension, forming a crack perpendicular to the pore in the pore.

[0051] Step 5: After the self-driving drill bit 3 completes the drilling and slitting process, the self-driving air supply valve 7 and the jet air supply valve 6 are closed, and the drill rod 5 is withdrawn from the main borehole;

[0052] Step 6: Seal the main borehole and connect the gas extraction pipeline to carry out gas extraction.

Claims

1. A device for coal seam gas extraction and permeability enhancement, characterized in that: The device comprises: a high-pressure gas cylinder, which is used to store a gas medium; An air compressor, the air compressor is connected to the gas outlet of the high-pressure gas cylinder, and the air compressor is used to pressurize the gas medium in the high-pressure gas cylinder; A drill rod, the end of which is provided with a drill bit; A jet nozzle, wherein a plurality of the jet nozzles are evenly arranged around the drill pipe, and the jet nozzles are located below the drill bit, and the jet nozzles are arranged radially outward along the drill pipe, and the jet nozzles are connected to the gas outlet of the high-pressure gas cylinder; A self-driving drill bit, wherein a plurality of self-driving drill bits are evenly arranged on the circumference of the drill pipe, the self-driving drill bit is located below the jet nozzle, a plurality of front spray holes are radially arranged at the front end of the self-driving drill bit, and the self-driving drill bit is connected to the gas outlet of the high-pressure gas cylinder; The gas outlet of the high-pressure gas cylinder is connected to a self-driving main pipe, and a self-driving gas supply valve is provided on the self-driving main pipe, and the self-driving gas supply valve is used to control the on and off of the self-driving main pipe; The self-driving main pipe is connected to a plurality of self-driving branch pipes, each of which is correspondingly connected to at least one self-driving drill bit, and air is supplied to the self-driving drill bit through the self-driving branch pipes; The self-driving drill bit comprises a high-pressure hose and a nozzle, one end of the high-pressure hose is connected to the self-driving branch pipe, and the other end is connected to the nozzle; a plurality of the front spray holes are radially arranged at the front end of the nozzle.

2. The device for coal seam gas extraction and permeability enhancement according to claim 1, characterized in that: The gas outlet of the high-pressure gas cylinder is connected to a jet main pipe, and a jet gas supply valve is arranged on the jet main pipe. The jet gas supply valve is used to control the on and off of the jet main pipe.

3. The device for coal seam gas extraction and permeability enhancement according to claim 2, characterized in that: The jet main pipe is connected with a plurality of jet branch pipes, each jet branch pipe is correspondingly connected with a jet nozzle, and air is supplied to the jet nozzle through the jet branch pipes.

4. The device for coal seam gas extraction and permeability enhancement according to claim 3, characterized in that: The jet branch pipe and the self-driving branch pipe are both located inside the drill pipe, and a plurality of self-driving branch pipes are located outside the plurality of jet branch pipes.

5. The device for coal seam gas extraction and permeability enhancement according to claim 1, characterized in that: A rear spray hole is arranged at the rear end of the nozzle, and the rear spray hole is inclined toward the high-pressure hose; A lateral spray hole is arranged in the middle of the spray head, the lateral spray hole is located between the front spray hole and the rear spray hole, and the direction of the lateral spray hole is perpendicular to the axis of the spray head.

6. The device for coal seam gas extraction and permeability enhancement according to claim 5, characterized in that: The device also includes a supercritical carbon dioxide generator, which is connected to the high-pressure gas cylinder and is used to provide supercritical carbon dioxide gas to the high-pressure gas cylinder.

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