A gas-gas exchange device for injecting CO2 to mine coalbed methane

Abstract

The present invention discloses a gas-gas exchange device for injecting CO2 to extract coalbed methane, comprising: a main well, a horizontal well, an extraction sleeve, an exchange cylinder, an adjusting device, and a gas injection device. The main well extends from the ground to the bottom of the target coal seam; the horizontal well is arranged in the middle of the target coal seam, with both ends respectively connected to the main well; the extraction sleeve is arranged in the main well; the exchange cylinder is horizontally arranged in the horizontal well, with both ends respectively fixedly connected to the extraction sleeve; the adjusting device is arranged in the extraction sleeve and fixedly connected to one end of the exchange cylinder; and the gas injection device is slidably arranged in the exchange cylinder. Compared with the prior art, the present invention performs multiple flow replacements on the injected carbon dioxide gas in the coal seam, thereby increasing the swept area of ​​the injected gas, extending the replacement time, improving the replacement efficiency of carbon dioxide, and thereby improving the extraction efficiency of coalbed methane.

Description

Technical Field

[0001] The present invention relates to the technical field of coalbed methane mining, and more particularly to a gas-gas exchange device for injecting CO2 to mine coalbed methane. Background Art

[0002] my country is rich in coalbed methane resources and has huge development potential. The efficient development of coalbed methane resources is of great significance to reducing the trend of global warming and improving my country's energy structure. Unlike conventional oil and gas reservoirs, coalbed methane refers to a self-generated and self-stored adsorbed gas stored in coal seams with methane as the main component. Coalbed methane is mainly adsorbed on the surface of coal matrix particles, and some is free in the coal pores. At present, injecting carbon dioxide gas into coal seams is an important means to improve the recovery rate of coalbed methane. At present, when using carbon dioxide for replacement, carbon dioxide is usually pressurized and injected into the well for free replacement. This method has the problem that some carbon dioxide is not replaced, resulting in a high level of carbon dioxide in the collected coalbed methane, and only one replacement is performed, resulting in a small area affected by the injected gas and a short replacement time, resulting in some coalbed methane not being fully collected, reducing the efficiency of coalbed methane extraction. Therefore, it is necessary to provide a gas-gas exchange device for injecting CO2 to extract coalbed methane to solve the problems raised in the above background technology. Summary of the Invention

[0003] To achieve the above objectives, the present invention provides the following technical solution: a gas-gas exchange device for injecting CO2 to mine coalbed methane, comprising:

[0004] The main shaft, which is drilled from the ground to the bottom of the target coal seam;

[0005] Horizontal wells are set in the middle of the target coal seam and connected to the main well at both ends;

[0006] The extraction sleeve is set in the main well;

[0007] The exchange cylinder is horizontally arranged in the horizontal well, and its two ends are fixedly connected to the extraction sleeve;

[0008] An adjusting device is provided in the extraction sleeve and is fixedly connected to one end of the exchange cylinder;

[0009] The gas injection device is slidably arranged in the exchange cylinder.

[0010] Furthermore, preferably, the extraction sleeve includes:

[0011] There are two sealing pistons distributed in a straight line, distributed on the upper and lower sides of the target coal seam, and slidingly set in the extraction sleeve;

[0012] The gas injection pipe is of right angle type, one side of which is arranged in the extraction sleeve and the other side is arranged coaxially with the exchange cylinder;

[0013] The extraction pipe passes through the upper sealing piston and is arranged in the extraction sleeve;

[0014] The transmission motor is fixed to the bottom of the upper sealing piston and connected to the regulating device. That is, under the action of the gas injection pipe, pressurized carbon dioxide is injected into the exchange cylinder, from which it diffuses into the target coal seam, replacing the coalbed methane. It should be noted that the gas injection pipe is a one-way conveying pipeline. Under the action of the gas injection device, the injected carbon dioxide undergoes multiple flow replacements, and the replaced coalbed methane is discharged into the extraction sleeve through the regulating device. Under the action of the sealing piston, the coalbed methane is effectively prevented from leaking, and the coalbed methane is collected and processed through the gas extraction pipe.

[0015] Furthermore, preferably, the exchange cylinder includes:

[0016] The rotating sealing surface is rotatably arranged on both sides of the exchange cylinder and is fixedly connected to the adjustment device;

[0017] Exhaust arc surfaces, with multiple annular distribution, fixed on the outside of both ends of the exchange cylinder;

[0018] The first exchange port is provided with a plurality of first exchange ports distributed in an annular manner and located in the center of the exchange cylinder;

[0019] Second exchange ports, multiple of which are distributed in an annular pattern and are located at both ends of the exchange cylinder;

[0020] An annular track is provided on the annular surface where the second exchange port is located;

[0021] The linear track is arranged on the inner wall of the exchange cylinder and corresponds to the second exchange port. That is to say, after the carbon dioxide gas is injected into the exchange cylinder through the gas injection pipe, it flows into the pores of the target coal seam through the first exchange port to replace the coalbed methane. When the carbon dioxide gas in the exchange cylinder diffuses slowly into the pores of the coal seam and reaches a critical value, the gas injection pipe stops conveying, and then the gas injection devices on both sides move toward the center along the linear track, squeezing and conveying the middle carbon dioxide gas into the coal seam through the first exchange port. At the same time, as the gas injection device moves, the second exchange port opens, and the replaced carbon dioxide and coalbed methane mixed gas returns to the two ends of the exchange cylinder. It should be noted that under the action of the rotating sealing surface, the two ends of the exchange cylinder are in a closed state. Then the gas injection device moves to both sides to reset, and the mixed gas flows into the coal seam again through the second exchange port, and then is discharged through the first exchange port. This cycle is repeated multiple times, thereby extending the residence time of the carbon dioxide gas inside the coal seam and improving the carbon dioxide replacement efficiency.

[0022] Furthermore, preferably, the regulating device includes:

[0023] The planetary gear set is adjusted and fixedly connected to the exchange cylinder, and the outer ring is fixed to the inner wall of the extraction sleeve;

[0024] A plurality of closed cambered surfaces are provided in an annular distribution, are spaced apart from the exhaust cambered surface, and are fixedly connected to the regulating planetary gear set;

[0025] The transmission assembly is fixed to the end of the adjustable planetary gear set opposite the exchange cylinder and meshes with the transmission gear on the transmission motor. Driven by the transmission assembly, the planetary gear set is adjusted to drive the closed arc surface to rotate, so that the closed arc surface and the exhaust arc surface form a complete annular surface, sealing the target coal seam and the extraction sleeve to prevent the emission of unreplaced carbon dioxide. After the carbon dioxide has been replaced multiple times, the closed arc surface rotates to the same position as the exhaust arc surface, allowing the replaced coal seam gas to be discharged into the extraction sleeve through the gap between the exhaust arc surfaces and collected by the extraction pipe.

[0026] Furthermore, preferably, the adjusting planetary gear set includes:

[0027] a positioning ring fixed to the interior of the extraction sleeve;

[0028] The gear ring is rotatably arranged in the positioning ring, and the side portion is fixedly connected to the closed arc surface;

[0029] Surrounding the gear, a plurality of gears are provided in an annular distribution and mesh with the ring gear;

[0030] The outer rotating member is fixed on the gear ring, and the middle portion is coaxially arranged with the gas injection pipe in the horizontal direction;

[0031] The inner rotating member has one end that is rotatably arranged between the outer rotating member and the gas injection pipe, and the other end that passes through the surrounding gear and is fixedly connected to the rotating sealing surface. Driven by the outer rotating member, the ring gear drives the closed arc surface to rotate on the exhaust arc surface, closing or opening the connection between the target coal seam and the extraction sleeve. After the carbon dioxide has completely replaced the coalbed methane, the outer rotating member drives the closed arc surface to rotate and open, releasing the coalbed methane. During continuous replacement, the outer rotating member drives the closed arc surface to remain closed to prevent incomplete carbon dioxide replacement and carbon dioxide leakage. Under the action of the inner rotating member, the surrounding gear rotates around the ring gear, while driving the rotating sealing surface to continuously rotate on the exchange cylinder, dynamically adjusting the internal gas injection device, so that the gas injection device can switch between driving carbon dioxide for cyclic replacement and coalbed methane discharge.

[0032] Furthermore, preferably, the transmission assembly includes:

[0033] The outer ring of the reversing gear ring is meshed with the transmission gear of the transmission motor, and the inner ring is provided with a reversing block;

[0034] The reversing inner ring is fixed on the outer rotating member, and the outer ring is provided with a reversing limiter corresponding to the reversing block;

[0035] The forward-rotating snap ring is fixed on the reverse gear ring on the side, and the inner ring is provided with a forward-rotating snap block;

[0036] The forward inner ring is fixed on the inner rotating part, and the outer ring is provided with a forward limit piece corresponding to the forward clamping piece. When the transmission motor drives the reverse gear ring to rotate counterclockwise through the transmission gear, under the action of the reverse clamping piece and the reverse limit piece, the reverse inner ring rotates along with the reverse gear ring, and at the same time drives the outer rotating part to rotate, adjusting the position of the closed arc surface. At this time, under the action of the forward clamping piece and the forward limit piece, the forward clamping ring rotates along with the reverse gear ring, but the forward inner ring remains stationary. When the transmission motor drives the reverse gear ring to rotate clockwise through the transmission gear, under the action of the reverse clamping piece and the reverse limit piece, the reverse inner ring remains stationary, and the forward clamping ring rotates clockwise. Under the action of the forward clamping piece and the forward limit piece, the forward inner ring rotates along with the reverse gear ring clockwise, thereby driving the inner rotating part to rotate, and adjusting the rotation of the rotating sealing surface.

[0037] Furthermore, preferably, the gas injection device includes:

[0038] The gas injection cylinder is divided into a front cylinder and a rear cylinder, which are slidably arranged in the exchange cylinder;

[0039] There are two symmetrically distributed gas injection pistons, which are fixed at both ends of the gas injection cylinder and are slidably connected to the exchange cylinder;

[0040] The movable motor is fixed in the front cylinder and can be movably arranged on the gas injection pipe by rotating a nut;

[0041] The sliding block is fixed to the outside of the rear cylinder and corresponds to the linear track on the inner wall of the exchange cylinder. In other words, when the carbon dioxide gas needs to be circulated and replaced, the sliding block is located on the linear track. Driven by the moving motor, the gas injection cylinder moves toward the center, allowing the carbon dioxide gas in the center to enter the coal seam pores through the first exchange port, and then flow from the second exchange port to the two ends of the exchange cylinder. The gas injection cylinder then moves to both sides and resets, allowing the mixed gas at both ends of the exchange cylinder to flow from the second exchange port to the coal seam pores and return through the first exchange port. This process is repeated multiple times to improve the carbon dioxide replacement efficiency.

[0042] Furthermore, as a preference, the front cylinder and the rear cylinder are rotationally connected, and the gas injection piston fixedly connected to the rear cylinder is slidably connected to the rotating sealing surface and rotates coaxially with the rotating sealing surface. When the carbon dioxide gas needs to be cyclically replaced, the rotating sealing surface is driven to rotate by the transmission component, and the rear cylinder is driven to rotate by the gas injection piston. When the sliding block rotates to a position corresponding to the linear track in the annular track, the rear cylinder and the front cylinder are in a stuck state, that is, the gas injection cylinder is a whole, and then the gas injection cylinder is driven back and forth in the exchange cylinder by the mobile motor, promoting the carbon dioxide gas to flow multiple times in the pores of the coal seam for replacement. When the replacement effect is achieved and the coalbed methane needs to be discharged, the rotating sealing surface is driven to rotate by the transmission component, and at the same time The rear cylinder is driven to rotate by the gas injection piston. When the sliding block rotates to a position staggered with the linear track in the circular track, the front cylinder and the rear cylinder are in a detachable state. The mobile motor drives the gas injection cylinder to move toward the middle of the exchange cylinder, only driving the front cylinder to move toward the middle. Then the gas in the middle passes through the first exchange port, flows between the pores of the coal seam, and is discharged at the exhaust arc surface. It should be noted that in order to ensure the sealing of the exchange cylinder, the gas injection piston on the front cylinder fits into the linear track. Under the restriction of the linear track, when the rear cylinder rotates, the front cylinder remains stationary.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] In the present invention, the injected carbon dioxide gas is moved and replaced multiple times in the coal seam through the reciprocating movement of the gas injection device in the exchange cylinder, thereby increasing the affected area of ​​the injected gas, extending the replacement time, and improving the replacement efficiency of carbon dioxide, thereby improving the coalbed methane extraction efficiency. Under the action of the regulating device, the closedness of the coal seam is maintained during the replacement process, preventing the outflow of carbon dioxide gas, and the coalbed methane is discharged in time after the replacement is completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of the overall structure of a gas-gas exchange device for injecting CO2 to mine coalbed methane;

[0046] Figure 2 This is a schematic diagram of the structure of the exchange cylinder and regulating device in a gas-gas exchange device for injecting CO2 to mine coalbed methane;

[0047] Figure 3 A schematic diagram of the structure of a planetary gear set for regulating gas exchange equipment for injecting CO2 to mine coalbed methane;

[0048] Figure 4 A detailed diagram of the planetary gear set used in a gas-gas exchange device for injecting CO2 to mine coalbed methane.

[0049] Figure 5This is a schematic diagram of the internal rotating parts connection in a gas-gas exchange device for injecting CO2 to mine coalbed methane;

[0050] Figure 6 This is a schematic diagram of the transmission component structure in a gas-gas exchange device for injecting CO2 to mine coalbed methane;

[0051] Figure 7 A schematic diagram of the replacement of the gas injection device in a gas-gas exchange device for injecting CO2 to mine coalbed methane;

[0052] Figure 8 A schematic diagram of the exhaust of a gas injection device in a gas-gas exchange device for injecting CO2 to mine coalbed methane;

[0053] Figure: 1, main well; 2, horizontal well; 3, extraction sleeve; 4, exchange cylinder; 5, adjustment device; 6, gas injection device; 7, target coal seam; 31, sealing piston; 32, gas injection pipe; 33, gas extraction pipe; 34, transmission motor; 41, rotating sealing surface; 42, exhaust arc surface; 43, first exchange port; 44, second exchange port; 45, circular track; 46, linear track; 51, adjustment planetary gear set; 52, closed arc surface; 53, transmission assembly; 61 , gas injection cylinder; 62, gas injection piston; 63, moving motor; 64, sliding block; 511, positioning ring; 512, ring gear; 513, surrounding gear; 514, outer rotating member; 515, inner rotating member; 531, reverse gear ring; 532, reverse clamping block; 533, reverse inner ring; 534, reverse limiter; 535, forward clamping ring; 536, forward clamping block; 537, forward inner ring; 538, forward limiter; 611, front cylinder; 612, rear cylinder. DETAILED DESCRIPTION

[0054] See also Figures 1 to 8 In an embodiment of the present invention, a gas-gas exchange device for injecting CO2 to mine coalbed methane comprises:

[0055] Main shaft 1, which is drilled from the ground to the bottom of the target coal seam 7;

[0056] Horizontal well 2 is set in the middle of the target coal seam 7, and its two ends are connected to the main well 1;

[0057] The extraction sleeve 3 is arranged in the main well 1;

[0058] The exchange cylinder 4 is horizontally arranged in the horizontal well 2, and its two ends are fixedly connected to the extraction sleeve 3;

[0059] The regulating device 5 is arranged in the extraction sleeve 3 and is fixedly connected to one end of the exchange cylinder 4;

[0060] The gas injection device 6 is slidably arranged in the exchange cylinder 4.

[0061] In this embodiment, the extraction sleeve 3 includes:

[0062] Two sealing pistons 31 are linearly distributed, located on the upper and lower sides of the target coal seam 7, and are slidably arranged in the extraction sleeve 3;

[0063] The gas injection pipe 32 is in a right-angle shape, one side of which is arranged in the extraction sleeve 3 and the other side is coaxially arranged with the exchange cylinder 4;

[0064] The extraction pipe 33 passes through the upper sealing piston 31 and is arranged in the extraction sleeve 3;

[0065] The transmission motor 34 is fixed to the bottom of the upper sealing piston 31 and is connected to the regulating device 5. That is, under the action of the gas injection pipe 32, pressurized carbon dioxide is injected into the exchange cylinder 4, diffuses from the exchange cylinder 4 to the interior of the target coal seam 7, and replaces the coalbed methane. It should be noted that the gas injection pipe 32 is a one-way conveying pipe. Under the action of the gas injection device 6, the injected carbon dioxide is subjected to multiple flow replacements, and the replaced coalbed methane is discharged into the extraction sleeve 3 through the regulating device 5. Under the action of the sealing piston 31, the leakage of coalbed methane is effectively prevented, and the coalbed methane is collected and processed through the extraction pipe 33.

[0066] In this embodiment, the exchange cylinder 4 includes:

[0067] The rotating sealing surface 41 is rotatably arranged on both sides of the exchange cylinder 4 and is fixedly connected to the adjustment device 5;

[0068] The exhaust arc surface 42 is provided with a plurality of annular distributions and fixed on the outer sides of both ends of the exchange cylinder 4;

[0069] The first exchange port 43 is provided with a plurality of ring-shaped distributions and is located in the center of the exchange cylinder 4;

[0070] The second exchange ports 44 are provided in a plurality of annular distributions and are located at both ends of the exchange cylinder 4;

[0071] An annular track 45 is provided on the annular surface where the second exchange port 44 is located;

[0072] The linear track 46 is provided on the inner wall of the exchange cylinder 4, corresponding to the second exchange port 44. That is, after the carbon dioxide gas is injected into the exchange cylinder 4 through the gas injection pipe 32, it flows into the pores of the target coal seam 7 through the first exchange port 43, replacing the coalbed methane. When the carbon dioxide gas in the exchange cylinder 4 slowly diffuses into the coal seam pores and reaches a critical value, the gas injection pipe 32 stops supplying the gas. The gas injection devices 6 on both sides then move toward the center along the linear track 46, squeezing the carbon dioxide gas in the middle into the coal seam through the first exchange port 43. Simultaneously, as the gas injection devices 6 move, the second exchange port 44 opens, and the replaced carbon dioxide and coalbed methane mixture returns to the two ends of the exchange cylinder 4. It should be noted that, under the action of the rotating sealing surface 41, the two ends of the exchange cylinder 4 are in a closed state. The gas injection device 6 then moves to the sides to reset, and the mixed gas flows into the coal seam again through the second exchange port 44, and is then discharged through the first exchange port 43. This cycle is repeated multiple times, extending the residence time of the carbon dioxide gas in the coal seam and improving the carbon dioxide replacement efficiency.

[0073] In this embodiment, the regulating device 5 includes:

[0074] The planetary gear set 51 is fixedly connected to the exchange cylinder 4, and the outer ring is fixed to the inner wall of the extraction sleeve 3;

[0075] A plurality of closed arc surfaces 52 are provided in an annular distribution, are spaced apart from the exhaust arc surface 42, and are fixedly connected to the regulating planetary gear set 51;

[0076] The transmission assembly 53 is fixed to the end of the adjustable planetary gear set 51 opposite the exchange cylinder 4 and meshes with the transmission gear on the transmission motor 34. Driven by the transmission assembly 53, the adjustable planetary gear set 51 drives the closed arc surface 52 to rotate, so that the closed arc surface 52 and the exhaust arc surface 42 form a complete annular surface, sealing the area between the target coal seam 7 and the extraction sleeve 3 and preventing the emission of unreplaced carbon dioxide. After the carbon dioxide has been replaced multiple times, the closed arc surface 52 rotates to the same position as the exhaust arc surface 42, allowing the replaced coalbed methane to pass through the gap between the exhaust arc surfaces 42 and discharge into the extraction sleeve 3, where it is collected by the extraction pipe 33.

[0077] In this embodiment, the regulating planetary gear set 51 includes:

[0078] A positioning ring 511 is fixed to the inside of the extraction sleeve 3;

[0079] The gear ring 512 is rotatably disposed in the positioning ring 511, and its side is fixedly connected to the closed arc surface 52;

[0080] A plurality of gears are provided in an annular distribution around the gear 513 and mesh with the ring gear 512;

[0081] The outer rotating member 514 is fixed to the ring gear 512, and the middle portion is coaxially arranged with the gas injection pipe 32 in the horizontal direction;

[0082] The inner rotating member 515 has one end that is rotatably disposed between the outer rotating member 514 and the gas injection pipe 32, and the other end that passes through the surrounding gear 513 and is fixedly connected to the rotating sealing surface 41. Driven by the outer rotating member 514, the ring gear 512 drives the closed arc surface 52 to rotate on the exhaust arc surface 42, sealing or opening the connection between the target coal seam 7 and the extraction sleeve 3. After carbon dioxide has completely replaced the coalbed methane, the outer rotating member 514 drives the closed arc surface 52 to rotate and open, releasing the coalbed methane. During continuous replacement, the outer rotating member 514 drives the closed arc surface 52 to remain closed to prevent incomplete carbon dioxide replacement and carbon dioxide leakage. Under the action of the inner rotating member 515, the surrounding gear 513 rotates around the ring gear 512, while driving the rotating sealing surface 41 to continuously rotate on the exchange cylinder 4, dynamically adjusting the internal gas injection device 6 so that the gas injection device 6 switches between driving carbon dioxide for cyclic replacement and coalbed methane discharge.

[0083] In this embodiment, the transmission assembly 53 includes:

[0084] The outer ring of the reversing gear ring 531 is meshed with the transmission gear of the transmission motor 34, and the inner ring is provided with a reversing block 532;

[0085] The reversing inner ring 533 is fixed on the outer rotating member 514, and the outer ring is provided with a reversing limiter 534 corresponding to the reversing block 532;

[0086] The forward-rotating snap ring 535 is fixed on the reverse gear ring 531 at its side, and has a forward-rotating snap block 536 on its inner ring;

[0087] The forward-rotating inner ring 537 has an inner ring fixed on the inner rotating member 515 and an outer ring provided with a forward-rotating limit member 538 corresponding to the forward-rotating block 536 . When the transmission motor 34 drives the reverse gear ring 531 to rotate counterclockwise through the transmission gear, under the action of the reverse clamping block 532 and the reverse limiter 534, the reverse inner ring 533 rotates along with the reverse gear ring 531, and at the same time drives the outer rotating member 514 to rotate, thereby adjusting the position of the closed arc surface 52. At this time, under the action of the forward rotation clamping block 536 and the forward rotation limiter 538, the forward rotation clamping ring 535 rotates along with the reverse gear ring 531, but the forward rotation inner ring 537 remains stationary; when the transmission motor 34 drives the reverse gear ring 531 to rotate clockwise through the transmission gear, under the action of the reverse clamping block 532 and the reverse limiter 534, the reverse inner ring 533 remains stationary, and at the same time the forward rotation clamping ring 535 rotates clockwise. Under the action of the forward rotation clamping block 536 and the forward rotation limiter 538, the forward rotation inner ring 537 rotates along with the reverse gear ring 531 clockwise, thereby driving the inner rotating member 515 to rotate, thereby rotating and adjusting the rotating sealing surface 41.

[0088] In this embodiment, the gas injection device 6 includes:

[0089] The gas injection cylinder 61 is divided into a front cylinder 611 and a rear cylinder 612, and is slidably arranged in the exchange cylinder 4;

[0090] There are two symmetrically distributed gas injection pistons 62, which are fixed at both ends of the gas injection cylinder 61 and are slidably connected to the exchange cylinder 4;

[0091] The movable motor 63 is fixed in the front cylinder 611 and can be moved on the gas injection pipe 32 by rotating the nut;

[0092] The sliding block 64 is fixed to the outside of the rear cylinder 612 and corresponds to the linear track 46 on the inner wall of the exchange cylinder 4. In other words, when the carbon dioxide gas needs to be circulated and replaced, the sliding block 64 is located on the linear track 46. Driven by the moving motor 63, the gas injection cylinder 61 moves toward the middle, allowing the carbon dioxide gas in the middle to enter the coal seam pores through the first exchange port 43, and then flow from the second exchange port 44 to the two ends of the exchange cylinder 4. The gas injection cylinder 61 then moves to both sides and resets, allowing the mixed gas at the two ends of the exchange cylinder 4 to flow from the second exchange port 44 to the coal seam pores and return through the first exchange port 43. This process is repeated multiple times to improve the carbon dioxide replacement efficiency.

[0093] In this embodiment, the front cylinder 611 and the rear cylinder 612 are rotatably connected, and the gas injection piston 62 fixedly connected to the rear cylinder 612 is slidably connected to the rotating sealing surface 41 and rotates coaxially with the rotating sealing surface 41. When the carbon dioxide gas needs to be circulated and replaced, the rotating sealing surface 41 is driven to rotate by the transmission component 53, and the rear cylinder 612 is driven to rotate by the gas injection piston 62. When the sliding block 64 rotates to a position corresponding to the linear track 46 in the annular track 45, the rear cylinder 612 and the front cylinder 611 are in a stuck state, that is, the gas injection cylinder 61 is a whole. Then, the gas injection cylinder 61 is driven back and forth in the exchange cylinder 4 by the moving motor 63, promoting the carbon dioxide gas to flow multiple times in the pores of the coal seam for replacement. When the replacement effect is achieved and the coal seam gas needs to be discharged, the rotating sealing surface 41 is driven to rotate by the transmission component 53, and the gas injection piston is driven to rotate. 62 drives the rear cylinder 612 to rotate. When the sliding block 64 rotates to a position staggered with the linear track 46 in the annular track 45, the front cylinder 611 and the rear cylinder 612 are in a detachable state. The moving motor 63 drives the gas injection cylinder 61 to move toward the middle of the exchange cylinder 4, and only drives the front cylinder 611 to move toward the middle. Then the gas in the middle passes through the first exchange port 43, between the pores of the coal seam, and flows to the exhaust arc surface 42 for discharge. It should be noted that in order to ensure the sealing of the exchange cylinder 4, the gas injection piston 62 on the front cylinder 611 is in contact with the linear track 46. Under the restriction of the linear track 46, when the rear cylinder 612 rotates, the front cylinder 611 remains stationary.

[0094] During specific implementation, the closed arc surface 52 is first rotated by the transmission component 53, so that the closed arc surface 52 and the exhaust arc surface 42 form a complete sealing surface to prevent gas leakage inside the target coal seam 7, and then the second exchange port 44 is closed by the gas injection device 6, and then carbon dioxide gas is pressurized and injected into the exchange cylinder 4 through the gas injection pipe 32. The carbon dioxide gas flows into the pores of the target coal seam 7 through the first exchange port 43 to replace the coalbed methane. When the carbon dioxide gas in the exchange cylinder 4 diffuses slowly into the coal seam pores and reaches a critical value, the gas injection pipe 32 stops conveying, and then the transmission component 53 drives the rotating sealing surface 41 to rotate, and at the same time drives the rear cylinder 612 to rotate through the gas injection piston 62, so that the sliding block 64 rotates in the annular track 45 to a position corresponding to the linear track 46, and then through The mobile motor 63 drives the gas injection cylinder 61 to move back and forth in the exchange cylinder 4, promoting multiple flows of carbon dioxide gas in the coal seam pores and performing multiple replacements. After achieving the expected replacement effect, the closed arc surface 52 is rotated to the same position as the exhaust arc surface 42 through the transmission component 53, opening the channel between the target coal seam 7 and the extraction sleeve 3, and then the transmission component 53 drives the rotating sealing surface 41 to rotate, and at the same time drives the rear cylinder 612 to rotate through the gas injection piston 62, so that the sliding block 64 rotates in the annular track 45 to a position staggered with the linear track 46. At this time, the mobile motor 63 only drives the front cylinder 611 of the gas injection cylinder 61 to move toward the middle, and then the middle gas flows between the coal seam pores through the first exchange port 43, enters the extraction sleeve 3 through the exhaust arc surface 42, and is collected and processed by the extraction pipe 33.

[0095] The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A gas-gas exchange device for injecting CO2 to mine coalbed methane, characterized by: include: The main well (1) is drilled from the ground to the bottom of the target coal seam (7); A horizontal well (2) is set in the middle of the target coal seam (7), and its two ends are connected to the main well (1); A pumping sleeve (3) is arranged in the main well (1); The exchange cylinder (4) is horizontally arranged in the horizontal well (2), and its two ends are fixedly connected to the extraction sleeve (3); An adjusting device (5) is arranged in the extraction sleeve (3) and is fixedly connected to one end of the exchange cylinder (4); A gas injection device (6) is slidably arranged in the exchange cylinder (4); The exchange cylinder (4) comprises: Rotating sealing surfaces (41) are rotatably arranged on both sides of the exchange cylinder (4) and are fixedly connected to the adjustment device (5); A plurality of exhaust arc surfaces (42) are provided in an annular distribution and fixed on the outer sides of both ends of the exchange cylinder (4); A plurality of first exchange ports (43) are provided in an annular distribution and are located at the center of the exchange cylinder (4); A plurality of second exchange ports (44) are provided in an annular distribution and are located at both ends of the exchange cylinder (4); An annular track (45) is provided on the annular surface where the second exchange port (44) is located; A linear track (46) is provided on the inner wall of the exchange cylinder (4) and corresponds to the second exchange port (44); The gas injection device (6) comprises: The gas injection cylinder (61) is divided into a front cylinder (611) and a rear cylinder (612), and is slidably arranged in the exchange cylinder (4); Two gas injection pistons (62) are symmetrically distributed and fixed at both ends of the gas injection cylinder (61) and are slidably connected to the exchange cylinder (4); A movable motor (63) is fixed in the front cylinder (611) and can be movably arranged on the gas injection pipe (32) by rotating a nut; A sliding block (64) is fixed on the outside of the rear cylinder (612) and corresponds to the linear track (46) on the inner wall of the exchange cylinder (4); The regulating device (5) comprises: The planetary gear set (51) is fixedly connected to the exchange cylinder (4), and the outer ring is fixed to the inner wall of the extraction sleeve (3); A plurality of closed arc surfaces (52) are provided in an annular distribution, are spaced apart from the exhaust arc surface (42), and are fixedly connected to the regulating planetary gear set (51); The transmission assembly (53) is fixed to the end of the regulating planetary gear set (51) opposite to the exchange cylinder (4) and meshes with the transmission gear on the transmission motor (34).

2. The gas-gas exchange device for injecting CO2 to mine coalbed methane according to claim 1, characterized in that: The extraction sleeve (3) comprises: Two sealing pistons (31) are linearly distributed and located on the upper and lower sides of the target coal seam (7), and are slidably arranged in the extraction sleeve (3); The gas injection pipe (32) is in a right-angled shape, one side of which is arranged in the extraction sleeve (3) and the other side is coaxially arranged with the exchange cylinder (4); An air extraction pipe (33) passes through the upper sealing piston (31) and is disposed in the extraction sleeve (3); The transmission motor (34) is fixed to the bottom of the upper sealing piston (31) and is connected to the regulating device (5).

3. The gas-gas exchange device for injecting CO2 to mine coalbed methane according to claim 1, characterized in that: The regulating planetary gear set (51) comprises: A positioning ring (511) is fixed on the inside of the extraction sleeve (3); A gear ring (512) is rotatably disposed in the positioning ring (511), and its side is fixedly connected to the closed arc surface (52); A plurality of gears (513) are provided in an annular distribution around the gear (513) and mesh with the ring gear (512); The outer rotating member (514) is fixed on the gear ring (512), and the middle portion is coaxially arranged with the gas injection pipe (32) in the horizontal direction; The inner rotating member (515) has one end rotatably disposed between the outer rotating member (514) and the gas injection pipe (32), and the other end passes through the surrounding gear (513) and is fixedly connected to the rotating sealing surface (41).

4. The gas-gas exchange device for injecting CO2 to mine coalbed methane according to claim 1, characterized in that: The transmission assembly (53) comprises: A reversing gear ring (531), the outer ring tooth groove is meshed with the transmission gear of the transmission motor (34), and the inner ring is provided with a reversing block (532); An inverted inner ring (533), wherein the inner ring is fixed on the outer rotating member (514), and the outer ring is provided with an inverted limiter (534) corresponding to the inverted clamping block (532); A forward-rotating snap ring (535) is fixed on the side of the reverse-rotating gear ring (531), and a forward-rotating snap block (536) is provided on the inner ring; The inner ring (537) is fixed on the inner rotating member (515), and the outer ring is provided with a forward rotation limiting member (538) corresponding to the forward rotation clamping block (536).

5. The gas-gas exchange device for injecting CO2 to mine coalbed methane according to claim 1, characterized in that: The front cylinder (611) and the rear cylinder (612) are rotatably connected, and the gas injection piston (62) fixedly connected to the rear cylinder (612) is slidably connected to the rotating sealing surface (41) and rotates coaxially with the rotating sealing surface (41).

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