Coal bed gas well efficient well washing device and use method

Abstract

The application discloses a coal bed gas well efficient well washing device and a use method, which comprises a cleaning mechanism, an anchoring mechanism and a gas production mechanism. The gas-liquid double-channel structure realizes the purpose of synchronous production without affecting each other in liquid discharge and gas production. The gas production mechanism utilizes the working principle that the piston relies on gravity to descend under the pressure balance state, and only by closing the casing valve, the gas production channel cleaning is closed, so that the problem of non-pollution stratum cleaning under the condition of the double-channel structure is solved. The gas production and cleaning both adopt the piston to open and close the channel, so that the problem that the sand, coal slime and other impurities gather in the opening and closing part caused by the spherical seal to cause the problem of not being tightly closed is completely solved. The piston seal greatly increases the reliability of the seal. The application solves the problem of cleaning in the gas well discharge and production process, avoids the pollution of cleaning to the stratum, improves the cleaning efficiency, and prolongs the service life of the cleaning tool.

Description

Technical Field

[0001] This invention relates to the field of coalbed methane production technology, specifically to a high-efficiency well washing device and its usage method for coalbed methane wells. Background Technology

[0002] Currently, coalbed methane fields primarily utilize large-scale fracturing for production. While fracturing increases production capacity, it also introduces production problems. The return of fracturing sand and the entry of fine coal dust into the pump casing lead to frequent pump inspections. To prevent impurities such as coal dust and sand from jamming the pump, frequent cleaning of the pump casing is necessary to maintain normal well production. However, with the development of oil fields, formation energy is continuously declining, and formation depletion is severe. Cleaning is having an increasingly significant impact on production. On the one hand, it damages water-sensitive formations, leading to a substantial reduction in production; on the other hand, formation depletion allows large amounts of cleaning fluid to enter the oil layer, resulting in high water consumption and prolonged drainage time. Therefore, while cleaning prevents well failure, it also has a significant impact on subsequent normal production.

[0003] Publication (Announcement) No.: CN211173992U, Publication (Announcement) Date: 2020-08-04 discloses a straightening well protection device for oil formation washing, including a connecting pipe. Two straightening mechanisms are sleeved on the outer wall of the connecting pipe, and each straightening mechanism includes two fixed structures. This straightening well protection device for oil formation washing achieves a detachable installation method for the straightening mechanism through the cooperative use of the straightening mechanism, fixed structures, arc-shaped elastic strips, hinge seats, rotating blocks, stationary arc-shaped seats, movable arc-shaped seats, rubber layers, baffles, connecting columns, threaded holes, connecting blocks, and screws. It also simplifies the assembly and disassembly structure of the straightening mechanism and reduces the difficulty of assembly and disassembly, allowing for quick installation and disassembly of the straightening mechanism. This facilitates maintenance and replacement of the straightening mechanism, promotes reuse, avoids waste, and is energy-saving and environmentally friendly. Furthermore, the design of the two straightening mechanisms ensures that the connecting pipe is centered, resulting in excellent straightening effect.

[0004] Publication (Announcement) No.: CN202832314U, Publication (Announcement) Date: 2013-03-27 discloses a novel well-washing device, belonging to an oilfield production device. It comprises a pump barrel, a well-washing piston, a first valve seat with a first valve ball mounted on top of it, a second valve seat with a second valve ball mounted on top of it, a first valve cover below the first valve seat, a first fixed valve seat below the first valve cover, and a first valve ball mounted on top of the first fixed valve seat. A well-washing protector is located below a common screen pipe, with a tail plug fixed below the common screen pipe. A second valve cover is located between the well-washing protector and the common screen pipe, with a second fixed valve seat below the second valve cover and a hollow second valve ball mounted on top of the second fixed valve seat. In this well-washing device, during operation, when well-washing fluid is introduced into the well, the second valve ball seals, preventing the well-washing fluid from flowing out through the common screen pipe below it, reducing the loss and waste of well-washing fluid, and improving the well-washing effect. Moreover, it has a simple and reasonable structure, is easy to manufacture, and is reliable in use.

[0005] Publication (Announcement) No.: CN202325321U, Publication (Announcement) Date: 2012-07-12 discloses a formation lost circulation well washing protection device, including an upper connector, a connecting positioning sleeve, a valve ball, a sealing assembly, and an inner tube. The valve ball is mounted on the inner tube, and the upper connector is connected to the upper part of the inner tube. The connecting positioning sleeve and the sealing assembly are mounted on the outside of the inner tube, with the connecting positioning sleeve positioned above the sealing assembly. Both the connecting positioning sleeve and the inner tube have connecting grooves, with the connecting grooves on the inner tube corresponding to those on the connecting positioning sleeve. The valve ball is positioned below the connecting groove on the inner tube. An adjusting cap is connected to the lower part of the upper connector via an external thread, with the lower end face of the adjusting cap contacting the upper end face of the connecting positioning sleeve. The sealing assembly is a one-way horn shape, with the horn opening facing one side of the connecting groove on the inner tube. This device prevents washing fluid from entering the formation from the annular space of the oil casing, protects the oil layer from contamination, reduces washing water usage, improves washing efficiency, lowers washing costs, and reduces drainage time after oil well washing, thereby increasing crude oil production.

[0006] None of the above well-washing devices consider the need for a dual-channel structure, where gas is discharged through the annulus and liquid is discharged through the pump.

[0007] Publication (Announcement) No.: CN215718649U, Publication (Announcement) Date: 2022-02-01 discloses a dual-channel well-washing tool for gas-liquid co-production, including a double-layer working cylinder. The double-layer working cylinder includes a shell with two types of axial channels: a central axial channel and an eccentric axial channel. It also includes an axial single-flow radial switching mechanism. The shell also has a side through-hole that allows radial communication between the central axial channel and the eccentric axial channel. The axial single-flow radial switching mechanism is installed within the eccentric axial channel. This utility model not only increases the oil and gas production of high gas-oil ratio wells but also effectively improves the flushing effect, thereby achieving high-efficiency production.

[0008] All the above-mentioned well-washing devices are ball-type check valves. During use, the check valve opens and closes synchronously with the pump. When the well fluid contains impurities, these impurities gradually accumulate in the upper space of the check valve ball, causing the check valve to not close tightly. This results in the well-washing fluid entering the formation during the wash process, significantly reducing the effectiveness of the well-washing tool. Furthermore, because these well-washing devices lack anchoring components, during pumping, especially in the initial post-washing pumping process, the annulus above the casing contains a large amount of well-washing fluid. The casing is under considerable pressure, and during pumping, the frictional force between the casing and the casing inner wall is several times greater than before the wash. This excessive friction can easily cause the casing to tear and fail.

[0009] The technical solutions, technical problems to be solved, and beneficial effects of the above-disclosed technologies are all different from those of the present invention. For more technical features, technical problems to be solved, and beneficial effects of the present invention, the above-disclosed technical documents do not provide any technical inspiration. Summary of the Invention

[0010] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a high-efficiency well cleaning device and method for coalbed methane wells. During production, the coalbed methane, after gas-liquid separation, enters the annulus through the outer channel of the device and is discharged, while the liquid enters the pumping unit through the inner channel and is drawn down, thus achieving the extraction of gas and liquid to the surface through different channels. When the pump barrel needs cleaning, the wellhead casing valve is closed. After the well barrel pressure balances with the formation pressure, the gas outlet is closed, and the annulus above the sealing sleeve is separated from the coal seam. When cleaning the pump barrel through the annulus, the cleaning fluid enters the central pipe through the cleaning hole and flows back up, washing out impurities such as sand and coal sludge that have entered the pump barrel. This avoids formation contamination during cleaning and improves cleaning efficiency.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A high-efficiency well washing device for coalbed methane wells includes a washing mechanism, an anchoring mechanism, and a gas production mechanism;

[0013] The cleaning mechanism, anchoring mechanism, and gas extraction mechanism are connected sequentially from top to bottom, with the upper end of the anchoring mechanism connected to the cleaning mechanism and the lower end connected to the gas extraction mechanism.

[0014] The cleaning mechanism includes a cleaning piston, an outer cleaning tube, an inner cleaning tube, and a support spring;

[0015] The outer cleaning tube is fitted over the inner cleaning tube, and the two form a piston cavity where a cleaning piston is installed.

[0016] The outer cleaning tube has a cleaning hole that connects to the space above the cleaning piston, and the inner cleaning tube has a production liquid inlet that connects to the space below the cleaning piston. The bottom end of the inner cleaning tube is a blind end.

[0017] The upper end of the support spring presses against the cleaning piston, and the lower end presses against the inner shoulder platform opened on the inner wall of the cleaning outer tube.

[0018] The upper ends of both the outer and inner cleaning tubes are connected to the upper connector.

[0019] The anchoring mechanism includes an outer anchoring tube, an anchoring piston, an inner anchoring tube, an anchoring cone, a locking block, a locking block support, and a locking block pin.

[0020] The outer anchoring tube is fitted over the outer part of the inner anchoring tube, and the two form a piston cavity where the anchoring piston is installed.

[0021] The outer anchoring tube has an anchoring pressure transmission hole that connects to the space above the anchoring piston, and the inner anchoring tube has an anchoring balance hole that connects to the space below the anchoring piston.

[0022] The lower end of the anchoring piston is provided with an integral piston rod that extends out of the anchoring piston cavity and abuts against the upper end face of the anchoring cone;

[0023] The bottom end of the locking block is hinged to the upper end of the locking block support body, and the locking block support body is fitted onto the outer wall of the anchoring inner tube and fixedly connected by the locking block pin.

[0024] The outer wall of the anchoring cone and the inner wall of the locking block are simultaneously provided with mutually cooperating sliding friction and extrusion cone surfaces.

[0025] Lock teeth are formed on the outer wall of the lock block.

[0026] The inner wall of the anchoring piston and the outer wall of the anchoring inner tube are simultaneously provided with matching toothed fasteners, so that the anchoring piston can only move downwards.

[0027] The gas extraction mechanism includes a sealed outer pipe, a sealing spring, a sealing piston, and a lower connector;

[0028] The sealing outer tube is fitted over the anchoring inner tube, and the two form a piston cavity where a sealing piston is installed.

[0029] The outer sealing tube has a sealing balance hole that connects to the space above the sealing piston, and the outer sealing tube has an air outlet that connects to the space below the sealing piston.

[0030] The lower end of the sealing spring abuts against the upper end of the sealing piston, and the upper end of the sealing spring abuts against the end cap of the sealing outer tube.

[0031] The upper end of the lower connector is connected to the anchoring inner tube, and the lower connector has an axial air passage. The upper port of the axial air passage is connected to the air outlet, and the lower port of the axial air passage is connected to the air inlet of the lower connector.

[0032] The lower connector is fitted with a sealing cup on its outer wall.

[0033] The gas extraction mechanism has multiple rows of staggered round or elongated holes as its outlets.

[0034] To achieve the above objectives, the present invention adopts the following technical solution:

[0035] A method for using a high-efficiency well washing device for coalbed methane wells includes the following steps:

[0036] The anchoring piston pushes the anchoring cone downward under hydraulic pressure, and the anchoring cone enters the locking block, thereby locking the locking block to the inner wall of the sleeve;

[0037] A sealing cup is placed on the inner wall of the sleeve;

[0038] During cleaning, the wellhead casing valve is closed. When the annular pressure no longer changes, the gas pressure above and below the sealing piston is balanced. The sealing spring will push the sealing piston downward to close the vent hole. That is, during production, the upward gas pressure overcomes the sealing spring force, and the sealing piston is located above the vent hole, without hindering the upward transmission of gas from the annular space above and below the sealing cup. During cleaning, the sealing piston blocks the vent hole. This allows gas and liquid to be extracted to the surface through different channels.

[0039] After pressure equalization, cleaning fluid is injected into the annulus of the oil casing. The cleaning piston moves down to below the production inlet, preventing the cleaning fluid from entering the outlet. At the same time, the lower end of the cleaning inner tube is a blind end, and the cleaning fluid will return upward through the production inlet in the cleaning inner tube. This achieves the cleaning of coal and sand in the pump barrel, washing out impurities such as sand and coal slurry that have entered the pump barrel, avoiding formation pollution during cleaning and improving cleaning efficiency.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] Technical Features: The dual-channel gas-liquid structure achieves simultaneous production without interference between liquid drainage and gas production. The gas production mechanism utilizes the principle of a piston moving downwards under gravity in a pressure-balanced state, closing the gas production channel during cleaning simply by closing the casing valve, thus solving the problem of non-contamination of the formation during cleaning under dual-channel structure conditions. Both gas production and cleaning employ piston-driven opening and closing channels, completely resolving the problem of sand, coal sludge, and other impurities accumulating in the opening and closing parts, leading to incomplete closure, caused by current spherical seals. The piston surface seal offers significantly better performance than the spherical line seal. This invention solves the cleaning problem during gas well drainage and production, avoiding formation contamination during cleaning, improving cleaning efficiency, and extending the lifespan of cleaning tools. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of a high-efficiency well washing device for coalbed methane wells according to the present invention.

[0043] 1. Upper connector; 2. Cleaning hole; 3. Cleaning piston; 4. Cleaning outer tube; 5. Production liquid inlet; 6. Support spring; 7. Cleaning inner tube; 8. Anchoring pressure transmission hole; 9. Anchoring piston; 10. Anchoring balance hole; 11. Anchoring cone; 12. Locking block; 13. Locking block support; 14. Locking block pin; 15. Sealing balance hole; 16. Sealing spring; 17. Sealing piston; 18. Air outlet; 19. Sealing cup; 20. Sealing cup; 21. Air inlet; 22. Lower connector; 23. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1:

[0046] like Figure 1 As shown, this embodiment provides a high-efficiency well washing device for coalbed methane wells, including a cleaning mechanism, an anchoring mechanism, and a gas production mechanism;

[0047] The cleaning mechanism, anchoring mechanism, and gas extraction mechanism are connected by threaded connections. The upper end of the anchoring mechanism is connected to the cleaning mechanism, and the lower end is connected to the gas extraction mechanism.

[0048] The cleaning mechanism includes a cleaning piston 3, a cleaning outer tube 4, a cleaning inner tube 7, and a support spring 6;

[0049] The outer cleaning tube is fitted over the inner cleaning tube, and the two form a piston cavity where the cleaning piston is installed; the cleaning piston 3 is provided with two sealing rings; the sealing rings are made of polyethylene hard sealing rings.

[0050] The outer cleaning tube has a cleaning hole 2 that connects to the space above the cleaning piston, and the inner cleaning tube has a production liquid inlet hole 5 that connects to the space below the cleaning piston. The bottom end of the inner cleaning tube is a blind end. The cleaning hole 2 is inclined at a 45-degree upward angle.

[0051] The upper end of the support spring abuts against the cleaning piston, and the lower end abuts against the inner shoulder platform opened on the inner wall of the cleaning outer tube. The support spring 7 is a columnar spring, which ensures that the cleaning piston 3 is located above the production inlet hole 6 during production, and that the cleaning piston 3 reaches the lower part of the production inlet hole 6 under the hydraulic action during cleaning.

[0052] The upper ends of both the outer cleaning tube and the inner cleaning tube are connected to the upper connector 1.

[0053] The anchoring mechanism includes an outer anchoring tube, an anchoring piston 9, an inner anchoring tube 10, an anchoring cone 12, a locking block 13, a locking block support 14, and a locking block pin 15.

[0054] The outer anchoring tube is fitted over the outer part of the inner anchoring tube, and the two form a piston cavity where the anchoring piston is installed; the lower half of the anchoring piston 9 is annular; the anchoring cone 12 is fitted over the inner anchoring tube 10 and can move along the outer wall of the inner tube.

[0055] The outer anchoring tube has an anchoring pressure transmission hole that connects to the space above the anchoring piston, and the inner anchoring tube has an anchoring balance hole that connects to the space below the anchoring piston.

[0056] The lower end of the anchoring piston is provided with an integral piston rod that extends out of the anchoring piston cavity and abuts against the upper end face of the anchoring cone;

[0057] The bottom end of the locking block is hinged to the upper end of the locking block support body, and the locking block support body is fitted onto the outer wall of the anchoring inner tube and fixedly connected by the locking block pin.

[0058] The outer wall of the anchoring cone and the inner wall of the locking block are simultaneously provided with mutually cooperating sliding friction and extrusion cone surfaces.

[0059] Lock teeth are formed on the outer wall of the lock block.

[0060] The inner wall of the anchoring piston and the outer wall of the anchoring inner tube are simultaneously provided with matching toothed fasteners, so that the anchoring piston can only move downwards.

[0061] The gas extraction mechanism includes a sealed outer pipe, a sealing spring 17, a sealing piston 18, and a lower connector 23;

[0062] The sealing outer tube is fitted over the outside of the anchoring inner tube 10, and the two form a piston cavity where a sealing piston 18 is installed.

[0063] The outer sealing tube has a sealing balance hole 16 that connects to the space above the sealing piston, and an air outlet hole 19 that connects to the space below the sealing piston.

[0064] The lower end of the sealing spring presses against the upper end of the sealing piston, and the upper end of the sealing spring presses against the end cap at the upper end of the sealing outer tube.

[0065] The upper end of the lower connector is connected to the anchoring inner tube, and the lower connector has an axial air passage. The upper port of the axial air passage is connected to the air outlet, and the lower port of the axial air passage is connected to the air inlet 22 of the lower connector.

[0066] The lower connector is fitted with a sealing cup on its outer wall. At least one sealing cup is provided.

[0067] The balance hole 16 has a porous structure with a diameter of 6-8mm, 5-6 rows longitudinally and 4-5 rows transversely;

[0068] The air outlet 19 is located on the upper part of the sealing cup 21, and the air inlet 22 is located on the lower part of the sealing cup 21.

[0069] The usage method is as follows:

[0070] The anchoring piston pushes the anchoring cone downward under hydraulic pressure, and the anchoring cone enters the locking block, thereby locking the locking block to the inner wall of the sleeve;

[0071] A sealing cup is placed on the inner wall of the sleeve; this step is a known technique.

[0072] During cleaning, the wellhead casing valve is closed. When the annular pressure no longer changes, the gas pressure above and below the sealing piston is balanced. The sealing spring will push the sealing piston downward to close the vent hole. That is, during production, the upward gas pressure overcomes the sealing spring force, and the sealing piston is located above the vent hole, without hindering the upward transmission of gas from the annular space above and below the sealing cup. During cleaning, the sealing piston blocks the vent hole. This allows gas and liquid to be extracted to the surface through different channels.

[0073] After pressure equalization, cleaning fluid is injected into the annulus of the oil casing. The cleaning piston moves down to below the production inlet, preventing the cleaning fluid from entering the outlet. At the same time, the lower end of the cleaning inner tube is a blind end, and the cleaning fluid will return upward through the production inlet in the cleaning inner tube. This achieves the cleaning of coal and sand in the pump barrel, washing out impurities such as sand and coal slurry that have entered the pump barrel, avoiding formation pollution during cleaning and improving cleaning efficiency.

[0074] Example 2:

[0075] Please see Figure 1 The present invention provides a technical solution: based on the technical solution of embodiment 1, the outer diameter of the lateral liquid inlet 6, cleaning hole 4, and air outlet 15 is 1.5 mm smaller than the outer diameter of the pipe in which they are located;

[0076] The air inlet 22 is wrapped with a filter screen, and the mesh size of the filter screen is designed according to the particle size of the sand particles discharged.

[0077] The cleaning piston 3, anchoring plunger 9, and sealing piston 18 are treated with anti-corrosion and wear-resistant methods, and both ends are sealed with oil seals.

[0078] The sealing cup 20 is a self-sealing cup with a maximum diameter that is 6-7 mm larger than the inner diameter of the sleeve.

[0079] Furthermore, the distance between the sealing cup 20 and the air outlet 19 is greater than 0.5m.

[0080] Although all the above embodiments use Figure 1However, those skilled in the art will clearly understand that separate drawings are not necessary; simply removing missing components or structural features from the drawings is sufficient. This is clear to those skilled in the art. Of course, embodiments with more components are merely optimal embodiments, while embodiments with fewer components are basic embodiments, but all can achieve the basic objectives of the present invention. Therefore, all these modified embodiments are within the scope of protection of the present invention.

[0081] All components not discussed in detail in this application, as well as the connection methods of these components, are well-known technologies in this field. They can be directly applied and will not be elaborated further.

[0082] In this invention, the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0083] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0084] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-efficiency well washing device for coalbed methane wells, characterized in that, Includes cleaning mechanism, anchoring mechanism, and gas extraction mechanism; The cleaning mechanism, anchoring mechanism, and gas extraction mechanism are connected sequentially from top to bottom, that is, the upper end of the anchoring mechanism is connected to the cleaning mechanism, and the lower end is connected to the gas extraction mechanism. The cleaning mechanism includes a cleaning piston, an outer cleaning tube, an inner cleaning tube, and a support spring; The outer cleaning tube is fitted over the inner cleaning tube, and the two form a piston cavity where a cleaning piston is installed. The outer cleaning tube has a cleaning hole that connects to the space above the cleaning piston, and the inner cleaning tube has a production liquid inlet that connects to the space below the cleaning piston. The bottom end of the inner cleaning tube is a blind end. The upper end of the support spring abuts against the cleaning piston, and the lower end abuts against the inner shoulder platform opened on the inner wall of the cleaning outer tube. The anchoring mechanism includes an outer anchoring tube, an anchoring piston, an inner anchoring tube, an anchoring cone, a locking block, a locking block support, and a locking block pin. The outer anchoring tube is fitted over the outer part of the inner anchoring tube, and the two form a piston cavity where the anchoring piston is installed. The outer anchoring tube has an anchoring pressure transmission hole that connects to the space above the anchoring piston, and the inner anchoring tube has an anchoring balance hole that connects to the space below the anchoring piston. The lower end of the anchoring piston is provided with an integral piston rod that extends out of the anchoring piston cavity and abuts against the upper end face of the anchoring cone; The bottom end of the locking block is hinged to the upper end of the locking block support body, and the locking block support body is fitted onto the outer wall of the anchoring inner tube and fixedly connected by the locking block pin. The outer wall of the anchoring cone and the inner wall of the locking block are simultaneously provided with mutually cooperating sliding friction and extrusion cone surfaces; The gas extraction mechanism includes a sealed outer pipe, a sealing spring, a sealing piston, and a lower connector; The sealing outer tube is fitted over the anchoring inner tube, and the two form a piston cavity where a sealing piston is installed. The outer sealing tube has a sealing balance hole that connects to the space above the sealing piston, and the outer sealing tube has an air outlet that connects to the space below the sealing piston. The lower end of the sealing spring abuts against the upper end of the sealing piston, and the upper end of the sealing spring abuts against the end cap of the sealing outer tube. The upper end of the lower connector is connected to the anchoring inner tube, and the lower connector has an axial air passage. The upper port of the axial air passage is connected to the air outlet, and the lower port of the axial air passage is connected to the air inlet of the lower connector. The lower connector is fitted with a sealing cup on its outer wall.

2. The high-efficiency well washing device for coalbed methane wells according to claim 1, characterized in that, The upper ends of both the outer and inner cleaning tubes are connected to the upper connector.

3. The high-efficiency well washing device for coalbed methane wells according to claim 1, characterized in that, Lock teeth are formed on the outer wall of the lock block.

4. The high-efficiency well washing device for coalbed methane wells according to claim 1, characterized in that, The inner wall of the anchoring piston and the outer wall of the anchoring inner tube are simultaneously provided with matching toothed fasteners, so that the anchoring piston can only move downwards.

5. The high-efficiency well washing device for coalbed methane wells according to claim 1, characterized in that, The gas extraction mechanism has multiple rows of staggered round or elongated holes as its outlets.

6. A method for using a high-efficiency well washing device for coalbed methane wells, characterized in that, Using the high-efficiency well washing device for coalbed methane wells according to claim 1 includes the following steps: The anchoring piston pushes the anchoring cone downward under hydraulic pressure, and the anchoring cone enters the locking block, thereby locking the locking block to the inner wall of the sleeve; A sealing cup is placed on the inner wall of the sleeve; During cleaning, the wellhead casing valve is closed. When the annular pressure no longer changes, the gas pressure above and below the sealing piston is balanced. The sealing spring will push the sealing piston downward to close the vent hole. That is, during production, the upward gas pressure overcomes the sealing spring force, and the sealing piston is located above the vent hole, without hindering the upward transmission of gas from the annular space above and below the sealing cup. During cleaning, the sealing piston blocks the vent hole. This allows gas and liquid to be extracted to the surface through different channels. After pressure equalization, cleaning fluid is injected into the annulus of the oil casing. The cleaning piston moves down to below the production inlet, preventing the cleaning fluid from entering the outlet. At the same time, the lower end of the cleaning inner tube is a blind end, and the cleaning fluid will return upward through the production inlet in the cleaning inner tube. This achieves the cleaning of coal and sand in the pump barrel, washing out sand and coal slurry impurities that have entered the pump barrel, avoiding formation pollution during cleaning and improving cleaning efficiency.

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