A plugging device for coal bed gas low pressure well wellhead annular steel plate leak point

Abstract

The utility model discloses a kind of for coal-bed gas low-pressure well wellhead annular steel plate leak point's leak stoppage device, including arc pressing plate assembly, auxiliary installation base and top pressing plate assembly, arc pressing plate assembly includes the arc pressing plate of symmetrical setting in wellhead casing structure, the inner wall of arc pressing plate is equipped with annular boss and one open casing contact at near lower end, annular boss top is equipped with filling sealing washer and one open casing interference fit connection, arc pressing plate inboard is equipped with the air bag that can be tightly pressed, air bag can make after inflation tightly pressed sealing washer and wellhead annular steel plate, two open casing wall and top pressing plate assembly adhere to enhance sealing, auxiliary installation base is set in arc pressing plate assembly below, for quickly install and prevent arc pressing plate assembly slide down, top pressing plate assembly is set in arc pressing plate assembly above, for pressing tightly pressed sealing washer and blocking rainwater into leak point, realize quick splicing by modular assembly design, and optimization sealing mechanism can prevent leakage problem after long-term use.

Description

Technical Field

[0001] This utility model belongs to the technical field of low-pressure coalbed methane wells, and particularly relates to a leak-sealing device for leak points in annular steel plates at the wellhead of low-pressure coalbed methane wells. Background Technology

[0002] In underground coal mining systems, when the working face advances to a critical area about 100m from the wellhead, the redistribution and disturbance of geological stress caused by mining can easily lead to non-uniform deformation of the wellhead casing. This deformation acts on the annular steel plate welded joint at the connection between the first and second casing sections, causing stress concentration and crack defects, which threaten the wellhead structure and the safety of underground operations, requiring urgent repair.

[0003] The current mainstream repair solution uses a "ground booster pump drainage + on-site welding" process. While this can seal cracks in the short term, it has technical limitations. As mining progresses, stress accumulates at the welded joints and is difficult to release, leading to frequent secondary cracking and unstable repair results, creating a vicious cycle and increasing operating costs and safety management difficulties. Furthermore, the booster pump operates under strict pressure control thresholds at the wellhead. Actual operating conditions easily disrupt this pressure balance; positive pressure can cause coalbed methane leakage, resulting in energy loss and the risk of exceeding gas limits; negative pressure can cause air to be drawn in, interfering with coalbed methane extraction and transportation. These problems hinder the coordinated advancement of mining and drainage, posing safety hazards and energy waste. Therefore, there is an urgent need to develop a transitional temporary plugging technology to support safe and efficient coal mine production. Utility Model Content

[0004] To address the challenge of sealing dynamic cracks in the annular steel plate at the wellhead under low-pressure conditions, this invention provides a leak-sealing device for leak points in the annular steel plate at the wellhead of low-pressure coalbed methane wells. The device features a modular assembly design for rapid assembly and an optimized sealing mechanism to prevent leakage after long-term use.

[0005] The present invention provides a leak-sealing device for a leak point in the annular steel plate at the wellhead of a low-pressure coalbed methane well. The device includes an arc-shaped pressure plate assembly, an auxiliary installation base, and a top pressure plate assembly. The arc-shaped pressure plate assembly comprises symmetrically arranged arc-shaped pressure plates on the wellhead casing structure. A second connecting plate is integrally provided at the connecting ends of the arc-shaped pressure plates. The second connecting plates are connected and sealed with a sealing gasket by bolts and nuts. An annular boss is provided on the inner wall of the arc-shaped pressure plate near its lower end, contacting a first-opening casing. A filling sealing gasket is provided above the annular boss and is interference-fitted with the first-opening casing. An air bladder is provided on the inner side of the arc-shaped pressure plate, which adhesively presses and compresses the sealing gasket. When inflated, the gasket adheres to the annular steel plate at the wellhead, the second-opening casing wall, and the top pressure plate assembly to enhance the seal. The auxiliary installation base is located below the arc-shaped pressure plate assembly for quick installation and to prevent the arc-shaped pressure plate assembly from sliding down. The top pressure plate assembly is located above the arc-shaped pressure plate assembly to press and compress the sealing gasket and prevent rainwater from entering the leak point.

[0006] Furthermore, the upper and lower ends of the airbag are respectively fitted with fixing grooves. The fixing grooves are adapted to the contour of the airbag end and are sealed to position and restrain the airbag. Two fixing slots are opened on the inner side of the arc-shaped pressure plate from top to bottom along the axial direction. The fixing grooves and the fixing slots form an interference fit.

[0007] Furthermore, a first through hole and a second through hole are provided on the inner side of the arc-shaped pressure plate between the fixing slots. A pressure gauge assembly and an inflation valve assembly are provided on the outer side of the airbag. The pressure gauge assembly includes a pressure gauge connecting pipe, and the inflation valve assembly includes an inflation valve connecting pipe. A first slot is provided on the inner side of the first through hole, and a first sealing ring is provided in the first slot. The other end of the pressure gauge connecting pipe extends to the outer side of the arc-shaped pressure plate through the first through hole and is fixed by screwing the first nut into the external thread section of the pressure gauge connecting pipe. A second slot is provided on the inner side of the second through hole, and a second sealing ring is provided in the second slot. The other end of the inflation valve connecting pipe extends to the outer side of the arc-shaped pressure plate through the second through hole and is fixed by screwing the second nut into the external thread section of the inflation valve connecting pipe.

[0008] Furthermore, the compression sealing gasket is made of a highly elastic sealing material with a thickness of 2-5mm, and its edge extends 3-8mm beyond the edge of the airbag.

[0009] Furthermore, the upper end of the auxiliary mounting base is provided with a concave stop that cooperates with the convex stop at the lower end of the arc-shaped pressure plate. The auxiliary mounting base includes symmetrically arranged arc-shaped clamping seats. The connecting ends of the arc-shaped clamping seats are provided with a first connecting plate. A first anti-slip pad is provided between the first connecting plates and is connected and fastened by a first bolt and nut assembly.

[0010] Furthermore, the top pressure plate assembly includes a top rubber pressure plate and a top pressure plate arranged symmetrically from bottom to top. The adjacent ends of the top pressure plates are provided with a third connecting plate, and a third anti-slip pad is provided between the third connecting plates and connected and fastened by a third bolt and nut assembly.

[0011] Furthermore, the top pressure plate is truncated cone-shaped, and its lower diameter is larger than the diameter of an open sleeve.

[0012] Furthermore, the inner wall of the lower end of the arc-shaped clamping seat that contacts the first open sleeve is coated with anti-slip material, the inner wall of the top pressure plate that contacts the second open sleeve is coated with anti-slip material, and the upper surface of the top pressure plate is provided with rainproof protrusions extending in the radial direction.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. This utility model, through the cooperation of the top pressure plate assembly and the arc-shaped pressure plate assembly, can adapt to certain changes in the relative position of the two sleeves and maintain the leak-stopping effect. At the same time, an adaptable airbag is installed according to the relative position of the two sleeves. Through the elastic deformation characteristics of the airbag, it can adapt to the dynamic expansion and contraction of cracks around the leak point, maintain a stable sealing pressure, effectively avoid sealing failure caused by secondary cracking, and further reduce air leakage caused by relative displacement.

[0014] 2. The core sealing component uses an airbag as the power unit. The upper and lower ends of the airbag are interference-fitted with the fixing groove of the arc-shaped pressure plate through the fixing groove of the fixing part to achieve circumferential positioning. Except for the side of the airbag that is attached to the arc-shaped pressure plate, the rest of the airbag is bonded with a high-elasticity sealing gasket to form a "airbag-sealing gasket" composite sealing structure with good sealing effect.

[0015] 3. The sealing condition of the arc-shaped pressure plate assembly, auxiliary mounting base, and top pressure plate assembly can be quantitatively analyzed by measuring the pressure changes of the two pressure gauges. The arc-shaped pressure plate integrates a detachable inflation valve assembly and a pressure gauge assembly, both of which achieve radial sealing through sealing rings. This allows for precise control of the airbag inflation, ensuring a tight fit between the sealing gasket and the leak area of ​​the annular steel plate, the sleeve wall, and the top rubber pressure plate. The airbag fixing groove of the arc-shaped pressure plate assembly allows the inflation part and the pressure gauge to be in an independent, sealed space, further improving the leak-sealing effect of the arc-shaped pressure plate assembly.

[0016] 4. The top pressure plate assembly features a rainproof protrusion, combining enhanced sealing with protection against rainwater intrusion. The entire assembly employs a modular design for rapid assembly, suitable for short-term leak-sealing operations lasting 1-2 months. It balances wellhead pressure, reduces the risk of coalbed methane leakage and reverse air intake, and provides safety support for the coordinated advancement of coal mine mining and drainage.

[0017] 5. The auxiliary installation base adopts a variable diameter assembly structure with a large upper diameter and a small lower diameter. The lower part is positioned by abutting against a sleeve through an arc-shaped clamping seat, and the upper part forms a ring-shaped installation support platform, which provides a coaxiality reference and temporary fixed support for the radial splicing of the arc-shaped pressure plate, greatly simplifying the assembly process and ensuring installation accuracy. Attached Figure Description

[0018] Figure 1 A schematic diagram of the structure of this utility model; Figure 2 A schematic diagram of the pressure gauge assembly and inflation valve group of this utility model; Figure 3 This utility model presents a schematic diagram of the connecting plate assembly.

[0019] In the diagram: 1. Wellhead casing structure; 2. Auxiliary installation base; 3. Arc-shaped pressure plate assembly; 4. Top pressure plate assembly; 5. Two-stage casing; 6. One-stage casing; 7. Wellhead annular steel plate; 8. Arc-shaped clamping seat; 9. First connecting assembly; 91. First connecting plate; 92. First bolt and nut assembly; 93. First anti-slip pad; 10. Second connecting assembly; 101. Second connecting plate; 102. Second bolt and nut assembly; 103. Connecting sealing gasket; 11. Interface; 12. Filling sealing gasket; 13. Arc 14. Pressing sealing gasket; 15. Fixing slot; 16. Fixing groove; 17. Pressure gauge assembly; 171. First nut; 172. First slot; 173. First sealing ring; 18. Inflation valve assembly; 181. Second nut; 182. Second slot; 183. Second sealing ring; 19. Airbag; 20. Third connecting assembly; 201. Third connecting plate; 202. Third bolt and nut assembly; 203. Second anti-slip pad; 21. Top rubber pressure plate; 22. Top pressure plate. Detailed Implementation

[0020] To better understand the purpose, structure, and function of this utility model, the following description, in conjunction with the accompanying drawings, provides a more detailed description of a leak-sealing device for a leak point in an annular steel plate at the wellhead of a low-pressure coalbed methane well.

[0021] like Figure 1 As shown, a leak-sealing device for a leak point in the annular steel plate at the wellhead of a low-pressure coalbed methane well consists of an auxiliary mounting base 2, an arc-shaped pressure plate assembly 3, and a top pressure plate assembly 4, all of which are assembled on the outside of the wellhead casing structure 1.

[0022] The arc-shaped pressure plate assembly 3 includes symmetrically arranged arc-shaped pressure plates 13. The internal design of the arc-shaped pressure plate assembly 3 integrates multi-layer sealing and monitoring, including a filling sealing gasket 12, a pressing sealing gasket 14, a fixing groove 15, a fixing slot 16, a pressure gauge assembly 17, an inflation valve assembly 18, and an airbag 19. The inner wall of the arc-shaped pressure plate 13 has an annular boss near its lower end that contacts an open sleeve 6. An interface 11 formed above the annular boss is fitted with a filling sealing gasket 12 that is interference-fitted with the open sleeve 6. The inner side of the arc-shaped pressure plate 13 is filled with a sealing gasket 12. Two fixing slots 15 are evenly opened from top to bottom along the axial direction above the sealing gasket 12. The fixing slots 15 are engaged one-to-one with the fixing slots 16 prefabricated on the outside of the airbag 19 to ensure that the airbag 19 is assembled in a precise position without displacement. The pressure gauge assembly 17 and the inflation valve assembly 18 are arranged between the fixing slots 15 to form an "inflation-monitoring" linkage structure. The fixing slots 15 can not only fix the position of the airbag 19, but also separate the pressure gauge assembly 17 and the inflation valve assembly 18 in an independent space, reducing their impact on the sealing performance of the arc-shaped pressure plate assembly 3.

[0023] Multiple sizes of airbags 19 need to be manufactured, with a thickness interval of 10mm between different sizes to accommodate different gaps. Except for the side near the arc-shaped pressure plate 13, the rest of the airbag 19 is bonded with a special sealant to the compression sealing gasket 14. The compression sealing gasket 14 is made of a highly elastic sealing material with a thickness controlled between 2-5mm, and its edge must extend 3-8mm beyond the edge of the airbag 19. The extended part can form a "skirt seal" under pressure, further improving the sealing effect. When installing the airbag 19, airbags 19 of different thicknesses and matching compression sealing gaskets 14 can be selected according to the offset of the wellhead annular steel plate 7 to ensure that the arc-shaped pressure plate assembly 3 can maintain the sealing effect when the first-opening casing 6 and the second-opening casing 5 are relatively displaced.

[0024] like Figure 2 As shown, the inner side of the arc-shaped pressure plate 13 is provided with a first through hole and a second through hole between the fixing slots 15. The pressure gauge assembly 17 includes a pressure gauge connecting pipe that connects to the airbag 19. The inner side of the first through hole is provided with a first slot 172. The inner end of the pressure gauge connecting pipe is embedded in the first slot 172. The mating surface of the first slot 172 and the pressure gauge connecting pipe is also provided with a first sealing ring 173 to ensure sealing performance. The outer end of the pressure gauge connecting pipe extends to the outside of the arc-shaped pressure plate 13 and is fixed by screwing the first nut 171 into the external thread section of the pressure gauge connecting pipe to form a detachable sealed connection to ensure accurate pressure monitoring data. The inflation valve assembly 18 includes an inflation valve connecting pipe that connects to the airbag 19. A second slot 182 is provided inside the second through hole. The inner end of the inflation valve connecting pipe is embedded in the second slot 182. A second sealing ring 183 is provided on the mating surface of the second slot 182 and the inflation valve connecting pipe to achieve radial sealing. The outer end extends to the outside of the arc-shaped pressure plate 13 and is tightened by screwing the second nut 181 into the external thread section of the inflation valve connecting pipe to form a detachable sealing connection, which is convenient for later maintenance and replacement.

[0025] The auxiliary installation base 2 is located below the arc-shaped pressure plate assembly 3 for quick installation and to prevent the arc-shaped pressure plate assembly 3 from sliding down. The upper end of the auxiliary installation base 2 is provided with a concave stop that cooperates with the convex stop at the lower end of the arc-shaped pressure plate 13. The auxiliary installation base 2 includes symmetrically arranged arc-shaped clamping seats 8. The inner wall of the lower end of the arc-shaped clamping seat 8 that contacts the open sleeve 6 is coated with anti-slip material. The arc-shaped clamping seats 8 can be quickly connected through the first connecting assembly 9 to build an installation platform.

[0026] Before installing the auxiliary mounting base 2, the surface of the wellhead casing structure 1 must be cleaned of oil, rust, and other impurities. Then, a depth gauge should be used to accurately measure the installation position to ensure that the compression sealing gasket 14 is completely fitted with the wellhead annular steel plate 7, avoiding sealing failure due to installation deviation. The filling sealing gasket 12 is placed between the compression sealing gasket 14 and the interface 11, and the size of the filling sealing gasket 12 matches the contact surface of the interface 11 and the compression sealing gasket 14 to ensure full contact among the three, forming a multi-layer sealing structure.

[0027] The top pressure plate assembly 4 is positioned above the arc-shaped pressure plate assembly 3 to press and tighten the sealing gasket 14 and prevent rainwater and dust from entering the leak point. It consists of a top rubber pressure plate 21 and a top pressure plate 22. The top rubber pressure plate 21 is made of silicone rubber with a Shore A60 hardness and a thickness of 5mm. The top pressure plate 22 is made of steel plate and its surface is hot-dip galvanized to prevent corrosion. The top pressure plate 22 is frustoconical, and its lower end is larger than the radius of the first sleeve 6. The inner wall of the top pressure plate 22 that contacts the second sleeve 5 is coated with anti-slip material. The upper surface of the top pressure plate 22 has rainproof protrusions extending radially. The top pressure plate 22 is connected to the arc-shaped clamping seat 8 in the same way, and is fixed by the third connecting assembly 20. After installation, a feeler gauge should be used to check the gap between the top rubber pressure plate 21, the top pressure plate 22 and the sealing gasket 14 to ensure that the gap is no greater than 0.1mm, ensuring a tight fit between them, and providing a guarantee for the sealing effect after the airbag 19 is pressurized.

[0028] like Figure 3 As shown, the first connecting assembly 9 includes a first connecting plate 91 integrally formed at both ends of the arc-shaped clamping seat 8, a first bolt and nut assembly 92, and a first anti-slip washer 93, which can effectively prevent the bolt from loosening. The second connecting assembly 10 includes a second connecting plate 101 integrally formed at both ends of the arc-shaped pressure plate 13, a connecting sealing gasket 103 and a second bolt and nut assembly 102 installed between the second connecting plates 101. The connecting sealing gasket 103 is made of oil-resistant nitrile rubber with a thickness of 2mm, and its size must be completely matched with the mating surface of the second connecting plate 101. The bolt in the second bolt and nut assembly 102 passes through the second connecting plate 101 and the connecting sealing gasket 103, and the length of the bolt must ensure that the nut can completely press the second connecting plate 101 after tightening to avoid gaps. The structure of the third connecting assembly 20 is the same as that of the first connecting assembly 9, also including a third connecting plate 201, a third bolt and nut assembly 202 and a second anti-slip washer 203, to ensure the tightness and sealing of each connection part.

[0029] The installation sequence of the device must strictly follow the "bottom-up" principle: first fix the auxiliary installation base 2, then assemble the arc-shaped pressure plate assembly 3 on top of it, and finally install the top pressure plate assembly 4 tightly against the top of the arc-shaped pressure plate assembly 3. After installation, considering the working condition that the wellhead pressure of low-pressure coalbed methane wells is usually less than 0.03MPa, first inflate the airbag 19 to 0.05MPa. After the airbag 19 is inflated, it can compress the sealing gasket 14 to fit against the wellhead annular steel plate 7, the outer wall of the two-stage casing 5, and the top rubber pressure plate 21 to enhance the seal. Then, the pressure changes are monitored in real time through the pressure gauge assembly 17, and the pressure is adjusted according to the sealing status to ensure a stable sealing effect.

[0030] The workflow of this utility model must strictly follow the four steps of "prefabrication-assembly-inflation-monitoring", as detailed below: 1. Based on the gap width between the arc-shaped pressure plate 13 and the double-opening sleeve 5, select an airbag 19 of matching specifications. Inflate the airbag 19 to the fully open state through the inflation valve group 18 (at this time, the outer diameter of the airbag 19 matches the gap width and there are no obvious wrinkles). Then, use special sealant to bond the compression sealing gasket 14 to the other surfaces of the airbag 19 except the side close to the arc-shaped pressure plate 13. During the bonding process, it is necessary to ensure that the compression sealing gasket 14 is flat and free of air bubbles, and that the edges of the compression sealing gasket 14 on the upper and lower sides extend 3-8mm beyond the edge of the airbag 19.

[0031] 2. Secure the prefabricated airbag 19 to the fixing slot 15 of the arc-shaped pressure plate 13 by engaging the fixing slot 16 with the fixing slot 16. During assembly, ensure that the fixing slot 15 and the fixing slot 16 correspond one-to-one and that the engagement depth is not less than 5mm. At the same time, check the second sealing ring 183 of the inflation valve assembly 18 and the first sealing ring 173 of the pressure gauge assembly 17 to ensure that the rings are undamaged and undeformed, and that the interference contact with the slot is 0.2-0.3mm to ensure sealing performance.

[0032] 3. Use a depth gauge to measure the distance from the bottom of the interface 11 to the bottom of the sealing gasket 14. Adjust the height of the auxiliary mounting base 2 according to the measurement data, and then fix it on the open casing 6. After fixing, install the arc-shaped pressure plate assembly 3 with the airbag 19 installed on the wellhead casing structure 1. Use the concave stop of the auxiliary mounting base 2 to support and temporarily fix the arc-shaped pressure plate 13, which can effectively reduce the shaking of the arc-shaped pressure plate assembly 3 during installation and improve installation efficiency.

[0033] 4. Press the top pressure plate assembly 4 onto the arc-shaped pressure plate assembly 3 and tighten it using the third bolt and nut assembly 202. During tightening, a torque wrench should be used to tighten it in stages in a diagonal sequence. After installation, pressurize the airbag 19 through the inflation valve assembly 18. Considering that the casing pressure at the wellhead of low-pressure coalbed methane wells is mostly less than 0.03 MPa, first increase the pressure to 0.05 MPa. At this time, the airbag 19 expands, causing the compression sealing gasket 14 to fit tightly against the wellhead annular steel plate 7, the filling sealing gasket 12, the outer wall of the second-opening casing 5, and the top rubber pressure plate 21, thereby sealing the dynamic cracks in the wellhead annular steel plate 7. Later, the pressure changes inside the airbag 19 can be monitored in real time through the pressure gauge assembly 17. If the pressure drop exceeds 0.01 MPa, the pressure needs to be replenished in time through the inflation valve assembly 18 to ensure the continuous and stable sealing effect.

[0034] It is understood that this utility model has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this utility model. Furthermore, under the teachings of this utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this utility model.

Claims

1. A plugging device for leaks at the annular steel plate at the wellhead of a low-pressure coalbed methane well, characterized in that, The assembly includes an arc-shaped pressure plate assembly (3), an auxiliary mounting base (2), and a top pressure plate assembly (4). The arc-shaped pressure plate assembly (3) includes arc-shaped pressure plates (13) symmetrically arranged on the wellhead casing structure (1). The connecting ends of the arc-shaped pressure plates (13) are integrally provided with a second connecting plate (101). The second connecting plates (101) are connected and sealed by bolts and nuts and a sealing gasket (103). The inner wall of the arc-shaped pressure plate (13) has an annular boss near the lower end that contacts an open casing (6). A filling sealing gasket (12) is provided above the annular boss and passes through the open casing (6). The inner side of the arc-shaped pressure plate (13) is provided with an airbag (19) that can be tightly pressed. The airbag (19) is glued to the sealing gasket (14) so ​​that after it is inflated, the sealing gasket (14) can be pressed to fit with the wellhead annular steel plate (7), the wall of the second casing (5) and the top pressure plate assembly (4) to enhance the seal. The auxiliary installation base (2) is set below the arc-shaped pressure plate assembly (3) for quick installation and to prevent the arc-shaped pressure plate assembly (3) from sliding down. The top pressure plate assembly (4) is set above the arc-shaped pressure plate assembly (3) for pressing and tightening the sealing gasket (14) and blocking rainwater from entering the leak point.

2. The plugging device for the leak point of the annular steel plate at the wellhead of a low-pressure coalbed methane well according to claim 1, characterized in that, The upper and lower ends of the airbag (19) are respectively fitted with fixing grooves (16). The fixing grooves (16) are adapted to the end contours of the airbag (19) and are sealed to position and constrain the airbag (19). Two fixing slots (15) are opened on the inner side of the arc-shaped pressure plate (13) from top to bottom along the axial direction. The fixing grooves (16) and the fixing slots (15) form an interference fit.

3. The plugging device for the annular steel plate leak point at the wellhead of a low-pressure coalbed methane well according to claim 2, characterized in that, The inner side of the arc-shaped pressure plate (13) is provided with a first through hole and a second through hole between the fixed slots (15). The outer side of the airbag (19) is provided with a pressure gauge assembly (17) and an inflation valve assembly (18). The pressure gauge assembly (17) includes a pressure gauge connecting pipe, and the inflation valve assembly (18) includes an inflation valve connecting pipe. The inner side of the first through hole is provided with a first slot (172), and a first sealing ring (173) is provided in the first slot (172). The other end of the pressure gauge connecting pipe extends to the outer side of the arc-shaped pressure plate (13) through the first through hole and is fixed by screwing the first nut (171) into the external thread section of the pressure gauge connecting pipe. The inner side of the second through hole is provided with a second slot (182), and a second sealing ring (183) is provided in the second slot (182). The other end of the inflation valve connecting pipe extends to the outer side of the arc-shaped pressure plate (13) through the second through hole and is fixed by screwing the second nut (181) into the external thread section of the inflation valve connecting pipe.

4. The plugging device for the annular steel plate leak point at the wellhead of a low-pressure coalbed methane well according to claim 1, characterized in that, The compression sealing gasket (14) is made of a highly elastic sealing material with a thickness of 2-5 mm and an edge that extends 3-8 mm beyond the edge of the airbag.

5. The plugging device for the annular steel plate leak point at the wellhead of a low-pressure coalbed methane well according to claim 1, characterized in that, The upper end of the auxiliary mounting base (2) is provided with a concave stop and the lower end of the arc-shaped pressure plate (13) is connected to the convex stop. The auxiliary mounting base (2) includes symmetrically arranged arc-shaped clamping seats (8). The connecting end of the arc-shaped clamping seats (8) is provided with a first connecting plate (91). The first anti-slip pad (93) is provided between the first connecting plates (91) and is connected and fastened by the first bolt and nut assembly (92).

6. The plugging device for the annular steel plate leak point at the wellhead of a low-pressure coalbed methane well according to claim 1, characterized in that, The top pressure plate assembly (4) includes a top rubber pressure plate (21) and a top pressure plate (22) arranged symmetrically from bottom to top. The adjacent ends of the top pressure plate (22) are provided with a third connecting plate (201). A second anti-slip pad (203) is provided between the third connecting plates (201) and is connected and fastened by a third bolt and nut assembly (202).

7. The plugging device for the leak point of the annular steel plate at the wellhead of a low-pressure coalbed methane well according to claim 6, characterized in that, The top pressure plate (22) is truncated cone in shape, and its lower end diameter is larger than the diameter of the open sleeve (6).

8. The plugging device for the annular steel plate leak point at the wellhead of a low-pressure coalbed methane well according to claim 7, characterized in that, The top plate (22) has a rainproof protrusion extending in the radial direction on its upper surface.

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