Coalbed methane well oil pipe gas recovery wellhead sealing device and use method thereof

Abstract

The present invention discloses a coalbed methane well oil pipe gas recovery wellhead sealing device and its use method, which comprises: a vertical shaft, in which a wellbore is vertically inserted, and the wellbore is used to transport underground coalbed methane upward; an oil pipe, which is vertically arranged above the wellbore, and the end bolts of the wellbore are fixed with an end cover; a mounting seat, which is fixed to the upper end of the end cover, and the oil pipe is connected to the mounting seat; a sealing ring, which is arranged in the mounting seat and sleeved on the outside of the oil pipe; a dynamic isolation unit, which is coaxially arranged above the mounting seat and located outside the oil pipe, and an elastic rubber ring is provided in the dynamic isolation unit, and is in sealing contact with the oil pipe through the elastic rubber ring; an air guide seat, which is installed above the inside of the wellbore, and the air guide seat is externally connected to a first air sealing cylinder; a rectifying seat, which is installed inside the wellbore and below the air guide seat, and the rectifying seat is used to rectify the coalbed methane transported in the wellbore; and the rectifying seat is externally connected to a second air sealing cylinder.

Description

Technical Field

[0001] The present invention belongs to the technical field of coalbed methane extraction, and in particular relates to a coalbed methane well oil pipe gas recovery wellhead sealing device and a use method thereof. Background Art

[0002] Coalbed methane (CBM) well pipeline gas recovery is an important technology designed to effectively utilize CBM resources, reduce environmental pollution, and improve energy efficiency. Currently, CBM recovery through pipelines can significantly reduce direct methane emissions and mitigate the greenhouse effect. Traditionally, wellheads use rubber rings to seal the pipeline to block internal pressure. However, due to the uneven distribution of CBM within the wellhead, high-pressure blowouts are prone to occur. Conventional rubber rings are static seals with limited elasticity during use. They cannot automatically adjust their sealing effect with pressure changes, which can easily lead to leakage. Furthermore, long-term use in high-temperature environments causes the rubber rings to remain compressed, which can easily age, harden, or become brittle, reducing their sealing performance and requiring frequent replacement and maintenance, increasing operational difficulty and cost.

[0003] Therefore, it is necessary to provide a coalbed methane well oil pipe gas recovery wellhead sealing device and a method of using the same to solve the problems raised in the above background technology. Summary of the Invention

[0004] To achieve the above-mentioned object, the present invention provides the following technical solution: a coalbed methane well oil pipe gas recovery wellhead sealing device, comprising:

[0005] A vertical shaft, in which a wellbore is vertically inserted, and the wellbore is used to transport underground coalbed methane upward;

[0006] An oil pipe is vertically arranged above the wellbore, an end cap is fixed by bolts at the end of the wellbore, and one end of the oil pipe is coaxially inserted into and connected to the end cap;

[0007] A mounting seat, fixed to the upper end of the end cover, and the oil pipe is connected to the mounting seat;

[0008] A sealing ring is arranged in the mounting seat and sleeved on the outside of the oil pipe;

[0009] A dynamic isolation unit is coaxially arranged above the mounting seat and outside the oil pipe, wherein an elastic rubber ring is provided in the dynamic isolation unit and is in sealing contact with the oil pipe through the elastic rubber ring;

[0010] An air guide seat is installed above the interior of the wellbore, and a first air seal tube is connected to the outside of the air guide seat, one end of which is connected to the dynamic isolation unit; the first air seal tube dynamically adjusts the radial pressure of the elastic rubber ring in the dynamic isolation unit according to the changes in the coalbed methane flow in the air guide seat;

[0011] The rectifier seat is installed inside the wellbore and is located below the gas guide seat. The rectifier seat is used to rectify the coalbed methane transported in the wellbore; the rectifier seat is externally connected to a second gas seal tube, and one end of the second gas seal tube is connected to the dynamic isolation unit; the second gas seal tube dynamically adjusts the axial pressure of the elastic rubber ring in the dynamic isolation unit according to the pressure of the coalbed methane after rectification.

[0012] Furthermore, preferably, the dynamic isolation unit comprises:

[0013] A cylinder is coaxially fixed above the mounting seat, a ring seat is coaxially fixed in the cylinder, the ring seat is sleeved outside the oil pipe, and the elastic rubber ring is coaxially installed above the ring seat;

[0014] The guide cavities are symmetrically arranged in the cylinder, and each of the guide cavities is provided with a high-pressure bag ring;

[0015] The first top shaft and the second top shaft are slidably connected in the two guide cavities. The guide cavities are both connected to outer tubes. One end of the outer tube is connected to the high-pressure bag ring, and the other end of each outer tube is connected to the first air sealing cylinder and the second air sealing cylinder respectively. The first air sealing cylinder drives the first top shaft to slide downward under the air pressure adjustment of the high-pressure bag ring.

[0016] A lifting spring is sleeved outside the first jacking shaft and the second jacking shaft, and is used to lift the first jacking shaft and the second jacking shaft upward and reset them;

[0017] an axial pressure plate, slidably connected to the cylinder, wherein the lower end of the first top shaft is connected to the axial pressure plate;

[0018] A ring sleeve is coaxially rotatably connected to the ring seat and is located outside the elastic rubber ring, and a guide ring is fixed outside the ring sleeve;

[0019] A guide groove is circumferentially provided on the side wall of the guide ring, and a plurality of shaft pins are horizontally fixed on the shaft pressure plate, and each shaft pin is slidably connected to the guide groove;

[0020] The upper pressing plate is sleeved on the outside of the oil pipe and contacts and rests on the elastic rubber ring. The lower end of the second top shaft is connected to the upper pressing plate.

[0021] Furthermore, preferably, an installation gap is left between the ring seat and the oil pipe, and the lower end of the elastic rubber ring extends downward to form a sleeve layer, and the sleeve layer is deeply connected in the installation gap.

[0022] Furthermore, preferably, the unfolded cross-section of the guide groove is an oblique structure, so that the axial pressure plate can control the forward and reverse rotation of the guide ring through the axial pin during the up and down sliding.

[0023] Furthermore, preferably, a plurality of tooth plates are distributed around the circumference of the lower end of the upper pressure plate.

[0024] Furthermore, preferably, the cross section of the elastic rubber ring is a toothed disc structure, and a plurality of protrusions are distributed on the inner wall of the ring sleeve;

[0025] A mounting sleeve is fixed to the middle of the elastic rubber ring, and the mounting sleeve is fixed to the oil pipe through a connecting key.

[0026] Furthermore, preferably, the first airtight cylinder includes:

[0027] The bobbin has two sealed cavities arranged in the upper and lower parts;

[0028] A piston is slidably connected in each of the sealing chambers, and a connecting rod is fixed between two of the pistons;

[0029] An inner spring is sleeved on the connecting rod and located in the sealing cavity below;

[0030] The second airtight cylinder has the same composition and structure as the first airtight cylinder.

[0031] Furthermore, preferably, an exhaust pipe is fixed in the shaft below the air guide seat, a collecting channel is provided in the middle of the exhaust pipe, and the air guide seat is located directly above the collecting channel; a plurality of side row holes are opened on the side wall of the air guide seat.

[0032] Furthermore, preferably, a central column is fixed in the rectifier seat, an annular rectifier space is formed between the central column and the rectifier seat, and a plurality of diverter blocks are staggered and distributed on the side wall of the central column, and one end face of each diverter block is in sealing contact with the inner wall of the rectifier seat;

[0033] An annular cavity is provided above the rectification space in the rectification seat. The annular cavity is sealed and connected to the rectification space through a plurality of branch holes. The second air sealing cylinder is connected to the annular cavity.

[0034] Furthermore, as a preferred embodiment, a method for using a gas recovery wellhead sealing device for an oil pipe in a coalbed methane well comprises the following steps: S1. Clean the contact surface between the wellbore and the oil pipe to ensure that there are no impurities and dirt; at the same time, check the gas concentration of the coalbed methane in the wellbore to ensure that it is within the safe range;

[0035] S2. Manually install the air guide and rectifier seats in their corresponding positions in the wellbore. Then, tighten the end cap bolts to the upper end of the wellbore. This will ensure that the sealing ring inside the mounting seat above the end cap contacts the tubing, forming a static seal.

[0036] S3. The dynamic isolation unit is mounted on the tubing so that the elastic ring in the dynamic isolation unit is in sealing contact with the tubing. One of the guide cavities in the dynamic isolation unit is connected to the first air seal tube through the outer tube, while the other guide cavity is connected to the second air seal tube through the outer tube.

[0037] S4. During coalbed methane flow, it first passes through the rectifying space in the rectifying seat for rectification, forming a steady-state flow. A portion of the coalbed methane then flows through the annular cavity into the second gas seal, pushing the piston in the second gas seal. The second gas seal then pushes down on the upper pressure plate in the cylinder, achieving dynamic axial pressure regulation of the elastic rubber ring. The remaining coalbed methane flows upward along the wellbore.

[0038] S5. When coalbed methane passes through the gas guide seat, it is preferentially concentrated into the first gas seal tube through the collecting channel, thereby pushing the piston in the first gas seal tube. The first gas seal tube then presses down the axial pressure plate in the cylinder body, so that the ring sleeve forms a dynamic radial pressure adjustment on the elastic rubber ring during rotation. When the first gas seal tube is full, it is discharged into the wellbore through the side discharge hole in the gas guide seat.

[0039] S6. The coalbed methane is finally discharged and collected through the oil pipeline.

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

[0041] The dynamic sealing unit mainly used in the present invention can achieve dynamic sealing between the oil pipe and the wellbore, so that the elastic rubber ring can be dynamically adjusted based on the coalbed methane pressure after rectification and the changes in the coalbed methane airflow in the wellbore, so that its sealing effect is more significant in high-pressure and unstable extraction environments; a sealing ring is also used as a static sealing structure, which can form a double seal and further improve the wellhead safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a structural schematic diagram of the present invention;

[0043] Figure 2 It is a cross-sectional schematic diagram of the present invention;

[0044] Figure 3 Schematic diagram of the structure of the dynamic isolation unit in the present invention;

[0045] Figure 4 Schematic diagram of the structure of the elastic rubber ring in the present invention;

[0046] Figure 5 It is a structural diagram of the ring sleeve and the installation sleeve in the present invention;

[0047] Figure 6 Schematic diagram of the structure of the first air seal cylinder in the present invention;

[0048] Figure 7 Schematic diagram of the structure of the air guide seat in the present invention;

[0049] Figure 8 It is a structural diagram of the rectifier seat in the present invention;

[0050] In the figure: 1. Wellbore; 11. End cover; 12. Mounting seat; 2. Oil pipe; 3. Dynamic isolation unit; 31. Cylinder; 32. Ring seat; 33. High-pressure bag ring; 34. First top shaft; 35. Outer tube; 36. Shaft pressure plate; 37. Guide ring; 38. Upper pressure plate; 4. Elastic rubber ring; 41. Ring sleeve; 42. Protrusion; 43. Mounting sleeve; 5. Air guide seat; 51. Exhaust pipe; 52. Collecting channel; 53. Side discharge hole; 6. First air seal cylinder; 61. Cylinder tube; 62. Sealing chamber; 63. Piston; 7. Rectifier seat; 71. Center column; 72. Diverter block; 73. Annular chamber. DETAILED DESCRIPTION

[0051] See also Figures 1-8 In an embodiment of the present invention, a coalbed methane well oil pipe gas recovery wellhead sealing device comprises:

[0052] A vertical shaft, in which a shaft 1 is vertically inserted, and the shaft 1 is used to transport underground coalbed methane upward;

[0053] The oil pipe 2 is vertically arranged above the wellbore 1. An end cap 11 is fixed to the end of the wellbore 1 with bolts. One end of the oil pipe 2 is coaxially inserted into the end cap 11. The end cap can be sealed with the wellbore.

[0054] A mounting seat 12 is fixed to the upper end of the end cover 11, and the oil pipe 2 is connected to the mounting seat 12;

[0055] A sealing ring 13 is provided in the mounting seat and sleeved on the outside of the oil pipe 2;

[0056] A dynamic isolation unit 3 is coaxially arranged above the mounting seat and outside the oil pipe 2. An elastic rubber ring 4 is provided inside the dynamic isolation unit 3, and the dynamic isolation unit 3 is in sealing contact with the oil pipe 2 through the elastic rubber ring 4.

[0057] The gas guide seat 5 is installed above the interior of the wellbore 1. The gas guide seat 5 is externally connected to a first gas sealing tube 6. One end of the first gas sealing tube 6 is connected to the dynamic isolation unit 3. The first gas sealing tube 6 dynamically adjusts the radial pressure of the elastic rubber ring 4 in the dynamic isolation unit 3 according to the changes in the coalbed methane flow in the gas guide seat 5.

[0058] The rectifier seat 7 is installed inside the wellbore 1 and is located below the gas guide seat 6. The rectifier seat 7 is used to rectify the coalbed methane transported in the wellbore 1; the rectifier seat 7 is externally connected to a second gas seal tube, and one end of the second gas seal tube is connected to the dynamic isolation unit 3; the second gas seal tube dynamically adjusts the axial pressure of the elastic rubber ring 4 in the dynamic isolation unit 3 according to the pressure of the coalbed methane after rectification; that is to say, for the sealing installation between the oil pipe and the wellbore, on the one hand, a static sealing structure can be formed by the sealing ring, and on the other hand, a dynamic sealing structure can be formed through the dynamic deformation of the elastic rubber ring during use, thereby achieving a double sealing effect, and is more adaptable to unstable extraction environments, avoiding aging failure of a single sealing structure to cause gas leakage.

[0059] In this embodiment, the dynamic isolation unit 3 includes:

[0060] The cylinder 31 is coaxially fixed above the mounting seat 12. A ring seat 32 is coaxially fixed inside the cylinder 31. The ring seat 32 is sleeved outside the oil pipe 2, and the elastic rubber ring 4 is coaxially installed above the ring seat 32.

[0061] The guide cavities are symmetrically arranged in the cylinder 31, and each of the guide cavities is provided with a high-pressure bag ring 33; the high-pressure bag ring can gradually fill the entire guide cavity during inflation adjustment;

[0062] The first top shaft 34 and the second top shaft are slidably connected in the two guide cavities. The guide cavities are both connected to outer tubes 35. One end of the outer tube 35 is connected to the high-pressure bag ring 33, and the other end of each outer tube 35 is connected to the first air sealing cylinder 6 and the second air sealing cylinder respectively. The first air sealing cylinder 6 drives the first top shaft 34 to slide downward under the air pressure regulation of the high-pressure bag ring 33.

[0063] A lifting spring (not shown in the figure) is sleeved outside the first jacking shaft 34 and the second jacking shaft, and is used to lift the first jacking shaft 34 and the second jacking shaft upward and reset them;

[0064] An axial pressure plate 36 is slidably connected to the cylinder 31 , and the lower end of the first top shaft 34 is connected to the axial pressure plate 36 ;

[0065] A ring sleeve 41 is coaxially connected to the ring seat and is located outside the elastic rubber ring 4. A guide ring 37 is fixed outside the ring sleeve 41.

[0066] A guide groove is circumferentially provided on the side wall of the guide ring 37 , and a plurality of shaft pins are horizontally fixed on the shaft pressure plate 36 , and each shaft pin is slidably connected to the guide groove;

[0067] The upper pressing plate 38 is sleeved on the outside of the oil pipe 2 and contacts and rests on the elastic rubber ring 4 . The lower end of the second top shaft is connected to the upper pressing plate 38 .

[0068] As a preferred embodiment, an installation gap is left between the ring seat 32 and the oil pipe 2, and the lower end of the elastic rubber ring 4 extends downward to form a sleeve layer, which is deeply connected to the installation gap. That is to say, the elastic rubber ring can seal and fill the installation gap through the sleeve layer, and when the elastic rubber ring is deformed and adjusted, it can form different shapes and sealing effects above the installation gap.

[0069] In this embodiment, the unfolded cross-section of the guide groove is a diagonal structure, so that the axial pressure plate 36 controls the forward and reverse rotation adjustment of the guide ring 37 through the axial pin during the up and down sliding, thereby forming different radial extrusion effects on the elastic rubber ring during the synchronous driving of the ring sleeve rotation adjustment by the guide ring 37.

[0070] In this embodiment, a plurality of tooth plates are distributed around the circumference of the lower end of the upper pressure plate 38, so that the elastic rubber ring is further pressed axially downward by the tooth plates.

[0071] In this embodiment, the cross section of the elastic rubber ring 4 is a toothed disc structure, and a plurality of protrusions 42 are distributed on the inner wall of the ring sleeve 41;

[0072] A mounting sleeve 43 is fixed to the middle of the elastic rubber ring 4, and the mounting sleeve 43 is fixed to the oil pipe 2 through a connecting key to prevent the elastic rubber ring 4 from rotating synchronously with the guide ring 37 during radial extrusion; wherein, the material molecular chains of the elastic rubber ring 4 are arranged more tightly and orderly in the axial direction (or fiber reinforcement materials are added in the axial direction to improve the axial strength and rigidity), thereby providing stronger pressure resistance and tightness in the axial direction, and it introduces more microscopic gaps in the radial direction, which can be partially closed when subjected to radial pressure, so that the ability to resist deformation in the radial direction is relatively weak, so that the sealing effect of the elastic rubber ring 4 in axial extrusion is close to twice the radial extrusion sealing effect, so that the second air seal can provide different strengths of axial extrusion sealing to the elastic rubber ring based on the coalbed methane pressure, and then the first air seal can achieve appropriate radial extrusion sealing for the elastic rubber ring according to the subtle changes in the coalbed methane flow rate to ensure that the elastic rubber ring achieves the corresponding sealing effect.

[0073] As a preferred embodiment, the first air sealing cylinder 6 includes:

[0074] The bobbin 61 has two sealed cavities 62 arranged in the upper and lower parts thereof;

[0075] A piston 63 is slidably connected in each of the sealing chambers 62, and a connecting rod is fixed between the two pistons 63;

[0076] An inner spring, sleeved on the connecting rod and located in the sealing cavity 62 below;

[0077] The second air seal tube has the same composition structure as the first air seal tube 6, that is, when the coalbed methane flows and fills the tube 61, the piston can slide upward. At this time, the sealing chamber 62 located above can adjust the high-pressure bag ring in the dynamic isolation unit 3 through the piston.

[0078] In this embodiment, an exhaust pipe 51 is fixed in the wellbore 1 below the gas guide seat 5, a collecting channel 52 is provided in the middle of the exhaust pipe 51, and the gas guide seat 5 is located directly above the collecting channel 52; a plurality of side discharge holes 53 are provided on the side wall of the gas guide seat 5, that is, the coalbed methane can enter the first gas seal tube through the collecting channel 52 and the gas guide seat 5 first. When the first gas seal tube is filled with coalbed methane, the coalbed methane can be discharged into the wellbore from the side discharge holes 53, so that when the coalbed methane airflow in the collecting channel 52 changes (that is, the coalbed methane airflow becomes larger or smaller), the first gas seal tube can sense it in the first time and make synchronous adjustments, so that the elastic rubber ring 4 in the dynamic isolation unit produces a corresponding radial extrusion effect.

[0079] In this embodiment, a central column 71 is fixed in the rectifier seat 7, and an annular rectifier space is formed between the central column and the rectifier seat 7. A plurality of diverter blocks 72 are staggered and distributed on the side wall of the central column 71, and one end surface of each diverter block 72 is in sealing contact with the inner wall of the rectifier seat 7;

[0080] An annular cavity 73 is provided above the rectification space in the rectification seat 7. The annular cavity 73 is sealed and connected to the rectification space through multiple branch holes. The second air seal tube is connected to the annular cavity 73, so as to form a circulation monitoring of the coalbed methane pressure. When the coalbed methane pressure in the wellbore increases or decreases, the second air seal tube can form a corresponding axial extrusion effect on the elastic rubber ring 4 in the dynamic isolation unit.

[0081] A method for using a gas recovery wellhead sealing device for an oil pipe in a coalbed methane well comprises the following steps: S1. Clean the contact surface between the wellbore 1 and the oil pipe 2 to ensure that there are no impurities and dirt. At the same time, check the gas concentration of the coalbed methane in the wellbore 1 to ensure that it is within a safe range.

[0082] S2. The air guide seat 5 and the rectifier seat 7 are manually installed in the corresponding positions in the wellbore 1, and then the end cover 11 is bolted and installed at the upper end of the wellbore 1. At this time, the inner sealing ring 13 of the mounting seat 12 above the end cover 11 contacts the oil pipe 2 to form a static sealing structure;

[0083] S3. The dynamic isolation unit 3 is mounted on the outer surface of the oil pipe 2 so that the elastic rubber ring 4 in the dynamic isolation unit 3 is in sealing contact with the oil pipe 2. At this time, one of the guide cavities in the dynamic isolation unit 3 is connected to the first air seal tube 6 through the outer tube, and the other guide cavity is connected to the second air seal tube through the outer tube;

[0084] S4. During coalbed methane flow, it first passes through the rectifying space in the rectifying seat 7 for rectification to form a steady-state flow. A portion of the coalbed methane then enters the second gas seal through the annular cavity 73, thereby pushing the piston 63 in the second gas seal. The second gas seal then presses down the upper pressure plate 38 in the cylinder 31, achieving dynamic axial pressure regulation of the elastic rubber ring 4. The remaining coalbed methane flows upward along the wellbore.

[0085] S5. When the coalbed methane passes through the gas guide seat 5, it is preferentially concentrated into the first gas seal tube 6 through the collecting channel 52, thereby pushing the piston 63 in the first gas seal tube 6. The first gas seal tube 6 then presses down the axial pressure plate 36 in the cylinder body 31, so that the ring sleeve 41 forms a dynamic radial pressure regulation on the elastic rubber ring 4 during rotation. When the first gas seal tube 6 is full, it is discharged into the wellbore 1 through the side discharge hole 53 on the gas guide seat 5.

[0086] S6. The coalbed methane is finally discharged and collected through the oil pipe 2.

[0087] 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 coalbed methane well oil pipe gas recovery wellhead sealing device, characterized in that: It includes: A vertical shaft, in which a wellbore (1) is vertically inserted, and the wellbore (1) is used to transport underground coalbed methane upward; An oil pipe (2) is vertically arranged above the wellbore (1), an end cap (11) is fixed to the end of the wellbore (1) with bolts, and one end of the oil pipe (2) is coaxially inserted into and connected to the end cap (11); A mounting seat (12) is fixed to the upper end of the end cover (11), and the oil pipe (2) is connected to the mounting seat (12); A sealing ring (13) is arranged in the mounting seat and sleeved on the outside of the oil pipe (2); A dynamic sealing unit (3) is coaxially arranged above the mounting seat and located outside the oil pipe (2); an elastic rubber ring (4) is provided in the dynamic sealing unit (3) and is in sealing contact with the oil pipe (2) via the elastic rubber ring (4); An air guide seat (5) is installed above the interior of the wellbore (1); the air guide seat (5) is externally connected to a first air seal tube (6); one end of the first air seal tube (6) is connected to the dynamic isolation unit (3); the first air seal tube (6) dynamically adjusts the radial pressure of the elastic rubber ring (4) in the dynamic isolation unit (3) according to the change of the coalbed methane gas flow in the air guide seat (5); A rectifier seat (7) is installed inside the wellbore (1) and below the gas guide seat (5). The rectifier seat (7) is used to rectify the coalbed methane transported in the wellbore (1); the rectifier seat (7) is externally connected to a second gas seal tube, one end of which is connected to the dynamic isolation unit (3); the second gas seal tube dynamically adjusts the axial pressure of the elastic rubber ring (4) in the dynamic isolation unit (3) according to the pressure of the coalbed methane after rectification.

2. A coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 1, characterized in that: The dynamic isolation unit (3) comprises: A cylinder (31) is coaxially fixed above the mounting seat (12), a ring seat (32) is coaxially fixed inside the cylinder (31), the ring seat (32) is sleeved outside the oil pipe (2), and the elastic rubber ring (4) is coaxially installed above the ring seat (32); Guide cavities are symmetrically arranged in the cylinder (31), and a high-pressure bag ring (33) is provided in each guide cavity; The first top shaft (34) and the second top shaft are slidably connected in the two guide cavities, and the guide cavities are both connected to outer tubes (35), one end of the outer tubes (35) is connected to the high-pressure bag ring (33), and the other end of each outer tube (35) is connected to the first air sealing cylinder (6) and the second air sealing cylinder respectively; the first air sealing cylinder (6) drives the first top shaft (34) to slide downward under the air pressure regulation of the high-pressure bag ring (33); A lifting spring is sleeved outside the first top shaft (34) and the second top shaft, and is used to lift the first top shaft (34) and the second top shaft upward and reset them; An axial pressure plate (36) is slidably connected in the cylinder (31), and the lower end of the first top shaft (34) is connected to the axial pressure plate (36); A ring sleeve (41) is coaxially rotatably connected to the ring seat and is located outside the elastic rubber ring (4), and a guide ring (37) is fixed outside the ring sleeve (41); A guide groove is circumferentially opened on the side wall of the guide ring (37), and a plurality of shaft pins are horizontally fixed on the shaft pressure plate (36), and each shaft pin is slidably connected to the guide groove; An upper pressing plate (38) is sleeved outside the oil pipe (2) and contacts and rests against the elastic rubber ring (4). The lower end of the second top shaft is connected to the upper pressing plate (38).

3. A coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 2, characterized in that: An installation gap is left between the ring seat (32) and the oil pipe (2), and the lower end of the elastic rubber ring (4) extends downward to form a sleeve layer, which is deeply connected in the installation gap.

4. A coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 2, characterized in that: The expanded cross section of the guide groove is an oblique structure, so that the shaft pressure plate (36) can be regulated in forward and reverse rotation by controlling the guide ring (37) through the shaft pin during the upward and downward sliding.

5. A coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 4, characterized in that: A plurality of tooth plates are distributed around the circumference of the lower end of the upper pressing plate (38).

6. The coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 2, characterized in that: The cross section of the elastic rubber ring (4) is a toothed disc structure, and a plurality of protrusions (42) are distributed on the inner wall of the ring sleeve (41); A mounting sleeve (43) is fixed to the middle of the elastic rubber ring (4), and the mounting sleeve (43) is fixed to the oil pipe (2) via a connecting key.

7. The coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 1, characterized in that: The first air sealing cylinder (6) comprises: The bobbin (61) has two sealed cavities (62) provided in the upper and lower parts thereof; A piston (63) is slidably connected in each of the sealing chambers (62), and a connecting rod is fixed between two of the pistons (63); An inner spring, sleeved on the connecting rod and located in the sealing cavity (62) below; The second air-sealing cylinder has the same composition and structure as the first air-sealing cylinder (6).

8. The coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 1, characterized in that: An exhaust pipe (51) is fixed in the shaft (1) below the air guide seat (5), a collecting channel (52) is provided in the middle of the exhaust pipe (51), and the air guide seat (5) is located directly above the collecting channel (52); a plurality of side discharge holes (53) are provided on the side wall of the air guide seat (5).

9. The coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 1, characterized in that: A central column (71) is fixed in the rectifier seat (7), and an annular rectifier space is formed between the central column and the rectifier seat (7). A plurality of diverter blocks (72) are staggered and distributed on the side wall of the central column (71), and one end surface of each diverter block (72) is in sealing contact with the inner wall of the rectifier seat (7); An annular cavity (73) is provided above the rectification space in the rectification seat (7); the annular cavity (73) is sealed and communicated with the rectification space through a plurality of branch holes; and the second air-sealing cylinder is connected to the annular cavity (73).

10. A method for using a coalbed methane well oil pipe gas recovery wellhead sealing device, which uses a coalbed methane well oil pipe gas recovery wellhead sealing device according to any one of claims 1 to 9, characterized in that: It includes the following steps: S1. Clean the contact surface between the wellbore (1) and the oil pipe (2) to ensure that there are no impurities and dirt; at the same time, check the gas concentration of the coalbed methane in the wellbore (1) to ensure that it is within a safe range; S2. Manually install the air guide seat (5) and the rectifier seat (7) at corresponding positions in the wellbore (1), and then fasten the end cover (11) with bolts to the upper end of the wellbore (1). At this time, the inner sealing ring (13) of the mounting seat (12) above the end cover (11) contacts the oil pipe (2) to form a static sealing structure; S3. The dynamic isolation unit (3) is mounted on the outside of the oil pipe (2) so that the elastic rubber ring (4) in the dynamic isolation unit (3) is in sealing contact with the oil pipe (2). At this time, one of the guide cavities in the dynamic isolation unit (3) is connected to the first air sealing tube (6) through the outer tube, and the other guide cavity is connected to the second air sealing tube through the outer tube; S4. During the flow of coalbed methane, it first passes through the rectifying space in the rectifying seat (7) for rectification to form a steady-state flow, and a portion of the coalbed methane enters the second gas seal cylinder through the annular cavity (73), thereby pushing the piston (63) in the second gas seal cylinder, and the second gas seal cylinder drives the upper pressure plate (38) in the cylinder (31) downward to achieve dynamic axial variable pressure regulation of the elastic rubber ring (4), and the remaining coalbed methane flows upward along the wellbore; S5. When the coalbed methane passes through the gas guide seat (5), it is preferentially concentrated into the first gas seal tube (6) through the collecting channel (52), thereby pushing the piston (63) in the first gas seal tube (6) with airflow, and the first gas seal tube (6) presses down the axial pressure plate (36) in the cylinder body (31) so that the ring sleeve (41) forms a dynamic radial pressure adjustment on the elastic rubber ring (4) during rotation, and when the first gas seal tube (6) is full, it is discharged into the wellbore (1) through the side discharge hole (53) on the gas guide seat (5); S6. The coalbed methane is finally discharged and collected through the oil pipeline (2).

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