Wellhead sealing device for oil pipe gas recovery of coal-bed gas well and using method of wellhead sealing device

Abstract

The invention discloses a coal-bed gas well tubing gas recovery wellhead sealing device and a using method thereof.The coal-bed gas well tubing gas recovery wellhead sealing device comprises a vertical shaft, a sealing device and a sealing device, the oil pipe is vertically arranged above the shaft, and an end cover is fixed to the end of the shaft through a bolt; the mounting seat is fixed at the upper end of the end cover, and the oil pipe is connected in the mounting seat in a penetrating manner; the sealing ring is arranged in the mounting seat and sleeves the oil pipe; the dynamic packing unit is coaxially arranged above the mounting seat and located outside the oil pipe, an elastic rubber ring is arranged in the dynamic packing unit, and the dynamic packing unit is in sealing contact with the oil pipe through the elastic rubber ring; the air guide seat is installed on the upper portion of the interior of the shaft, and the air guide seat is externally connected with a first air seal cylinder; the rectification seat is mounted in the shaft and located below the gas guide seat, and the rectification seat is used for rectifying coal bed gas conveyed in the shaft; and the rectification seat is externally connected with a second air seal cylinder.

Description

Technical Field

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

[0002] Gas recovery through oil pipes in coalbed methane wells is an important technology, which aims to effectively utilize coalbed methane resources, reduce environmental pollution, and improve energy efficiency. At present, coalbed methane recovery through oil pipes can significantly reduce direct methane emissions and mitigate the greenhouse effect; in traditional technologies, the wellhead uses rubber rings to seal the oil pipe to block the pressure inside the wellhead. Due to the uneven distribution of coalbed methane in the wellhead, high-pressure blowouts are prone to occur. General rubber rings are static seals, which have limited elasticity during use and cannot automatically adjust the sealing effect as the pressure changes, which is prone to leakage; and when used in high temperature environments for a long time, the rubber rings remain in a compressed state and are prone to aging, hardening or brittleness, which reduces their sealing performance and requires frequent replacement and maintenance, increasing the difficulty and cost of operation.

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

[0004] To achieve the above 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] The oil pipe is vertically arranged above the wellbore, the end of the wellbore is bolted with an end cap, and one end of the oil pipe is coaxially extended into and connected to the end cap;

[0007] A mounting seat, fixed to the upper end of the end cover, the oil pipe being passed through the mounting seat;

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

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

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

[0011] A rectifier seat is installed inside the wellbore below the gas guide seat, and 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] Further, preferably, the dynamic isolation unit comprises:

[0013] A cylinder is coaxially fixed above the mounting seat, a ring seat is coaxially fixed inside 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, and the guide cavities are connected to outer tubes, one end of the outer tubes is connected to the high-pressure bag ring, and the other end of each outer tube is connected to the first air sealing tube and the second air sealing tube respectively; the first air sealing tube drives the first top shaft to slide downward under the air pressure adjustment of the high-pressure bag ring;

[0016] A lifting spring, sleeved outside the first jack shaft and the second jack shaft, used for lifting and resetting the first jack shaft and the second jack shaft upward;

[0017] An axial pressure plate is slidably connected in the cylinder, and 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 opened 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 outside the oil pipe and contacts and abuts against the elastic rubber ring. The lower end of the second top shaft is connected to the upper pressing plate.

[0021] Further, 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] Further, preferably, a plurality of tooth plates are distributed on the circumference of the lower end of the upper pressure plate.

[0024] Further, 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 in the middle of the elastic rubber ring, and the mounting sleeve is fixed to the oil pipe through a connecting key.

[0026] Further, preferably, the first air sealing cylinder comprises:

[0027] The bobbin has two sealed chambers 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, sleeved on the connecting rod and located in the sealing cavity below;

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

[0031] Further, as a preference, an exhaust pipe is fixed in the wellbore 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] Further, as a preference, a central column is fixed in the rectifier seat, an annular rectifier space is formed between the central column and the rectifier seat, a plurality of shunt blocks are staggeredly distributed on the side wall of the central column, and one side end face of each shunt block is in sealing contact with the inner wall of the rectifier seat;

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

[0034] Further, as a preferred embodiment, a method for using a coalbed methane well oil pipe gas recovery wellhead sealing device 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 coalbed methane in the wellbore to ensure that it is within the safe range;

[0035] S2. Manually install the air guide seat and the rectifier seat at the corresponding positions in the wellbore, and then fasten the end cover bolts to the upper end of the wellbore. At this time, the inner sealing ring of the mounting seat above the end cover contacts the oil pipe to form a static sealing structure;

[0036] S3. The dynamic isolation unit is mounted outside the oil pipe so that the elastic rubber ring in the dynamic isolation unit is in sealing contact with the oil pipe. At this time, one of the guide cavities in the dynamic isolation unit is connected to the first gas sealing tube through the outer tube, and the other guide cavity is connected to the second gas sealing tube through the outer tube;

[0037] S4. During the flow of coalbed methane, it first passes through the rectifying space in the rectifying seat for rectification to form a steady-state flow, and a part of the coalbed methane enters the second gas seal cylinder through the annular cavity, thereby pushing the piston in the second gas seal cylinder, and the second gas seal cylinder drives the upper pressure plate in the cylinder downward to realize the dynamic axial pressure change regulation of the elastic rubber ring, and the rest of the coalbed methane flows upward along the wellbore;

[0038] S5. When the coalbed methane passes through the gas guide seat, it is preferentially concentrated into the first gas seal tube through the collecting channel, so that the piston in the first gas seal tube is pushed by the airflow, and the first gas seal tube drives the axial pressure plate in the cylinder downward, so that the ring sleeve forms a dynamic radial pressure adjustment for the elastic rubber ring during rotation, and when the first gas seal tube is full, it is discharged into the wellbore through the side discharge hole on 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 realize dynamic sealing between the oil pipe and the wellbore, so that the elastic rubber ring can be dynamically adjusted based on the size of the coalbed methane pressure after rectification and the change of the coalbed methane airflow in the wellbore, so that the sealing effect is more significant in high-pressure and unstable extraction environment; a sealing ring is also used as a static sealing structure, which can form a double seal and further improve the safety of the wellhead. 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 It is a structural schematic diagram of the dynamic isolation unit in the present invention;

[0045] Figure 4 It is a schematic diagram of the structure of the elastic rubber ring in the present invention;

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

[0047] Figure 6 It is a schematic structural diagram of the first air seal cylinder in the present invention;

[0048] Figure 7 It is a schematic diagram of the structure of the air guide seat in the present invention;

[0049] Figure 8 It is a structural schematic 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. rectifying seat; 71. center column; 72. diverter block; 73. annular chamber. DETAILED DESCRIPTION

[0051] See also Figure 1-Figure 8 In an embodiment of the present invention, a gas recovery wellhead sealing device for a coalbed methane well oil pipe 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. The end of the wellbore 1 is bolted with an end cap 11. One end of the oil pipe 2 is coaxially inserted into and connected to the end cap 11. The end cap can be sealed and installed with the wellbore.

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

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

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

[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 seal tube 6. One end of the first gas seal tube 6 is connected to the dynamic isolation unit 3. The first gas 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 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, one end of which is connected to the dynamic isolation unit 3; the second gas seal tube dynamically axially changes the 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 by the dynamic deformation of the elastic rubber ring during use, thereby achieving a double sealing effect, and being more adaptable to unstable extraction environments, avoiding gas leakage caused by aging failure of a single sealing structure.

[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, 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 tube 6 and the second air sealing tube respectively; the first air sealing tube 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), which is sleeved outside the first lifting shaft 34 and the second lifting shaft, is used to lift the first lifting shaft 34 and the second lifting shaft upward and reset;

[0064] 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;

[0065] A ring sleeve 41 is coaxially rotatably 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 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;

[0067] The upper pressing plate 38 is sleeved on the outside of the oil pipe 2 and contacts and abuts against 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, and the sleeve layer is deeply connected to the installation gap, that is, 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 an oblique structure, so that the axial pressure plate 36 can control 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 guide ring 37 to rotate.

[0070] In this embodiment, a plurality of tooth plates are distributed on 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 introducing 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 nearly twice that of the radial extrusion sealing effect, so that the second air seal can provide axial extrusion seals of different strengths to the elastic rubber ring based on the coalbed methane pressure, and then the first air seal can achieve appropriate radial extrusion seals 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 tube 6 comprises:

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

[0075] 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;

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

[0077] The second gas seal tube has the same composition structure as the first gas 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 the present embodiment, an exhaust pipe 51 is fixed below the gas guide seat 5 in the wellbore 1, 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 to say, the coalbed methane can enter the first gas seal tube through the collecting channel 52 and preferentially through the gas guide seat 5; 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 at 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 shunt blocks 72 are staggered and distributed on the side wall of the central column 71, and one side end surface of each shunt 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 a plurality of branch holes. The second air seal tube is connected to the annular cavity 73, so as to form a flow 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 coalbed methane well oil pipe gas recovery wellhead sealing device, comprising 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 at the corresponding positions in the wellbore 1, and then the end cover 11 is bolted and installed on 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 outside 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 gas sealing tube 6 through the outer tube, and the other guide cavity is connected to the second gas sealing tube through the outer tube;

[0084] 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 part 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 realize the dynamic axial variable pressure regulation of the elastic rubber ring 4, and the rest of the 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, so that the piston 63 in the first gas seal tube 6 is pushed by the airflow, and the first gas seal tube 6 presses down the axial pressure plate 36 in the cylinder 31, so that the ring sleeve 41 forms a dynamic radial variable 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;

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

[0087] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A gas recovery wellhead sealing device for a coalbed methane well oil pipe, characterized in that: It includes: A vertical shaft, in which a shaft (1) is vertically inserted, and the shaft (1) is used to transport underground coalbed methane upward; An oil pipe (2) is vertically arranged above the wellbore (1), an end cap (11) being fixed by bolts at the end of the wellbore (1), and one end of the oil pipe (2) is coaxially inserted into and connected to the end cap (11); A mounting seat (12) fixed to the upper end of the end cover (11), the oil pipe (2) passing through 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 arranged inside 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 coalbed methane gas flow in the air guide seat (5); A rectifying seat (7) is installed inside the wellbore (1) and below the gas guide seat (6). The rectifying seat (7) is used to rectify the coalbed methane transported in the wellbore (1). The rectifying seat (7) is externally connected to a second gas sealing tube, one end of which is connected to the dynamic isolation unit (3). The second gas sealing tube dynamically adjusts the axial pressure of the elastic rubber ring (4) in the dynamic isolation unit (3) according to the gas pressure of the rectified coalbed methane.

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 arranged in each of the guide cavities; 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, sleeved outside the first lifting shaft (34) and the second lifting shaft, used to lift the first lifting shaft (34) and the second lifting 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 formed on the side wall of the guide ring (37); a plurality of shaft pins are horizontally fixed on the shaft pressure plate (36); each shaft pin is slidably connected to the guide groove; An upper pressing plate (38) is sleeved outside the oil pipe (2) and abuts against the top of 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 to the installation gap.

4. A coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 2, characterized in that: The unfolded cross section of the guide groove is an oblique line 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. A 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 in the shape of a toothed disc, and a plurality of protrusions (42) are distributed on the inner wall of the ring sleeve (41); A mounting sleeve (43) is fixed in 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. A coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 1, characterized in that: The first air sealing cylinder (6) comprises: A bobbin (61) having two sealed cavities (62) disposed 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 flow collecting channel (52) is provided in the middle of the exhaust pipe (51), and the air guide seat (5) is located directly above the flow collecting channel (52); a plurality of side discharge holes (53) are provided on the side wall of the air guide seat (5).

9. A coalbed methane well oil pipe gas recovery wellhead sealing device according to claim 1, characterized in that: A central column (71) is fixed inside the rectifying seat (7), an annular rectifying space is formed between the central column and the rectifying seat (7), a plurality of diverter blocks (72) are staggeredly distributed on the side wall of the central column (71), and one side end surface of each diverter block (72) is in sealing contact with the inner wall of the rectifying seat (7); An annular cavity (73) is provided above the rectifying space in the rectifying seat (7); the annular cavity (73) is sealed and connected to the rectifying space via 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 as claimed in 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. The air guide seat (5) and the rectifier seat (7) are manually installed at corresponding positions in the wellbore (1), and then the end cover (11) is bolted and installed on the upper end of the wellbore (1), at which 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 outside 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), and 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 body (31) downward to achieve dynamic axial 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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