An oilfield wellhead sealing connection structure

Abstract

The application discloses an oil field well mouth sealing connection structure and relates to the field of oil well sealing structure.The oil field well mouth sealing connection structure solves the problems of insufficient sealing performance and easy introduction of impurities into oil and gas during use of the existing oil field well mouth sealing connection structure.The oil field well mouth sealing connection structure comprises a polish rod, a connecting head, a sealing structure and a check mechanism.The sealing structure comprises a connecting cylinder, an air bag ring and a sealing ring.The check mechanism comprises a check cylinder, a sealing ball and a swing shaft.The sealing structure is driven by the hydraulic pressure in the oil field to expand the air bag ring, and the inner wall of the sealing ring is tightly attached to the outer wall of the polish rod, so that the sealing efficiency is improved.The check mechanism controls the sealing ball to swing along a set path around the swing shaft when the polish rod is pulled out, and the sealing operation on the middle part of the check cylinder is completed.The swing direction is stable, the sealing performance is excellent, and the impurities mixed into the oil and gas can be reduced while the sealing performance is improved.

Description

Technical Field

[0001] This invention relates to the field of oil wellbore sealing structure technology, specifically to an oilfield wellhead sealing connection structure. Background Technology

[0002] The polished rod seal at the wellhead is a core component of oil production equipment, and its sealing performance directly determines the safety of oil well production, the environmental friendliness of the wellhead, and the duration of continuous production. Existing oil wellhead seals mostly employ traditional packing compression sealing structures, relying on mechanical compression of the packing filler with a pressure cap to achieve static sealing. This structure is simple and has limited functionality, exhibiting significant technical shortcomings under the complex operating conditions of oilfields.

[0003] Patent CN207879294U discloses an oilfield wellhead sealing device, comprising a blowout preventer cap, a sealing box, an adjustment base, and a connector, which are sequentially mounted on the polished rod from top to bottom. The upper end of the sealing box is connected to the blowout preventer cap, and a first nylon gasket and a first rubber gasket are provided at the connection. An annular groove is provided at the lower end of the sealing box, and a first compression spring is provided in the annular groove. A second nylon gasket and a second rubber gasket are provided above the first compression spring. A rubber injection pipe is connected in the middle of the sealing box, and rubber granules are injected into the sealing box. It has the feature of not requiring shutdown to replace the packing. This device uses a large amount of rubber for filling and elastic sealing. Firstly, the rubber granules are more prone to wear and tear and debris during use than the rubber rings, which can mix into the oil and gas and introduce impurities. Some additives in the rubber can directly reduce the quality of the oil and gas. Secondly, when the polished rod is pulled out, the position of the rubber granules cannot be maintained, and they are very easy to mix into the oil and gas. Summary of the Invention

[0004] The purpose of this invention is to provide an oilfield wellhead sealing connection structure that can improve sealing performance while reducing the mixing of impurities into oil and gas, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an oilfield wellhead sealing connection structure, comprising a polished rod, a connector, a sealing structure, and a check mechanism. The sealing structure includes a connecting cylinder installed on the upper side of the connector. The connecting cylinder contains an air bladder ring and a sealing ring. The sealing structure can utilize hydraulic pressure within the oilfield to drive the air bladder ring to expand, thereby assisting in ensuring a tight fit between the inner wall of the sealing ring and the outer wall of the polished rod, improving sealing efficiency. The check mechanism includes a check cylinder installed on the upper side of the connecting cylinder. The check cylinder contains a sealing ball and a swing shaft. When the polished rod is withdrawn, the check mechanism can control the sealing ball to swing around the swing shaft along a set path, completing the sealing operation at the middle position of the check cylinder, thus improving sealing performance while reducing impurities from mixing into the oil and gas.

[0006] Preferably, the sealing structure further includes an adjusting cylinder installed above the connector. The adjusting cylinder has an adjusting groove, and an adjusting ball is rotatably connected in the adjusting groove. The adjusting ball has a threaded groove. A threaded pipe that is threadedly connected to the threaded groove is rotatably connected to the bottom of the connector. Multiple sets of insertion pipes are evenly provided on the adjusting ball. Multiple sets of connecting pipes that can be inserted into the inner wall of the insertion pipes are fixedly connected inside the connector. The upper end of the connecting pipe is connected to the airbag ring. The connector is provided with a pressure-increasing component for improving the sealing strength of the sealing ring, which facilitates the expansion of the airbag ring by using the hydraulic pressure inside the oil field, and helps to make the inner wall of the sealing ring fit tightly with the outer wall of the polished rod, thereby improving the sealing efficiency.

[0007] Preferably, the pressurizing component includes a first threaded sleeve threadedly connected to the outer wall of the upper end of the connecting cylinder. An inner sleeve is rotatably connected to the inner wall of the first threaded sleeve. A top plate is fixedly connected to the outer wall of the inner sleeve. An elastic element is fixedly connected to the bottom of the top plate. A lifting ring is fixedly connected to the bottom end of the elastic element. A rubber pad is fixedly connected to the bottom of the lifting ring. The bottom of the rubber pad abuts against the top of the sealing ring. The inner walls of the lifting ring and the rubber pad are slidably connected to the outer wall of the inner sleeve in the vertical direction, which facilitates improving the sealing strength of the sealing ring.

[0008] Preferably, the check valve mechanism further includes two sets of semi-cylinders inserted into the inner wall of the check valve cylinder. The two sets of semi-cylinders can be combined to form a cylindrical structure. The bottom of the check valve cylinder can be threadedly connected to the first threaded sleeve. A communication port is provided on the semi-cylinder, and a swing groove communicating with the bottom end of the communication port is provided inside the semi-cylinder. The sealing ball slides against the inner wall of the swing groove. A connector connected to the sealing ball is provided on the swing shaft, so as to control the sealing ball to swing around the swing shaft along a set path when the guide rod is pulled out, thereby completing the sealing operation of the middle position of the check valve cylinder.

[0009] Preferably, the connector includes a mounting rod fixedly installed on the side of the middle part of the swing shaft, the two ends of the swing shaft are respectively rotatably connected to the semi-cylinder, the side of the sealing ball is fixedly connected to a sleeve tube that slides and fits into the outer wall of the mounting rod, and a tension spring is fixedly connected to the mounting rod and fixedly connected to the outer wall of the sealing ball, so that the sealing ball can move slightly when it enters the position of the communication port, ensuring sealing efficiency.

[0010] Preferably, a fixing ring is fixedly connected inside the semi-cylinder, and a spring-loaded spring fixedly connected to the inner wall of the fixing ring is fixedly connected to the outer wall of the swing shaft, so as to actively push the sealing ball to swing to one side of the communication port.

[0011] Preferably, a rubber sleeve is fixedly connected to the inner wall of the check cylinder, the outer wall of the semi-cylinder abuts against the inner wall of the rubber sleeve, and a locking cap is threaded to the upper side of the check cylinder to facilitate sealing the position between the semi-cylinder and the check cylinder.

[0012] Preferably, the outer wall of the connector is rotatably connected to a second threaded sleeve that is threadedly connected to the adjusting cylinder, so as to facilitate the fixed connection between the connector and the adjusting cylinder.

[0013] Preferably, a sealing gasket is provided between the two sets of semi-cylinders to facilitate sealing the position between the two sets of semi-cylinders.

[0014] Preferably, the upper side of the adjusting cylinder is threaded with a third threaded sleeve, which facilitates the disassembly and replacement of the adjusting ball.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention provides an oilfield wellhead sealing connection structure that solves the problems of insufficient sealing performance and easy introduction of impurities into the oil and gas during the use of existing oilfield wellhead sealing connection structures. The sealing structure utilizes the hydraulic power inside the oilfield to drive the expansion of the airbag ring, which helps to ensure that the inner wall of the sealing ring fits tightly against the outer wall of the polished rod, thereby improving sealing efficiency. When the polished rod is withdrawn, the check valve mechanism controls the sealing ball to swing around the swing axis along a set path to complete the sealing operation at the middle position of the check valve. The swing direction is stable and the sealing performance is excellent, which can improve the sealing performance while reducing the mixing of impurities into the oil and gas. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a partial structural diagram of the sealing structure of the present invention; Figure 3 for Figure 2 Enlarged view of region A in the middle; Figure 4 for Figure 2 Enlarged view of region B in the middle; Figure 5 This is a partial structural diagram of the check valve mechanism of the present invention; Figure 6 for Figure 5 Enlarged view of region C; Figure 7 for Figure 5 Enlarged view of region D in the middle; Figure 8 This is a partial structural exploded view of the check valve mechanism of the present invention; Figure 9 for Figure 8 Enlarged view of region E in the middle.

[0017] In the diagram: 1. Smooth rod; 2. Connector; 3. Connecting cylinder; 4. Airbag ring; 5. Check valve; 6. Sealing ball; 7. Swing shaft; 8. Adjusting cylinder; 9. Adjusting groove; 10. Adjusting ball; 11. Threaded groove; 12. Threaded pipe; 13. Insert pipe; 14. Connecting pipe; 15. First threaded sleeve; 16. Inner sleeve; 17. Top plate; 18. Elastic element; 19. Lifting ring; 20. Rubber pad; 21. Semi-cylinder; 22. Connecting port; 23. Swing groove; 25. Mounting rod; 26. Sleeve pipe; 27. Tension spring; 28. Fixing ring; 29. ​​Clockwork spring; 30. Rubber sleeve; 31. Locking cap; 33. Sealing ring; 34. Second threaded sleeve; 35. Third threaded sleeve. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: Please refer to Figures 1-9The diagram illustrates an oilfield wellhead sealing connection structure, including a polished rod 1, a connector 2, a sealing structure, and a check mechanism. The sealing structure includes a connecting cylinder 3 mounted on the upper side of the connector 2. The connecting cylinder 3 contains an air bladder ring 4 and a sealing ring 33. The sealing structure utilizes hydraulic pressure within the oilfield to inflate the air bladder ring 4, facilitating a tight seal between the inner wall of the sealing ring 33 and the outer wall of the polished rod 1, thus improving sealing efficiency. The check mechanism includes a check cylinder 5 mounted on the upper side of the connecting cylinder 3. The check cylinder 5 contains a sealing ball 6 and a swing shaft 7. When the polished rod 1 is withdrawn, the check mechanism controls the sealing ball 6 to swing around the swing shaft 7 along a predetermined path, thus achieving check valve operation. The sealing operation at the middle position of cylinder 5 includes a sealing structure that also includes an adjusting cylinder 8 installed above the connector 2. The adjusting cylinder 8 has an adjusting groove 9, and an adjusting ball 10 is rotatably connected inside the adjusting groove 9. The adjusting ball 10 has a threaded groove 11. The bottom of the connecting cylinder 3 is rotatably connected to a threaded tube 12 that is threaded to the threaded groove 11. Multiple sets of insertion tubes 13 are evenly distributed on the adjusting ball 10. Multiple sets of connecting tubes 14 that can be inserted into the inner wall of the insertion tubes 13 are fixedly connected inside the connecting cylinder 3. The upper end of the connecting tube 14 is connected to the airbag ring 4. The connecting cylinder 3 is provided with a pressure-increasing component for improving the sealing strength of the sealing ring 33. The pressure-increasing component includes a component that is threaded to the outer wall of the upper end of the connecting cylinder 3. The first threaded sleeve 15 has an inner sleeve 16 rotatably connected to its inner wall. A top plate 17 is fixedly connected to the outer wall of the inner sleeve 16. An elastic element 18 is fixedly connected to the bottom of the top plate 17. The elastic element 18 can be any existing elastic structure, such as a spring, for optimal replacement. A lifting ring 19 is fixedly connected to the bottom of the elastic element 18. A rubber pad 20 is fixedly connected to the bottom of the lifting ring 19. The bottom of the rubber pad 20 abuts against the top of the sealing ring 33. The inner walls of the lifting ring 19 and the rubber pad 20 are slidably connected to the outer wall of the inner sleeve 16 in a vertical direction. During a slight wobbling motion, the guide rod 1 will cause the adjustment ball 10 to swing within the adjustment groove 9. To avoid damage to the guide rod 1 and surrounding accessories, the lifting ring 19 and rubber pad 20 slide downwards under the push of the elastic element 18, and come into contact with and squeeze the upper side of the sealing ring 33, causing the sealing ring 33 to deform to the side, increasing the sealing performance between the sealing ring 33 and the outer wall of the guide rod 1. At the same time, the setting of the elastic element 18 makes the sealing strength relatively stable. When the deformation of the sealing ring 33 is too large, the elastic element 18 is compressed and the rubber pad 20 moves upward, preventing the sealing ring 33 from being over-compressed and affecting its use. In addition, the sealing ring 33 adopts an internal fluid filling design, which makes the sealing ring 33 have good overall extensibility and can be squeezed tightly to fit the outer wall of the guide rod 1, resulting in good sealing performance.

[0020] Example 2: Please refer to Figures 2-9This embodiment further illustrates Embodiment 1. The check valve mechanism shown in the figure also includes two sets of semi-cylinders 21 that are inserted into the inner wall of the check valve cylinder 5. The two sets of semi-cylinders 21 can be combined to form a cylindrical structure. The bottom of the check valve cylinder 5 can be threadedly connected to the first threaded sleeve 15. A communication port 22 is provided on the semi-cylinder 21, and a swing groove 23 communicating with the bottom end of the communication port 22 is provided inside the semi-cylinder 21. The sealing ball 6 slides against the inner wall of the swing groove 23. A connecting member connected to the sealing ball 6 is provided on the swing shaft 7. The connecting member includes a mounting rod 25 fixedly installed on the side of the middle part of the swing shaft 7. The two ends of the swing shaft 7 are respectively rotatably connected to the semi-cylinder 21. A sleeve 26 that slides against the outer wall of the mounting rod 25 is fixedly connected to the side of the sealing ball 6. A tension spring 27 that is fixedly connected to the outer wall of the sealing ball 6 is fixedly connected to the mounting rod 25. A fixed spring 27 is fixedly connected inside the semi-cylinder 21. The outer wall of the fixed ring 28 and the swing shaft 7 is fixedly connected to a spring 29 that is fixedly connected to the inner wall of the fixed ring 28. The inner wall of the check cylinder 5 is fixedly connected to a rubber sleeve 30. The outer wall of the semi-cylinder 21 abuts against the inner wall of the rubber sleeve 30. The upper side of the check cylinder 5 is threaded with a locking cap 31. A sealing gasket is provided between the two sets of semi-cylinders 21. When the polished rod 1 needs to be pulled out, the side wall of the polished rod 1 releases the push on the sealing ball 6. Under the drive of the spring 29, the swing shaft 7 swings to one side of the polished rod 1. The swing shaft 7 drives the mounting rod 25 to make the sleeve 26 and the sealing ball 6 swing synchronously. The sealing ball 6 will swing in the swing groove 23 towards the lower position of the connecting port 22. With the pressure of the oil and gas above and below, it will continue to push the sealing ball 6 into the connecting port 22. During this process, the swing path of the sealing ball 6 is relatively consistent and there will be no deviation.

[0021] Example 3: Please refer to Figures 1-9 This embodiment further illustrates Embodiment 1. The outer wall of the connector 2 in the figure is rotatably connected to a second threaded sleeve 34 that is threadedly connected to the adjusting cylinder 8. The upper side of the adjusting cylinder 8 is threadedly connected to a third threaded sleeve 35. Sealing gaskets are provided between the connector 2 and the adjusting cylinder 8, the adjusting cylinder 8 and the third threaded sleeve 35, the threaded tube 12 and the threaded groove 11, the connecting cylinder 3 and the first threaded sleeve 15, and the first threaded sleeve 15 and the check cylinder 5. The smooth rod 1 passes through the connector 2, the adjusting cylinder 8, the adjusting ball 10, the connecting cylinder 3, the inner sleeve 16, the check pipe, the connecting port 22 and the locking cover 31, and has a certain gap with their inner walls.

[0022] Working principle: The smooth rod 1 passes through the connector 2, the adjusting cylinder 8, the adjusting ball 10, the connecting cylinder 3, the inner sleeve 16, the check pipe, the connecting port 22, and the locking cap 31, and is slidably connected to their inner walls. The adjusting ball 10 is clamped in the adjusting groove 9 by the third threaded sleeve 35. During the slight shaking of the smooth rod 1, the adjusting ball 10 will swing in the adjusting groove 9 to avoid damage to the smooth rod 1 and surrounding accessories. During installation, the connector 2 is connected and fixed to the bottom of the adjusting cylinder 8 by the second threaded sleeve 34. The multiple sets of connecting pipes 14 on the connecting cylinder 3 are inserted into the insertion pipes 13 in the adjusting ball 10, so that the bottom end of the connecting pipe 14 is connected to the connector 2 below. The first threaded sleeve 15 is then inserted. Installed above the connecting cylinder 3, the inner sleeve 16 is inserted into the connecting cylinder 3. Under the push of the elastic element 18, the lifting ring 19 and the rubber pad 20 slide downwards and press against the upper side of the sealing ring 33, causing the sealing ring 33 to deform to the side, increasing the sealing performance between the sealing ring 33 and the outer wall of the smooth rod 1. At the same time, the setting of the elastic element 18 makes the sealing strength relatively stable. When the deformation of the sealing ring 33 is too large, the elastic element 18 is compressed and the rubber pad 20 moves upward, avoiding excessive compression of the sealing ring 33 and affecting its use. At the same time, the sealing ring 33 adopts the design of internal fluid filling, which makes the sealing ring 33 have good overall extensibility and can be squeezed tightly to fit the outer wall of the smooth rod 1, resulting in good sealing performance.

[0023] The two sets of semi-cylinders 21 are combined into a cylindrical structure and placed in the rubber sleeve 30 inside the check cylinder 5. At the same time, nuts for spiral compression and fixing are set on both sides of the check cylinder 5. The semi-cylinder 21 structure is fixed by tightening. Then, the locking cover 31 on the top is screwed on to limit the upper end of the check cylinder 5. The device is easy to disassemble and assemble, and it is easy to replace some easily worn parts individually. In use, the oil and gas below are transported to the airbag ring 4 above through the connecting pipe 14, causing the airbag ring 4 to expand and compress the sealing ring 33. The upper part of the sealing ring 33 is subjected to the elastic force of the elastic element 18, so that the upper and lower parts of the sealing ring 33 are subjected to force simultaneously, thereby improving the sealing performance between the sealing ring 33 and the outer wall of the polished rod 1. No external pressure design is required. The sealing efficiency can be improved by relying on the internal pressure of the oil and gas.

[0024] When the guide rod 1 needs to be pulled out, the side wall of the guide rod 1 releases the push on the sealing ball 6. Driven by the spring 29, the swing shaft 7 swings to one side of the guide rod 1. The swing shaft 7 drives the mounting rod 25, causing the sleeve 26 and the sealing ball 6 to swing synchronously. The sealing ball 6 will swing in the swing groove 23 towards the lower position of the connecting port 22. With the pressure of the oil and gas above and below, it will continue to push the sealing ball 6 into the connecting port 22. During this process, the swing path of the sealing ball 6 is relatively consistent and there will be no deviation. At the same time, by setting the sleeve 26 and the tension spring 27, during the process of the sealing ball 6 continuing to slide and squeeze into the connecting port 22, the sleeve 26 will slide slightly relative to the mounting rod 25. The tension spring 27 is stretched, which will not affect the stability of the equipment. When the guide rod 1 is reinserted, the bottom of the guide rod 1 pushes the sealing ball 6 downward to swing down along the swing groove 23 to the bottom position. The path of the sealing ball 6 is consistent throughout the process and there will be no obstruction of the movement of the guide rod 1. At the same time, its anti-return effect is more stable and efficient.

[0025] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0026] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sealing connection structure for oilfield wellheads, characterized in that, include: The bare rod (1) and the connector (2); Also includes: The sealing structure includes a connecting cylinder (3) installed on the upper side of the connector (2). The connecting cylinder (3) is provided with an airbag ring (4) and a sealing ring (33). The sealing structure can use the hydraulic pressure inside the oil field to drive the airbag ring (4) to expand and assist in making the inner wall of the sealing ring (33) fit tightly with the outer wall of the polished rod (1), thereby improving the sealing efficiency. The check mechanism includes a check cylinder (5) installed on the upper side of the connecting cylinder (3). The check cylinder (5) is provided with a sealing ball (6) and a swing shaft (7). The check mechanism can control the sealing ball (6) to swing around the swing shaft (7) along a set path when the light rod (1) is pulled out, so as to complete the sealing operation of the middle position of the check cylinder (5). The sealing structure also includes an adjustment cylinder (8) installed above the connector (2). The adjustment cylinder (8) is provided with an adjustment groove (9). An adjustment ball (10) is rotatably connected in the adjustment groove (9). A threaded groove (11) is provided on the ball (10). A threaded tube (12) that is threaded to the threaded groove (11) is rotatably connected to the bottom of the connecting cylinder (3). Multiple sets of insertion tubes (13) are evenly provided on the ball (10). Multiple sets of connecting tubes (14) that can be inserted into the inner wall of the insertion tube (13) are fixedly connected inside the connecting cylinder (3). The upper end of the connecting tube (14) is connected to the airbag ring (4). A pressure-increasing component for improving the sealing strength of the sealing ring (33) is provided inside the connecting cylinder (3). The pressure-increasing component includes a threaded connection to the outer wall of the upper end of the connecting cylinder (3). A first threaded sleeve (15) is rotatably connected to an inner sleeve (16). A top plate (17) is fixedly connected to the outer wall of the inner sleeve (16). An elastic element (18) is fixedly connected to the bottom of the top plate (17). A lifting ring (19) is fixedly connected to the bottom end of the elastic element (18). A rubber pad (20) is fixedly connected to the bottom of the lifting ring (19). The bottom of the rubber pad (20) abuts against the top of the sealing ring (33). The inner walls of the lifting ring (19) and the rubber pad (20) are perpendicular to the outer wall of the inner sleeve (16) in the vertical direction. The sliding connection, the check mechanism also includes two sets of semi-cylinders (21) that are inserted into the inner wall of the check cylinder (5). The two sets of semi-cylinders (21) can be combined to form a cylindrical structure. The bottom of the check cylinder (5) can be threadedly connected to the first threaded sleeve (15). A communication port (22) is provided on the semi-cylinder (21). A swing groove (23) connected to the bottom end of the communication port (22) is provided in the semi-cylinder (21). The sealing ball (6) slides against the inner wall of the swing groove (23). A connecting piece connected to the sealing ball (6) is provided on the swing shaft (7).

2. The oilfield wellhead sealing connection structure according to claim 1, characterized in that: The connector includes a mounting rod (25) fixedly installed on the side of the middle part of the swing shaft (7). The two ends of the swing shaft (7) are rotatably connected to the semi-cylinder (21). The side of the sealing ball (6) is fixedly connected to a sleeve (26) that slides and fits into the outer wall of the mounting rod (25). The mounting rod (25) is fixedly connected to a tension spring (27) that is fixedly connected to the outer wall of the sealing ball (6).

3. The oilfield wellhead sealing connection structure according to claim 1, characterized in that: A fixed ring (28) is fixedly connected inside the semi-cylinder (21), and a spring spring (29) is fixedly connected to the inner wall of the swing shaft (7).

4. The oilfield wellhead sealing connection structure according to claim 1, characterized in that: The inner wall of the check cylinder (5) is fixedly connected with a rubber sleeve (30), the outer wall of the semi-cylinder (21) is in contact with the inner wall of the rubber sleeve (30), and the upper side of the check cylinder (5) is threaded with a locking cap (31).

5. The oilfield wellhead sealing connection structure according to claim 1, characterized in that: The outer wall of the connector (2) is rotatably connected to a second threaded sleeve (34) that is threadedly connected to the adjusting cylinder (8).

6. The oilfield wellhead sealing connection structure according to claim 1, characterized in that: A sealing gasket is provided between the two sets of semi-cylinders (21).

7. The oilfield wellhead sealing connection structure according to claim 1, characterized in that: The upper side of the adjusting cylinder (8) is threaded with a third threaded sleeve (35).

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