An oil pumping well head polish rod sealer for deep sea oil exploitation

Abstract

The present application relates to pumping unit polish rod seal field, disclose a kind of for deep sea oil exploitation pumping unit wellhead polish rod seal ware, including for with wellhead equipment fixed connection fixed casing and the polish rod of penetrating fixed casing, the polish rod is located on the outer wall in fixed casing and is equipped with multistage sealing assembly, by setting multistage sealing assembly effectively disperses the friction stroke in the process of polish rod up and down movement, so that the friction stroke of single friction pair is greatly reduced compared with the overall movement stroke of polish rod, to greatly reduce the wear rate of annular seal ring, and there is no relative movement between polish rod and annular seal ring in the whole process, will not cause abrasion to polish rod, effectively prolongs the service life of annular seal ring and polish rod.

Description

Technical Field

[0001] This invention relates to the field of polished rod sealing technology for oil pumping units, and particularly to a polished rod seal for wellheads of oil pumping units used in deep-sea oil extraction. Background Technology

[0002] Besides flowing wells, most oilfield production relies on reciprocating pumping units. During operation, the polished rod connects the suspension cable and the sucker rod string, driving the pump piston in a reciprocating motion. The resulting high pressure pumps oil to the surface, where it is transported via pipelines to the gathering and distribution station. During this reciprocating motion, the polished rod slides against the wellhead assembly. If gaps develop in these sliding surfaces, pressurized oil can leak out, causing environmental pollution and oil waste. Therefore, high-performance polished rod seals are essential for effective oil extraction.

[0003] Currently, the polished rod seals at the wellhead of pumping units typically use rubber rings, asbestos rings, or other packing materials for internal sealing. To ensure reliable sealing, axial compression is applied to the packing material, causing radial deformation and forcing it against the polished rod surface to achieve a seal. Since the relative travel between the polished rod and the packing material is equal to the vertical travel of the polished rod, and the vertical travel of the polished rod is usually quite long (typically 3-4 meters), sliding at a high speed of 5-15 reciprocating strokes per minute, the sealing material wears rapidly, shortening its lifespan (usually only 15-30 days). Furthermore, friction between the packing material and the polished rod generates a large amount of heat, keeping both the polished rod and the packing material in contact with it at high temperatures for extended periods, accelerating the aging of the packing material. This results in reduced sealing effectiveness or complete loss of sealing performance, necessitating frequent packing material replacement to maintain an effective seal. Moreover, untimely replacement can lead to oil and gas leaks, causing energy loss and environmental pollution. During packing material replacement, the polished rod must be shut down, which is both labor-intensive and time-consuming. Summary of the Invention

[0004] The purpose of this invention is to provide a polished rod seal for wellheads of pumping units used in deep-sea oil extraction. By setting up a multi-stage sealing assembly, the frictional stroke during the up-and-down movement of the polished rod is effectively dispersed, so that the frictional stroke of a single friction pair is greatly reduced compared to the overall movement stroke of the polished rod. This greatly reduces the wear rate of the annular seal ring. Moreover, there is no relative movement between the polished rod and the annular seal ring during the entire process, so it will not cause wear to the polished rod, effectively extending the service life of the annular seal ring and the polished rod.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A wellhead polished rod seal for deep-sea oil extraction includes a fixed housing for fixed connection with wellhead equipment and a polished rod penetrating the fixed housing. A multi-stage sealing assembly is fitted onto the outer wall of the polished rod within the fixed housing. The multi-stage sealing assembly includes multiple sealing sleeves coaxially arranged with the polished rod. These sealing sleeves are interconnected from the inside out, with the innermost sealing sleeve fitting onto the outer wall of the polished rod. Annular sealing grooves are provided on the inner walls of both the fixed housing and each sealing sleeve. Annular sealing rings are fixedly installed on the outer walls of both the polished rod and each sealing sleeve. These annular sealing rings are located within annular sealing grooves on the inner walls of the sealing sleeves or fixed housing that are axially fitted to them. The outer walls of each annular sealing ring abut against the side walls of the annular sealing grooves. The axial dimension of each annular sealing ring is larger than the axial dimension of the annular sealing groove.

[0007] By adopting the above technical solution, when the polished rod moves axially, the first-stage annular sealing ring fixed to its outer wall slides from one end of the annular sealing groove of its corresponding sealing sleeve to the other end (stroke L1), and then drives its corresponding sealing sleeve to move synchronously. The second-stage annular sealing ring on the outer wall of its corresponding sealing sleeve begins to slide in its corresponding lower-stage annular sealing groove (stroke L2), and so on, until it is transmitted to the Nth-stage sealing unit (i.e., the sealing sleeve to which the annular sealing ring of the annular sealing groove on the inner wall of the fixed housing is fixed). When all levels of annular sealing rings have completed the full sliding within the groove, the single movement stroke of the polished rod ends (total stroke L = ∑L). n Each annular seal only bears the local friction within its corresponding annular sealing groove (L). n The total wear is distributed across N independent friction pairs. The friction stroke of a single friction pair is significantly reduced compared to the overall movement stroke of the polished rod, thereby greatly reducing the wear rate of the annular seal ring in a single friction pair. Furthermore, there is no relative movement between the polished rod and the seal ring during the entire process, which will not cause wear to the polished rod and effectively extend the service life of the annular seal ring and the polished rod.

[0008] A further feature of the present invention is that the outer walls of the optical rod and each sealing sleeve are provided with an annular mounting groove for installing an annular sealing ring, the two ends of the annular sealing ring abut against the upper and lower sides of the annular mounting groove respectively, and the inner wall of the annular sealing ring abuts against the side wall of the annular mounting groove.

[0009] By adopting the above technical solution, each annular sealing ring is fixedly connected to the smooth rod and each sealing sleeve through the annular mounting groove on the outer wall of each sealing sleeve, so that each annular sealing ring is axially fixed relative to the smooth rod and each sealing sleeve. This ensures that during the movement of the smooth rod, the friction pairs formed by each annular sealing ring and each sealing sleeve can move relative to or synchronously, thereby achieving the effect of dispersing the friction stroke. After the two ends of each annular sealing ring abut against the downward sides of the annular sealing groove, an axial compression effect can be formed on the annular sealing ring. After being axially compressed, the inner and outer walls of the annular sealing ring undergo radial deformation, thereby forming a tight fit with the side walls of the annular mounting groove and the annular sealing groove on its corresponding sealing sleeve, which is beneficial to ensuring a good sealing effect.

[0010] A further feature of the present invention is that the multi-stage sealing assembly divides the fixed housing into upper and lower chambers, and the annular sealing grooves on the inner walls of the fixed housing and each sealing sleeve are respectively provided with through holes communicating with the upper and lower chambers of the fixed housing.

[0011] By adopting the above technical solution, during the process of each annular sealing ring in the multi-stage sealing assembly sliding from one end of the annular sealing groove of its respective sealing sleeve to the other end, the space formed between the upper and lower ends of the annular sealing ring and the upper and lower end faces of the annular sealing groove changes in real time. When the upper space increases, the lower space decreases, and when the upper space decreases, the upper space increases. When the space increases, negative pressure is generated, and when the space decreases, positive pressure is generated. Whether it is negative pressure or positive pressure, it will hinder the sliding movement of the annular sealing ring relative to the annular sealing groove. This will not only accelerate the wear of the annular sealing ring, but also increase the driving load of the polished rod. However, by connecting the upper and lower sides of the annular sealing groove to the two chambers through through holes, when a negative pressure is formed in the space formed between the upper and lower ends of the annular sealing ring and the upper and lower end faces of the annular sealing groove, air will be drawn from the chamber connected to it. When a positive pressure is formed in the space formed between the upper and lower ends of the annular sealing ring and the upper and lower end faces of the annular sealing groove, gas will be discharged into the chamber connected to it. This ensures that the pressure in the space formed between the upper and lower ends of the annular sealing ring and the upper and lower end faces of the annular sealing groove is relatively balanced, thereby effectively avoiding the impact of pressure on the movement of the annular sealing ring on its service life and the additional burden on the drive of the polished rod.

[0012] A further provision of the present invention is that a semiconductor cooling chip is embedded in the inner wall of the fixed housing, the cold end of the semiconductor cooling chip is connected to the inner cavity of the fixed housing, and the hot end of the semiconductor cooling chip is connected to the outside of the fixed housing.

[0013] By adopting the above technical solution, the semiconductor cooling chip can continuously cool the internal space of the fixed housing, keeping the upper and lower chambers of the fixed housing at a constant low temperature. This not only cools the optical rod and each sealing sleeve, but also cools the annular sealing ring and the annular sealing groove that rubs against it during gas exchange (intake or exhaust) between the space formed by the upper and lower ends of the annular sealing ring and the upper and lower end faces of the annular sealing groove and the connected chamber. This greatly reduces the aging rate of each component and further improves the service life of the device.

[0014] A further feature of the present invention is that the outer wall of the fixed housing is provided with a plurality of heat dissipation fins, and the heat dissipation fins are connected to the hot end of the semiconductor cooling chip.

[0015] By adopting the above technical solution, the heat dissipation fins can promptly conduct and dissipate the heat from the hot end of the semiconductor cooling chip, ensuring good heat exchange between the inside and outside of the fixed housing.

[0016] A further feature of the present invention is that the fixed housing is provided with a through hole for the light rod to pass through, a ball is embedded in the through hole, the outer wall of the light rod contacts the ball, and the ball rolls in the through hole.

[0017] By adopting the above technical solution, the ball bearings can support the optical rod, making the axial movement stability of the optical rod relative to the fixed housing better. At the same time, the rolling of the ball bearings greatly reduces the friction between the optical rod and the inner wall of the through hole, thereby effectively reducing the energy consumption and wear during optical rod driving, extending the service life of the optical rod, and improving the working efficiency and reliability of the overall device.

[0018] A further feature of the present invention is that the fixed housing is also provided with a dust cover, the dust cover covers the through hole, and a sealing rubber is provided at the connection between the dust cover and the optical rod. The sealing rubber is corrugated and one end of the sealing rubber is fixed to the dust cover, and the other end of the sealing rubber is tightly fitted with the optical rod.

[0019] By adopting the above technical solutions, the dust cover and sealing rubber can effectively block external dust from entering the through hole, thereby preventing dust from wearing the ball bearings and the guide rod. The corrugated tubular sealing rubber can ensure that the guide rod can extend and retract synchronously with the guide rod when it moves, thus ensuring that the sealing rubber has good sealing performance without generating additional friction with the guide rod, further improving the dustproof effect and the durability of the device, and ensuring long-term stable operation.

[0020] A further feature of the present invention is that each of the annular sealing rings is embedded with a metal skeleton.

[0021] By adopting the above technical solution, the metal skeleton can effectively increase the mechanical strength of the annular seal ring, making the annular seal ring more pressure-bearing and effectively reducing the probability of axial deformation caused by frictional resistance during the sliding process of the annular seal ring relative to the annular sealing groove, thus preventing seal failure.

[0022] A further configuration of the present invention is that the metal skeleton includes a rectangular frame and an X-shaped support frame located within the rectangular frame, wherein the four ends of the X-shaped support frame are respectively fixedly connected to the four corners of the rectangular frame.

[0023] By adopting the above technical solution, the rectangular frame and the X-shaped support frame are connected to form four mutually restrictive triangular structures. Therefore, stable support can be provided to the annular seal ring from both ends of the axial direction and from both the inner and outer sides, which further increases the mechanical strength and pressure bearing capacity of the annular seal ring.

[0024] A further feature of the present invention is that both the rectangular frame and the X-shaped support frame are made of rigid materials.

[0025] By adopting the above technical solutions, the rigid material metal skeleton is not easily deformed, ensuring that the metal skeleton structure composed of rectangular frame and X-shaped support frame has better strength and stability.

[0026] The beneficial effects of this invention are:

[0027] 1. In this invention, when the smooth rod moves axially, the first-stage annular sealing ring fixed to its outer wall slides from one end of the annular sealing groove of its corresponding sealing sleeve to the other end (stroke L1), and then drives its corresponding sealing sleeve to move synchronously. The second-stage annular sealing ring on the outer wall of its corresponding sealing sleeve begins to slide in its corresponding lower-stage annular sealing groove (stroke L2), and so on, until it reaches the Nth-stage sealing unit (i.e., the sealing sleeve to which the annular sealing ring of the annular sealing groove on the inner wall of the fixed housing is fixed). When all the annular sealing rings of all stages have completed the full sliding within the groove, the single movement stroke of the smooth rod ends (total stroke L = ∑L). n Each annular seal only bears the local friction within its corresponding annular sealing groove (L). n The total wear is distributed across N independent friction pairs. The friction stroke of a single friction pair is significantly reduced compared to the overall movement stroke of the polished rod, thereby greatly reducing the wear rate of the annular seal ring in a single friction pair. Furthermore, there is no relative movement between the polished rod and the seal ring during the entire process, which will not cause wear to the polished rod and effectively extend the service life of the annular seal ring and the polished rod.

[0028] 2. In this invention, each annular sealing ring is fixedly connected to the smooth rod and the sealing sleeve respectively through the annular mounting groove on the outer wall of each sealing sleeve. This ensures that each annular sealing ring is axially fixed relative to the smooth rod and the sealing sleeve, thereby ensuring that the friction pair formed by each annular sealing ring and the sealing sleeve can move relative to or synchronously during the movement of the smooth rod, thus achieving the effect of dispersing the friction stroke. After the two ends of each annular sealing ring abut against the downward sides of the annular sealing groove, an axial compression effect is formed on the annular sealing ring. After being axially compressed, the inner and outer walls of the annular sealing ring undergo radial deformation, thus forming a tight fit with the side walls of the annular mounting groove and the annular sealing groove on its corresponding sealing sleeve, which helps to ensure a good sealing effect.

[0029] 3. By connecting the upper and lower sides of the annular sealing groove to the two chambers through through holes, when a negative pressure is formed in the space between the upper and lower ends of the annular sealing ring and the upper and lower end faces of the annular sealing groove, air will be drawn from the chambers connected to it. When a positive pressure is formed in the space between the upper and lower ends of the annular sealing ring and the upper and lower end faces of the annular sealing groove, the gas will be discharged into the chambers connected to it. This ensures that the pressure in the space between the upper and lower ends of the annular sealing ring and the upper and lower end faces of the annular sealing groove is relatively balanced, thereby effectively avoiding the impact of pressure on the movement of the annular sealing ring, which would affect its service life and cause additional burden on the drive of the optical rod.

[0030] 4. The semiconductor cooling chip in this invention can continuously reduce the temperature inside the fixed housing, keeping the upper and lower chambers at a constant low temperature. It can not only cool the light rod and each sealing sleeve, but also cool the annular sealing ring and annular sealing groove when the space between its two ends and the annular sealing groove exchanges gas with the upper and lower chambers (inhalation or exhaust) as the annular sealing ring slides up and down. This greatly reduces the aging rate of each component and extends the service life of the device.

[0031] 5. By embedding a metal skeleton within each annular sealing ring, this invention effectively increases the mechanical strength of the annular sealing ring, thereby improving its pressure-bearing capacity and reducing the probability of axial deformation caused by frictional resistance during the sliding process of the annular sealing ring relative to the annular sealing groove, which could lead to sealing failure.

[0032] 6. In this invention, the metal skeleton forms four mutually constraining triangular structures by connecting a rectangular frame and an X-shaped support frame. This provides stable support to the annular sealing ring from both axial ends and the inner and outer sides, further increasing the mechanical strength and pressure-bearing capacity of the annular sealing ring. Moreover, both the rectangular frame and the X-shaped support frame are made of rigid materials, making the metal skeleton less prone to deformation and ensuring better structural strength and stability of the metal skeleton composed of the rectangular frame and the X-shaped support frame. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic cross-sectional view of the wellhead polished rod seal of a pumping unit for deep-sea oil extraction, where each annular sealing ring is located at the lowest end of its respective annular sealing groove.

[0035] Figure 2 This is a schematic cross-sectional view of the wellhead polished rod seal of a pumping unit for deep-sea oil extraction, where each annular sealing ring is located at the uppermost end of its respective annular sealing groove.

[0036] Figure 3 yes Figure 1 A magnified view of part A in the diagram.

[0037] In the diagram, 1. Fixed housing; 2. Smooth rod; 3. Multi-stage sealing assembly; 31. Sealing sleeve; 32. Annular sealing groove; 33. Annular sealing ring; 34. Annular mounting groove; 35. Chamber; 36. Through hole; 4. Semiconductor cooling chip; 41. Cold end; 42. Hot end; 5. Heat dissipation fins; 6. Through hole; 7. Ball bearing; 8. Metal skeleton; 81. Rectangular frame; 82. X-shaped support frame; 9. Dust cover; 10. Sealing rubber. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] like Figures 1-3As shown, a wellhead polished rod seal for deep-sea oil extraction includes a fixed housing 1 for fixed connection with wellhead equipment and a polished rod 2 penetrating the fixed housing 1. A multi-stage sealing assembly 3 is fitted onto the outer wall of the polished rod 2 within the fixed housing 1. The multi-stage sealing assembly 3 includes multiple sealing sleeves 31 coaxially arranged with the polished rod 2. Each sealing sleeve 31 is nested around the others from the inside out, with the innermost sealing sleeve 31 fitted onto the outer wall of the polished rod 2. Annular sealing grooves 32 are provided on the inner walls of the fixed housing 1 and each sealing sleeve 31. Annular sealing rings 33 are fixedly provided on the outer walls of the polished rod 2 and each sealing sleeve 31. The annular sealing rings 33 fixed on the polished rod 2 and each sealing sleeve 31 are respectively located within the annular sealing grooves 32 on the inner wall of the sealing sleeve 31 or the fixed housing 1, which are axially matched with them. The outer wall of each annular sealing ring 33 abuts against the side wall of the annular sealing groove 32. The axial dimension of the annular sealing ring 33 is larger than the axial dimension of the annular sealing groove 32.

[0040] Furthermore, the outer walls of the light rod 2 and each sealing sleeve 31 are provided with annular mounting grooves 34 for installing annular sealing rings 33. The two ends of the annular sealing ring 33 abut against the upper and lower sides of the annular mounting groove 34 respectively, and the inner wall of the annular sealing ring 33 abuts against the side wall of the annular mounting groove 34.

[0041] Furthermore, the multi-stage sealing assembly 3 divides the fixed housing 1 into upper and lower chambers 35, and the annular sealing grooves 32 on the inner walls of the fixed housing 1 and each sealing sleeve 31 are respectively provided with through holes 36 communicating with the upper and lower chambers 35 of the fixed housing 1.

[0042] Furthermore, a semiconductor cooling chip 4 is embedded in the inner wall of the fixed housing 1. The cold end 41 of the semiconductor cooling chip 4 is connected to the inner cavity of the fixed housing 1, and the hot end 42 of the semiconductor cooling chip 4 is connected to the outside of the fixed housing 1.

[0043] Furthermore, the outer wall of the fixed housing 1 is provided with a plurality of heat dissipation fins 5, and the heat dissipation fins 5 are connected to the hot end 42 of the semiconductor cooling chip 4.

[0044] Furthermore, the fixed housing 1 is provided with a through hole 6 for the light rod 2 to pass through, and a ball bearing 7 is embedded in the through hole 6. The outer wall of the light rod 2 contacts the ball bearing 7, and the ball bearing 7 rolls in the through hole 6.

[0045] Furthermore, the fixed housing 1 is also provided with a dust cover 9, which covers the through hole 6. A sealing rubber 10 is provided at the connection between the dust cover 9 and the light rod 2. The sealing rubber 10 is corrugated and one end of the sealing rubber 10 is fixed to the dust cover 9, and the other end of the sealing rubber 10 is tightly fitted with the light rod 2.

[0046] Furthermore, each of the annular sealing rings 33 is embedded with a metal skeleton 8.

[0047] Furthermore, the metal frame 8 includes a rectangular frame 81 and an X-shaped support frame 82 located within the rectangular frame 81, with the four ends of the X-shaped support frame 82 fixedly connected to the four corners of the rectangular frame 81 respectively.

[0048] Furthermore, both the rectangular frame 81 and the X-shaped support frame 82 are made of rigid materials.

[0049] The working principle of this invention: When the guide rod 2 moves axially, the first-stage annular sealing ring 33 fixed to its outer wall slides from one end of the annular sealing groove 32 of its corresponding sealing sleeve 31 to the other end (stroke L1), and then drives its corresponding sealing sleeve 31 to move synchronously. The second-stage annular sealing ring 33 on the outer wall of its corresponding sealing sleeve 31 begins to slide in its corresponding lower-stage annular sealing groove 32 (stroke L2), and is sequentially transmitted to the Nth-stage sealing unit (i.e., the sealing sleeve 31 to which the annular sealing ring 33 of the annular sealing groove 32 on the inner wall of the fixed housing 1 is fixed). When all the annular sealing rings 33 of all stages have completed the full sliding in the groove, the single movement stroke of the guide rod 2 ends (total stroke L=∑L n Each annular sealing ring 33 only bears the local friction (L) within its corresponding annular sealing groove 32. n The total wear is distributed across N independent friction pairs. The friction stroke of a single friction pair is significantly reduced compared to the overall movement stroke of the polished rod 2, thereby greatly reducing the wear rate of the annular seal ring 33 in a single friction pair. Furthermore, there is no relative movement between the polished rod 2 and the seal ring during the entire process, which will not cause wear to the polished rod 2, effectively extending the service life of the annular seal ring 33 and the polished rod 2.

Claims

1. A wellhead polished rod seal for deep-sea oil extraction, characterized in that: The system includes a fixed housing (1) for fixed connection with wellhead equipment and a polished rod (2) penetrating the fixed housing (1). A multi-stage sealing assembly (3) is fitted onto the outer wall of the polished rod (2) within the fixed housing (1). The multi-stage sealing assembly (3) includes multiple sealing sleeves (31) coaxially arranged with the polished rod (2). Each sealing sleeve (31) is connected to the others from the inside out, with the innermost sealing sleeve (31) fitted onto the outer wall of the polished rod (2). The fixed housing (1) and the inner walls of each sealing sleeve (31) are equipped with... There is an annular sealing groove (32). The outer walls of the smooth rod (2) and each sealing sleeve (31) are fixed with an annular sealing ring (33). The annular sealing ring (33) fixed on the smooth rod (2) and each sealing sleeve (31) is located in the annular sealing groove (32) on the inner wall of the sealing sleeve (31) or the fixed housing (1) that is axially matched with it. The outer wall of each annular sealing ring (33) is abutted against the side wall of the annular sealing groove (32). The axial dimension of the annular sealing groove (32) is greater than the axial dimension of the annular sealing ring (33). The multi-stage sealing assembly (3) divides the fixed housing (1) into upper and lower chambers (35). The annular sealing groove (32) on the inner wall of the fixed housing (1) and each sealing sleeve (31) is provided with through holes (36) on the upper and lower sides, respectively, which communicate with the upper and lower chambers (35) of the fixed housing (1).

2. The wellhead polished rod seal for deep-sea oil extraction as described in claim 1, characterized in that: The outer walls of the light rod (2) and each sealing sleeve (31) are provided with annular mounting grooves (34) for installing annular sealing rings (33). The two ends of the annular sealing ring (33) abut against the upper and lower sides of the annular mounting groove (34) respectively, and the inner wall of the annular sealing ring (33) abuts against the side wall of the annular mounting groove (34).

3. The wellhead polished rod seal for deep-sea oil extraction as described in claim 1, characterized in that: A semiconductor cooling chip (4) is embedded on the inner wall of the fixed housing (1). The cold end (41) of the semiconductor cooling chip (4) is connected to the inner cavity of the fixed housing (1), and the hot end (42) of the semiconductor cooling chip (4) is connected to the outside of the fixed housing (1).

4. The wellhead polished rod seal for deep-sea oil extraction as described in claim 3, characterized in that: The outer wall of the fixed housing (1) is provided with a plurality of heat dissipation fins (5), and the heat dissipation fins (5) are connected to the hot end (42) of the semiconductor cooling chip (4).

5. A wellhead polished rod seal for deep-sea oil extraction as described in claim 1, characterized in that: The fixed housing (1) is provided with a through hole (6) for the light rod (2) to pass through. A ball (7) is embedded in the through hole (6). The outer wall of the light rod (2) contacts the ball (7), and the ball (7) rolls in the through hole (6).

6. A wellhead polished rod seal for deep-sea oil extraction according to claim 5, characterized in that: The fixed housing (1) is also provided with a dust cover (9), which covers the through hole (6). The connection between the dust cover (9) and the light rod (2) is provided with a sealing rubber (10). The sealing rubber (10) is corrugated. One end of the sealing rubber (10) is fixed on the dust cover (9), and the other end of the sealing rubber (10) is tightly fitted with the light rod (2).

7. A wellhead polished rod seal for deep-sea oil extraction as described in claim 1, characterized in that: Each of the aforementioned annular sealing rings (33) is fitted with a metal skeleton (8).

8. A wellhead polished rod seal for deep-sea oil extraction according to claim 7, characterized in that: The metal frame (8) includes a rectangular frame (81) and an X-shaped support frame (82) located inside the rectangular frame (81). The four ends of the X-shaped support frame (82) are fixedly connected to the four corners of the rectangular frame (81).

9. A wellhead polished rod seal for deep-sea oil extraction according to claim 8, characterized in that: Both the rectangular frame (81) and the X-shaped support frame (82) are made of rigid materials.

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