Wellhead casing head for oil production

Abstract

The present application belongs to the technical field of oil exploitation, and particularly relates to a wellhead casing head for oil production, which comprises a casing head main body, a surface casing inserted into the lower end of the casing head main body, a triple sealing assembly arranged between the casing head main body and the surface casing, a hanger arranged on the upper end of the casing head main body, a top thread sealing assembly arranged between the casing head main body and the hanger, and a flat valve assembly arranged on the side surface of the casing head main body. The triple sealing assembly comprises mechanical bite sealing, elastic extrusion sealing and air bag inflation sealing. The triple sealing is independent and complementary to each other. Even if one of the triple sealing fails, the remaining sealing can still ensure the safety of the system, thereby greatly reducing the risk of wellhead leakage.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, and in particular relates to a wellhead casing head for oil production. Background Technology

[0002] In the process of oil extraction, the wellhead casing head is a key component connecting the wellhead and surface equipment. Its sealing performance is directly related to the safety and efficiency of oil production operations. Traditional casing heads have a simple sealing structure, usually using only a single mechanical seal or rubber seal. When the downhole pressure fluctuates greatly or the seals age due to long-term use, the seals are prone to failure, causing wellhead leakage. This not only affects oil production efficiency but may also lead to serious safety accidents.

[0003] For example, Chinese patent application number CN202311018014.1 discloses an oil wellhead casing head, including a casing body assembly. The casing body assembly includes a casing head body, a surface casing, and a technical casing. The surface casing is disposed inside the bottom port of the casing head body. Inside the casing head body, above the surface casing, an upper anti-surge assembly and a lower anti-surge assembly are arranged sequentially from top to bottom. The outside of the technical casing is inserted into the inside of the casing head body and located inside the surface casing. The outside of the technical casing passes through the inside of the upper and lower anti-surge assemblies. However, the disadvantage of this technical solution is that the sealing structure of the oil wellhead casing head is simple, usually using only a single rubber seal. When the downhole pressure fluctuates greatly or the seals age due to long-term use, the seal is prone to failure, causing wellhead leakage. This not only affects oil production efficiency but may also lead to serious safety accidents. Summary of the Invention

[0004] The purpose of this invention is to provide a wellhead casing head for oil production to solve the problems in the prior art. The specific technical solution is as follows:

[0005] A wellhead casing head for oil production includes a casing head body, a surface casing inserted into the lower end of the casing head body, a triple sealing assembly between the casing head body and the surface casing, a hanger installed at the upper end of the casing head body, a top screw sealing assembly between the casing head body and the hanger, and a flat valve assembly installed on the side of the casing head body.

[0006] Furthermore, the lower end of the sleeve head body is fixedly connected to the support base via a bracket, the flat valve assembly is connected to the side pipe, and a pressure gauge is installed on the side pipe.

[0007] Furthermore, the triple sealing assembly includes an outer pressure block and a locking screw. The outer pressure block and the locking screw are rotatably connected. The lower end of the locking screw is threaded into the sleeve head body. The inclined surface of the outer pressure block presses against the inclined surface of the inner pressure block. Engaging teeth are provided between the inner pressure block and the surface sleeve. A right-angle sealing gasket is provided at the upper end of the inner pressure block. One end of the right-angle sealing gasket is pressed between the inner pressure block and the surface sleeve, and the other end of the right-angle sealing gasket is pressed between the inner pressure block and the sleeve head body.

[0008] Furthermore, the lower end of the locking screw abuts against one end of the piston rod, the piston rod is slidably disposed within the sleeve head body, the other end of the piston rod is slidably connected to the piston plate, the piston plate is slidably disposed within the cavity provided in the sleeve head body, the piston rod is fixedly connected to the spring support plate, and a spring is provided between the spring support plate and the piston plate.

[0009] Furthermore, the cavity is connected to the airbag through a connecting pipe. The airbag is fixed in an annular groove provided inside the main body of the sleeve head. The airbag is inflated and squeezed against the outer wall of the surface sleeve. A sealing gasket is provided between the upper end of the surface sleeve and the main body of the sleeve head.

[0010] Furthermore, the set screw sealing assembly includes an annular pressure block, which is slidably connected to the outside of the hanger. The lower end of the hanger abuts against the inside of the sleeve head body. A spring is provided between the annular pressure block and the hanger. A technical sleeve is fixed inside the hanger. A flange is fixed to the upper end of the sleeve head body. Four sleeves are equidistantly fixed in the circumferential direction inside the flange. Four set screws are threaded into the four sleeves respectively. All four set screws are slidably connected to the flange. The front ends of the four set screws are slidably connected to the annular pressure block.

[0011] Furthermore, the lower end of the annular pressure block is pressed against the upper end of the upper sealing block, the upper sealing block is pressed against the inner wall of the sleeve head body, the inclined surface of the upper sealing block is slidably connected to the inclined surface of the lower sealing block, the lower sealing block is pressed against the hanger, and an inclined groove is provided at the connection between the upper sealing block and the lower sealing block, and a sealing ring is provided in the inclined groove.

[0012] Furthermore, a right-angle sealing gasket is provided on the outer side of the upper sealing block. One end of the right-angle sealing gasket is pressed between the upper sealing block and the annular pressure block, and the other end of the right-angle sealing gasket is pressed between the upper sealing block and the sleeve head body. A right-angle sealing gasket is provided between the lower sealing block and the hanger, and two sealing rings are provided between the hanger and the sleeve head body.

[0013] Furthermore, the flat valve assembly includes a valve body, which is fixed to the side of the sleeve head body. The upper end of the valve body is fixedly connected to the valve cover, and a sealing gasket is provided between the valve body and the valve cover. The lower end of the valve body is fixedly connected to the base, and a sealing gasket is provided between the valve body and the base. Two valve seats are provided inside the valve body, and a sealing gasket is provided between each of the two valve seats and the valve body. Both valve seats are slidably connected to the valve plate. The valve plate is rotatably connected to one end of the valve stem, and the other end of the valve stem is fixedly connected to the handwheel. The valve stem is threadedly connected to the valve cover, and a valve seat support assembly is slidably connected inside the valve body.

[0014] Furthermore, the valve seat support assembly includes a support plate, which slides within a groove 1 inside the valve body. The front end of the support plate abuts against an annular groove on the valve seat. A push rod is slidably connected inside the support plate. An equilateral triangular protrusion is fixed on the push rod, and an inverted triangular protrusion is fixed on the valve seat. The equilateral triangular protrusion and the inverted triangular protrusion are slidably connected. The upper end of the push rod is inserted into a socket inside the valve body. A second groove is provided inside the support plate, and a boss on the push rod slides within the second groove. A third spring is provided between the support plate and the boss. A connecting frame is fixed to the end of the push rod, and the connecting frame is fixed between the valve body and the base.

[0015] The advantages of this invention are:

[0016] This application sets up a triple sealing assembly between the casing head body and the surface casing, which includes a mechanical interlocking seal, an elastic compression seal and a gasbag expansion seal. The three seals are independent of each other and complement each other. Even if one seal fails, the remaining seals can still ensure system safety and greatly reduce the risk of wellhead leakage.

[0017] Triple sealing can be achieved simultaneously by tightening the locking screws, which simplifies the installation process, reduces the workload of on-site operators, ensures the consistency of sealing effect, and avoids fluctuations in sealing quality caused by differences in human operation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the main structure of the sleeve head of the present invention. Figure 1 ;

[0020] Figure 3 This is a schematic diagram of the main structure of the sleeve head of the present invention. Figure 2 ;

[0021] Figure 4 for Figure 3 Enlarged view of a portion of point A in the middle;

[0022] Figure 5 for Figure 3 Enlarged view of a section at point B in the middle;

[0023] Figure 6 This is an exploded view of the flat plate valve assembly structure of the present invention;

[0024] Figure 7 This is a schematic diagram of the flat plate valve assembly structure of the present invention. Figure 1 ;

[0025] Figure 8 This is a schematic diagram of the flat plate valve assembly structure of the present invention. Figure 2 ;

[0026] Figure 9 This is a schematic diagram of the valve body structure of the present invention;

[0027] Figure 10 This is a schematic diagram of the valve seat support assembly structure of the present invention. Figure 1 ;

[0028] Figure 11 This is a schematic diagram of the valve seat support assembly structure of the present invention. Figure 2 ;

[0029] Figure 12 This is a schematic diagram of the valve seat support assembly structure of the present invention. Figure 3 ;

[0030] Explanation of markings in the diagram:

[0031] 1. Sleeve head body; 2. Bracket; 3. Support seat; 4. Surface sleeve; 5. Locking screw; 6. Outer pressure block; 7. Inner pressure block; 8. Right angle sealing gasket one; 9. Piston rod; 10. Cavity; 11. Spring support plate; 12. Spring one; 13. Piston plate; 14. Connecting pipe; 15. Airbag; 16. Sealing flat gasket one; 17. Flange; 18. Sleeve; 19. Set screw; 20. Technical sleeve; 21. Hanger; 22. Annular pressure block; 23. Spring two; 24. Upper sealing block; 25. Right angle sealing gasket two; 26. Lower sealing block; 27. Right angle sealing gasket three; 28. Sealing ring 1; 29. ​​Sealing ring 2; 30. Valve body; 31. Sealing gasket 2; 32. Valve cover; 33. Valve stem; 34. Handwheel; 35. Valve plate; 36. Valve seat support assembly; 3601. Support plate; 3602. Connecting bracket; 3603. Push rod; 3604. Right triangle protrusion; 3605. Boss; 3606. Spring 3; 3607. Slide groove 2; 37. Sealing gasket 3; 38. Base; 39. Pressure gauge; 40. Slide groove 1; 41. Insertion hole; 42. Valve seat; 43. Inverted triangle protrusion; 44. Annular groove; 45. Sealing gasket 4. Detailed Implementation

[0032] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0033] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] Example 1: As Figures 1-12 As shown, an oil wellhead casing head includes a casing head body 1, a surface casing 4 inserted into the lower end of the casing head body 1, a triple sealing assembly between the casing head body 1 and the surface casing 4, a hanger 21 installed at the upper end of the casing head body 1, a top screw sealing assembly between the casing head body 1 and the hanger 21, and a flat valve assembly installed on the side of the casing head body 1.

[0035] The working principle of the above technical solution is as follows: a triple sealing assembly is provided between the main body 1 of the casing head and the outer casing 4. The triple seals are independent of each other and complement each other. Even if one of the seals fails, the remaining seals can still ensure the safety of the system. A top screw sealing assembly is provided between the main body 1 of the casing head and the hanger 21. The top screw sealing assembly adopts a multi-point sealing structure design to maintain the sealing effect between the hanger 21 and the main body 1 of the casing head and prevent fluid leakage.

[0036] Example 2: Figures 1-12 As shown, the lower end of the sleeve head body 1 is fixedly connected to the support base 3 through the bracket 2, the flat valve assembly is connected to the side pipe, and a pressure gauge 39 is installed on the side pipe;

[0037] The working principle of the above technical solution is as follows: the casing head body 1 can be installed and fixed to the wellhead through the support seat 3 to ensure the stability of the oil wellhead casing head during operation and prevent it from shaking easily. The pressure gauge 39 can display the fluid pressure inside the casing head body 1.

[0038] Example 3: Figures 1-12 As shown, the triple sealing assembly includes an outer pressure block 6 and a locking screw 5. The outer pressure block 6 and the locking screw 5 are rotatably connected. The lower end of the locking screw 5 is threaded into the sleeve head body 1. The inclined surface of the outer pressure block 6 presses against the inclined surface of the inner pressure block 7. There are interlocking teeth between the inner pressure block 7 and the outer sleeve 4. A right-angle sealing gasket 8 is provided at the upper end of the inner pressure block 7. One end of the right-angle sealing gasket 8 is pressed between the inner pressure block 7 and the outer sleeve 4, and the other end of the right-angle sealing gasket 8 is pressed between the inner pressure block 7 and the sleeve head body 1.

[0039] The lower end of the locking screw 5 abuts against one end of the piston rod 9. The piston rod 9 is slidably disposed in the sleeve head body 1. The other end of the piston rod 9 is slidably connected to the piston plate 13. The piston plate 13 is slidably disposed in the cavity 10 provided in the sleeve head body 1. The piston rod 9 is fixedly connected to the spring support plate 11. A spring 12 is provided between the spring support plate 11 and the piston plate 13.

[0040] The cavity 10 is connected to the airbag 15 through the connecting pipe 14. The airbag 15 is fixed in the annular groove provided in the sleeve head body 1. The airbag 15 is inflated and squeezed on the outer wall of the surface sleeve 4. A sealing gasket 16 is provided between the upper end of the surface sleeve 4 and the sleeve head body 1.

[0041] The working principle of the above technical solution is as follows: When the locking screw 5 is rotated and pressed up, the inclined surface of the outer pressure block 6 presses against the inclined surface of the inner pressure block 7, causing the inner pressure block 7 to move towards the surface sleeve 4, so that the inner pressure block 7 generates two forces in the radial and axial directions towards the surface sleeve 4. The inner pressure block 7 presses one end of the right angle sealing gasket 8 tightly against the surface sleeve 4, and the inner pressure block 7 presses the other end of the right angle sealing gasket 8 tightly against the sleeve head body 1, forming the first seal.

[0042] The lower end of the locking screw 5 abuts against the piston rod 9, pushing the piston rod 9 and the piston plate 13 to move in the cavity 10. The cavity 10 inflates the airbag 15 through the connecting pipe 14, causing the airbag 15 to expand and tightly press against the outer wall of the outer sleeve 4, forming a second seal.

[0043] The inner pressure block 7 drives the outer sleeve 4 to move upward through the meshing teeth, and the upper end of the outer sleeve 4 is pressed tightly on the sealing gasket 16 to form a third seal.

[0044] The three seals are independent yet complementary to each other. Even if one seal fails, the remaining seals can still ensure system safety.

[0045] In the second sealing, when the air pressure inside the airbag 15 exceeds the preset value, the piston plate 13 will no longer move. When the locking screw 5 continues to press up, the front end of the locking screw 5 squeezes the cavity 10 and the spring support plate 11 to continue moving upward. The front end of the piston rod 9 slides between the piston plate 13 and the piston rod 12, which compresses the spring 12 and plays a buffering role, preventing the locking screw 5 from being over-screwed, which could cause the piston rod 9 to bend or the airbag 15 to burst.

[0046] It is easy to operate, and triple sealing effect can be achieved by simply tightening the locking screw 5, which greatly reduces the risk of wellhead leakage;

[0047] In addition, the design of the triple sealing components forms a triple protection mechanism of mechanical interlocking, elastic compression and airbag expansion. Even under extreme working conditions, if a single seal fails, the remaining seals can still work effectively, greatly reducing the risk of wellhead leakage.

[0048] Example 4: Figures 1-12 As shown, the set screw sealing assembly includes an annular pressure block 22, which is slidably connected to the outside of the hanger 21. The lower end of the hanger 21 abuts against the inside of the sleeve head body 1. A spring 23 is provided between the annular pressure block 22 and the hanger 21. A technical sleeve 20 is fixed inside the hanger 21. A flange 17 is fixed to the upper end of the sleeve head body 1. Four sleeves 18 are equidistantly fixed in the circumferential direction inside the flange 17. Four set screws 19 are threadedly connected to the four sleeves 18 respectively. All four set screws 19 are slidably connected to the flange 17. The front ends of all four set screws 19 are slidably connected to the annular pressure block 22.

[0049] The lower end of the annular pressure block 22 is pressed against the upper end of the upper sealing block 24, the upper sealing block 24 is pressed against the inner wall of the sleeve head body 1, the inclined surface of the upper sealing block 24 is slidably connected to the inclined surface of the lower sealing block 26, the lower sealing block 26 is pressed against the hanger 21, and an inclined groove is provided at the connection between the upper sealing block 24 and the lower sealing block 26, and a sealing ring 28 is provided in the inclined groove.

[0050] The upper sealing block 24 is provided with a right-angle sealing gasket 25 on its outer side. One end of the right-angle sealing gasket 25 is pressed between the upper sealing block 24 and the annular pressure block 22, and the other end of the right-angle sealing gasket 25 is pressed between the upper sealing block 24 and the sleeve head body 1. A right-angle sealing gasket 27 is provided between the lower sealing block 26 and the hanger 21. Two sealing rings 29 are provided between the hanger 21 and the sleeve head body 1.

[0051] The working principle of the above technical solution is as follows: The hanger 21 is placed inside the sleeve head body 1, and the lower end of the hanger 21 abuts against the protruding edge inside the sleeve head body 1. The four set screws 19 are rotated, and the set screws 19 are pushed inward through the sleeve 18 inside the flange 17. The front end of the set screw 19 pushes the annular pressure block 22 to move downward, which causes the spring 23 to be compressed. The annular pressure block 22 squeezes the upper sealing block 24 to move downward. The inclined surface of the upper sealing block 24 interacts with the inclined surface of the lower sealing block 26, so that the upper sealing block 24 is tightly attached to the sleeve head body 1 through the right angle sealing gasket 25, and the lower sealing block 26 is tightly attached to the hanger 21 through the right angle sealing gasket 3 27. The upper sealing block 24 and the lower sealing block 26 are sealed by the sealing ring 28. The three-point sealing of the right angle sealing gasket 25, the right angle sealing gasket 3 27 and the sealing ring 28 maintains the sealing effect between the hanger 21 and the sleeve head body 1.

[0052] The spring 23 and multi-point sealing structure design in the top screw sealing assembly enable the system to automatically adapt to changes in wellhead pressure. When the pressure fluctuates in the well, the sealing assembly can automatically adjust the pressure distribution to avoid sealing failure caused by local overpressure, significantly extending the service life of the casing head and reducing maintenance frequency and costs.

[0053] Example 5: Figures 1-12As shown, the flat valve assembly includes a valve body 30, which is fixed to the side of the sleeve head body 1. The upper end of the valve body 30 is fixedly connected to the valve cover 32. A sealing gasket 2 31 is provided between the valve body 30 and the valve cover 32. The lower end of the valve body 30 is fixedly connected to the base 38. A sealing gasket 37 is provided between the valve body 30 and the base 38. Two valve seats 42 are provided inside the valve body 30. A sealing gasket 45 is provided between each of the two valve seats 42 and the valve body 30. Both valve seats 42 are slidably connected to the valve plate 35. The valve plate 35 is rotatably connected to one end of the valve stem 33. The other end of the valve stem 33 is fixedly connected to the handwheel 34. The valve stem 33 is threadedly connected to the valve cover 32. A valve seat support assembly 36 is slidably connected inside the valve body 30.

[0054] The valve seat support assembly 36 includes a support plate 3601, which slides within a first groove 40 in the valve body 30. The front end of the support plate 3601 abuts against an annular groove 44 on the valve seat 42. A push rod 3603 is slidably connected within the support plate 3601. An equilateral triangular protrusion 3604 is fixed on the push rod 3603, and an inverted triangular protrusion 43 is fixed on the valve seat 42. The equilateral triangular protrusion 3604 and the inverted triangular protrusion 43 are slidably connected. The upper end of the push rod 3603 is inserted into an insertion hole 41 in the valve body 30. A second groove 3607 is provided within the support plate 3601, and a boss 3605 on the push rod 3603 slides within the second groove 3607. A third spring 3606 is provided between the support plate 3601 and the boss 3605. A connecting frame 3602 is fixed to the end of the push rod 3603, and the connecting frame 3602 is fixed between the valve body 30 and the base 38.

[0055] The working principle of the above technical solution is as follows: When the handwheel 34 is turned, the valve stem 33 rotates and drives the valve plate 35 to move, thereby realizing the opening and closing of the valve. The sealing gasket 2 31 increases the sealing between the valve body 30 and the valve cover 32, and the sealing gasket 37 increases the sealing between the valve body 30 and the base 38.

[0056] When the valve seat 42 is worn and needs to be replaced, the base 38 is removed from the bottom of the sleeve head body 1, the connecting bracket 3602 is pulled outward, and the two sets of push rods 3603 are moved outward. The boss 3605 slides in the second slide groove 3607 and abuts against the inner wall of the second slide groove 3607. When the push rod 3603 moves outward, it drives the support plate 3601 to move outward. The valve seat 42 loses the squeezing support of the support plate 3601, and the valve seat 42 can be removed from the valve body 30 for repair or replacement.

[0057] When installing the valve seat 42, place the two available valve seats 42 on the upper ends of the two support plates 3601 respectively. The two support plates 3601 are used to push the two valve seats 42 into the valve body 30. The two support plates 3601 slide inward in the groove 40 of the valve body 30. The front end of the push rod 3603 is inserted into the insertion hole 41. After the valve seat 42 has moved into position, neither the valve seat 42 nor the support plate 3601 can move further. Then, install the base 38 to the bottom of the valve body 30. Because there is a certain gap between the support plate 3601 and the connecting bracket 3602, the base 38 will not move further into the valve body 30. During the locking process, the base 38 presses the push rod 3603 to slide upward in the support plate 3601, and the boss 3605 slides upward in the second slide groove 3607, which causes the spring 3606 to be compressed. The push rod 3603 moves upward, causing the equilateral triangular protrusion 3604 to move upward. The equilateral triangular protrusion 3604 slides with the inclined surface of the inverted triangular protrusion 43. The equilateral triangular protrusion 3604 presses the inverted triangular protrusion 43 to move laterally, which causes the valve seat 42 to move laterally, thereby causing the valve seat 42 to press against the sealing gasket 45, thus increasing the sealing between the valve seat 42 and the valve body 30.

[0058] The valve seat support assembly 36 enables convenient disassembly and installation of the valve seat 42. When the valve seat 42 is worn and needs to be replaced, it is not necessary to replace the entire flat valve assembly. Only the base 38 needs to be removed to replace the valve seat 42 separately, which greatly reduces maintenance costs, shortens downtime, and improves work efficiency.

[0059] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A wellhead casing head for oil production, characterized in that, Includes a casing head body (1), a surface casing (4) is inserted into the lower end of the casing head body (1), a triple sealing assembly is provided between the casing head body (1) and the surface casing (4), a hanger (21) is installed at the upper end of the casing head body (1), a set screw sealing assembly is provided between the casing head body (1) and the hanger (21), and a flat valve assembly is installed on the side of the casing head body (1). The lower end of the sleeve head body (1) is fixedly connected to the support base (3) through the bracket (2), the flat valve assembly is connected to the side pipe, and a pressure gauge (39) is installed on the side pipe. The triple sealing assembly includes an outer pressure block (6) and a locking screw (5). The outer pressure block (6) and the locking screw (5) are rotatably connected. The lower end of the locking screw (5) is threaded into the sleeve head body (1). The inclined surface of the outer pressure block (6) is pressed against the inclined surface of the inner pressure block (7). There are interlocking teeth between the inner pressure block (7) and the surface sleeve (4). The upper end of the inner pressure block (7) is provided with a right angle sealing gasket (8). One end of the right angle sealing gasket (8) is pressed between the inner pressure block (7) and the surface sleeve (4), and the other end of the right angle sealing gasket (8) is pressed between the inner pressure block (7) and the sleeve head body (1). The lower end of the locking screw (5) abuts against one end of the piston rod (9), the piston rod (9) is slidably disposed in the sleeve head body (1), the other end of the piston rod (9) is slidably connected to the piston plate (13), the piston plate (13) is slidably disposed in the cavity (10) provided in the sleeve head body (1), the piston rod (9) is fixedly connected to the spring support plate (11), and a spring (12) is provided between the spring support plate (11) and the piston plate (13). The cavity (10) is connected to the airbag (15) through the connecting pipe (14). The airbag (15) is fixed in the annular groove provided in the sleeve head body (1). The airbag (15) is inflated and squeezed on the outer wall of the surface sleeve (4). A sealing gasket (16) is provided between the upper end of the surface sleeve (4) and the sleeve head body (1). The top screw sealing assembly includes an annular pressure block (22), which is slidably connected to the outside of the hanger (21). The lower end of the hanger (21) abuts against the sleeve head body (1). A spring (23) is provided between the annular pressure block (22) and the hanger (21). A technical sleeve (20) is fixed inside the hanger (21). A flange (17) is fixed at the upper end of the sleeve head body (1). Four sleeves (18) are equidistantly fixed in the circumferential direction inside the flange (17). Four top screws (19) are threadedly connected to the four sleeves (18). All four top screws (19) are slidably connected to the flange (17). The front ends of the four top screws (19) are slidably connected to the annular pressure block (22). When the top screw (19) is pushed inward through the sleeve (18) inside the flange (17), the front end of the top screw (19) pushes the annular pressure block (22) downward. The lower end of the annular pressure block (22) is pressed against the upper end of the upper sealing block (24), the upper sealing block (24) is pressed against the inner wall of the sleeve head body (1), the inclined surface of the upper sealing block (24) is slidably connected to the inclined surface of the lower sealing block (26), the lower sealing block (26) is pressed against the hanger (21), and an inclined groove is provided at the connection between the upper sealing block (24) and the lower sealing block (26), and a sealing ring (28) is provided in the inclined groove. The upper sealing block (24) is provided with a right-angle sealing gasket two (25) on the outside. One end of the right-angle sealing gasket two (25) is pressed between the upper sealing block (24) and the annular pressure block (22), and the other end of the right-angle sealing gasket two (25) is pressed between the upper sealing block (24) and the sleeve head body (1). A right-angle sealing gasket three (27) is provided between the lower sealing block (26) and the hanger (21). Two sealing rings two (29) are provided between the hanger (21) and the sleeve head body (1).

2. The wellhead casing head for oil production according to claim 1, characterized in that, The flat valve assembly includes a valve body (30), which is fixed to the side of the sleeve head body (1). The upper end of the valve body (30) is fixedly connected to the valve cover (32). A sealing gasket two (31) is provided between the valve body (30) and the valve cover (32). The lower end of the valve body (30) is fixedly connected to the base (38). A sealing gasket three (37) is provided between the valve body (30) and the base (38). Two valve seats (42) are provided inside the valve body (30). A sealing gasket four (45) is provided between the two valve seats (42) and the valve body (30). Both valve seats (42) are slidably connected to the valve plate (35). The valve plate (35) is rotatably connected to one end of the valve stem (33). The other end of the valve stem (33) is fixedly connected to the handwheel (34). The valve stem (33) is threadedly connected to the valve cover (32). A valve seat support assembly (36) is slidably connected inside the valve body (30).

3. The wellhead casing head for oil production according to claim 2, characterized in that, The valve seat support assembly (36) includes a support plate (3601), which slides in a groove (40) provided in the valve body (30). The front end of the support plate (3601) abuts against an annular groove (44) provided on the valve seat (42). A push rod (3603) is slidably connected in the support plate (3601). An equilateral triangular protrusion (3604) is fixed on the push rod (3603), and an inverted triangular protrusion (43) is fixed on the valve seat (42). The equilateral triangular protrusion (3604) and the inverted triangular protrusion (43) are connected in a tandem. The push rod (3603) is slidably connected. The upper end of the push rod (3603) is inserted into the insertion hole (41) provided in the valve body (30). The support plate (3601) is provided with a second sliding groove (3607). The boss (3605) provided on the push rod (3603) slides in the second sliding groove (3607). A third spring (3606) is provided between the support plate (3601) and the boss (3605). A connecting frame (3602) is fixed at the end of the push rod (3603). The connecting frame (3602) is fixed between the valve body (30) and the base (38).

Images