Self-adjusting top locking device with sealing casing hanger for ocean wellhead

Abstract

The top locking device comprises a driving ring, a locking ring, a threaded pressing ring, an upper body and a lower body, the inner side of the upper end of the lower body is in threaded connection with the outer side of the lower end of the upper body, and the lower end of the threaded pressing ring is in threaded connection with the corresponding position of the outer side of the upper body. The whole axial clearance self-adjusting function of the locking device is achieved, the bottom of the inner side of the upper end of the threaded pressing ring conducts guiding limiting on a lower end protruding structure of the driving ring, accidental unlocking of the locking ring is avoided, a sealing face is arranged on the upper portion in the upper body, two seals are arranged on the outer portion of the upper body, and bidirectional annular space sealing is achieved. An inverted-L-shaped groove is further formed in the lower side of the inner side of the upper body so that the inverted-L-shaped groove can be in butt joint with an installation tool, installation and recovery of the locking device are facilitated, reliable axial locking is achieved through the whole top locking device of the self-adjusting casing hanger with the sealing function, the integrity of a well mouth can be guaranteed, and the reliability of the ocean well mouth is improved.

Description

Technical Field

[0001] This invention relates to the field of offshore oil production equipment technology. More specifically, this invention relates to a self-adjusting top locking device for a sealing casing hanger at offshore wellheads. Background Technology

[0002] As countries worldwide intensify their exploration of offshore oil and gas, subsea wellhead systems, as key equipment for offshore oil and gas exploration and development, are being used more and more widely. During the development of deep-water oil and gas in the South China Sea, wellhead uplift caused by casing thermal deformation has occurred repeatedly, seriously affecting production safety. Top locking devices are installed on the upper part of the casing hanger to provide additional axial locking force and limit casing axial uplift. However, current top locking devices have fixed connections between components, lack axial adjustment capabilities, and are prone to gaps, affecting the stability of the structural connection. Furthermore, top locking devices are often used in production wellheads and require local annular sealing functionality; the structural locking state and sealing performance both affect the reliability of subsea casing operations in the ocean. Summary of the Invention

[0003] The purpose of this invention is to provide a self-adjusting top locking device for sealing casing hangers in marine wellheads, so as to solve the technical problem of insufficient sealing and locking capacity of existing top locking devices.

[0004] To achieve these objectives and other advantages according to the present invention, a self-adjusting casing hanger top locking device for offshore wellheads is provided, comprising a drive ring, a locking ring, a threaded pressure ring, an upper body, and a lower body. The outer side of the lower end of the lower body is locked to the inner side of the casing hanger. The inner side of the upper end of the lower body is threaded to the outer side of the lower end of the upper body and is also connected to an anti-rotation component. The inner side of the upper end of the upper body is a sealing surface. The threaded pressure ring is sleeved on the outer side of the upper end of the upper body, and the lower end of the threaded pressure ring is threaded to the corresponding position on the outer side of the upper body and together they are connected. The upper anti-loosening structure is provided, and the upper anti-loosening structure is provided on the inner side of the upper end of the threaded pressure ring, forming an annular limiting cavity with the corresponding position on the outer side of the upper body. The thickness of the lower end of the drive ring is set to match the limiting cavity, and the lower end of the drive ring extends downward and outward to form an annular protrusion structure. The protrusion structure can be displaced after being compressed radially. The protrusion structure is connected with the lower anti-loosening structure. The outer side of the drive ring is provided with a conical surface on the upper side of the protrusion structure. The locking ring is fitted onto the conical surface. The outer side of the upper end of the drive ring is used to press down and open the locking ring, and then lock it with the wellhead.

[0005] Preferably, the outer side of the drive ring has a first groove radially inward on the lower side of the conical surface, and an annular support band is fitted into the first groove. The inner side of the threaded pressure ring extends radially inward at the upper end of the limiting cavity to form a groove platform, and the outer side of the support band is located within the extension range of the groove platform in the radial direction.

[0006] Preferably, the conical surface is provided with two segments of the same size at intervals on the outer side of the drive ring, forming a first conical groove and a second conical groove continuously connected on the outer side of the drive ring, respectively. The locking ring can slide up and down in the first conical groove and the second conical groove. The depth of the first conical groove is less than the ring width of the locking ring. When the locking ring is located in the second conical groove, its outer side does not exceed the outer side of the threaded pressure ring. The upper anti-loosening structure is provided with two segments continuously connected on the inner wall of the threaded pressure ring, wherein the upper segment is a sliding groove and the lower segment is a hook groove. The lower end of the protrusion structure is an outwardly oriented hook structure. The hook structure is matched with the upper end of the hook groove and can slide up and down along the sliding groove. In the axial direction, the dimensions of the hook groove and the sliding groove are matched with the dimensions of the first conical groove and the second conical groove.

[0007] Preferably, the lower anti-loosening structure includes a plurality of threaded through holes opened circumferentially on the outer surface of the threaded pressure ring, and anti-loosening screws are screwed into the threaded through holes.

[0008] Preferably, the outer diameter of the upper end of the upper body is larger than the outer diameter of the lower end, so as to form a radial limiting step surface between the upper and lower ends of the upper body. The upper end of the upper body is divided vertically upward into a sealing section and an installation section for connecting the threaded pressure ring. The outer diameter of the sealing section is larger than the outer diameter of the installation section. The lower end of the threaded pressure ring is threadedly connected to the lower end of the installation section.

[0009] Preferably, two seals are provided on the outer side of the sealing section. The upper outer side of the sealing section is provided with an open sealing groove for installing a cup-type sealing ring to form a first seal at the bottom of the threaded pressure ring. The lower outer side of the sealing section is provided with a closed sealing groove for installing an S-type sealing ring to form a second seal.

[0010] Preferably, the lower inner side of the upper body is provided with an inverted L-shaped groove for cooperating with the transmission block of the installation tool. The inverted L-shaped grooves are symmetrically distributed along 180 degrees. The upper body has a return flow hole through the top of the vertical section of the inverted L-shaped groove in an outward and downward direction. The top of the outer port of the return flow hole extends to the limiting step surface.

[0011] Preferably, the anti-rotation component includes a stop ring, which is a ring-shaped split structure. The stop ring is sleeved and connected to the lower outer side of the lower body and is located near the limiting step surface. The bottom surface of the stop ring is used to abut against the top surface of the lower body. The side of the stop ring is provided with multiple backflow grooves for alignment with the backflow hole. Multiple first shear pin holes are provided circumferentially on the stop ring. An upper first shear pin is embedded in the first shear pin hole. The outer diameter of the head end of the first shear pin is larger than the outer diameter of the tail end. A set screw is also installed on the outer side of the head end of the first shear pin to prevent the sheared first shear pin from falling into the well.

[0012] Preferably, a marking groove is provided on the outer side of the upper end of the lower body, corresponding to the return flow groove and parallel to the axial direction. An anti-rotation hole is provided radially through the lower end of the lower body, and an anti-rotation key is installed thereon. The anti-rotation key is used to connect with the anti-rotation groove on the casing hanger. A second shear pin hole is also provided through the lower end of the lower body. An upper second shear pin is inserted through the second shear pin hole. The outer diameter of the tail end of the second shear pin is smaller than the outer diameter of the head end and penetrates into the inner side of the lower body. An annular groove is provided at the tail end of the second shear pin for installing an O-ring to prevent the second shear pin from falling into the well after shearing.

[0013] The present invention has at least the following beneficial effects: The self-adjusting top locking device for a sealing casing hanger for marine wellheads includes a drive ring, a locking ring, a threaded pressure ring, an upper body, and a lower body. The inner upper end of the lower body is threadedly connected to the outer lower end of the upper body, and the lower end of the threaded pressure ring is threadedly connected to the corresponding position on the outer side of the upper body, realizing the overall axial clearance self-adjustment function of the locking device. The bottom inner upper end of the threaded pressure ring guides and limits the lower end protruding structure of the drive ring, preventing the locking ring from being accidentally unlocked. The upper body has a sealing surface on the upper part and two seals on the outside, realizing bidirectional annular sealing. An inverted L-shaped groove is also provided on the lower inner side of the upper body to mate with the installation tool, facilitating the installation and retrieval of the locking device. The entire self-adjusting top locking device for a sealing casing hanger achieves reliable axial locking, ensuring the integrity of the wellhead and improving the reliability of marine wellheads.

[0014] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of the present invention; Figure 2 This is a diagram of the external structure of the present invention; Figure 3 This is an enlarged structural diagram of the present invention at the threaded pressure ring; Figure 4 This is a schematic diagram of the structure of the present invention installed on the sleeve hanger; Figure 5 This is a schematic diagram of the structure of the present invention when the installation tool is inserted into the inner side.

[0016] Explanation of reference numerals in the accompanying drawings: 1. Drive ring, 2. Locking ring, 3. Threaded pressure ring, 4. Upper body, 5. Lower body, 6. Sealing surface, 7. Lower anti-loosening structure, 8. Upper anti-loosening structure, 9. Limiting cavity, 10. Protruding structure, 11. Conical surface, 12. Support band, 13. Anti-loosening screw, 14. Limiting stepped surface, 15. Cup-type sealing ring, 16. S-shaped sealing ring, 17. Inverted L-shaped groove, 18. Return hole, 19. Stop ring, 20. Return groove, 21. First shear pin, 22. Set screw, 23. Marking vertical groove, 24. Anti-rotation key, 25. Second shear pin, 26. Casing hanger, 27. Wellhead, 28. Installation tool. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0018] In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" 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 this invention and 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 this invention.

[0019] like Figure 1-3 As shown, the self-adjusting sealed casing hanger top locking device for marine wellheads of the present invention includes a drive ring 1, a locking ring 2, a threaded pressure ring 3, an upper body 4, and a lower body 5. The lower outer side of the lower body 5 is locked to the inner side of the casing hanger 26. The upper inner side of the lower body 5 is threaded to the lower outer side of the upper body 4 and is also connected to an anti-rotation component. The upper inner side of the upper body 4 is a sealing surface 6. The threaded pressure ring 3 is sleeved on the upper outer side of the upper body 4, and the lower end of the threaded pressure ring 3 is threaded to the corresponding position on the outer side of the upper body 4 and is provided with a lower anti-loosening structure 7. The upper inner side of the ring 3 is provided with an upper anti-loosening structure 8, which forms an annular limiting cavity 9 with the corresponding position on the outer side of the upper body 4. The thickness of the lower end of the drive ring 1 is matched with the limiting cavity 9, and the lower end of the drive ring 1 extends downward and outward to form an annular protrusion structure 10. The protrusion structure 10 can be displaced after being pressed radially. The protrusion structure 10 is connected with the lower anti-loosening structure 7. The outer side of the drive ring 1 is provided with a conical surface 11 on the upper side of the protrusion structure 10. The locking ring 2 is fitted onto the conical surface 11. The upper outer side of the drive ring 1 is used to press down and open the locking ring 2, and then lock it with the wellhead 27.

[0020] The drive ring 1 is a ring structure with a conical surface 11 on its outer surface that cooperates with the locking ring 2. The drive ring 1 has an anti-loosening protrusion 10 below it, which achieves axial positioning between the drive ring 1 and the threaded pressure ring 3 and the upper body 4 through the limiting cavity 9.

[0021] The threaded pressure ring 3 is a ring structure with internal threads that engage with the upper thread of the upper body 4. The shape of the upper inner wall matches and limits the movement of the drive ring 1. An upper anti-loosening structure 8 is provided inside to cooperate with the protrusion structure 10 of the drive ring 1. A lower anti-loosening structure 7 is provided between the upper body 4 and the threaded pressure ring 3 with screws.

[0022] The inner side of the upper body 4 is a hollow structure, which is used to rotate and press down with the transmission block of the installation / recovery tool. The outer diameter of the upper end of the lower body 5 is larger than the outer diameter of the lower end of the lower body 5. The outer surface of the upper body 4 is provided with a left-hand thread and screws into the thread on the inner surface of the lower body 5 to eliminate axial clearance. There is a stepped surface above the left-hand thread, and the upper part of the interior is a sealing surface 6.

[0023] A stepped cavity is formed on the inner side of the upper end of the lower body 5 to axially limit the bottom of the upper body 4 upward. The lower section of the stepped cavity has a thread that screws into the upper body 4. An anti-rotation component is provided between the upper end face and the upper body 4 to prevent the upper body 4 from rotating directly relative to the lower body 5.

[0024] The self-adjusting sealing casing top locking device for marine wellheads in this embodiment includes a drive ring 1, a locking ring 2, a threaded pressure ring 3, an upper body 4, and a lower body 5. A limiting cavity 9 is formed between the inner side of the upper end of the threaded pressure ring 3 and the outer side of the upper body 4, which dynamically limits and guides the axial movement of the lower end protrusion 10 of the drive ring 1. A conical surface 11 is provided on the upper side of the protrusion 10 of the drive ring 1, and the locking ring 2 is fitted on it. When the drive ring 1 moves up and down relative to the limiting cavity 9, the drive ring 1 opens the locking ring 2, and the protrusion 10... The structure 10 is compressed by the reverse force of the locking ring 2, causing a radial position change. It extends into the bottom of the limiting cavity 9 to lock and prevent loosening, thus avoiding accidental unlocking of the locking ring 2. The inner side of the upper end of the lower body 5 is threadedly connected to the outer side of the lower end of the upper body 4, and the lower end of the threaded pressure ring 3 is threadedly connected to the corresponding position on the outer side of the upper body 4. They can rotate relative to each other, and the final relative position is determined by setting an anti-rotation component. This achieves the overall axial clearance self-adjustment function of the locking device, realizes reliable axial locking, and improves the reliability of marine operations.

[0025] In another technical solution, such as Figure 1-3 As shown, the outer side of the drive ring 1 has a first groove radially inward on the lower side of the conical surface 11. An annular support band 12 is fitted and installed in the first groove. The inner side of the threaded pressure ring 3 extends radially inward at the upper end of the limiting cavity 9 to form a groove platform. The outer side of the support band 12 is located within the extension range of the groove platform in the radial direction.

[0026] When the protruding structure 10 of the drive ring 1 moves up to the upper part of the limiting cavity 9, the top outer end of the support belt 12 abuts against the bottom of the groove platform, thereby driving the threaded pressure ring 3 to move up when the drive ring 1 moves up, and at the same time driving the upper body 4 and the lower body 5 to move up.

[0027] In another technical solution, such as Figure 1-3 As shown, the conical surface 11 is provided with two segments of the same size on the outer side of the drive ring 1, forming a first conical groove and a second conical groove that are continuous on the outer side of the drive ring 1. The locking ring 2 can slide up and down in the first conical groove and the second conical groove. The depth of the first conical groove is less than the ring width of the locking ring 2. When the locking ring 2 is located in the second conical groove, its outer side does not exceed the outer side of the threaded pressure ring 3. The upper anti-loosening structure 8 is provided with two segments continuously on the inner wall of the threaded pressure ring 3, wherein the upper segment is a sliding groove and the lower segment is a hook groove. The lower end of the protruding structure 10 is a hook-shaped structure that is set outward. The hook-shaped structure is matched with the upper end of the hook groove and can slide up and down along the sliding groove. In the axial direction, the size of the hook groove and the sliding groove are matched with the size of the first conical groove and the second conical groove.

[0028] The conical surface 11 is downward and radially inward. The lower side of the two conical surfaces 11 is connected to a vertical surface to form a first conical groove and a second conical groove that are continuous from top to bottom. When the locking ring 2 is subjected to vertical pressure, it can slide along the conical surface 11, thereby realizing the relative position movement between the locking ring 2 and the drive ring 1. When the locking ring 2 is located in the first conical groove or the second conical groove, the hook-shaped structure is located in the corresponding sliding groove or hook groove to guide the movement or to prevent the drive ring 1 from being accidentally unlocked.

[0029] In another technical solution, such as Figure 1 , 3 As shown, the lower anti-loosening structure 7 includes a plurality of threaded through holes opened circumferentially on the outer surface of the threaded pressure ring 3, and anti-loosening screws 13 are screwed into the threaded through holes.

[0030] Four threaded through holes are opened at intervals on the outer surface of the threaded pressure ring 3, and anti-loosening screws 13 are screwed into them to prevent relative movement between the threaded pressure ring 3 and the upper body 4. Two threaded holes are also provided for rotating the threads.

[0031] In another technical solution, such as Figure 1-3As shown, the outer diameter of the upper end of the upper body 4 is larger than the outer diameter of the lower end, so as to form a radial limiting step surface 14 between the upper and lower ends of the upper body 4. The upper end of the upper body 4 is divided into a sealing section and an installation section for connecting the threaded pressure ring 3 in a vertical upward direction. The outer diameter of the sealing section is larger than the outer diameter of the installation section. The lower end of the threaded pressure ring 3 is threadedly connected to the lower end of the installation section. The sealing section is used to achieve annular sealing to ensure a sealed connection between the bottom of the threaded pressure ring 3 and the upper body 4.

[0032] In another technical solution, such as Figure 1-3 As shown, two seals are provided on the outer side of the sealing section. The upper outer side of the sealing section is provided with an open sealing groove for installing a cup-type sealing ring 15 to form a first seal at the bottom of the threaded pressure ring 3. The lower outer side of the sealing section is provided with a closed sealing groove for installing an S-type sealing ring 16 to form a second seal, thereby achieving bidirectional annular sealing.

[0033] In another technical solution, such as Figure 1 As shown, the lower inner side of the upper body 4 is provided with an inverted L-shaped groove 17 for cooperating with the transmission block of the installation tool 28. The inverted L-shaped groove 17 is symmetrically distributed along 180 degrees. The upper body 4 has a return flow hole 18 extending outward and downward in the top of the vertical section of the inverted L-shaped groove 17. The top of the outer port of the return flow hole 18 extends to the limiting step surface 14. When the transmission block is initially inserted into the upper body 4, it is located in the horizontal groove section. After rotating, it reaches the vertical groove section and then moves downward. This facilitates the rotation and movement guidance operation of the transmission block of the installation tool, and facilitates the rotation of the upper body 4 and lower body 5 of the locking device to align the anti-rotation key into the casing hanger. The anti-rotation key, sealing surface 6, and similar functions of the casing hanger can be found in a locking mechanism for a submersible high-pressure wellhead with patent number ZL202011594674.0.

[0034] In another technical solution, such as Figure 1-3 As shown, the anti-rotation component includes a stop ring 19, which is a ring-shaped split structure. The stop ring 19 is sleeved and connected to the lower outer side of the lower body 5 and is set near the limiting step surface 14. The bottom surface of the stop ring 19 is used to abut against the top surface of the lower body 5. The side of the stop ring 19 is provided with multiple backflow grooves 20 for alignment with the backflow hole 18. Multiple first shear pin holes 21 are provided on the circumferential side of the stop ring 19. Upper first shear pins 21 are embedded in the first shear pin holes. The outer diameter of the head end of the first shear pin 21 is larger than the outer diameter of the tail end. A set screw 22 is also installed on the outer side of the head end of the first shear pin 21 to prevent the sheared first shear pin 21 from falling into the well.

[0035] The first shearing pin 21 is conveniently set on the stop ring 19 to restrict the relative rotation between the upper body 4 and the lower body 5. After shearing, the upper body 4 and the lower body 5 can rotate relative to each other. Then, the locking ring 2 contacts the outer high pressure head mating surface to restrict the continued rotation between the upper body 4 and the lower body 5.

[0036] In another technical solution, such as Figure 1-3 As shown, a marking groove 23 is provided on the outer upper end of the lower body 5, corresponding to the return flow inclined groove 20 and parallel to the axial direction. An anti-rotation key 24 is installed at the lower end of the lower body 5. The anti-rotation key 24 is used to connect with the anti-rotation groove on the casing hanger. A second shear pin 25 hole is also provided through the lower end of the lower body 5. An upper second shear pin 25 is inserted through the second shear pin 25 hole. The outer diameter of the tail end of the second shear pin 25 is smaller than the outer diameter of the head end and penetrates inward into the inner side of the lower body 5. An annular groove is provided at the tail end of the second shear pin 25 for installing an O-ring to prevent the second shear pin 25 from falling into the well after shearing. The second shear pin 25 is used to connect with the installation tool. Before shearing the second shear pin 25, the installation tool drives the lower body 5 to rotate until the anti-rotation key of the lower body 5 connects with the anti-rotation keyway of the casing hanger. After connection, torque is applied to shear the second shear pin 25. The cut part of the second shear pin 25 captured by the installation tool is connected to the installation tool through the O-ring to prevent it from falling into the well.

[0037] The following describes the installation and retrieval process of the top locking device.

[0038] Installation instructions: During connection, the transmission block on the installation tool 28 enters the upper body 4 through the short side of the inverted L-shaped groove 17. The tool rotates a certain angle within the inverted L-shaped groove 17 to cut off the second shearing pin 25 on the corresponding lower body 5. During installation, after the tool rotates 90 degrees within the inverted L-shaped groove 17 of the upper body 4, it cuts off the second shearing pin 25 assembly. At this time, the transmission block on the tool is located on the long side of the inverted L-shaped groove 17 of the upper body 4.

[0039] Using a tool, press down on the drive ring 1. The bottom surface of the locking ring 2 abuts against the top surface of the threaded pressure ring 3. The drive ring 1 moves downward to open the locking ring 2. As it continues to move downward, the annular protrusion 10 on the drive ring 1 contacts the anti-loosening inclined surface at the sliding groove on the inner surface of the threaded pressure ring 3. The annular protrusion 10 on the drive ring 1 gradually compresses radially inward and continues to move downward until the drive ring 1 contacts the hook groove cone surface 11 on the inner wall of the threaded pressure ring 3. At this time, the transmission block on the tool is located in the middle of the inverted L-shaped groove on the upper body.

[0040] At this time, there is still a certain gap between the conical surface 11 on the locking ring 2 and the high-pressure head's mating conical surface 11. The installation tool rotates clockwise, and the transmission block on the tool fits against the vertical long side of the inverted L-shaped groove 17 inside the upper body 4, causing the top locking device to rotate together. After rotating a certain angle, the anti-rotation key assembly on the lower body 5 will fall into the anti-rotation groove of the sleeve hanger. Now the lower body 5 does not rotate. If the torque is increased further, it will shear off the first shearing pin 21 on the upper body 4 and the stop ring 19, thereby causing the upper body 4 and the lower body 5 to rotate relative to each other.

[0041] The upper body 4 and the lower body 5 are directly connected by a left-hand thread. Clockwise rotation will cause the upper body 4 to move upward as a whole until the conical surface 11 of the locking ring 2 contacts the mating surface of the high-pressure head. At this time, the relative rotation of the upper body 4 and the lower body 5 will be restricted, and the top locking device will be installed in place.

[0042] Afterwards, the transmission block on the tool is located inside the inverted L-shaped groove 17 inside the upper body 4, and the long side can be directly lifted to retrieve the tool.

[0043] Recycling Instructions: Pressing down the tool causes the recovery ring on the tool to enter the drive ring 1, and lifting the tool causes the drive ring 1 to move upward, resulting in the locking ring 2 being retracted.

[0044] To prevent the locking ring 2 from failing to retract, the tool will continue to rotate clockwise. At this time, the anti-rotation key on the tool will fall into the vertical long side of the inverted L-shaped groove 17 inside the upper body 4, and continue to drive the upper body 4 to rotate and push out the locking ring 2.

[0045] Then, lift the tool directly, and the recovery ring hooks the drive ring 1. The upper support belt 12 inside the drive ring 1 hooks the threaded pressure ring 3, which drives the entire top locking device to be recovered.

[0046] The invention incorporates a threaded connection structure between its main components, allowing for axial clearance adjustment through threaded rotation. An inverted L-shaped groove 17 is added to the inner side of the upper body 4, facilitating quick docking with the tool transmission block for easy rotation and pressure operation. An internal sealing surface 6 is added for sealing and pressure testing with the underwater production tree isolation sleeve, while an external sealing structure achieves bidirectional annular sealing. An anti-unlocking structure is added between the drive ring 1 and the threaded pressure ring 3 to prevent accidental unlocking of the locking ring 2. Anti-fall-in structures are provided for the first shear pin 21 assembly and the second shear pin 25 assembly. Simultaneously, it functions as an axial limiter for the casing hanger, provides self-adjusting axial clearance, and offers bidirectional annular sealing.

[0047] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. Other modifications can be easily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and the drawings shown and described herein.

Claims

1. A self-adjusting top locking device for a sealing casing hanger in marine wellheads, characterized in that, The device includes a drive ring, a locking ring, a threaded pressure ring, an upper body, and a lower body. The outer side of the lower end of the lower body is locked to the inner side of the casing hanger. The inner side of the upper end of the lower body is threaded to the outer side of the lower end of the upper body and is also connected to an anti-rotation component. The inner side of the upper end of the upper body is a sealing surface. The threaded pressure ring is sleeved on the outer side of the upper body, and the lower end of the threaded pressure ring is threaded to the corresponding position on the outer side of the upper body and is provided with a lower anti-loosening structure. The inner side of the upper end of the threaded pressure ring is provided with an upper anti-loosening structure, which forms an annular limiting cavity with the corresponding position on the outer side of the upper body. The thickness of the lower end of the drive ring is set to match the limiting cavity, and the lower end of the drive ring extends downward and outward to form an annular protrusion structure. The protrusion structure can be displaced after being compressed radially. The protrusion structure is connected to the lower anti-loosening structure. The outer side of the drive ring has a conical surface on the upper side of the protrusion structure, and the locking ring is sleeved on the conical surface. The outer side of the upper end of the drive ring is used to press down and open the locking ring, and then lock it to the wellhead.

2. The self-adjusting top locking device for a sealing casing hanger for offshore wellheads as described in claim 1, characterized in that, The outer side of the drive ring has a first groove radially inward on the lower side of the conical surface. An annular support band is fitted into the first groove. The inner side of the threaded pressure ring extends radially inward at the upper end of the limiting cavity to form a groove platform. The outer side of the support band is located within the extension range of the groove platform in the radial direction.

3. The self-adjusting top locking device for a sealing casing hanger for marine wellheads as described in claim 1, characterized in that, The conical surface is provided with two equal upper and lower sections on the outer side of the drive ring, forming a first conical groove and a second conical groove on the outer side of the drive ring respectively. The locking ring can slide up and down in the first and second conical grooves. The depth of the first conical groove is less than the ring width of the locking ring. When the locking ring is located in the second conical groove, its outer side does not exceed the outer side of the threaded pressure ring. The upper anti-loosening structure is provided with two consecutive upper and lower sections on the inner wall of the threaded pressure ring, wherein the upper section is a sliding groove and the lower section is a hook groove. The lower end of the protruding structure is an outwardly oriented hook structure. The hook structure is matched with the upper end of the hook groove and can slide up and down along the sliding groove. In the axial direction, the dimensions of the hook groove and the sliding groove are matched with the dimensions of the first and second conical grooves.

4. The self-adjusting top locking device for a sealing casing hanger for offshore wellheads as described in claim 1, characterized in that, The lower anti-loosening structure includes multiple threaded through holes opened circumferentially on the outer surface of the threaded pressure ring, and anti-loosening screws are screwed into the threaded through holes.

5. The self-adjusting top locking device for a sealing casing hanger for offshore wellheads as described in claim 1, characterized in that, The outer diameter of the upper end of the upper body is larger than the outer diameter of the lower end, so as to form a radial limiting step surface between the upper and lower ends of the upper body. The upper end of the upper body is divided into a sealing section and an installation section for connecting the threaded pressure ring in a vertical upward direction. The outer diameter of the sealing section is larger than the outer diameter of the installation section. The lower end of the threaded pressure ring is threadedly connected to the lower end of the installation section.

6. The self-adjusting top locking device for a sealing casing hanger for marine wellheads as described in claim 5, characterized in that, Two seals are provided on the outer side of the sealing section. An open sealing groove is provided at the upper outer end of the sealing section for installing a cup-type sealing ring to form a first seal at the bottom of the threaded pressure ring. A closed sealing groove is provided at the lower outer end of the sealing section for installing an S-type sealing ring to form a second seal.

7. The self-adjusting top locking device for a sealing casing hanger for offshore wellheads as described in claim 5, characterized in that, The lower inner side of the upper body is provided with an inverted L-shaped groove for cooperating with the transmission block of the installation tool. The inverted L-shaped grooves are symmetrically distributed along 180 degrees. The upper body has a return flow hole through the top of the vertical section of the inverted L-shaped groove in an outward and downward direction. The top of the outer port of the return flow hole extends to the limiting step surface.

8. The self-adjusting top locking device for a sealing casing hanger for offshore wellheads as described in claim 7, characterized in that, The anti-rotation component includes a stop ring, which is a ring-shaped split structure. The stop ring is sleeved and connected to the lower outer side of the lower body and is located near the limiting step surface. The bottom surface of the stop ring is used to abut against the top surface of the lower body. Multiple backflow grooves are opened on the side of the stop ring for alignment with the backflow hole. Multiple first shear pin holes are provided on the circumferential direction of the stop ring. Upper first shear pins are embedded in the first shear pin holes. The outer diameter of the head end of the first shear pin is larger than the outer diameter of the tail end. A set screw is also installed on the outer side of the head end of the first shear pin to prevent the sheared first shear pin from falling into the well.

9. The self-adjusting top locking device for a sealing casing hanger for marine wellheads as described in claim 1, characterized in that, The upper outer side of the lower body has a marking groove parallel to the axial direction corresponding to the return flow chute. The lower end of the lower body has an anti-rotation hole and an anti-rotation key installed radially. The anti-rotation key is used to connect with the anti-rotation groove on the casing hanger. The lower end of the lower body also has a second shear pin hole. A second shear pin is inserted through the second shear pin hole. The outer diameter of the tail end of the second shear pin is smaller than the outer diameter of the head end and penetrates into the inner side of the lower body. An annular groove is provided at the tail end of the second shear pin for installing an O-ring to prevent the second shear pin from falling into the well after shearing.

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