A connector for underwater wellheads and Christmas trees

Abstract

The application relates to the underwater production technical field and discloses a connector for underwater wellheads and Christmas trees, which comprises a connecting frame installed at the top end of the wellhead and a connecting disc at the bottom of the Christmas tree, the bottom of the connecting disc is provided with a group of circumferentially-arranged butt joints, the inside of each butt joint is provided with a butt joint hole, and the bottom end inner wall of each butt joint hole is in a conical structure. The connector for underwater wellheads and Christmas trees is matched with the spherical head structure at the top end of the connecting rod through the conical butt joint hole at the bottom of the connecting disc, and can automatically correct the lateral deviation during the lowering of the Christmas tree. When the connecting rod contacts the inclined wall of the conical hole, the radial component force of the spherical head pushes the Christmas tree to reset, the butt joint deviation caused by the submarine current and the ship sway is overcome, and the operation cost of repeated lifting and retry is reduced.

Description

Technical Field

[0001] This application relates to the field of underwater production technology, specifically a connector for underwater wellheads and wellheads. Background Technology

[0002] With the development of offshore oil fields, conventional platform mining methods can no longer be used for deep-sea development, and subsea production systems are the most effective means of developing deep-water subsea oil and gas fields.

[0003] An existing patent (publication number: CN206309329U) discloses a connector for subsea wellheads and Christmas trees, comprising: a connecting flange disposed at the lower part of the Christmas tree; a hydraulic base plate fitted into the subsea wellhead; a hydraulic connector fitted onto the subsea wellhead and connected between the connecting flange and the hydraulic base plate, with several through holes radially formed in its cylindrical wall; and a locking tooth disposed within the through holes of the hydraulic connector. Pushing the locking tooth causes it to contact the connecting surface of the subsea wellhead, resulting in relative axial movement between the subsea wellhead and the Christmas tree. This invention features high reliability, simple structure, and long service life, making it suitable for the development needs of deep-water subsea oil and gas fields.

[0004] Traditional oil trees are often lowered from the sea surface by cables. Due to ocean currents, ship swaying, and limitations in the accuracy of the release system, they are prone to lateral shifting or tilting during docking. The aforementioned connectors lack a correction mechanism. Because the tooth engagement requires extremely high precision, the connection is difficult when tilted. This often leads to the initial contact between the locking teeth and the tooth profile groove failing due to misalignment, requiring repeated lifting and retrying. Utility Model Content

[0005] To address the shortcomings of existing technologies, this application provides a connector for subsea wellheads and wellheads, which has advantages such as easy docking and solves the problems mentioned in the background art.

[0006] To achieve the above objectives, this application provides the following technical solution: a connector for a subsea wellhead and a wellhead tree, comprising a connecting frame installed at the top of the wellhead and a connecting plate at the bottom of the wellhead tree. The bottom of the connecting plate is provided with a set of circumferentially arranged docking platforms. Each docking platform has a docking hole inside. The bottom inner wall of each docking hole is a conical structure. Each docking platform has a through disassembly groove at the bottom.

[0007] The inner bottom wall of the connecting frame is rotatably connected to a set of connecting hydraulic rods arranged in a matrix through a bearing seat. Each connecting hydraulic rod has a connecting rod fixedly connected to its top end. Each connecting rod has two symmetrically arranged wedges horizontally slidably inserted at its top end. A compression spring is installed between each pair of adjacent wedges. Each connecting rod has a ball-shaped structure at its top end.

[0008] Furthermore, a sealing ring is provided between the connecting plate and the connecting frame.

[0009] The above solution improves sealing performance under high-pressure underwater conditions, resisting seawater corrosion and oil and gas penetration.

[0010] Furthermore, each of the connecting rods has a reinforcing rib inside its top end, and the reinforcing rib and the connecting rod adjacent to it are integrally formed.

[0011] The above solution enhances the bending strength of the ball end by reinforcing the rib structure, thereby improving the mechanical strength of the connection.

[0012] Furthermore, a synchronous gear is fixedly connected to the outer surface of each of the connecting hydraulic rods, a rotating drum is rotatably connected to the outer surface of the wellhead, a drive gear is fixedly connected to the bottom of the rotating drum, each synchronous gear is meshed with the drive gear, a power gear is fixedly connected to the top of the rotating drum, a power hydraulic rod is fixedly installed on the inner bottom wall of the connecting frame, a power gear plate is fixedly connected to the output end of the power hydraulic rod, and the power gear plate is meshed with the power gear.

[0013] The above scheme allows for the separation of the Christmas tree from the wellhead. A power hydraulic rod drives a power gear plate, which in turn rotates the power gear. This power gear, through a drive gear and a synchronous gear, rotates the connecting hydraulic rod, which in turn rotates the connecting rod and the wedge. The wedge moves above the disassembly groove and drives the connecting hydraulic rod to move the connecting rod downwards, allowing the wedge to pass through the docking platform from the disassembly groove, thus releasing the connection between the Christmas tree and the subsea wellhead.

[0014] Furthermore, the top of each wedge has a beveled structure.

[0015] With the above scheme, the guide slope forms a line contact with the conical inner wall of the docking hole, and a radial force is generated when the connecting rod is inserted to drive the wedge to retract automatically.

[0016] Furthermore, both the connecting frame and the connecting plate are made of alloy material.

[0017] The above solution possesses excellent corrosion resistance and high strength, enabling it to adapt to extreme working environments such as deep sea, ensuring the long-term stable operation of the connector.

[0018] Furthermore, the top of each connecting rod and the inner wall of the mating hole are polished.

[0019] The above solutions reduce surface roughness and frictional resistance during the connection process. In addition, appropriate coating treatments can be used to further improve the smoothness and durability of the connection.

[0020] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0021] This connector, used for subsea wellheads and Christmas trees, uses a tapered mating hole at the bottom of the connecting plate to engage with a ball head structure at the top of the connecting rod, automatically correcting lateral misalignment during Christmas tree lowering. When the connecting rod contacts the inclined wall of the tapered hole, the ball head generates a radial force to push the Christmas tree back into place, overcoming docking deviations caused by ocean currents and ship swaying, and reducing the operational costs of repeated lifting and retrying.

[0022] When the connecting rod is inserted into the docking hole, the inner wall of the conical hole squeezes the wedge block inward. After passing through, the wedge block automatically pops open and locks above the connecting plate. When the connecting hydraulic rod moves down, the right-angled surfaces of multiple wedge blocks abut against the connecting plate, forming multiple rigid fixed anchor points, which effectively resist the impact of deep sea currents and the separation force generated by the weight of the oil well tree, and improve its connection stability.

[0023] A power hydraulic rod drives a toothed plate, which in turn rotates a drum and a synchronous gear, aligning the wedge with the disassembly slot. Lowering the connecting hydraulic rod releases the wedge, facilitating the separation of the wellhead from the production tree. This significantly simplifies the inspection and maintenance process, making it particularly suitable for high-cost operating environments in deep-sea areas. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of the overall structure of this application;

[0025] Figure 2 This is a three-dimensional schematic diagram of the overall structure of this application;

[0026] Figure 3 This is a sectional view of the overall structure of this application from below;

[0027] Figure 4 This is a cross-sectional view of the connecting rod in this application.

[0028] In the picture:

[0029] 1. Wellhead; 101. Connecting frame; 2. Christmas tree; 201. Connecting plate;

[0030] 3. Docking platform; 301. Docking hole; 302. Disassembly groove;

[0031] 4. Connect the hydraulic rod;

[0032] 5. Connecting rod; 501. Wedge block; 502. Compression spring; 503. Reinforcing rib;

[0033] 6. Sealing ring; 7. Synchronizing gear;

[0034] 8. Rotary drum; 801. Drive gear; 802. Power gear;

[0035] 9. Power hydraulic rod; 901. Power gear plate. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Please see Figure 1 , Figure 2 and Figure 3 This embodiment provides a connector for subsea wellheads and Christmas trees, including a connecting frame 101 mounted at the top of the wellhead 1 and a connecting disc 201 at the bottom of the Christmas tree 2. A sealing ring 6 is provided between the connecting disc 201 and the connecting frame 101 to improve sealing performance under high-pressure underwater conditions and resist seawater corrosion and oil and gas medium penetration. Both the connecting frame 101 and the connecting disc 201 are made of alloy materials, which have excellent corrosion resistance and high strength characteristics, and can adapt to extreme working environments such as deep sea, ensuring the long-term stable operation of the connector.

[0038] Please see Figure 1 , Figure 2 and Figure 3 The bottom of the connecting plate 201 is provided with a set of docking platforms 3 arranged in a circle. Each docking platform 3 has a docking hole 301 inside. The bottom inner wall of each docking hole 301 is a conical structure. Each docking platform 3 has a through disassembly groove 302 at the bottom.

[0039] Please see Figure 1 , Figure 2 and Figure 4 The inner bottom wall of the connecting frame 101 is rotatably connected to a set of connecting hydraulic rods 4 arranged in a matrix through a bearing seat. The top of each connecting hydraulic rod 4 is fixedly connected to a connecting rod 5. The top of each connecting rod 5 is provided with a reinforcing rib 503. The reinforcing rib 503 and the connecting rod 5 adjacent to it are integrally formed. The reinforcing rib 503 structure enhances the bending strength of the ball end and improves the mechanical strength of the connection. The top of each connecting rod 5 is horizontally slidably inserted with two symmetrically arranged wedges 501. A compression spring 502 is installed between each two adjacent wedges 501. The top of each wedge 501 is a sloping structure. The guide sloping surface forms a line contact with the conical inner wall of the docking hole 301. When the connecting rod 5 is inserted, a radial component force is generated to drive the wedge 501 to automatically retract.

[0040] Please see Figure 1 , Figure 2 and Figure 4Each connecting rod 5 has a ball-shaped tip. When the tree 2 moves downward, the tapered docking hole 301 on the connecting plate 201 facilitates the entry of the connecting rod 5. The tip of each connecting rod 5 and the inner wall of the docking hole 301 are polished to reduce surface roughness and frictional resistance during connection. Appropriate coating treatment can further improve the smoothness and durability of the connection. When the tree 2 shifts, the ball-shaped tip of the connecting rod 5 can engage with the tapered inner wall of the docking hole 301. The wall contact allows the Christmas tree 2 to automatically correct its position and ensure precise docking between the Christmas tree 2 and the wellhead 1. When the connecting rod 5 enters the docking hole 301, the inner wall of the conical structure can automatically squeeze the two wedges 501 closer to each other and into the interior of the connecting rod 5. When the wedges 501 pass through the docking hole 301 and come above the connecting plate 201, the wedges 501 can automatically reset and extend. By connecting the hydraulic rod 4, the connecting rod 5 is driven to move downward, and the wedges 501 can pull the connecting plate 201 to bring the Christmas tree 2 into close contact with the wellhead 1.

[0041] Please see Figure 1 , Figure 2 and Figure 3 Each connecting hydraulic rod 4 has a synchronizing gear 7 fixedly connected to its outer surface. A rotating drum 8 is rotatably connected to the outer surface of the wellhead 1. A drive gear 801 is fixedly connected to the bottom of the rotating drum 8. Each synchronizing gear 7 meshes with the drive gear 801. A power gear 802 is fixedly connected to the top of the rotating drum 8. A power hydraulic rod 9 is fixedly installed on the inner bottom wall of the connecting frame 101. A power gear plate 901 is fixedly connected to the output end of the power hydraulic rod 9. The power gear plate 901 meshes with the power gear 802. This requires the wellhead 2 to... When separated from the wellhead 1, the power hydraulic rod 9 drives the power gear plate 901 to move, which in turn drives the power gear 802 to rotate. The power gear 802 is driven by the drive gear 801 and the synchronous gear 7 to realize the rotation of the connecting hydraulic rod 4, which in turn drives the connecting rod 5 and the wedge 501 to rotate, so that the wedge 501 comes above the disassembly groove 302 and drives the connecting hydraulic rod 4 to move the connecting rod 5 down, so that the wedge 501 passes through the docking platform 3 from the disassembly groove 302, thereby releasing the connection and fixation between the production tree 2 and the subsea wellhead 1.

[0042] It should be noted that the power hydraulic rod 9 needs to be equipped with a dual-channel oil supply system, so that the unlocking operation can still be completed even if one channel fails.

[0043] The working principle of the above embodiment is as follows: When the Christmas tree 2 is lowered, the conical docking hole 301 at the bottom of the connecting plate 201 contacts the ball head structure at the top of the connecting rod 5. The ball head and the inclined wall of the conical hole form a sliding contact surface. If the Christmas tree 2 is horizontally offset due to ocean currents or ship swaying, the radial component force generated by the conical surface pushes the Christmas tree 2 to automatically correct its position and achieve initial alignment. When the connecting rod 5 is fully inserted into the docking hole 301, the conical inner wall continuously squeezes the inclined top of the wedge 501, forcing the symmetrical wedge 501 to overcome the resistance of the compression spring 502 and retract inward until it passes through the docking platform 3. After passing through the docking platform 3, the compression spring 502 pushes the wedge 501 to automatically pop out and reset, locking it above the docking platform 3, thus starting the process. The moving hydraulic rod 4 pushes the connecting rod 5 downward, the right-angled surface of the wedge 501 hooks onto the docking platform 3, and pulls the connecting plate 201 to drive the entire tree 2 downward. The sealing ring 6 is compressed to achieve high-pressure sealing. The reinforcing rib 503 inside the connecting rod 5 enhances the bending strength and prevents deformation caused by the impact of deep water fluid. When separation is required, the power hydraulic rod 9 pushes the power gear plate 901 to move, driving the power gear 802 to rotate. Through the meshing transmission of the drive gear 801 and the synchronous gear 7, all the connecting hydraulic rods 4 are driven to rotate synchronously. When the wedge 501 turns to the top of the disassembly groove 302, the connecting hydraulic rod 4 pushes down, and the wedge 501 slides out of the docking platform 3 along the disassembly groove 302, releasing the mechanical lock.

[0044] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0045] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A connector for a subsea wellhead and a Christmas tree, comprising a connector frame (101) mounted at the top of the wellhead (1) and a connector plate (201) at the bottom of the Christmas tree (2), characterized in that: The bottom of the connecting plate (201) is provided with a set of docking platforms (3) arranged in a circle. Each docking platform (3) has a docking hole (301) inside. The bottom inner wall of each docking hole (301) is a conical structure. Each docking platform (3) has a through disassembly groove (302) at the bottom. The inner bottom wall of the connecting frame (101) is rotatably connected to a set of connecting hydraulic rods (4) arranged in a matrix through a bearing seat. Each connecting hydraulic rod (4) is fixedly connected to a connecting rod (5) at its top end. Each connecting rod (5) has two symmetrically arranged wedges (501) horizontally slidably inserted at its top end. A compression spring (502) is installed between each pair of adjacent wedges (501). The top end of each connecting rod (5) is set as a ball-shaped structure.

2. A connector for subsea wellheads and wellheads according to claim 1, characterized in that: A sealing ring (6) is provided between the connecting plate (201) and the connecting frame (101).

3. A connector for subsea wellheads and wellheads according to claim 1, characterized in that: Each of the connecting rods (5) has a reinforcing rib (503) inside its top end, and the reinforcing rib (503) and the connecting rod (5) adjacent to it are integrally formed.

4. A connector for subsea wellheads and wellheads according to claim 1, characterized in that: Each of the connecting hydraulic rods (4) has a synchronous gear (7) fixedly connected to its outer surface. A rotating drum (8) is rotatably connected to the outer surface of the wellhead (1). A drive gear (801) is fixedly connected to the bottom of the rotating drum (8). Each synchronous gear (7) meshes with the drive gear (801). A power gear (802) is fixedly connected to the top of the rotating drum (8). A power hydraulic rod (9) is fixedly installed on the inner bottom wall of the connecting frame (101). A power toothed plate (901) is fixedly connected to the output end of the power hydraulic rod (9). The power toothed plate (901) meshes with the power gear (802).

5. A connector for subsea wellheads and wellheads according to claim 1, characterized in that: The top of each wedge (501) has a beveled structure.

6. A connector for subsea wellheads and wellheads according to claim 1, characterized in that: Both the connecting frame (101) and the connecting plate (201) are made of alloy material.

7. A connector for subsea wellheads and wellheads according to claim 1, characterized in that: The top of each connecting rod (5) and the inner wall of the mating hole (301) are polished.

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