A subsea oil production tree with a connecting device

Abstract

This invention discloses an underwater production tree with a connecting device, relating to the technical field of underwater production trees. It solves the problem of high seawater resistance during the installation and dismantling of existing underwater production tree protective covers. Through optimized structural design, the overall performance of the production tree is improved. The invention includes a production tree body and a production tree cap. The production tree cap is equipped with a protective cover detachably connected to the production tree body and features a unique diversion mechanism. After the production tree cap enters the water, the opening and closing plates in the diversion channel open under seawater pressure, allowing seawater to be quickly discharged through the diversion channel, significantly reducing the resistance during the production tree cap's descent, accelerating the descent speed, and shortening the installation time. During dismantling, the combined work of the guide plate and outer sheath, as well as the water guide ring, pressure relief groove, and movable plate, guides the seawater flow, reducing the resistance of the protective cover's ascent and making the dismantling process more efficient. This significantly improves the efficiency of underwater production tree installation and dismantling, reduces offshore operation time, and lowers operating costs.

Description

Technical Field

[0001] This invention relates to the technical field of subsea production trees, specifically to a subsea production tree with a connecting device. Background Technology

[0002] In the process of offshore oil and gas development, the subsea production tree is a key core device of the subsea production system. It connects the subsea wellhead and the subsea production manifold, providing a barrier between the formation oil and gas and the marine environment to prevent leakage and pollution accidents. At the same time, it provides an oil and gas production channel, from which formation oil and gas pass through the wellbore-production tree-subsea production manifold to the oil and gas processing unit.

[0003] A subsea wellhead consists of several key components, each with its unique function. These include the wellhead body, upper connector (mechanical locking mechanism, rubber seals, etc.), lower connector (hydraulic control connection, mechanical locking structure, etc.), and a protective cover. The wellhead body is the core component, forming the basic structure of the entire wellhead. It connects tubing, casing, etc., providing a channel for oil and gas extraction and transmission, and bearing the internal high pressure and external seawater pressure. The upper and lower connectors connect the wellhead cap and the subsea wellhead, respectively, using mechanical locking and rubber seals to ensure the airtightness of oil and gas transmission, preventing leaks and ensuring a stable connection between the various parts of the wellhead. The wellhead cap is installed on top of the wellhead body, primarily protecting key components such as the upper connector and valves from marine organisms, external impacts, and debris blockage, maintaining the normal operation of the wellhead. The protective cover surrounds the outside of the wellhead body, providing protection.

[0004] Chinese patent application CN215169873U discloses a shallow-water horizontal wellhead with a dual-horizontal crossing device. The wellhead includes a wellhead body with a wellhead cap fixedly mounted on its top. A tubing hanger is fixedly mounted inside the wellhead body. The tubing hanger has a vertically formed production channel with a plug at the top opening. A tubing connection port leading to the production channel is located on the outer wall of the tubing hanger, in the lower half of the hanger. A horizontal crossing channel is located in the upper half of the hanger, allowing water to pass horizontally. The horizontal crossing devices and tubing are arranged at a 90° angle. Each port of the horizontal crossing channel is equipped with a hydraulic connector, which connects to downhole equipment via hydraulic lines. Horizontal crossing devices, fixedly connected to the horizontal crossing channels, are installed on both sides of the wellhead. The electric submersible pump cable inside the wellhead cap is connected to the tubing hanger via a wet-type electrical connector. This single plug ensures the sealing requirements of the production channel are met even in shallow water. Compared to the two plugs used in deepwater wellheads, this design reduces manufacturing costs while still meeting the wellhead pressure and sealing requirements. The two symmetrical horizontal crossing devices distribute the hydraulic lines, cable lines, and chemical injection lines on both sides, facilitating underwater installation and control via ROV or divers. Furthermore, the horizontal crossing devices are installed on the upper part of the tubing hanger, while the tubing connection is located in the lower middle part of the tubing hanger, allowing for a staggered arrangement of the horizontal crossing devices and tubing in the horizontal direction, simplifying on-site installation and layout.

[0005] However, current subsea production trees still have certain problems in actual use. For example, most of the protective covers in current production trees have the same structure, mostly using solid flat plates or simple frame structures with rectangular or trapezoidal cross-sections, and lacking flow guidance design. When the production tree cap is submerged, this structure needs to displace a large amount of seawater, creating significant frontal resistance and reducing the submersion speed. During dismantling, the water flow cannot pass smoothly when the protective cover moves in the opposite direction, further increasing the lifting resistance. In addition, some protective covers adopt a fully enclosed design to enhance protection. Although this can block debris, it completely blocks the water flow channel, leading to an increased internal and external pressure difference, which exacerbates the resistance problem. This resistance not only prolongs the operation time and increases the cost of offshore operations, but may also cause equipment fatigue due to excessive operation time. In order to increase the installation and dismantling time of subsea production trees, it is urgent to improve the existing subsea production trees. Summary of the Invention

[0006] The purpose of this invention is to provide a subsea production tree with a connecting device to solve the problems mentioned in the background art.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] The present invention provides an underwater oil production tree with a connecting device, comprising an oil production tree body, an upper connector, a lower connector, and an oil production tree cap. The oil production tree cap is equipped with a protective cover that is detachably connected to the oil production tree body. The protective cover is located on the outside of the oil production tree body and is used to protect the oil production tree body.

[0009] A diversion mechanism, mounted on a protective cover and driven by water flow, includes:

[0010] The diversion channel is located on the top of the protective cover, and an opening and closing plate is provided inside the diversion channel and is rotatably connected to the protective cover. When the opening and closing plate is closed, the diversion channel is in the closed state. After the oil production tree cap is submerged in water, the angle of the opening and closing plate changes, and the diversion channel is in the open state.

[0011] The limiting mechanism, which is installed on the oil wellhead and the protective cover, is used to limit the position of the protective cover and the opening and closing plate.

[0012] As a preferred embodiment of the present invention, the protective cover is composed of a support plate, a guide plate and an outer sheath, and the cross-section of the protective cover is designed in an M shape;

[0013] The support plate is installed on the oil well cap, the guide plate is installed on the support plate, and the outer sheath is installed on the guide plate.

[0014] As a preferred embodiment of the present invention, the support plate is a rectangular plate, and guide plates are installed at all four corners of the support plate, forming a flow divider between two sets of adjacent guide plates;

[0015] The top of the outer sheath is fixedly connected to the ends of the four sets of guide plates, and the outer sheath is designed in a trapezoidal shape.

[0016] As a preferred embodiment of the present invention, the plane at the top of the guide plate is higher than the plane at the support plate, and the guide plate is designed to be inclined towards the support plate, and the connection position between the guide plate and the outer sheath is provided with an arc-shaped rounded corner;

[0017] The top of the guide plate has multiple sets of water inlets with rounded corners.

[0018] As a preferred embodiment of the present invention, the limiting mechanism includes:

[0019] A positioning frame, wherein multiple sets of the positioning frame are installed on the top of the oil production tree, and multiple sets of docking holes corresponding to the positioning frame are opened through the support plate;

[0020] The positioning block is installed on the outer wall of the opening and closing plate and contacts the end of the positioning frame. After the oil production tree cap is connected to the upper connector, the positioning block will be restricted by the positioning frame.

[0021] As a preferred embodiment of the present invention, the top corner of the positioning frame and the bottom corner of the docking hole are both designed with beveled angles;

[0022] Two sets of positioning blocks are symmetrically installed on the outer wall of the opening and closing plate, and the outer end of the positioning block is provided with a docking groove corresponding to the positioning frame. After the outer wall of the positioning frame is attached to the docking groove, the angle of the opening and closing plate is fixed.

[0023] As a preferred embodiment of the present invention, the top of the support plate is equipped with a plurality of bearing seats that are rotatably connected to the opening and closing plate, and the opening and closing plate is connected to the support plate through the bearing seats;

[0024] Wherein, the length of the positioning block is greater than the width of the bearing seat, and when the opening and closing plate is perpendicular to the bearing seat, the outer wall of the opening and closing plate is in contact with the side wall of the bearing seat, and the installation position of the bearing seat is staggered from the opening position of the mating hole.

[0025] As a preferred embodiment of the present invention, the diversion mechanism further includes:

[0026] Pressure relief grooves are provided at all four corners of the support plate, and the positions of the grooves are staggered from the docking holes.

[0027] A movable plate is rotatably mounted on the bottom surface of a support plate via an elastic element, and the mounting position of the movable plate corresponds to the pressure relief groove, which is used to close the pressure relief groove.

[0028] As a preferred embodiment of the present invention, the top corner of the pressure relief groove is designed with an angle, and the bottom opening of the pressure relief groove is smaller than the coverage area of ​​the movable plate.

[0029] As a preferred embodiment of the present invention, water guide rings are installed at both the upper and lower ends of the support plate, and the installation positions of the water guide rings are staggered from the docking hole, the shaft seat, the pressure relief groove and the movable plate.

[0030] The end faces of the water guide rings are all designed to be inclined toward the support plate, and the distance between the middle of the water guide ring and the support plate is the largest.

[0031] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects:

[0032] 1. This submersible production tree with a connecting device features a unique diversion mechanism. After the production tree cap is submerged, the opening and closing plates in the diversion channel open under seawater pressure, allowing seawater to be quickly discharged through the diversion channel. This significantly reduces the resistance during the submersion of the production tree cap, accelerates the submersion speed, and shortens the installation time. During dismantling, the combined action of the guide plate and outer sheath, along with the water guide ring, pressure relief groove, and movable plate, guides the seawater flow, reduces the resistance of the protective cover's ascent, and makes the dismantling process more efficient. This greatly improves the efficiency of submersible production tree installation and dismantling, reduces offshore operation time, and lowers operating costs.

[0033] 2. This underwater production tree with a connecting device uses a positioning frame and a docking hole in a limiting mechanism for precise matching. The beveled design of the top corner of the positioning frame and the bottom corner of the docking hole facilitates the accurate insertion of the positioning frame into the docking hole during the descent of the production tree cap, ensuring accurate docking between the production tree cap and the production tree body. The design of the positioning block and docking groove fixes the angle of the opening and closing plate and closes the diversion groove after the production tree cap is connected to the upper connector, preventing the entry of debris. The shaft seat is rotatably connected to the opening and closing plate, and the installation position of the shaft seat is staggered from the docking hole to avoid mutual interference, ensuring the normal rotation and positioning accuracy of the opening and closing plate. These designs enhance the stability and reliability of the overall connection of the production tree, reduce the risk of equipment failure, and improve the stability of equipment operation.

[0034] 3. This submersible wellhead with a connecting device, through its M-shaped protective cover structure design, combined with a guide plate and an outer sheath, effectively blocks marine organisms from attaching, external impacts, and debris, providing reliable protection for the wellhead. Simultaneously, the guide plate's top is higher than the support plate and is angled, and the rounded corners at the connection point with the outer sheath, along with the water inlet, not only optimize the seawater flow path and reduce water flow impact, but also increase the seawater flow area, reducing resistance while improving the structural stability of the protective cover. This reduces seawater erosion and external damage to the equipment, extends its service life, and lowers maintenance costs.

[0035] 4. This type of underwater production tree with a connecting device, after the production tree cap is connected to the upper connector, the opening and closing plate closes the diversion channel, effectively preventing debris from entering the protective cover through the diversion channel, protecting the key components inside the production tree; the design of the pressure relief channel and the movable plate can prevent debris from entering the equipment under normal conditions, further ensuring the normal operation of the equipment, reducing equipment failures caused by debris entering, and improving production efficiency.

[0036] 5. This subsea production tree with a connecting device allows seawater to enter the pressure relief trough when the protective cover rises, forcing the movable plate to open and releasing the seawater pressure, thus preventing damage to the equipment due to excessive pressure. This design improves the safety of the equipment during installation and disassembly, ensures long-term stable operation of the equipment in complex marine environments, reduces safety hazards, and protects the safety of operators and equipment. Attached Figure Description

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0038] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0039] Figure 1 This is a schematic diagram of the structure of the invention when it is not assembled.

[0040] Figure 2 This is a schematic diagram of the assembled structure of the present invention;

[0041] Figure 3 This is a schematic diagram of the structure of the present invention after assembly (side section).

[0042] Figure 4 This is a side sectional view of the overall structure of the invention from another perspective;

[0043] Figure 5 This is a schematic diagram of the structure of the protective cover of the present invention during the process of diving along with the oil well cap;

[0044] Figure 6 This is a schematic diagram of the protective cover in the open state of the opening and closing plate of the present invention;

[0045] Figure 7 This is a schematic diagram of the side section of the protective cover during the floating process of the oil well cap according to the present invention;

[0046] Figure 8 This is a schematic diagram of the positioning frame and positioning block during the docking process between the oil production tree body and the oil production tree cap of the present invention;

[0047] Figure 9 This is a schematic diagram of the protective cover of the present invention viewed from below;

[0048] Figure 10 This is a schematic diagram of the components installed on the protective cover of the present invention;

[0049] In the picture:

[0050] 1. Oil production tree body; 2. Upper connector; 3. Lower connector; 4. Oil production tree cap; 5. Protective cover; 50. Support plate; 51. Flow guide plate; 52. Outer sheath; 53. Docking door; 6. Positioning frame; 7. Docking hole; 8. Diversion channel; 81. Water inlet; 9. Opening and closing plate; 90. Shaft seat; 91. Positioning block; 92. Docking groove; 10. Water guide ring; 11. Pressure relief groove; 12. Movable plate. Detailed Implementation

[0051] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0052] This invention aims to solve the problem of high seawater resistance during the installation and disassembly of existing underwater production tree protective covers, and improves the overall performance of the production tree by optimizing the structural design.

[0053] Please see Figures 1-10 A subsea production tree with a connecting device is mainly composed of a production tree body 1, an upper connector 2, a lower connector 3, a production tree cap 4, and a protective cover 5. The production tree body 1 is the main foundation, serving as the core structure of the entire production tree and undertaking important tasks such as connecting oil pipes and casing, thus building a key channel for oil and gas extraction and transmission. During the oil and gas extraction process, the production tree body 1 is subjected to high pressure inside and huge pressure from seawater outside, making its stability and sealing crucial.

[0054] Among them, the upper connector 2 and the lower connector 3 are responsible for connecting the oil production tree cap 4 and the underwater wellhead, respectively. Through mechanical locking mechanism and rubber seals, the connection between each component is ensured to be stable and well sealed, preventing oil and gas leakage and ensuring the safe operation of the mining operation.

[0055] Specifically, the oil well cap 4 in this invention is installed on the top of the oil well body 1, acting like a sturdy shield to protect key components such as the upper connector 2 and valves, effectively resisting the attachment of marine organisms, external impacts, and blockages by debris, and maintaining the normal operation of the oil well.

[0056] For example, the protective cover 5 in this invention is arranged around the oil production tree 1, as detailed in the following reference. Figure 10 It is composed of a support plate 50, a guide plate 51 and an outer sheath 52 working together, with an overall cross-section in the shape of M. This shape design not only increases the strength of the protective cover 5, but also better guides the flow of seawater.

[0057] Among them, the support plate 50 serves as the basic support component of the entire protective cover 5. It is firmly installed on the oil production tree cap 4, providing a stable installation platform for components such as the guide plate 51 and the outer sheath 52.

[0058] Secondly, the guide plates 51 are installed at the four corners of the support plate 50, and the diversion channels 8 formed between adjacent guide plates 51 are a key structure for reducing seawater resistance. When the oil production tree cap 4 submerges, seawater will rush into the diversion channels 8, which reduces the resistance of seawater to the submersion of the oil production tree cap 4 by diversion, making the submersion process smoother and more efficient. This greatly shortens the submersion time of the oil production tree cap 4, improves the installation efficiency, and reduces the cost of offshore operations.

[0059] Meanwhile, the top of the outer sheath 52 is fixedly connected to the ends of the four sets of guide plates 51. The outer sheath 52 has a trapezoidal design, and it works in conjunction with the guide plates 51 to enhance the protection of the oil production tree 1. This not only enhances the protection of the oil production tree 1 but also further guides seawater flow, reducing the pressure of seawater on the protective cover 5 and improving the overall performance of the protective cover 5. This provides more reliable protection for the oil production tree 1, reduces the risk of equipment being corroded by seawater and subjected to external impacts, and extends the service life of the equipment.

[0060] For details, please refer to the following: Figure 10 In this embodiment, the plane at the top of the guide plate 51 is higher than the plane at the top of the support plate 50, and the guide plate 51 is tilted towards the support plate 50. This design further optimizes the flow path of seawater. The connection between the guide plate 51 and the outer sheath 52 is designed with an arc-shaped rounded corner, which not only makes the seawater flow smoother, but also effectively reduces the impact force of the water flow on the connection, and improves the structural stability of the protective cover 5. At the same time, multiple sets of water inlets 81 are opened through the arc-shaped rounded corner at the top of the guide plate 51, which further increases the flow path of seawater, reduces resistance, and makes the seawater resistance encountered by the oil production tree cap 4 when it submerges, further improving the submersion efficiency.

[0061] The present invention also includes a diversion mechanism, which is disposed on the protective cover 5, as detailed in the following reference. Figure 4 , Figure 5 and Figure 8 It includes a diversion channel 8 opened on the top of the protective cover 5, and an opening and closing plate 9 is provided in the diversion channel 8. The opening and closing plate 9 installed in the diversion channel 8 is rotatably connected to the protective cover 5. When the oil production tree cap 4 enters the water, the pressure of the seawater will cause the opening and closing plate 9 to quickly change its angle, thereby opening the diversion channel 8. When multiple diversion channels 8 are opened, a large amount of seawater can pass through smoothly, which significantly reduces the resistance when the oil production tree cap 4 dives, effectively improves the diving efficiency, and reduces the installation time and cost.

[0062] The subsea production tree with the connecting device is also equipped with a limiting mechanism, see details below. Figure 1 , Figure 2 , Figures 7-10The limiting mechanism in this invention is set on the oil production tree body 1 and the protective cover 5. The limiting mechanism plays a key role in ensuring the accuracy and stability of the connection between the oil production tree cap 4 and the oil production tree body 1. It includes multiple sets of positioning frames 6 installed on the top of the oil production tree body 1, and multiple sets of docking holes 7 that are opened through the support plate 50 and correspond to the positioning frames 6.

[0063] During the connection process between the oil well cap 4 and the upper connector 2, the precise matching of the positioning frame 6 and the docking hole 7 is crucial. As the oil well cap 4 descends, the positioning frame 6, guided by the beveled end angle and the beveled bottom angle of the docking hole 7, can smoothly insert into the docking hole 7 during the descent of the oil well cap 4, achieving precise positioning and ensuring accurate docking between the oil well cap 4 and the oil well body 1. This improves the success rate and efficiency of installation, reduces equipment damage and installation failures caused by inaccurate docking, and lowers maintenance and installation costs.

[0064] The limiting mechanism in this invention also includes a positioning block 91, wherein the positioning block 91 is installed on the outer wall of the opening and closing plate 9 and the positioning block 91 contacts the end of the positioning frame 6. At the same time, two sets of positioning blocks 91 are installed on the outer wall of the opening and closing plate 9 and are symmetrical to each other, and a docking groove 92 is provided at the outer end of the positioning block 91.

[0065] Once the oil well cap 4 is connected to the upper connector 2, the positioning frame 6 will contact and restrict the positioning block 91, thereby causing the opening and closing plate 9 to close the diversion channel 8. When the angle of the opening and closing plate 9 is fixed by the positioning block 91 and the positioning frame 6, it can be ensured that the diversion channel 8 is closed. This design effectively prevents debris from entering the protective cover 5 and protects the oil well body 1. This further ensures the normal operation of the equipment, reduces equipment failures caused by debris entering, extends the service life of the equipment, ensures the normal operation of the equipment, reduces the risk of equipment failure, lowers maintenance costs, and improves production efficiency.

[0066] The bearing seat 90 installed on the top of the support plate 50 is rotatably connected to the opening and closing plate 9, providing stable rotational support for the opening and closing plate 9; at the same time, the length of the positioning block 91 in this invention is greater than the width of the bearing seat 90. When the opening and closing plate 9 and the bearing seat 90 are perpendicular to each other, the outer wall of the opening and closing plate 9 is in contact with the side wall of the bearing seat 90, which restricts the rotation angle of the opening and closing plate 9 and prevents accidental damage caused by the unrestricted rotation angle of the opening and closing plate 9.

[0067] Meanwhile, in this embodiment, the installation position of the bearing seat 90 is offset from that of the docking hole 7. This design effectively avoids mutual interference between the bearing seat 90 and the docking hole 7, ensuring the normal rotation and positioning accuracy of the opening and closing plate 9, as well as the smooth sliding connection between the positioning frame 6 and the docking hole 7, thus ensuring the stable operation of the diversion mechanism. This enables the diversion mechanism to work stably, further improving the overall performance and reliability of the oil well tree.

[0068] It should be noted that in this invention, water guide rings 10 are installed at both the upper and lower ends of the support plate 50, with their end faces inclined towards the support plate 50 and the middle part having the largest distance from the support plate 50. During the submersion of the oil production tree cap 4 and the ascent of the protective cover 5, the corresponding water guide rings 10 can effectively guide the seawater flow, further reducing seawater resistance and making the submersion of the oil production tree cap 4 and the ascent of the protective cover 5 smoother, thus improving the operating efficiency of the equipment. This further shortens the installation and disassembly time and reduces operating costs.

[0069] Meanwhile, pressure relief grooves 11 are provided at all four corners of the support plate 50 of the present invention, as detailed in the reference. Figures 7-10 Its position is offset from the docking hole 7; to prevent the setting of the pressure relief groove 11 from affecting the normal use of the docking hole 7;

[0070] Meanwhile, in this embodiment, the movable plate 12 is rotatably mounted on the bottom surface of the support plate 50 via an elastic element, corresponding to the pressure relief groove 11. When the protective cover 5 rises, seawater enters the pressure relief groove 11, forcing the movable plate 12 to open. At this time, the elastic element of the movable plate 12 will be under pressure. When the movable plate 12 is opened, seawater can pass through the pressure relief groove 11, effectively reducing the resistance when the protective cover 5 rises.

[0071] Meanwhile, under the action of the elastic element, the movable plate 12 can close the pressure relief groove 11 when the pressure given by the seawater is lost or when it is normal, to prevent debris from entering and protect the internal structure of the equipment. This improves the stability of the equipment during installation and disassembly, reduces damage to the equipment caused by excessive pressure, and extends the service life of the equipment.

[0072] In some examples, the elastic element of the movable plate 12 can be a torsion spring, so that after the movable plate 12 is subjected to pressure and its angle changes, it will automatically return to its original position under the action of the torsion spring.

[0073] Of course, in other examples, the elastic element of the movable plate 12 may also be a spring, an elastic sheet, or other components. In this embodiment, the elastic element of the movable plate 12 is not directly and completely limited.

[0074] The working principle of this invention is as follows: When it is necessary to use the subsea wellhead with the connection device, firstly, the wellhead body 1 is firmly connected to the subsea wellhead through the lower connector 3, and then the wellhead cap 4 is connected to the wellhead body 1 through the upper connector 2. At this time, the wellhead cap 4 protects the upper connector 2, valves and other components at the top of the wellhead, preventing marine organisms from attaching, external impacts or debris from clogging.

[0075] During actual installation, when the oil production tree cap 4 enters the water and begins to submerge, a large amount of seawater will enter the protective cover 5 during the descent of the oil production tree cap 4. As the oil production tree cap 4 continues to submerge, the opening and closing plate 9 will be washed open by the seawater, causing the diversion channel 8 to open. Since the protective cover 5 is equipped with multiple diversion channels 8, a large amount of seawater will pass through the diversion channels 8, thereby reducing the resistance that the protective cover 5 gives to the oil production tree cap 4 when it follows the oil production tree cap 4 into the water, and improving the descent efficiency of the oil production tree cap 4.

[0076] During the descent of the oil production tree cap 4, a large amount of seawater will pass through multiple sets of water inlets 81 to further reduce the impact of the protective cover 5 on the descent of the oil production tree cap 4. At the same time, as the oil production tree cap 4 descends, the water guide ring 10 at the bottom of the support plate 50 will also guide the seawater entering the protective cover 5 because the end face of the water guide ring 10 is inclined, further reducing the resistance of the protective cover 5 during descent.

[0077] As the oil well cap 4 approaches the upper connector 2, the connection between the oil well cap 4 and the upper connector 2 can be processed by an underwater robot (ROV) or diving equipment (both existing technologies, which will not be described in detail). During this process, the docking hole 7 will correspond to the position of the positioning frame 6. As the oil well cap 4 descends, the positioning frame 6 enters the docking hole 7 under the guidance of its end bevel and the bottom bevel of the docking hole 7. Then the positioning frame 6 will pass through the docking hole 7.

[0078] Because the oil well cap 4 is not yet fully connected to the upper connector 2, the oil well cap 4 will continue to descend, causing the positioning frame 6 to continue sliding in the docking hole 7. This causes the end of the positioning frame 6 to press against the outer wall of the positioning block 91, forcing the positioning block 91 to start driving the opening and closing plate 9 to change its angle until the oil well cap 4 is fully connected to the upper connector 2. At this time, the positioning frame 6 has slid to the position where it is in contact with the docking groove 92 at the end of the positioning block 91. At the same time, the opening and closing plate 9 is also in the state of closing the diversion groove 8, so that the oil well cap 4 is fully connected to the upper connector 2 and the diversion groove 8 is also closed to prevent debris from entering the protective cover 5 through the diversion groove 8 and affecting the internal oil well body 1.

[0079] When the oil well cap 4 is connected to the upper connector 2, the protective cover 5 is already in a state of protecting the oil well body 1. Because the outer wall of the protective cover 5 is provided with multiple sets of docking doors 53, oil pipelines, control cables, oil pipes, etc. can be connected to the oil well body 1 through the docking doors 53 (this is known prior art and will not be described in detail).

[0080] When it is necessary to dismantle the wellhead 1, firstly, using an underwater robot (ROV) or diving equipment, disconnect the connection between the wellhead 1 and the wellhead cap 4. As the wellhead cap 4 begins to separate from the upper connector 2, the positioning frame 6 begins to engage with the docking slot 92 and slides out of the docking hole 7. At this point, the restriction between the wellhead 1 and the protective cover 5 is released, and the wellhead cap 4 can be pulled towards the sea surface. After the wellhead cap 4 is removed, disconnect the hydraulic control connection and mechanical locking structure between the wellhead and the wellhead, and disconnect the oil pipeline and other components. Then, use specialized lifting equipment (such as a crane on an engineering vessel, which is known prior art and will not be described in detail) to lift the wellhead 1 as a whole, thus completing the dismantling of the wellhead 1.

[0081] During dismantling, as the protective cover 5 moves upward with the wellhead cap 4, the combination of the guide plate 51 and the outer sheath 52 can divert seawater, effectively reducing the resistance when the protective cover 5 rises. At the same time, the seawater is guided by the water guide ring 10 on the top surface of the support plate 50, directing the seawater to the outside of the water guide ring 10. The outside of the water guide ring 10 is provided with a pressure relief groove 11, allowing the seawater to enter the pressure relief groove 11 as the protective cover 5 rises. This forces the movable plate 12 to change its angle, at which point the pressure relief groove 11 opens, allowing the seawater to pass through. This reduces the resistance generated when the protective cover 5 moves towards the sea surface with the wellhead cap 4, further improving the efficiency of the wellhead during installation and dismantling.

[0082] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An underwater Christmas tree having a connection means comprising a tree body, an upper connector, a lower connector and a tree cap, characterised in that: The protective cover is detachably connected with the Christmas tree body and is located outside the Christmas tree body to protect the Christmas tree body; The shunt mechanism is arranged on the protective cover and is driven by water flow, and the shunt mechanism comprises: A shunt groove is arranged on the top of the protective cover, and the shunt groove is provided with an opening and closing plate which is rotatably connected with the protective cover, and when the opening and closing plate is closed, the shunt groove is in a closed state, and when the Christmas tree cap is submerged in water, the angle of the opening and closing plate is changed, and the shunt groove is in an open state; A limiting mechanism is arranged on the Christmas tree body and the protective cover to limit the position of the protective cover and the opening and closing plate; The protective cover is composed of a support plate, a guide plate and an outer sheath, and the cross section of the protective cover is designed in an M shape; The support plate is installed on the Christmas tree cap, the guide plate is installed on the support plate, and the outer sheath is installed on the guide plate; the support plate is a rectangular plate, and the four corners of the support plate are provided with the guide plates, and the shunt groove is formed between two adjacent guide plates; The top of the outer sheath is fixedly connected with the end portions of the four guide plates, and the outer sheath is designed in a trapezoidal shape as a whole; the top of the guide plate is located on a plane which is higher than the plane on which the support plate is located, and the guide plate is designed to be inclined towards the support plate, and the connection position of the guide plate and the outer sheath is provided with an arc-shaped round corner; The position of the arc-shaped round corner on the top of the guide plate is provided with a plurality of water inlet openings; The shunt mechanism further comprises: A pressure relief groove is arranged at the four corners of the support plate; 2. An underwater Christmas tree with connection means according to claim 1, characterized in that: An active plate is rotatably installed on the bottom surface of the support plate by an elastic member, and the installation position of the active plate corresponds to the pressure relief groove, and the active plate is used to close the pressure relief groove. The limiting mechanism comprises: A plurality of positioning frames are installed on the top of the Christmas tree body, a plurality of butt joint holes corresponding to the positioning frames are arranged through the support plate, and the arrangement position of the butt joint holes is staggered with the pressure relief groove; 3. An underwater Christmas tree with connection means according to claim 2, characterized in that: A positioning block is installed on the outer wall of the opening and closing plate, and the positioning block is in contact with the end portion of the positioning frame, and when the Christmas tree cap is connected with the upper connector, the positioning block is limited by the positioning frame. The top corners of the positioning frame and the bottom corners of the butt joint hole are designed in an inclined angle; 4. An underwater Christmas tree with connection means according to claim 3, characterized in that: The outer wall of the positioning frame is in contact with the butt joint groove, and the angle of the opening and closing plate is fixed. A plurality of shaft seats rotatably connected with the opening and closing plate are installed on the top of the support plate, and the opening and closing plate is connected with the support plate through the shaft seat; 5. An underwater Christmas tree with connection means according to claim 1, characterized in that: The length of the positioning block is greater than the width of the shaft seat, the outer wall of the opening and closing plate is in contact with the side wall of the shaft seat when the opening and closing plate is perpendicular to the shaft seat, and the installation position of the shaft seat is staggered with the arrangement position of the butt joint hole.

6. An underwater Christmas tree with connection means according to claim 4, characterized in that: The top corners of the pressure relief groove are designed in an inclined angle, and the opening at the bottom of the pressure relief groove is smaller than the coverage area of the active plate. Water guide rings are installed on the upper and lower ends of the support plate, and the installation position of the water guide ring is staggered with the butt joint hole, the shaft seat, the pressure relief groove and the active plate; The end face of the water guide ring is designed to be inclined towards the support plate, and the maximum distance is between the middle portion of the water guide ring and the support plate.

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