A guide base plate and underwater wellhead head locking mechanism

Abstract

This invention provides a locking mechanism between a guide base plate and a subsea wellhead, relating to the field of oil and gas exploration and development technology. The device includes a guide base plate with: a limiting hole penetrating the guide base plate, a bearing boss on the inner surface of the guide base plate, and a C-shaped locking ring groove on the outer surface of the guide base plate; a subsea wellhead with a U-shaped limiting groove on its outer surface and a support structure that can be mounted on the bearing boss; a pin for inserting into the limiting groove through the limiting hole when the limiting hole and the limiting groove are coaxial, thereby restricting the relative rotation between the guide base plate and the subsea wellhead; and a C-shaped locking ring that can be installed in the C-shaped locking ring groove. This invention improves the docking accuracy between the guide base plate and the subsea wellhead and reduces costs.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and in particular to a guide base plate and subsea wellhead locking mechanism. Background Technology

[0002] Guide base plate and subsea wellhead are wellhead devices installed on the seabed and are essential components of subsea production systems; they are required for every well.

[0003] The guide plate, installed outside the subsea wellhead or its extension casing, guides the drill pipe, casing, blowout preventer, Christmas tree, and service tools, improving operational efficiency, reducing unnecessary collisions, determining drilling positions, standardizing wellhead spacing, and regulating Christmas tree installation direction. The subsea wellhead, equivalent to the wellhead support ring on the surface wellhead, is anchored to the seabed to form a solid foundation, supporting part of the weight of the wellbore, riser, and blowout preventer assembly. A 36-inch or 30-inch casing can be welded to the lower part of the subsea wellhead.

[0004] According to the drilling process, after the guide vane is docked with the subsea wellhead, it must be adjusted to the designed heading position, and the relevant parameters of the guide vane attitude measurement instrument must be confirmed. This facilitates the heading determination during the subsequent installation of the production tree and the later installation of the jumper pipe. Therefore, the deflection accuracy control and locking limit of the guide vane docking with the subsea wellhead are crucial for the installation of the subsea production system.

[0005] The existing method of connecting the guide base plate to the underwater wellhead usually involves machining a ring of anti-rotation grooves evenly on the outer surface of the underwater wellhead. The number of anti-rotation grooves is about 36 or 24. After the anti-rotation grooves are clamped with the anti-rotation bosses of the guide base plate, a pin is inserted to achieve rotation limit.

[0006] Circumferential engagement accuracy is the maximum angular deviation threshold when the guide base plate and the subsea wellhead achieve anti-rotation limiting engagement in the circumferential direction. The circumferential engagement accuracy of existing guide base plates is determined by the total number of anti-rotation grooves on the subsea wellhead. It is calculated by dividing 360° by the total number of anti-rotation grooves, such as 15° for 24 grooves and 10° for 36 grooves.

[0007] When installing the guide base plate, the pin of the guide base plate will usually get stuck between two adjacent slots on the outer surface of the submersible wellhead. It is necessary to rotate the guide base plate forward or backward to make the pin of the guide base plate get stuck in the nearest anti-rotation slot.

[0008] The docking accuracy refers to the maximum angle required to align the guide base plate pin with the anti-rotation groove of the subsea wellhead when the guide base plate is not aligned with it, by rotating the guide base plate clockwise or counterclockwise. Taking a subsea wellhead with 36 anti-rotation grooves as an example, the 36 anti-rotation grooves are evenly distributed around a 360° circumference, with a spacing of 1 / 36 of a circumference (10°). The pin is positioned precisely in the middle of two adjacent grooves. Rotating the guide base plate clockwise or counterclockwise by 1 / 72 of a circumference (5°) will align the pin with the groove, achieving a docking accuracy of ±5°. Therefore, numerically, the docking accuracy is half the circumferential engagement accuracy; that is, 24 grooves correspond to 7.5°, and 36 grooves correspond to 5°.

[0009] However, this docking method has obvious drawbacks. On the one hand, the docking accuracy is limited, reaching only 5° or 7.5°, which is difficult to meet the requirements of high-precision operations. On the other hand, the underwater wellhead anti-rotation groove has a large number of grooves, which not only increases the complexity of the processing steps, but also significantly increases the production cost.

[0010] Therefore, there is an urgent need for a guide base plate and underwater wellhead locking mechanism to solve the above-mentioned technical problems. Summary of the Invention

[0011] The purpose of this invention is to provide a locking mechanism between a guide base plate and a subsea wellhead, thereby solving the technical problems of low docking accuracy and high production cost in the prior art. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] The present invention provides a locking mechanism between a guide base plate and a subsea wellhead, comprising:

[0014] The guide base plate is provided with: a limiting hole penetrating the guide base plate, a bearing boss provided on the inner surface of the guide base plate, and a C-shaped locking ring groove provided on the outer surface of the guide base plate;

[0015] The underwater wellhead has a U-shaped limiting groove and a support structure that can be erected on the bearing protrusion on its outer surface.

[0016] A pin is used to be inserted into the limiting groove through the limiting hole when the limiting hole and the limiting groove are coaxial, so as to limit the relative rotation between the guide base plate and the underwater wellhead.

[0017] C-type locking ring, wherein the C-type locking ring can be installed in the C-type locking ring slot.

[0018] Preferably, the guide base plate is a thin-walled cylindrical structure.

[0019] Preferably, the limiting hole includes a threaded through hole, the specifications of which are adapted to the external thread specifications of the pin.

[0020] Preferably, the number of limiting holes is nine, and the nine limiting holes are evenly distributed circumferentially on the outer surface of the guide base plate.

[0021] Preferably, there are 8 limiting grooves, which are evenly distributed circumferentially on the outer surface of the underwater wellhead.

[0022] Preferably, the C-shaped locking ring groove is disposed above the limiting hole; the bearing boss is located between the C-shaped locking ring groove and the limiting hole.

[0023] Preferably, the inner diameter of the C-shaped locking ring is adapted to the outer diameter of the C-shaped locking ring groove corresponding to the outer surface of the guide base plate, and the thickness of the C-shaped locking ring is not less than the depth of the C-shaped locking ring groove.

[0024] Preferably, the bearing boss is an annular boss, and the inner diameter of the annular boss is not greater than the outer diameter of the underwater wellhead.

[0025] Preferably, the length of the pin is not less than the sum of the wall thickness of the guide base plate and the groove depth of the limiting groove, and the end of the pin away from the limiting groove is provided with a structure that facilitates twisting operation.

[0026] The guide base plate and underwater wellhead locking mechanism provided by this invention, by providing a through limiting hole in the side wall of the guide base plate with a thin-walled cylindrical structure, and a U-shaped limiting groove on the outer surface of the underwater wellhead, allows the underwater wellhead or guide base plate to be rotated during the docking of the guide base plate and the underwater wellhead. After the limiting groove of the underwater wellhead and the limiting hole of the guide base plate are coaxial, the relative rotation between the underwater wellhead and the guide base plate is restricted by a pin. A C-shaped locking ring is installed at the end of the underwater wellhead to achieve locking and limiting of the guide base plate and the underwater wellhead, thereby improving the docking accuracy of the guide base plate and the underwater wellhead and ensuring that the guide base plate can be installed in the designed heading position after being launched into the water. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of an embodiment of the guide base plate and underwater wellhead locking mechanism of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the guide base plate in the underwater wellhead locking mechanism of the present invention;

[0030] Figure 3 This is a schematic diagram of the underwater wellhead in the guide base plate and underwater wellhead locking mechanism of the present invention.

[0031] In the figure: 1. Guide base plate; 101. Limiting hole; 102. Bearing boss; 103. C-type locking ring groove; 2. Subsea wellhead; 201. Limiting groove; 202. Support structure; 3. Pin; 4. C-type locking ring. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0033] In the description of this invention, it should be understood that the terms "center," "side," "length," "width," "height," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are 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.

[0034] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] Figure 1 This is a structural schematic diagram of this embodiment, as shown below. Figure 1 As shown, this embodiment provides a locking mechanism between a guide base plate and a subsea wellhead, including a guide base plate 1, a subsea wellhead 2, a pin 3, and a C-type locking ring 4.

[0036] in, Figure 2 This is a schematic diagram of the guide base plate in this embodiment, as shown below. Figure 2 As shown, the guide base plate 1 in this embodiment is a thin-walled cylindrical structure. The guide base plate 1 is provided with: a limiting hole 101 penetrating the guide base plate 1, a bearing boss 102 provided on the inner surface of the guide base plate 1, and a C-shaped locking ring groove 103 provided on the outer surface of the guide base plate 1. The C-shaped locking ring groove 103 has a rectangular cross-section and is opened at the top of the guide base plate 1.

[0037] Specifically, the C-type locking ring groove 103 is located above the limiting hole 101; the bearing boss 102 is located between the C-type locking ring groove 103 and the limiting hole 101. By layering the components in the vertical direction, the stress areas of each component can be dispersed, avoiding structural damage caused by local stress superposition.

[0038] Figure 3 This is a schematic diagram of the underwater wellhead structure in this embodiment, as shown below. Figure 3 As shown, the outer surface of the underwater wellhead 2 is provided with a U-shaped limiting groove 201 and a support structure 202 that can be mounted on the bearing boss 102. It is understood that the limiting groove in this application and the anti-rotation groove mentioned in the background art are the same type of groove structure used to limit the relative rotation of components. The only difference is the name due to different expression habits. The core function of both is to cooperate with the limiting component to achieve anti-rotation positioning.

[0039] In this embodiment, U-shaped limiting grooves 201 are distributed circumferentially along the outer surface of the subsea wellhead 2, and the openings of the limiting grooves 201 face radially outward. The lower surface of the support structure 202 is provided with a plane that can be adapted to the upper surface of the bearing boss 102, and the bearing boss 102 can bear the weight of the subsea wellhead 2.

[0040] The pin 3 is a cylindrical rod structure with a clearance fit between its diameter and the diameter of the limiting hole 101. When the limiting hole 101 and the limiting groove 201 are coaxial, the pin 3 can pass through the limiting hole 101 and be inserted into the limiting groove 201 to restrict the relative rotation between the guide base plate 1 and the underwater wellhead 2.

[0041] The C-type locking ring 4 is an open ring structure whose cross-sectional dimensions are adapted to the cross-sectional dimensions of the C-type locking ring slot 103, allowing it to be installed within the C-type locking ring slot 103. In use, the C-type locking ring 4 is located at the end of the underwater wellhead 2 to achieve locking and limiting between the guide base plate 1 and the underwater wellhead 2.

[0042] This guide base plate and underwater wellhead locking mechanism, through a through limiting hole 101 on the side wall of the thin-walled cylindrical guide base plate 1 and a U-shaped limiting groove 201 on the outer surface of the underwater wellhead 2, allows the underwater wellhead 2 or the guide base plate 1 to rotate during the docking of the guide base plate 1 and the underwater wellhead 2. After the limiting groove 201 of the underwater wellhead 2 and the limiting hole 101 of the guide base plate 1 are coaxial, the relative rotation between the underwater wellhead 2 and the guide base plate 1 is restricted by the pin 3. A C-type locking ring 4 is installed at the end of the underwater wellhead 2 to lock and limit the guide base plate 1 and the underwater wellhead 2, ensuring that the guide base plate 1 can be installed in the designed heading position after being launched into the water.

[0043] As an optional implementation, the limiting hole 101 includes a threaded through hole, the specifications of which are adapted to the external thread specifications of the pin 3. By setting the pin 3 to be threadedly engaged with the limiting hole 101, in use, the pin 3 is screwed into the limiting hole 101, and the threaded connection can be precisely locked through torque control, adapting to the fastening requirements under different geological conditions.

[0044] As an optional implementation, the number of limiting holes 101 is nine, and the nine limiting holes 101 are evenly distributed circumferentially on the outer surface of the guide base plate 1. By setting the nine limiting holes 101 evenly distributed, the guide base plate 1 can be balanced under force, avoiding local stress concentration that could lead to base plate deformation.

[0045] Optionally, the number of limiting grooves 201 may be less than the number of limiting holes 101. In this embodiment, the number of limiting grooves 201 is one less than the number of limiting holes 101, that is, the number of limiting grooves 201 is 8. The 8 limiting grooves 201 are evenly distributed circumferentially on the outer surface of the underwater wellhead 2.

[0046] By setting eight limiting grooves 201 arranged axially along the outer surface of the underwater wellhead 2, the amount of machining required for the underwater wellhead 2 is reduced, while the structural strength can be ensured by setting reasonable groove width and depth.

[0047] This guide base plate and underwater wellhead locking mechanism, through eight limiting grooves 201 axially arranged only on the outer surface of the underwater wellhead 2, has lower processing difficulty and production cost compared with the prior art. Furthermore, the limiting grooves 201 of the underwater wellhead 2 and the limiting holes 101 of the guide base plate 1 are matched with eight grooves and nine holes, achieving an installation accuracy of 2.5°, which is more precise.

[0048] Specifically, the inner ring has eight limiting grooves 201 evenly distributed around the 360° circumference with a spacing of 1 / 8 of the circumference, meaning the circumferential meshing accuracy is 1 / 8 of the circumference; the outer ring has nine limiting holes 101 evenly distributed around the 360° circumference with a spacing of 1 / 9 of the circumference, meaning the circumferential meshing accuracy is 1 / 9 of the circumference; when one of the limiting grooves 201 aligns with a limiting hole 101, the distance between the nearest adjacent limiting groove 201 and the limiting hole 101 is 1 / 8 - 1 / 9 of the circumference. The circumference is 1 / 72 of the circumference, which is 5°. That is, the circumferential meshing accuracy of the limiting groove 201 and the limiting hole 101 is 1 / 8 of the circumference - 1 / 9 of the circumference = 1 / 72 of the circumference = 5°. When the limiting groove 201 and the limiting hole 101 are not aligned, the pin 3 is stuck in the middle of the two adjacent limiting grooves 201. Rotating forward or backward by a maximum of 1 / 144 of the circumference = 2.5° can align the pin 3 with the limiting groove 201 and the limiting hole 101. At this time, the docking accuracy is ±2.5°.

[0049] As an optional implementation, the inner diameter of the C-type locking ring 4 is adapted to the outer diameter of the C-type locking ring groove 103 corresponding to the outer surface of the guide base plate 1, and the thickness of the C-type locking ring 4 is not less than the depth of the C-type locking ring groove 103.

[0050] In this embodiment, the inner diameter of the C-type locking ring 4 is fitted with a clearance of 0.1-0.3 mm at the outer diameter of the corresponding C-type locking ring groove 103 on the outer surface of the guide base plate 1. This ensures that the C-type locking ring 4 can be smoothly installed into the C-type locking ring groove 103 while preventing loosening after installation. The thickness of the C-type locking ring 4 is not less than the depth of the C-type locking ring groove 103, so that the protruding part of the C-type locking ring 4 can effectively prevent the underwater wellhead from moving upward, thus enhancing the limiting effect.

[0051] As an optional implementation, the bearing boss 102 is an annular boss, and the inner diameter of the annular boss is not greater than the outer diameter of the underwater wellhead 2.

[0052] By setting the bearing boss 102 as an annular boss, the annular structure ensures uniform distribution of bearing stress, avoids localized wear, and extends service life. In this embodiment, the flatness of the upper surface of the annular boss is no greater than 0.1 mm, ensuring a tight fit with the support structure of the underwater wellhead. The inner diameter of the annular boss is no greater than the outer diameter of the underwater wellhead 2, forming a radial limit to prevent radial displacement of the underwater wellhead 2 on the bearing boss 102.

[0053] As an optional implementation, the length of the pin 3 is not less than the sum of the wall thickness of the guide base plate 1 and the groove depth of the limiting groove 201, and the end of the pin 3 away from the limiting groove 201 is provided with a structure that facilitates the twisting operation.

[0054] In this embodiment, the length of the pin 3 is 5-10 mm greater than the sum of the wall thickness of the guide base plate 1 and the groove depth of the limiting groove 201, so as to ensure that the pin can completely penetrate the limiting hole and go deep into the limiting groove, and avoid the anti-rotation failure due to installation error.

[0055] The end of the pin 3 away from the limiting groove 201 is provided with a hexagonal head or an internal hexagonal groove. Optionally, the head diameter is 3mm-5mm larger than the pin shank diameter, which facilitates underwater wrench operation, meets the tool docking requirements in the deep sea environment, and the increased head diameter enhances the strength of the force during tightening, avoiding the problem of the pin 3 being unable to be disassembled due to head deformation.

[0056] The working process of this embodiment includes:

[0057] S1: Prepare guide base plate 1. With the watch vessel, adjust guide base plate 1 to the wellhead small platform and place it properly.

[0058] S2: Prepare subsea wellhead 2, lower a 30″ water-proof guide pipe according to the casing table, connect to subsea wellhead 2, insert the water-proof guide pipe short section with the bottom reverse buckle, use a 30″ belt clamp to tighten the torque to the position and install the anti-rotation block.

[0059] S3: The guide base plate is connected to the subsea wellhead 2. The delivery tool assembly is lowered and connected to the subsea wellhead 2. Then, the subsea wellhead 2 is lowered to the bearing boss 102 of the guide base plate 1. The subsea wellhead 2 or the guide base plate 1 is rotated slightly to make one of the limiting grooves 201 of the subsea wellhead 2 coaxial with one of the limiting holes 101 of the guide base plate 1. Then, the pin 3 is screwed in to prevent rotation and limit the movement. Finally, a C-type locking ring 4 is installed in the C-type locking ring groove 103 on the upper part of the guide base plate 1 to complete the locking of the guide base plate and the subsea wellhead.

[0060] S4: Install the guide base plate 1 and the underwater wellhead 2. Using the tooling assembly, lower the docked guide base plate 1 and the underwater wellhead 2 to the vicinity of the seabed. Adjust the guide base plate 1 to the designed heading position, confirm the relevant parameters of the attitude measurement instrument of the guide base plate 1, and finally lower it into place and retrieve the tooling assembly.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A guide base and underwater wellhead head locking mechanism, characterized in that, The utility model relates to a kind of underwater wellhead, which comprises: A guide base disc (1) is provided with: limit hole (101) through the guide base disc (1), load bearing boss (102) arranged on the inner surface of the guide base disc (1), and C-shaped lock ring clamping groove (103) arranged on the outer surface of the guide base disc (1), the number of limit hole (101) is 9, and 9 limit hole (101) is evenly distributed along the circumference on the outer surface of the guide base disc (1); An underwater wellhead (2) is provided with a U-shaped limit groove (201) on the outer surface thereof and a support structure (202) capable of being arranged on the load bearing boss (102), and the number of the limit groove (201) is 8, and the 8 limit grooves (201) are evenly distributed along the circumference on the outer surface of the underwater wellhead (2); A latch (3) is used to insert the limit hole (101) into the limit groove (201) when the limit hole (101) is coaxial with the limit groove (201) to limit the relative rotation of the guide base disc (1) and the underwater wellhead (2); A C-shaped lock ring (4) can be installed in the C-shaped lock ring clamping groove (103); Wherein, the 8 limit grooves (201) and the 9 limit holes (101) cooperate with each other, so that the butt joint accuracy between the guide base disc (1) and the underwater wellhead (2) reaches ±2.5°.

2. A guide base and underwater wellhead locking mechanism according to claim 1, characterized in that: The guide base disc (1) is a thin-walled cylindrical structure.

3. The guide base and underwater wellhead locking mechanism of claim 1, wherein: The limit hole (101) includes a threaded hole, and the size of the threaded hole is matched with the size of the external thread of the latch (3).

4. A guide base and underwater wellhead locking mechanism according to any one of claims 1 to 3, characterised in that: The C-shaped lock ring clamping groove (103) is arranged above the limit hole (101), and the load bearing boss (102) is located between the C-shaped lock ring clamping groove (103) and the limit hole (101).

5. A guide base and underwater wellhead locking mechanism according to any one of claims 1 to 3, characterised in that: The inner diameter of the C-shaped lock ring (4) is matched with the outer diameter of the corresponding C-shaped lock ring clamping groove (103) on the outer surface of the guide base disc (1), and the thickness of the C-shaped lock ring (4) is not less than the depth of the C-shaped lock ring clamping groove (103).

6. A guide base and underwater wellhead locking mechanism according to any one of claims 1 to 3, wherein: The load bearing boss (102) is an annular boss, and the inner diameter of the annular boss is not greater than the outer diameter of the underwater wellhead (2).

7. A guide base and underwater wellhead locking mechanism according to any one of claims 1 to 3, wherein: The length of the latch (3) is not less than the sum of the wall thickness of the guide base disc (1) and the groove depth of the limit groove (201), and the end of the latch (3) away from the limit groove (201) is provided with a structure facilitating screwing operation.

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