Split type self-compensation retention system of high-pressure wellhead hanger

Abstract

The invention relates to the field of oil development, and discloses a high-pressure wellhead hanger split type self-compensation retention system which comprises a shell, a mandrel hanger body, a locking ring, a pressing ring, a clamping ring, a check ring, an elastic clamping spring and a recycling tool. The mandrel hanger body is located in the shell; the pressing ring is mounted between the upper part of the mandrel hanger body and the lower part of the locking ring; the lower part of the pressing ring is a lower inclined surface which is gradually shrunk inwards; the locking ring and the pressing ring are connected into a whole through the check ring. The clamping ring is cut into a plurality of same split bodies, and dovetail grooves are machined in the outer sides of the split bodies of the clamping ring; and the elastic clamp spring is arranged in the dovetail groove of each split body of the clamp ring. The asymmetric split type clamping rings are adopted and connected through the elastic clamping springs, stress distribution compensation is achieved, and stress concentration is avoided; the device is compact in structure, does not need a special tool, improves the installation and recovery efficiency, achieves reliable retention and lossless repeated disassembly, and remarkably improves the maintainability and economical efficiency of downhole tools.

Description

Technical Field

[0001] The present invention relates to the field of oil development, and particularly to a split self-compensating retention system for a high-pressure wellhead hanger. Background Art

[0002] The wellhead mandrel hanger is a key wellhead device in the completion and production processes of oil and gas. It is mainly used for hanging the tubing string, sealing the annulus between the tubing and the casing, and adapting to complex well conditions such as high temperature, high pressure, and corrosive fluids. Its performance directly affects the production safety and operation efficiency of oil and gas wells.

[0003] Currently, in production, the retention structure of the mandrel hanger mostly uses an integral snap ring. However, in practice, based on the extreme working conditions of high pressure, high temperature, and strong corrosion in the oil industry, this retention structure has the following defects: 1. Special tools are required for expansion / contraction during the installation of the integral snap ring; 2. It cannot be adjusted after fixation, and has too high requirements for installation accuracy; 3. Repeated disassembly and assembly are likely to cause structural deformation; 4. Poor synchronism, uneven pre-tightening force, and uneven stress distribution under complex working conditions. Summary of the Invention

[0004] To overcome the defects of the prior art, the present invention provides a split self-compensating retention system for a high-pressure wellhead hanger, and its technical solution is as follows: A split self-compensating retention system for a high-pressure wellhead hanger includes a mandrel hanger body, a housing, a locking ring, a pressure ring, a snap ring, a retaining ring, and an elastic snap spring; the inner cavity of the housing includes a large-diameter cavity in the upper part and a small-diameter cavity in the lower part, and the housing is provided with a flared support platform at the position where the large-diameter cavity transitions to the lower small-diameter cavity; the outer diameter of the upper part of the mandrel hanger body is smaller than that of the large-diameter cavity and the end is provided with an external thread, the outer diameter of the middle part is consistent with that of the large-diameter cavity, the outer diameter of the lower part is consistent with that of the small-diameter cavity, and a flared seating platform matching the flared support platform is provided at the position where the middle part transitions to the lower part; the middle part of the locking ring has a thick wall and is provided with an internal thread meshing with the external thread of the mandrel hanger body, and the lower part has a thin wall and is provided with an inner ring groove; the pressure ring is installed between the upper part of the mandrel hanger body and the lower part of the locking ring, the upper part of the pressure ring is provided with an outer ring groove corresponding to the inner ring groove, and the lower part of the pressure ring is a downwardly tapered lower inclined surface; the retaining ring is installed in the inner ring groove and the outer ring groove to connect the locking ring and the pressure ring as a whole; the snap ring is an elastic shrinkage ring, which is cut into several identical segments, the inner side of the upper part of the segment is provided with an inner inclined surface matching the lower inclined surface, the outer side is provided with an outer inclined surface gradually shrinking upward, the outer side of the lower part of the segment is provided with an installation groove, and a receiving groove is provided on the inner surface of the housing corresponding to the snap ring, and the upper part of the receiving groove is provided with an upper inclined surface matching the outer inclined surface; the elastic snap spring is arranged in the installation groove of each segment of the snap ring, and it is an open structure and matches the shape of the installation groove.

[0005] Furthermore, it further includes a recovery tool; the recovery tool is used for the recovery operation after the locking ring, pressing ring and retaining ring are taken out. The middle part of the recovery tool has a thick wall and is provided with an internal thread that meshes with the external thread of the core shaft hanger body. The lower part of the recovery tool has a thin wall and the end is provided with a bottom inclined surface that cooperates with the split external inclined surface of the snap ring.

[0006] Furthermore, the installation groove of the split snap ring is a dovetail groove.

[0007] Furthermore, the snap ring includes six parts.

[0008] Furthermore, the split gap of the snap ring cutting is 15 mm.

[0009] Furthermore, the elastic snap ring is processed from spring steel.

[0010] Furthermore, the cross-section of the elastic snap ring is a dovetail-shaped structure.

[0011] Furthermore, an opening is formed by cutting 20 mm of the elastic snap ring.

[0012] Furthermore, the upper inclined surface of the housing accommodation groove is set at an angle of 45 degrees.

[0013] Furthermore, the external inclined surface of the split snap ring is set at an angle of 45 degrees.

[0014] Compared with the prior art, the present invention mainly has the following beneficial technical effects: 1. The structure of the present invention is compact, suitable for narrow wellhead spaces, and no special tools are required for installation and disassembly; through the synergistic effect of the retractable ring and the elastic connection, it has strong self-recovery characteristics, has low requirements for installation accuracy, and combines screw drive and conical surface locking to achieve efficient installation, reliable fixation and non-destructive repeated disassembly.

[0015] 2. The present invention adopts an asymmetric split snap ring to achieve stress distribution compensation and improve the axial bearing capacity.

[0016] 3. The present invention can reduce the stress peak under complex working conditions through the split snap ring, and avoid deformation caused by stress concentration. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the working state after the installation of the present invention; Figure 2 It is a schematic diagram of the state where the snap ring is not contracted during the recovery of the present invention; Figure 3 It is a schematic diagram of the state where the snap ring is completely contracted during the recovery of the present invention; Figure 4 It is Figure 1 The enlarged schematic diagram of part I in Figure 5Schematic top view of the original state of the snap ring of the present invention; Figure 6 Schematic front view of the original state of the snap ring of the present invention; Figure 7 Schematic top view of the contracted state of the snap ring of the present invention; Figure 8 is Figure 7 Schematic view A-A in Figure 9 is Figure 8 Enlarged schematic view of part II in Figure 10 Schematic connection diagram of the locking ring and the pressing ring of the present invention; Figure 11 is Figure 10 Enlarged schematic view of part III in In the figure: 1 - housing, 2 - mandrel hanger body, 3 - snap ring, 4 - elastic snap ring, 5 - pressing ring, 6 - retaining ring, 7 - locking ring, 8 - recovery tool, 9 - receiving groove, 10 - upper inclined surface, 11 - bottom inclined surface, 12 - flared seating platform, 13 - inner inclined surface, 14 - outer inclined surface, 15 - installation groove, 16 - lower inclined surface, 17 - split body, 18 - inner ring groove, 19 - outer ring groove. Specific embodiments

[0018] The present invention will be described in detail below in conjunction with the embodiments and the accompanying drawings. Embodiment 1

[0019] Refer to Figures 1 to 11. A split self-compensating retention system for a high-pressure wellhead hanger, which comprises a housing 1, a mandrel hanger body 2, a locking ring 7, a pressure ring 5, a snap ring 3, a retaining ring 6, an elastic snap spring 4 and a recovery tool 8; the inner cavity of the housing 1 includes a large-diameter cavity in the upper part and a small-diameter cavity in the lower part, and the housing 1 is provided with a flared platform at the position where the large-diameter cavity transitions to the lower small-diameter cavity; the outer diameter of the upper part of the mandrel hanger body 2 is smaller than that of the large-diameter cavity and the end is provided with an external thread, the outer diameter of the middle part is matched with that of the large-diameter cavity, the outer diameter of the lower part is matched with that of the small-diameter cavity, and a flared seating platform 12 matched with the flared platform is provided at the position where the middle part transitions to the lower part; the middle part of the locking ring 7 has a thick wall and is provided with an internal thread meshing with the external thread of the mandrel hanger body 2, and the lower part has a thin wall and is provided with an inner ring groove 18; the pressure ring 5 is installed between the upper part of the mandrel hanger body 2 and the lower part of the locking ring 7, the upper part of the pressure ring 5 is provided with an outer ring groove 19 corresponding to the inner ring groove 18, and the lower part of the pressure ring 5 is a downward inclined surface 16 that gradually contracts inward; the retaining ring 6 is installed in the inner ring groove 18 and the outer ring groove 19 to connect the locking ring 7 and the pressure ring 5 into one body to realize synchronous up and down movement; the snap ring 3 is an elastic contraction ring, which is cut into a number of identical segments 17, the inner side of the upper part of the segment 17 is set as an inner inclined surface 13 matched with the downward inclined surface 16, the outer side is set as an outer inclined surface 14 that gradually contracts upward, the outer side of the lower part of the segment 17 is provided with an installation groove 15, and a receiving groove 9 is provided on the inner surface of the housing 1 corresponding to the snap ring 3, and the upper part of the receiving groove 9 is set as an upper inclined surface 10 matched with the outer inclined surface 14; the elastic snap spring 4 is arranged in the installation groove 15 of each segment 17 of the snap ring 3, and it is an open structure and matches the shape of the installation groove 15; the recovery tool 8 is used for the recovery operation after the locking ring 7, the pressure ring 5 and the retaining ring 6 are taken out, the middle part of the recovery tool 8 has a thick wall and is provided with an internal thread meshing with the external thread of the mandrel hanger body 2, and the lower part of the recovery tool 8 has a thin wall and the end is set as a bottom inclined surface 11 matched with the outer inclined surface 14 of the segment 17 of the snap ring 3. Example 2

[0020] See Figures 1 to 11 . A split self-compensating retention system for a high-pressure wellhead hanger, on the basis of the technical solution described in Example 1, the installation groove 15 of the segment 17 of the snap ring 3 is set as a dovetail groove; the cross section of the elastic snap spring 4 is a dovetail-shaped structure. With such a design, the shapes of the two match, making the installation convenient and reliable. Example 3

[0021] See Figures 1 to 11 . A split self-compensating retention system for a high-pressure wellhead hanger, on the basis of the technical solution described in Example 1, the snap ring 3 includes six segments 17; the gap between the segments 17 cut from the snap ring 3 is 15 mm. The snap ring 3 is evenly cut to form an annular unit that can elastically expand / contract; through the connection of the elastic snap spring 4, an asymmetric split structure is formed, forming a staggered stress transmission path, improving the axial load-bearing capacity, and allowing each of the six segments 17 cut to generate a radial displacement, reducing the peak value of the contact stress and avoiding stress concentration. Example 4

[0022] See Figures 1 to 11 。A split self-compensating retention system for a high-pressure wellhead hanger. Based on the technical solution described in Example 1, since spring steel has a very high tensile strength and elastic limit, the elastic snap ring 4 is made of spring steel, and the elastic snap ring 4 is cut by 20 mm to form an opening. The elastic snap ring 4 passes through the installation groove 15 of the snap ring 3 to connect them into a whole, and uses its own elastic force to keep the snap ring 3 in a pre-contracted state. Example 5

[0023] See Figures 1 to 11 。A split self-compensating retention system for a high-pressure wellhead hanger. Based on the technical solution described in Example 1, the upper inclined surface 10 of the accommodation groove 9 of the housing 1 and the outer inclined surface 14 of the split part 17 of the snap ring 3 are both set to 45-degree angles to achieve the best matching state.

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, its basic working principle is briefly introduced as follows: 1. The structure of the present invention is compact, suitable for narrow wellhead spaces, and installation and disassembly do not require special tools; through the coordinated action of the retractable ring and the elastic connecting piece, it has strong self-recovery characteristics, has low requirements for installation accuracy, combines screw drive and conical surface locking to achieve efficient installation, reliable retention and non-destructive repeated disassembly. During the installation stage, the snap ring 3 is sleeved on the mandrel hanger body 2, the mandrel hanger body 2 and the locking ring 7 are connected by threads. When the locking ring 7 is tightened, it drives the pressure ring 5 to move downward, and the lower inclined surface 16 of the pressure ring 5 expands the snap ring 3 to make it snap into the accommodation groove 9 of the housing 1, forming an axial two-way mechanical lock to prevent the mandrel hanger body 2 from moving up and down, realizing retention. During the disassembly stage, reverse the locking ring 7. After removing the pressure ring 5, the snap ring 3 completely automatically contracts under the elastic force of the elastic snap ring 4; the mandrel hanger body 2 and the recovery tool 8 are connected by threads. After the recovery tool 8 is tightened in place, lift the recovery tool 8 to take out all parts. Without special tools, it can be disassembled and assembled repeatedly to achieve efficient installation, reliable retention and non-destructive disassembly. When the snap ring 3 cannot completely contract under the elastic force of the elastic snap ring 4, tighten the recovery tool 8, and its bottom inclined surface 11 acts on the outer inclined surface 14 of the snap ring 3, which can forcibly contract the snap ring 3 until it completely contracts; lift the recovery tool 8 to achieve non-destructive removal and avoid the problem of being unable to remove due to the elastic failure of the elastic snap ring 4.

[0025] 2. The present invention adopts an asymmetric split snap ring to achieve stress distribution compensation and improve the axial load-bearing capacity. The snap ring 3 is connected by an elastic snap ring 4, which can achieve a circumferentially non-uniform distribution pattern, forming a misaligned stress transfer path to avoid stress concentration, and can increase the axial load-bearing capacity by more than 2 times.

[0026] 3. The present invention can reduce the stress peak under complex working conditions through a split snap ring, avoiding deformation caused by stress concentration. When the downhole pressure fluctuates, resulting in unilateral stress concentration, the snap ring 3 allows a radial displacement of 0.2 - 0.5 mm, reducing the peak contact stress.

Claims

1. A split self-compensating retention system for a high-pressure wellhead hanger, comprising a mandrel hanger body, characterized in that, It also includes a housing, a locking ring, a pressing ring, a snap ring, a retaining ring and an elastic snap spring; the inner cavity of the housing includes a large-diameter cavity in the upper part and a small-diameter cavity in the lower part, and the housing is provided with a flared-shaped support platform at the position where the large-diameter cavity transitions to the lower small-diameter cavity; the upper outer diameter of the core shaft hanger body is smaller than the large-diameter cavity and the end is provided with an external thread, the middle outer diameter fits with the large-diameter cavity, and the lower outer diameter fits with the small-diameter cavity. A flared-shaped seating platform that cooperates with the flared-shaped support platform is provided at the position where the middle part transitions to the lower part; the middle part of the locking ring has a thick wall and is provided with an internal thread that meshes with the external thread of the core shaft hanger body, and the lower part has a thin wall and is provided with an inner ring groove; the pressing ring is installed between the upper part of the core shaft hanger body and the lower part of the locking ring. The upper part of the pressing ring is provided with an outer ring groove corresponding to the inner ring groove, and the lower part of the pressing ring is a downward-inclined surface that gradually contracts inward; the retaining ring is installed in the inner ring groove and the outer ring groove to connect the locking ring and the pressing ring into one body; the snap ring is an elastic shrinkage ring, which is cut into several identical segments. The inner side of the upper part of the segment is provided with an inner inclined surface that cooperates with the downward-inclined surface, and the outer side is provided with an outer inclined surface that gradually contracts upward. The outer side of the lower part of the segment is provided with an installation groove, and a receiving groove is provided on the inner surface of the housing corresponding to the snap ring. The upper part of the receiving groove is provided with an upper inclined surface that cooperates with the outer inclined surface; the elastic snap spring is arranged in the installation groove of each segment of the snap ring, and it is an open-type structure and matches the shape of the installation groove.

2. The split self-compensating retention system for a high-pressure wellhead hanger according to claim 1, wherein, It also includes a recovery tool; the recovery tool is used for the recovery operation after the locking ring, the pressing ring and the retaining ring are taken out. The middle part of the recovery tool has a thick wall and is provided with an internal thread that meshes with the external thread of the core shaft hanger body. The lower part of the recovery tool has a thin wall and the end is provided with a bottom inclined surface that cooperates with the outer inclined surface of the segment of the snap ring.

3. The split self-compensating retention system of a high-pressure wellhead hanger according to claim 1, wherein The installation groove of the segment of the snap ring is a dovetail groove.

4. A split self-compensating retention system for a high-pressure wellhead hanger according to claim 1, wherein, The snap ring includes six segments.

5. The split self-compensating retention system for a high-pressure wellhead hanger according to claim 4, wherein, The gap between the segments of the snap ring after cutting is 15 mm.

6. A split self-compensating retention system for a high-pressure wellhead hanger according to claim 1, characterized in that, The elastic snap spring is processed from spring steel.

7. A split self-compensating retention system for a high-pressure wellhead hanger, characterized in that, The cross-section of the elastic snap spring is a dovetail-shaped structure.

8. A split self-compensating retention system for a high-pressure wellhead hanger according to claim 1, characterized in that, 20 mm of the elastic snap spring is cut off to form an opening.

9. A split self-compensating retention system for a high-pressure wellhead hanger according to claim 1, characterized in that, The upper inclined surface of the receiving groove of the housing is set at an angle of 45 degrees.

10. A split self-compensating retention system for a high-pressure wellhead hanger according to claim 9, characterized in that, The outer inclined surface of the segment of the snap ring is set at an angle of 45 degrees.

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