A multi-stage expansion sleeve metal sealing joint structure

Abstract

This utility model relates to the field of oil and gas drilling and completion engineering technology, specifically a multi-stage expansion casing metal sealing joint structure, including an external thread joint and an internal thread joint. The sidewall of the external thread joint is provided with a first anti-torque shoulder, a secondary sealing cylindrical surface, a first-stage trapezoidal thread, a threaded stepped guide surface, a central sealing surface, a second-stage trapezoidal thread, a main sealing cylindrical surface, a metal end face guide surface, and a second anti-torque shoulder in sequence from left to right along the axial direction. The threaded stepped guide surface and the metal end face guide surface are both 30°. This multi-stage expansion casing metal sealing joint structure improves upon traditional metal sealing structures, which struggle to maintain stable sealing before and after expansion. The improved metal seal is a heterogeneous metal seal between cylindrical surfaces, using a super-elastic metal material. It leverages the superior recovery performance of the metal material after expansion compared to normal expansion casing materials, resulting in a tighter metal sealing surface after expansion.

Description

Technical Field

[0001] This utility model relates to the field of oil and gas drilling and completion engineering technology, specifically a multi-stage expansion casing metal sealing joint structure. Background Technology

[0002] Expandable casing technology is a technique that uses expandable tools downhole to cause radial and axial expansion deformation of the casing, thereby achieving the purpose of repairing damaged casing, enlarging the borehole diameter, or completing the well. This technology was first developed by Shell in the 1990s and first applied in 1999, and is considered "one of the core technologies for the development of the 21st-century oil industry." Expandable casing technology has significant value in oilfield development, and is particularly suitable for scenarios such as repairing damaged casing wells, deepening sidetracking in old wells, and tailpipe suspension.

[0003] Traditional expansion sleeve joints mainly use rubber ring seals or conical metal seal structures. Both of these methods have obvious defects in practical applications. When the temperature is too high, the service life of the seal is short. In the existing technology, even if metal seals are used, it is difficult to maintain the sealing performance for a long time under high temperature and high pressure conditions. Therefore, we propose a multi-stage expansion sleeve metal seal joint structure. Utility Model Content

[0004] This utility model provides the following technical solution: a multi-stage expansion sleeve metal sealing joint structure, including an external thread joint and an internal thread joint. The side wall of the external thread joint is provided with a first anti-torque shoulder, a secondary sealing cylindrical surface, a first-stage trapezoidal thread, a threaded stepped guide surface, a middle sealing surface, a second-stage trapezoidal thread, a main sealing cylindrical surface, a metal end face guide surface, and a second anti-torque shoulder in sequence from left to right along the axial direction. The threaded stepped guide surface and the metal end face guide surface are both 30°. The sidewall of the internal threaded joint is provided with a first anti-torque shoulder, a secondary sealing cylindrical surface, a first-stage trapezoidal thread, a middle sealing surface, a second-stage trapezoidal thread, a main sealing cylindrical surface, and a second anti-torque shoulder in sequence from left to right along the axial direction, wherein the first anti-torque shoulder is 15°. After the external threaded joint and the internal threaded joint are connected, the main sealing cylindrical surface, the middle sealing surface and the first superelastic metal sleeve are all in metal interference contact. The crest and root of the internal thread of the first-stage trapezoidal thread and the second-stage trapezoidal thread are all in metal interference contact with the external thread.

[0005] As a preferred technical solution of this utility model, the secondary sealing cylindrical surface includes a first superelastic metal sleeve disposed on the side wall of the internal threaded joint, the middle sealing surface includes a sealing rubber ring disposed on the side wall of the internal threaded joint, and the main sealing cylindrical surface includes a second superelastic metal sleeve disposed on the side wall of the internal threaded joint.

[0006] As a preferred technical solution of this utility model, the side wall of the internal threaded connector is provided with a bearing surface of a trapezoidal tapered thread, and the surface of the bearing surface of the trapezoidal tapered thread is provided with a chamfer of the bearing surface of the trapezoidal tapered thread. The side wall of the internal threaded connector is also provided with a guide surface of a trapezoidal thread, and the surface of the guide surface of the trapezoidal thread is provided with a chamfer of the guide surface of the trapezoidal thread.

[0007] As a preferred technical solution of this utility model, when the first torque shoulder and the second torque shoulder are fastened, an interference fit is adopted. A gap is provided between the metal end face guide surface and the external threaded joint, a gap is provided between the threaded step guide surface and the external threaded joint, and a gap is provided between the guide surfaces of the first-stage trapezoidal thread and the second-stage trapezoidal thread.

[0008] As a preferred embodiment of this utility model, the angle of the first torque shoulder is 15°, the bearing surface angle of the trapezoidal tapered thread is -5° to -15°, the guide surface angle of the trapezoidal thread is 5° to 15°, and the thread taper is 1:(16 to 32).

[0009] As a preferred technical solution of this utility model, the first and second superelastic metal sleeves can be sealed from cylindrical to cylindrical, or from cone to cone, cone to sphere, or cylindrical to sphere.

[0010] As a preferred embodiment of this utility model, the rectangular groove of the metal seal of the first and second superelastic metal sleeves has a depth of 1.2 mm and a width of 3 mm, and the first and second superelastic metal sleeves are made of nickel-titanium alloy, and the rectangular groove of the sealing rubber ring has a depth of 1.2 mm and a width of 2 mm.

[0011] As a preferred technical solution of this utility model, the thread seal adopts a two-stage thread seal, including a first-stage trapezoidal thread seal, a second-stage trapezoidal thread seal, and a sealing rubber ring seal on the middle sealing surface between the first-stage trapezoidal thread and the second-stage trapezoidal thread. The two-stage thread seal can also be a multi-stage thread seal structure, and the longitudinal distance of the two-stage threads is 1.6mm.

[0012] As a preferred technical solution of this utility model, the first superelastic metal sleeve, the second superelastic metal sleeve and the internal threaded joint are integrated into one design.

[0013] As a preferred embodiment of this utility model, the bearing surface angle and the guide surface angle of the trapezoidal tapered thread are both 10°, the thread taper is 1:32, the bearing surface chamfer of the trapezoidal tapered thread is 0.2mm, and the guide surface chamfer of the trapezoidal thread is 0.8mm.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This multi-stage expansion sleeve metal sealing joint structure is different from traditional metal sealing structures, which have difficulty maintaining stable sealing performance before and after expansion. The improved metal seal is a cylindrical-to-cylinder dissimilar metal seal, using a super-elastic metal material. It takes advantage of the fact that its recovery performance after expansion is stronger than that of normal expansion sleeve materials, and the metal sealing surface will be tighter after expansion.

[0015] 2. In this multi-stage expansion sleeve metal sealing joint structure, during the sleeve threading process, the rubber ring is easily squeezed out of the sealing groove by the external thread end. After the sleeve expands and the diameter increases, the rubber ring breaks due to excessive plastic deformation. The improved sealing thread adopts a trapezoidal thread, which has strong load-bearing capacity and good sealing performance. It also adopts a two-stage thread seal, which increases the tensile strength and sealing performance of the sleeve, reduces the contact stress on the tooth surface after expansion, and reduces tooth surface damage and sealing performance reduction.

[0016] 3. In this multi-stage expansion sleeve metal sealing joint structure, gaps will appear between the torque shoulders on the inner side of the sleeve after expansion, leading to sealing failure after expansion. Separation will also occur between the metal sealing surfaces, making it difficult to maintain sealing performance for a long time under high temperature and high pressure conditions, resulting in reduced or complete loss of sealing performance. It has a total of seven sealing structures, namely, a metal seal against the torque shoulder, a secondary sealing cylindrical metal seal, a first-stage trapezoidal thread seal, a central rubber sealing ring seal, a second-stage trapezoidal thread seal, a main sealing cylindrical metal seal, and a metal seal against the torque shoulder. The multiple sealing structures improve sealing performance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a single-sided transverse section of a multi-stage expansion sleeve metal sealing joint structure. Figure 2 This is a schematic diagram of the transverse cross-section of an external threaded joint with a multi-stage expansion sleeve metal sealing joint structure. Figure 3 This is a schematic diagram of the transverse cross-section of an internally threaded joint, which is a multi-stage expansion sleeve metal sealing joint structure.

[0018] Figure 4 This is the present invention. Figure 1 Enlarged cross-sectional view of point A in the middle.

[0019] Figure 5 This is the present invention. Figure 1 Enlarged cross-sectional view of section B in the middle.

[0020] Figure 6 This is the present invention. Figure 1 Enlarged cross-sectional view of point C in the middle.

[0021] Figure 7 This is the present invention. Figure 2 Enlarged cross-sectional view of point D in the middle.

[0022] In the diagram: 1. External threaded connector; 2. Internal threaded connector; 3. First super-elastic metal sleeve; 4. First-stage trapezoidal thread; 5. Sealing rubber ring; 6. Second-stage trapezoidal thread; 7. Second super-elastic metal sleeve; 8. First torque shoulder; 9. Threaded step guide surface; 10. Metal end face guide surface; 11. Second torque shoulder; 12. Bearing surface of the trapezoidal tapered thread; 13. Chamfer on the bearing surface of the trapezoidal tapered thread; 14. Chamfer on the guide surface of the trapezoidal thread; 15. Guide surface of the trapezoidal thread. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] Please see Figures 1 to 7 A multi-stage expansion sleeve metal sealing joint structure includes an external threaded joint 1 and an internal threaded joint 2. The sidewall of the external threaded joint 1 is provided with a first anti-torque shoulder 8, a secondary sealing cylindrical surface, a first-stage trapezoidal thread 4, a threaded stepped guide surface 9, a middle sealing surface, a second-stage trapezoidal thread 6, a main sealing cylindrical surface, a metal end face guide surface 10, and a second anti-torque shoulder 11 from left to right along the axial direction. The threaded stepped guide surface 9 and the metal end face guide surface 10 are both 30°. The sidewall of the internal threaded joint 2 is provided with a first anti-torque shoulder 8, a secondary sealing cylindrical surface, a first-stage trapezoidal thread 4, a middle sealing surface, a second-stage trapezoidal thread 6, a main sealing cylindrical surface, and a second anti-torque shoulder 11 in sequence from left to right along the axial direction, wherein the first anti-torque shoulder 8 is 15°. After the external threaded connector 1 and the internal threaded connector 2 are connected, the main sealing cylindrical surface, the middle sealing surface and the first superelastic metal sleeve 3 are all in metal interference contact. The internal threads of the first-stage trapezoidal thread 4 and the second-stage trapezoidal thread 6 are in metal interference contact with the crest and root of the external threads.

[0025] It should be noted that the threaded stepped guide surface 9 is 30° and the metal end face guide surface 10 is 30°, to ensure that the thread will not get stuck when it is being threaded, making the seal tighter and less prone to warping during expansion, thus increasing the sealing performance.

[0026] Please see Figure 1The secondary sealing cylindrical surface includes a first superelastic metal sleeve 3 disposed on the side wall of the internal threaded joint 2, the middle sealing surface includes a sealing rubber ring 5 disposed on the side wall of the internal threaded joint 2, and the main sealing cylindrical surface includes a second superelastic metal sleeve 7 disposed on the side wall of the internal threaded joint 2.

[0027] It should be noted that during the expansion process, the second superelastic metal sleeve 7 and the first superelastic metal sleeve 3 form a cylindrical-to-cylindrical dissimilar metal seal with the external threaded joint 1. The use of superelastic metal material takes advantage of its stronger recovery performance after expansion compared to normal expansion sleeve materials, resulting in a tighter metal seal surface after expansion. The second-stage thread seal formed by the first-stage trapezoidal thread 4 and the second-stage trapezoidal thread 6 increases the tensile strength and sealing performance of the sleeve, reduces the contact stress on the tooth surface after expansion, and minimizes tooth surface damage that could reduce sealing performance. Furthermore, a sealing rubber ring 5 is used in the middle of the second-stage thread seal, which is not squeezed out of the sealing groove by the external thread end, thus further enhancing the sealing performance.

[0028] Please see Figure 1 The side wall of the internal threaded connector 2 is provided with a bearing surface 12 of a trapezoidal tapered thread. The surface of the bearing surface 12 of the trapezoidal tapered thread is provided with a chamfer 13 of the bearing surface of the trapezoidal tapered thread. The side wall of the internal threaded connector 2 is also provided with a guide surface 15 of a trapezoidal thread. The surface of the guide surface 15 of the trapezoidal thread is provided with a chamfer 14 of the guide surface of the trapezoidal thread.

[0029] It should be noted that the fit has been improved, reducing the presence of gaps.

[0030] Please see Figure 1 When the first torque shoulder 8 and the second torque shoulder 11 are engaged, they are both interference fits. There is a gap between the metal end face guide surface 10 and the external threaded joint 1. There is a gap between the threaded step guide surface 9 and the external threaded joint 1. There is a gap between the guide surface 15 of the first-stage trapezoidal thread 4 and the second-stage trapezoidal thread 6.

[0031] It should be noted that after expansion, a gap will appear between the torque shoulders on the inner side of the sleeve due to the conical metal surface. This effectively reduces the possibility of sealing failure after expansion. Furthermore, separation will also occur between the metal sealing surfaces, making it difficult to maintain sealing performance for a long time under high temperature and high pressure conditions. This reduces the possibility of reduced or completely lost sealing performance and improves sealing efficiency.

[0032] Please see Figure 1 The angle of the first torque shoulder 8 is 15°, the bearing surface angle of the trapezoidal tapered thread 13 is -5° to -15°, the guide surface angle of the trapezoidal thread is 5° to 15°, and the thread taper is 1:(16 to 32).

[0033] It should be noted that the angle of the first torque shoulder 8 is 15°, which makes the seal tighter and less prone to warping during the expansion process, thus increasing the sealing performance.

[0034] Please see Figure 1 The first superelastic metal sleeve 3 and the second superelastic metal sleeve 7 adopt cylindrical-to-cylindrical sealing, as well as conical-to-conical, conical-to-spherical, and cylindrical-to-spherical sealing forms.

[0035] Please see Figure 1 The rectangular groove of the metal seal of the first superelastic metal sleeve 3 and the second superelastic metal sleeve 7 has a depth of 1.2 mm and a width of 3 mm. The first superelastic metal sleeve 3 and the second superelastic metal sleeve 7 are made of nickel-titanium alloy. The rectangular groove of the sealing rubber ring 5 has a depth of 1.2 mm and a width of 2 mm.

[0036] It should be noted that the first superelastic metal sleeve 3 and the second superelastic metal sleeve 7 are made of nickel-titanium alloy, which has high elastic modulus and high temperature resistance.

[0037] Please see Figure 1 The thread seal adopts a two-stage thread seal, including a first-stage trapezoidal thread 4 thread seal, a second-stage trapezoidal thread 6 thread seal, and a sealing rubber ring 5 sealing the middle sealing surface between the first-stage trapezoidal thread 4 and the second-stage trapezoidal thread 6. The two-stage thread seal can also be a multi-stage thread seal structure, with a longitudinal distance of 1.6mm between the two-stage threads.

[0038] It should be noted that you should ensure the threads do not get stuck when you re-thread them.

[0039] Please see Figure 1 The first super-elastic metal sleeve 3, the second super-elastic metal sleeve 7, and the internal threaded connector 2 are integrated into one design.

[0040] It should be noted that traditional metal sealing structures have difficulty maintaining stable sealing performance before and after expansion. The improved metal seal is a heterogeneous metal seal between cylindrical surfaces, using a super-elastic metal material. It takes advantage of the fact that its recovery performance after expansion is stronger than that of normal expansion sleeve materials, and the metal sealing surface will be tighter after expansion.

[0041] Please see Figure 1 The bearing surface angle 12 and the guide surface angle 15 of the trapezoidal tapered thread are both 10°, the thread taper is 1:32, the bearing surface chamfer 13 of the trapezoidal tapered thread is 0.2mm, and the guide surface chamfer 14 of the trapezoidal thread is 0.8mm.

[0042] It should be noted that the improved sealing thread adopts a trapezoidal thread, which has strong load-bearing capacity and good sealing performance. It also adopts a two-stage thread seal, which increases the tensile strength and sealing performance of the sleeve, reduces the contact stress on the tooth surface after expansion, and reduces tooth surface damage that would reduce the sealing performance.

[0043] Working principle: The main sealing cylindrical surface and secondary sealing cylindrical surface of the internal threaded connector 2 are in metal interference contact with the corresponding cylindrical surface of the external threaded connector 1. The first and second super-elastic metal sleeves are preferably nickel-titanium alloys, whose recovery performance after expansion far exceeds that of conventional sleeve materials. During the sleeve expansion process, conventional sleeve materials achieve strength improvement due to cold work hardening, while nickel-titanium alloys, with their high elastic modulus, can compensate for the gap caused by expansion through their own elastic deformation, making the cylindrical surface seal more tightly fitted, forming a self-tightening effect of "the more sufficient the expansion, the more reliable the seal". At the same time, the rectangular groove (1.2mm deep and 3mm wide) on the sealing surface provides reasonable space for metal deformation and avoids damage to the sealing surface.

[0044] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-stage expansion sleeve metal sealing joint structure, comprising an external threaded joint (1) and an internal threaded joint (2), characterized in that: The sidewall of the external threaded joint (1) is provided with a first anti-torque shoulder (8), a secondary sealing cylindrical surface, a first-stage trapezoidal thread (4), a threaded stepped guide surface (9), a middle sealing surface, a second-stage trapezoidal thread (6), a main sealing cylindrical surface, a metal end face guide surface (10), and a second anti-torque shoulder (11) in sequence from left to right along the axial direction. The threaded stepped guide surface (9) and the metal end face guide surface (10) are both 30°. The sidewall of the internal threaded joint (2) is provided with a first anti-torque shoulder (8), a secondary sealing cylindrical surface, a first-stage trapezoidal thread (4), a middle sealing surface, a second-stage trapezoidal thread (6), a main sealing cylindrical surface, and a second anti-torque shoulder (11) in sequence from left to right along the axial direction, wherein the first anti-torque shoulder (8) is 15°; After the external threaded connector (1) and the internal threaded connector (2) are connected, the main sealing cylindrical surface, the middle sealing surface and the first superelastic metal sleeve (3) are all in metal interference contact. The crest and root of the internal thread of the first-stage trapezoidal thread (4) and the second-stage trapezoidal thread (6) are in metal interference contact with the external thread.

2. The multi-stage expansion sleeve metal sealing joint structure according to claim 1, characterized in that: The secondary sealing cylindrical surface includes a first superelastic metal sleeve (3) disposed on the side wall of the internal threaded joint (2), the middle sealing surface includes a sealing rubber ring (5) disposed on the side wall of the internal threaded joint (2), and the main sealing cylindrical surface includes a second superelastic metal sleeve (7) disposed on the side wall of the internal threaded joint (2).

3. The multi-stage expansion sleeve metal sealing joint structure according to claim 1, characterized in that: The side wall of the internal threaded connector (2) is provided with a bearing surface (12) of a trapezoidal tapered thread. The surface of the bearing surface (12) of the trapezoidal tapered thread is provided with a chamfer (13) of the bearing surface of the trapezoidal tapered thread. The side wall of the internal threaded connector (2) is also provided with a guide surface (15) of a trapezoidal thread. The surface of the guide surface (15) of the trapezoidal thread is provided with a chamfer (14) of the guide surface of the trapezoidal thread.

4. A multi-stage expanded bushing metal seal joint structure according to claim 1, characterized by: When the first anti-torque shoulder (8) and the second anti-torque shoulder (11) are fastened, an interference fit is used. There is a gap between the metal end face guide surface (10) and the external threaded joint (1). There is a gap between the threaded step guide surface (9) and the external threaded joint (1). There is a gap between the guide surface (15) of the first step trapezoidal thread (4) and the second step trapezoidal thread (6).

5. The multi-stage expansion sleeve metal sealing joint structure according to claim 3, characterized in that: The angle of the first anti-torque shoulder (8) is 15°, the bearing surface angle of the bearing surface (12) of the biased trapezoidal tapered thread is -5° to -15°, the guide surface angle of the biased trapezoidal thread is 5° to 15°, and the thread taper is 1:(16 to 32).

6. The multi-stage expansion sleeve metal sealing joint structure according to claim 2, characterized in that: The first superelastic metal sleeve (3) and the second superelastic metal sleeve (7) can be sealed from cylindrical to cylindrical, or from cone to cone, cone to sphere, or cylindrical to sphere.

7. The multi-stage expansion sleeve metal sealing joint structure according to claim 1, characterized in that: The rectangular groove of the metal seal of the first superelastic metal sleeve (3) and the second superelastic metal sleeve (7) has a depth of 1.2 mm and a width of 3 mm. The first superelastic metal sleeve (3) and the second superelastic metal sleeve (7) are made of nickel-titanium alloy. The middle sealing surface includes a sealing rubber ring (5). The rectangular groove of the sealing rubber ring (5) has a depth of 1.2 mm and a width of 2 mm.

8. The multi-stage expansion sleeve metal sealing joint structure according to claim 1, characterized in that: The thread seal adopts a two-stage thread seal, including a first-stage trapezoidal thread (4) thread seal, a second-stage trapezoidal thread (6) thread seal, and a sealing rubber ring (5) seal on the middle sealing surface between the first-stage trapezoidal thread (4) and the second-stage trapezoidal thread (6).

9. The multi-stage expansion sleeve metal sealing joint structure according to claim 1, characterized in that: The first superelastic metal sleeve (3), the second superelastic metal sleeve (7), and the internal threaded connector (2) are designed as an integrated unit.

10. The multi-stage expansion sleeve metal sealing joint structure according to claim 3, characterized in that: The bearing surface angle of the bearing surface (12) of the trapezoidal tapered thread and the guide surface angle of the guide surface (15) of the trapezoidal thread are both 10°, the thread taper is 1:32, the bearing surface chamfer (13) of the trapezoidal tapered thread is 0.2mm, and the guide surface chamfer (14) of the trapezoidal thread is 0.8mm.

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