Threaded joint with double-sealing structure

Abstract

The utility model discloses a screwed joint with a double-sealing structure. The screwed joint comprises a female screwed joint and a male screwed joint which are assembled together, the male thread joint comprises a male inner sealing surface and a torque shoulder at the vertex of the male inner sealing surface, the upper surface of the male thread joint is sequentially provided with a tapered male thread and a tapered male thread, and an auxiliary sealing conical surface is arranged between the tapered male thread and the tapered male thread; the female threaded connector comprises a female outer sealing face, a female outer circular bead matched with the torque circular bead is arranged at the end of the female outer sealing face, two sections of female threads with conicity are sequentially arranged on the lower surface of the female threaded connector, and an auxiliary sealing conical face is arranged between the two sections of female threads with conicity. The joint is realized through the interference fit of the main sealing surface and the auxiliary sealing surface in the middle of the thread, and the bending resistance, the tensile property and the sealing property of the oil pipe joint are improved by adopting the improved buttress thread.

Description

Technical Field

[0001] The utility model relates to the technical field of oil well pipe threaded joints, in particular to a double sealing structure threaded joint. Background Art

[0002] The stress environment of the pipe string during oil and gas production is very complex, and the pipe string connection is achieved by threads. Therefore, the sealing performance of the threads determines the safety of oil field production to a certain extent. Ordinary API threaded joints can no longer meet the sealing requirements, and special threaded joints with better sealing performance and connection strength are required.

[0003] With the improvement of oil and gas exploration technology, oil and gas development continues to develop in deep formations. Oil well pipes are facing harsh working conditions such as ultra-high production, ultra-high temperature, ultra-high pressure, and ultra-high corrosion. The failure of oil pipe string joints is an extremely complex problem. The main reason for its failure is the loss of integrity of the threaded joint structure, which directly affects the production cycle of oil and gas wells. In order to ensure the safety and performance of oil well pipe string threaded joints, the first task is to improve their sealing performance.

[0004] In these complex oil and gas production processes, special processes such as high torque rotation, lifting and lowering are often required. This requires that the oil casing has the ability to resist large make-up torque and large rotation torque on the basis of high connection strength, high air sealing and high compression resistance. However, traditional API joints and ordinary special threaded joints cannot have the above properties at the same time. Utility Model Content

[0005] In order to overcome the defects of the above technologies, the purpose of the utility model is to provide a double-sealing structure threaded joint, which is achieved by interference fit between the main sealing surface and the auxiliary sealing surface in the middle of the thread, and adopts an improved trapezoidal thread to improve the bending resistance, tensile strength and sealing performance of the oil pipe joint.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] A double-seal structure threaded joint, comprising a female threaded joint 2 and a male threaded joint 1 assembled together;

[0008] The male threaded joint 1 comprises a male inner sealing surface 8, a torque shoulder 7 at the vertex of the male inner sealing surface 8, a male thread 1 9 with a taper and a male thread 2 11 with a taper on the upper surface of the male threaded joint 1, and an auxiliary sealing conical surface 2 10 between the male thread 1 9 with a taper and the male thread 2 11 with a taper;

[0009] The female threaded joint 2 includes a female external sealing surface 4, at the end of which a female external sealing surface 4 is provided with a female external shoulder 3 matching the torque shoulder 7, and two sections of tapered female threads 6 are sequentially arranged on the lower surface of the female threaded joint 2, and an auxiliary sealing cone surface 5 is arranged between the two sections of tapered female threads 6.

[0010] The torque shoulder 7 and the female outer shoulder 3 constitute the main sealing surface, the auxiliary sealing cone surface 2 10 and the auxiliary sealing cone surface 1 5 constitute the auxiliary sealing surface, and when the male threaded joint 1 and the female threaded joint 2 are in a tightened state, the main sealing surface and the auxiliary sealing surface produce a metal interference fit.

[0011] The angle between the torque shoulder 7 and the female outer shoulder 3 is δ=-15°.

[0012] The angle range of the main sealing surface and the auxiliary sealing cone surface γ, β is 9°-20°, and the main sealing surface and the auxiliary sealing surface are tightened by the threaded section to produce a metal interference fit. The interference length range of the main sealing surface is 2mm-4mm, and the interference amount range is 0.2mm-0.4mm. The interference length range of the auxiliary sealing surface is 1mm-2mm, and the interference amount range is 0.1mm-0.2mm.

[0013] The female threaded joint 2 and the male threaded joint 1 are integrally tapered structures, with a taper ε=1:16.

[0014] The tapered male thread 1 9 and the tapered male thread 2 11 and the tapered female thread 6 adopt a partial trapezoidal thread, and the thread load angle θ ranges from -5° to 3°.

[0015] The guide angle α between the male thread and the tapered female thread 6 is in the range of 10°-13°.

[0016] The pitch of the male thread is equal to the pitch of the tapered female thread 6, which is 5 mm. The tooth height of the male thread is in the range of 1.0 mm to 1.5 mm, and the tooth height of the tapered female thread 6 is in the range of 1.5 mm to 1.8 mm.

[0017] The tooth root of the male thread and the tooth top of the tapered female thread 6 produce a metal interference fit after tightening, and the interference contact σ ranges from 0.05mm to 0.13mm.

[0018] Beneficial effects of the utility model:

[0019] The utility model adopts a metal cone-to-cone sealing form for the main and auxiliary sealing surfaces. The main and auxiliary sealing surfaces produce a metal interference fit when the threaded sections are tightened to ensure sealing performance. The design ensures that the sealing pressure is evenly distributed.

[0020] An auxiliary sealing surface is added at the midpoint of the pipe thread, which cooperates with the main sealing surface to increase the stability of the sealing performance. Especially in the case of large-angle bending, the double sealing surface can better play the role of air sealing;

[0021] The -15° torque shoulder design can ensure the button-up positioning and also play an auxiliary sealing role; the improved trapezoidal thread tooth profile is adopted to improve the tensile resistance, composite load performance and sealing performance of the oil pipe joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the special threaded joint structure with double sealing structure of the utility model.

[0023] Figure 2 It is a schematic diagram of the male threaded joint of the utility model.

[0024] Figure 3 It is a schematic diagram of the female threaded joint of the utility model.

[0025] Figure 4 It is a partially enlarged schematic diagram of the sealing structure of the utility model.

[0026] Figure 5 It is a partial enlarged schematic diagram of the sealing thread part of the utility model. DETAILED DESCRIPTION

[0027] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0028] See also Figure 1-Figure 5 The figure shows an embodiment structure provided by the utility model.

[0029] This embodiment provides a special threaded joint with a double sealing surface structure, including a female threaded joint 2 and a male threaded joint 1 assembled together.

[0030] The male threaded joint 1 comprises a torque shoulder 7 at the apex of the male inner sealing surface, a male inner sealing surface 8, two sections of tapered male threads and an auxiliary sealing surface 10 between the two sections of male threads.

[0031] The female threaded joint 2 comprises a female external shoulder 3, a female external sealing surface 4, two tapered female threads and an auxiliary sealing surface 5 between the two female threads. When the male threaded joint and the female threaded joint are in a tightened state, the main sealing surface and the auxiliary sealing surface produce a metal interference fit.

[0032] Preferably, the angle between the inner torque shoulder and the outer torque shoulder surface is -15°.

[0033] Preferably, the angle between the main sealing cone surface and the auxiliary sealing cone surface is 18.9°, and the main sealing surface and the auxiliary sealing surface are tightened by the threaded section to produce a metal interference fit. The interference length of the main sealing surface is 3mm, and the interference amount is 0.3mm. The interference length range of the auxiliary sealing surface is 2.5mm, and the interference amount range is 0.2mm.

[0034] Preferably, the taper of the male thread and the female thread is 1:16.

[0035] Preferably, the male thread and the female thread are barbed-hook type threads, and the thread bearing surface angle is θ=-3°.

[0036] Preferably, the guide surface angle between the male thread and the female thread is α=10°.

[0037] Preferably, the pitch of the male thread is equal to the pitch of the female thread, which is P=5 mm, the tooth height of the male thread is h=1.5 mm, and the tooth height of the female thread is H=1.8 mm.

[0038] Preferably, the male thread tooth root and the female thread tooth top produce a metal interference fit after tightening, and the interference contact is 0.08 mm.

[0039] Preferably, the special threaded joint with double sealing structure retains the advantages of the existing special buckle type such as good sealing, strong anti-slip and anti-sticking properties. The double sealing structure improves the sealing performance, reduces the risk of sealing failure of the threaded joint, and is suitable for oil and gas wells with complex working conditions.

[0040] The working principle of the utility model is as follows:

[0041] The sealing surface and the auxiliary sealing surface adopt a cone-cone sealing design, which produces a metal interference fit when the threaded section is tightened to ensure sealing. The auxiliary sealing surface designed in the threaded section can increase the stability of the sealing performance, especially in the case of large-angle bending. The double sealing surface can better play an air-sealing role. The torque shoulder 7 at the vertex of the male inner sealing surface and the inner torque shoulder 3 at the female threaded joint end also produce an interference fit when the thread is tightened, assisting the seal, and the angle between the inner torque shoulder and the outer torque shoulder surface is δ=-15°.

[0042] The angles of the main sealing cone surface and the auxiliary sealing cone surface are γ, β=18.9°, the taper of the male thread and the female thread ε=1:16, the male thread and the female thread adopt improved trapezoidal threads, the thread load surface angle is θ=-3°, the guide surface angle is α=10°, the male thread pitch is equal to the female thread pitch P=5mm, the male thread tooth height is h=1.5mm, the female thread tooth height is H=1.8mm, and the male thread tooth root and the female thread tooth top produce a metal interference fit after tightening, and the interference contact σ=0.08mm.

Claims

1. A double sealing structure threaded joint, characterized in that: It comprises a female threaded joint (2) and a male threaded joint (1) assembled together; The male threaded joint (1) comprises a male inner sealing surface (8), a torque shoulder (7) at the apex of the male inner sealing surface (8), a male thread 1 (9) with a taper and a male thread 2 (11) with a taper on the upper surface of the male threaded joint (1), and an auxiliary sealing conical surface 2 (10) between the male thread 1 (9) with a taper and the male thread 2 (11); The female threaded joint (2) comprises a female external sealing surface (4), the end of which is provided with a female external shoulder (3) matching the torque shoulder (7), two sections of tapered female threads (6) are arranged in sequence on the lower surface of the female threaded joint (2), and an auxiliary sealing cone surface (5) is arranged between the two sections of tapered female threads (6).

2. A double-seal structure threaded joint according to claim 1, characterized in that: The torque shoulder (7) and the female outer shoulder (3) constitute a main sealing surface, the auxiliary sealing cone surface 2 (10) and the auxiliary sealing cone surface 1 (5) constitute an auxiliary sealing surface, and when the male threaded joint (1) and the female threaded joint (2) are in a tightened state, the main sealing surface and the auxiliary sealing surface produce a metal interference fit.

3. A double-seal structure threaded joint according to claim 2, characterized in that: The angle δ between the torque shoulder (7) and the female outer shoulder (3) is -15°.

4. A double-seal structure threaded joint according to claim 2, characterized in that: The angle range of the main sealing surface and the auxiliary sealing cone surface γ, β is 9°-20°, and the main sealing surface and the auxiliary sealing surface are tightened by the threaded section to produce a metal interference fit. The interference length range of the main sealing surface is 2mm-4mm, and the interference amount range is 0.2mm-0.4mm. The interference length range of the auxiliary sealing surface is 1mm-2mm, and the interference amount range is 0.1mm-0.2mm.

5. A double-seal structure threaded joint according to claim 1, characterized in that: The female threaded joint (2) and the male threaded joint (1) are integrally conical structures, with a taper ε=1:

16.

6. A double-seal structure threaded joint according to claim 1, characterized in that: The tapered male thread 1 (9) and the tapered male thread 2 (11) and the tapered female thread (6) adopt a partial trapezoidal thread, and the thread load angle θ ranges from -5° to -3°.

7. A double-seal structure threaded joint according to claim 6, characterized in that: The guide angle α between the male thread and the tapered female thread (6) is in the range of 10°-13°.

8. A double-seal threaded joint according to claim 6, characterized in that: The pitch of the male thread is equal to the pitch of the tapered female thread (6), which is 5 mm. The tooth height of the male thread ranges from 1.0 mm to 1.5 mm, and the tooth height of the tapered female thread (6) ranges from 1.5 mm to 1.8 mm.

9. A double-seal structure threaded joint according to claim 6, characterized in that: The tooth root of the male thread and the tooth top of the tapered female thread (6) produce a metal interference fit after tightening, and the interference contact σ range is 0.05mm-0.13mm.

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