High-connection-strength oil casing special screwed joint

Abstract

The utility model discloses a high-connection-strength special threaded connector for an oil casing. The high-connection-strength special threaded connector comprises a double-male connector body, a universal connector body and a double-female connector body. First external thread structures are symmetrically arranged on the outer circumferential surfaces of the two ends of the double male connector, and each first external thread structure comprises an external thread, an external sealing conical surface, an external right-angle circular bead and an internal inclined surface which are sequentially arranged from inside to outside; first internal thread structures are symmetrically arranged on the inner circumferential surfaces of the two ends of the double-female joint; the left end of the universal joint is provided with an inner joint, the right end is provided with an outer joint, and the middle part is connected by a universal joint structure; according to the utility model, the bearing surfaces and the guide surfaces of the male buckle and the female buckle are in interference fit, so that the tensile strength and the compressive strength are greatly improved, and the connection strength under complex well conditions such as a deep well, an ultra-deep well and a highly-deviated well is ensured; and the blocking risk under the environment of short radius, large dog leg degree and irregular well diameter is greatly reduced, and the safety and reliability under complex conditions are greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of threaded connection of oil and gas drilling pipes, in particular to a special threaded joint for oil casing with high connection strength. Background Art

[0002] As the petroleum industry evolves, oil and gas drilling operations are moving toward greater depths, higher pressures and temperatures, and more demanding operating conditions, coupled with advances in drilling technology. The API standard threaded joints commonly used in oilfield pipes are no longer able to meet the requirements of oilfield development. While API round threads offer excellent sealing properties, the threaded connection strength is only 60% to 80% of that of the pipe body. Meanwhile, API trapezoidal threads, while offering higher threaded connection strength, offer less than ideal sealing performance. Highly deviated wells, horizontal wells, and wells with significant doglegs, in particular, place even higher demands on the tensile strength, compression resistance, and sealing properties of oil casing and tubing. Consequently, major oilfield pipe manufacturers worldwide are committed to developing specialized threaded oil casing and tubing with superior tensile and compressive strength and gas-tightness to meet industry demands. Utility Model Content

[0003] The purpose of the utility model is to provide a special threaded joint for oil casing with high connection strength to meet the use requirements in the industry.

[0004] To achieve the above purpose, the technical solutions provided by the present invention are as follows:

[0005] A special threaded joint for oil casing with high connection strength, including a double male joint, a universal joint, and a double female joint;

[0006] The outer circumferential surfaces of both ends of the double male connector are symmetrically provided with a first external thread structure, each of which includes an external thread, an external sealing cone surface, an external right-angle shoulder and an internal bevel surface arranged in sequence from the inside to the outside, and the external thread is a conical thread with a taper of 1:16;

[0007] The inner circumferential surfaces at both ends of the double female connector are symmetrically provided with a first internal thread structure;

[0008] The left end of the universal joint is provided with an inner joint, the right end is provided with an outer joint, and the middle part is connected by a universal joint structure, wherein the inner side of the inner joint is provided with a second inner thread structure consistent with the first inner thread structure; the outer circumferential front end of the outer joint is provided with a second outer thread structure consistent with the first outer thread structure;

[0009] Each of the first internal thread structures includes an internal thread, an internal sealing cone surface, an internal cylindrical surface, and an internal right-angle shoulder arranged in sequence from the end surface to the middle portion, wherein the internal thread is a conical thread with a taper of 1:16;

[0010] When used in rotational engagement, the external thread of the first external thread structure is screwed into the internal thread of the first internal thread structure at the corresponding position, and the external guide surface and the external bearing surface of the external thread gradually contact the internal guide surface and the internal bearing surface of the internal thread at the corresponding position until an interference fit is achieved. As the thread is gradually screwed in, the external sealing cone surface and the external right-angle shoulder gradually contact the internal sealing cone surface and the internal right-angle shoulder until an interference fit is achieved.

[0011] Among them, the external guide angle of the external thread is 45°, the external bearing surface angle is 90°, the taper of the external sealing cone surface set at its front end is 1:12, and the right-angle shoulder angle is 90±1°.

[0012] Among them, the internal guide angle of the internal thread is 45°, the internal load-bearing surface angle is 90°, the taper of the internal sealing cone surface set at its rear end is 1:12, and the internal right-angle shoulder angle is 90±1°.

[0013] The outer circumference of the inner joint is provided with a clamping shoulder, and the tail end is provided with an outer universal ring, which is an elliptical arc with a groove provided inside, and the groove is filled with an elastic sealing belt.

[0014] Wherein, an inner universal ring is provided at the tail end of the external joint, and the inner universal ring is in an elliptical arc shape.

[0015] Among them, the outer diameter of the double male connector is 73.02mm~508.00mm, and its wall thickness is the inner connector wall thickness = the outer connector wall thickness.

[0016] Wherein, the outer diameter of the double female connector of the double female connector is equal to the outer diameter of the inner connector.

[0017] Among them, when the outer diameter of the specification is 73.02~114.3mm, the external thread pitch = internal thread pitch = 3.18mm; when the outer diameter of the specification is 127.00~508.00mm, the external thread pitch = internal thread pitch = 5.08mm.

[0018] The tooth tops and tooth bottoms of the external thread and the internal thread are parallel and parallel to the thread axis.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The bearing surfaces and guide surfaces of the male and female buckles of the utility model are designed with an interference fit, which greatly improves the tensile strength and compressive strength, ensuring the connection strength in complex well conditions such as deep wells, ultra-deep wells, and highly deviated wells. The elliptical ring universal joint connection structure greatly reduces the risk of blocking in short radius, large dogleg and irregular well diameter environments, greatly improving safety and reliability in complex situations. The design of the sealing cone surface and right-angle shoulder of the utility model ensures sealing in complex well conditions such as deep wells, ultra-deep wells, and highly deviated wells.

[0021] In addition, the utility model adopts a design in which the tooth tops and bottoms are parallel to the thread axis, which is convenient for screwing together during on-site use. It has strong operability, ensures the screwing quality and greatly improves the construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure shows the overall structure of the special threaded joint provided by the embodiment of the present utility model;

[0023] Figure 2 The figure shows the assembly diagram of the internal and external thread structures provided by the embodiment of the present utility model;

[0024] Figure 3 The figure shows a cross-sectional view of a double male connector provided by an embodiment of the present utility model;

[0025] Figure 4 The figure shows a schematic cross-sectional view of the external thread provided in this practical embodiment;

[0026] Figure 5 The figure shows a cross-sectional schematic diagram of the front end of the external thread provided by an embodiment of the present utility model;

[0027] Figure 6 Shown is a schematic diagram of the structure of a universal joint provided by an embodiment of the present utility model;

[0028] Figure 7 Shown is a schematic diagram of the universal joint structure provided by an embodiment of the present utility model;

[0029] Figure 8 The figure shows a schematic diagram of the double female connector structure provided by an embodiment of the present utility model;

[0030] Figure 9 The figure shows a schematic cross-sectional view of an internal thread provided by an embodiment of the present utility model;

[0031] Figure 10 The figure shows a schematic diagram of the internal thread tail end provided by an embodiment of the present utility model;

[0032] In the figure: 1-double male joint, 2-universal joint, 3-double female joint, 11-first external thread structure, 12-second external thread structure, 111-external thread, 112-external sealing cone, 113-external right-angle shoulder, 114-inner bevel, 115-external guide surface, 116-external bearing surface, 21-external joint, 22-inner joint, 211-inner universal ring, 221-clamping shoulder, 222-outer universal ring, 223-elastic sealing belt, 31-first internal thread structure, 32-second internal thread structure , 311-internal thread, 312-inner sealing cone, 313-inner cylindrical surface, 314-inner right-angle shoulder, 315-inner guide surface, 316-inner load-bearing surface, D-specification outer diameter, D1-inner joint outer diameter, D2-double female joint outer diameter, t-specification wall thickness, t1-inner joint wall thickness, t2-outer joint wall thickness, P-external thread pitch, p-internal thread pitch, A-external guide angle, B-external load-bearing surface angle, C-external right-angle shoulder angle, a-inner guide angle, b-inner load-bearing surface angle, c-inner right-angle shoulder angle. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0035] In the description of this patent, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," and "set" should be understood broadly. For example, they can refer to fixed connection or set, detachable connection or set, or integral connection or set, and can refer to direct connection or indirect connection. Those skilled in the art can understand the specific meanings of the above terms in this patent based on specific circumstances.

[0036] See also Figures 1-10 The structure shown is an embodiment provided by the present invention.

[0037] This embodiment provides a special threaded joint for oil casing with high connection strength, comprising a double male joint 1, a universal joint 2, and a double female joint 3;

[0038] The outer circumferential surfaces of both ends of the double male connector 1 are symmetrically provided with first external thread structures 11. Each of the first external thread structures 11 includes an external thread 111, an external sealing cone 112, an external right-angle shoulder 113, and an internal bevel 114, which are arranged in sequence from the inside to the outside. The external thread 111 is a conical thread with a taper of 1:16.

[0039] The inner circumferential surfaces of both ends of the double female connector 3 are symmetrically provided with first internal thread structures 31;

[0040] The left end of the universal joint 2 is provided with an inner joint 22, the right end is provided with an outer joint 21, and the middle part is connected by a universal joint structure, wherein the inner side of the inner joint 22 is provided with a second inner thread structure 32 having the same structure as the first inner thread structure 31; the outer circumferential front end of the outer joint 21 is provided with a second outer thread structure 12 having the same structure as the first outer thread structure 11;

[0041] Each of the first internal thread structures 31 includes an internal thread 311, an internal sealing cone 312, an internal cylindrical surface 313, and an internal right-angle shoulder 314 arranged in sequence from the end face to the middle part. The internal thread 311 is a conical thread with a taper of 1:16.

[0042] When used in rotational engagement, the external thread 111 of the first external thread structure 11 is screwed into the internal thread 311 of the first internal thread structure 31 at the corresponding position, and the external guide surface 115 and the external bearing surface 116 of the external thread gradually contact the internal guide surface 315 and the internal bearing surface 316 of the internal thread at the corresponding position until an interference fit is achieved. As the thread is gradually screwed in, the external sealing cone surface 112 and the external right-angle shoulder 113 gradually contact the internal sealing cone surface 312 and the internal right-angle shoulder 314 respectively until an interference fit is achieved.

[0043] The bearing surfaces and guide surfaces of the male and female buckles of the utility model are both designed with interference fit, which greatly improves the tensile strength and compressive strength, ensuring the connection strength under complex well conditions such as deep wells, ultra-deep wells, and highly deviated wells. The elliptical ring universal joint connection structure is adopted to greatly reduce the risk of obstruction in short radius, large dogleg and irregular well diameter environments, greatly improving the safety and reliability in complex situations. In addition, the design of the sealing cone surface and the right-angle shoulder of the utility model ensures the sealing performance under complex well conditions such as deep wells, ultra-deep wells, and highly deviated wells.

[0044] Preferably, the present application provides a specific embodiment structure of the external thread. Specifically, the external guide angle A of the external thread 111 is 45°, the external bearing surface angle B is 90°, the taper of the external sealing cone 112 provided at the front end is 1:12, and the right-angle shoulder angle C is 90±1°.

[0045] Preferably, the present application provides a specific embodiment structure of the internal thread. Specifically, the internal guide angle A of the internal thread 311 is 45°, the internal bearing surface angle B is 90°, the taper of the internal sealing cone 312 provided at the rear end is 1:12, and the internal right-angle shoulder angle C is 90±1°.

[0046] Preferably, the present application provides a specific embodiment of a universal joint structure. Specifically, the outer circumference of the inner joint 22 is provided with a clamping shoulder 221, and the tail end is provided with an outer universal ring 222. The outer universal ring is elliptical and has an internal groove filled with an elastic sealing band 223. Furthermore, the tail end of the outer joint 21 is provided with an inner universal ring 211. The inner universal ring is elliptical and has an internal groove filled with an elastic sealing band 223.

[0047] The outer diameter of the double male connector 1 is D=73.02mm~508.00mm, and the wall thickness is t=inner connector wall thickness t1=outer connector wall thickness t2.

[0048] The outer diameter D2 of the double female connector 3 is equal to the outer diameter D1 of the inner connector.

[0049] Among them, when the outer diameter D of the specification is 73.02~114.3mm, the external thread pitch P=internal thread pitch p=3.18mm; when the outer diameter D of the specification is 127.00~508.00mm, the external thread pitch P=internal thread pitch p=5.08mm.

[0050] The tooth tops and bottoms of the external thread 111 and the internal thread 311 are parallel and parallel to the thread axis. This design of the tooth tops and bottoms being parallel to the thread axis facilitates on-site screw connection, is highly maneuverable, ensures screw connection quality, and greatly improves construction efficiency.

[0051] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A special threaded joint for oil casing with high connection strength, characterized by: It comprises a double male joint (1), a universal joint (2), and a double female joint (3); The outer circumferential surfaces at both ends of the double male connector (1) are symmetrically provided with first external thread structures (11), each of the first external thread structures (11) comprises an external thread (111), an external sealing cone surface (112), an external right-angle shoulder (113) and an internal bevel (114) arranged in sequence from the inside to the outside, and the external thread (111) is a conical thread with a taper of 1:16; The inner circumferential surfaces at both ends of the double female connector (3) are symmetrically provided with first internal thread structures (31); The left end of the universal joint (2) is provided with an inner joint (22), the right end is provided with an outer joint (21), and the middle part is connected by a universal joint structure, wherein the inner side of the inner joint (22) is provided with a second inner thread structure (32) having the same structure as the first inner thread structure (31); the outer circumferential front end of the outer joint (21) is provided with a second outer thread structure (12) having the same structure as the first outer thread structure (11); Each of the first internal thread structures (31) comprises an internal thread (311), an internal sealing cone (312), an internal cylindrical surface (313), and an internal right-angle shoulder (314) arranged in sequence from the end face to the middle part, wherein the internal thread (311) is a conical thread with a taper of 1:16; When the first external thread structure (11) is used in rotational engagement, the external thread (111) of the first external thread structure (11) is screwed into the internal thread (311) of the first internal thread structure (31) at the corresponding position, and the external guide surface (115) and the external bearing surface (116) of the external thread gradually contact the internal guide surface (315) and the internal bearing surface (316) of the internal thread at the corresponding position respectively until an interference fit is achieved. As the thread is gradually screwed in, the external sealing cone surface (112) and the external right-angle shoulder (113) gradually contact the internal sealing cone surface (312) and the internal right-angle shoulder (314) respectively until an interference fit is achieved.

2. The special threaded joint for oil casing with high connection strength according to claim 1, characterized in that: The external guide angle (A) of the external thread (111) is 45°, the external bearing surface angle (B) is 90°, the taper of the external sealing cone surface (112) provided at the front end thereof is 1:12, and the right-angle shoulder angle (C) is 90±1°.

3. The special threaded joint for oil casing with high connection strength according to claim 1, characterized in that: The inner guide angle (a) of the internal thread (311) is 45°, the inner bearing surface angle (b) is 90°, the taper of the inner sealing cone surface (312) provided at the rear end thereof is 1:12, and the inner right-angle shoulder angle (c) is 90±1°.

4. The special threaded joint for oil casing with high connection strength according to claim 1, characterized in that: The outer circumference of the inner joint (22) is provided with a clamping shoulder (221), and the tail end is provided with an outer universal ring (222). The outer universal ring is elliptical arc-shaped and has a groove arranged inside. The groove is filled with an elastic sealing belt (223).

5. The special threaded joint for oil casing with high connection strength according to claim 1, characterized in that: An inner universal ring (211) is provided at the tail end of the outer joint (21), and the inner universal ring is in an elliptical arc shape.

6. The special threaded joint for oil casing with high connection strength according to claim 1, characterized in that: The outer diameter (D) of the double male connector (1) is 73.02 mm to 508.00 mm, and the wall thickness (t) is equal to the wall thickness of the inner connector (t1) and the wall thickness of the outer connector (t2).

7. The special threaded joint for oil casing with high connection strength according to claim 6, characterized in that: The outer diameter (D2) of the double female joint (3) is equal to the outer diameter (D1) of the inner joint.

8. The special threaded joint for oil casing with high connection strength according to claim 7, characterized in that: When the outer diameter (D) of the specification is 73.02~114.3mm, the external thread pitch (P) = the internal thread pitch (p) = 3.18mm; when the outer diameter (D) of the specification is 127.00~508.00mm, the external thread pitch (P) = the internal thread pitch (p) = 5.08mm.

9. The special threaded joint for oil casing with high connection strength according to claim 1, characterized in that: The tooth tops and tooth bottoms of the external thread (111) and the internal thread (311) are parallel and parallel to the thread axis.

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