Threaded joint for oil pipe and casing pipe

Abstract

The utility model discloses a screwed joint for oil and casing pipes, belongs to the technical field of screwed joints, and aims to solve the problems that the existing API (American Petroleum Institute) round threads are low in connection strength, buttress threads are poor in sealing performance, and the technical requirements of the oil exploitation industry cannot be met. The pipe fitting comprises a coupling and a pipe body, external threads are arranged on the outer side of the end of the pipe body, internal threads are arranged at the two ends of the inner side of the coupling, the pipe body and the coupling are in threaded connection through the external threads of the pipe body and the internal threads of the coupling, the tooth-shaped bearing face angle of the external threads is 0-5 degrees, and the tooth-shaped guide face angle of the external threads is 40-60 degrees. The bearing surface angle of the tooth form of the internal thread is 0-5 degrees, the guide surface angle of the tooth form of the internal thread is 40-60 degrees, the guide surface angle of the tooth form of the external thread is the same as the guide surface angle of the tooth form of the internal thread, and the bearing surface angle of the tooth form of the external thread is the same as the bearing surface angle of the tooth form of the internal thread. The utility model is suitable for the oil and casing pipe screwed joint.

Description

Technical Field

[0001] The utility model belongs to the technical field of threaded joints, and in particular relates to an oil and casing threaded joint. Background Art

[0002] There are two main types of threaded joints for oil and casing currently used in the oil extraction industry, namely API standard threaded joints and non-API standard threaded joints (special threaded joints).

[0003] API standard threaded joint is the most commonly used threaded joint at present. Its connection forms have two thread profiles: round thread and trapezoidal thread. Because of its simple structure, long promotion time and wide application range.

[0004] API thread features:

[0005] API round thread joint: good sealing performance, the connection strength is only 60-80% of the pipe body strength.

[0006] API partial trapezoidal thread joint: The connection strength is high and can be consistent with the strength of the pipe body, but the sealing performance is poor and lower than that of round thread.

[0007] With the development of the oil extraction industry, API threaded joints are increasingly unable to meet the technical requirements of the oil extraction industry. The oil and casing production industry has developed non-API standard threaded joints (special threaded joints) that can meet the technical requirements of different well conditions. The main structural form of special threaded joints is: pipe end sealing surface + trapezoidal thread connection. The sealing performance and connection strength of this joint form can reach the performance of the pipe body. However, its disadvantages are high processing accuracy requirements, fine requirements for downhole operations, high production costs and use costs, and it is not suitable for large-scale promotion. Utility Model Content

[0008] The utility model aims to provide an oil and casing threaded joint to solve the problems that the existing API round thread has low connection strength, the trapezoidal thread has poor sealing performance and cannot meet the technical requirements of the oil production industry.

[0009] The technical solution adopted by the utility model is as follows:

[0010] An oil and casing threaded joint comprises a coupling and a pipe body, wherein the outer side of the end of the pipe body is provided with an external thread, and the inner two ends of the coupling are provided with internal threads, and the pipe body and the coupling are threadedly connected via the external thread of the pipe body and the internal thread of the coupling, the bearing surface angle of the tooth profile of the external thread is 0-5°, the guide surface angle of the tooth profile of the external thread is 40-60°, the bearing surface angle of the tooth profile of the internal thread is 0-5°, the guide surface angle of the tooth profile of the internal thread is 40-60°, the guide surface angle of the tooth profile of the external thread is the same as the guide surface angle of the tooth profile of the internal thread, and the bearing surface angle of the tooth profile of the external thread is the same as the bearing surface angle of the tooth profile of the internal thread.

[0011] Furthermore, a pipe end cylinder is provided at the end of the pipe body, and a round hole column and a shoulder matched with the pipe end cylinder are provided on the inner side of the coupling.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are:

[0013] 1. In the utility model, the angle of the bearing surface of the round thread tooth type is improved. The bearing surface and guide surface angles of the traditional API round thread are both 30°. The bearing surface angles of the tooth type of the internal and external threads in the utility model are 0-5°, and the guide surface angles are 40-60°, which eliminates the possibility of slipping of the threaded connection due to the large bearing surface angle of the API round thread, while retaining the advantages of good sealing performance of the round thread. At the same time, the connection diameter of the end tooth bottom of the traditional API round thread is smaller than the outer diameter of the pipe body, and the end tooth bottom diameter of the external thread connection of the pipe body is changed to be larger than the outer diameter of the pipe body, so that the strength of the pipe body thread connection is consistent with the strength of the pipe body from the design point of view. After the machine is tightened, the inner diameter of the inner thread connection tooth bottom of the coupling exceeds the outer diameter of the pipe body, which structurally ensures that the connection strength of the coupling is consistent with the pipe body after being connected to the pipe body, solving the problems of low connection strength of the existing API round thread and poor sealing performance of the trapezoidal thread, which cannot meet the technical requirements of the oil extraction industry.

[0014] 2. In the utility model, the shoulder of the coupling makes the inner diameter of the pipe body in a continuous transition state, eliminating the discontinuous transition state of the inner diameter of the API round thread joint connection, so that the threaded joint has the excellent sealing performance of the round thread and the pipe body connection strength of the partial trapezoidal thread. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present utility model and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work, including:

[0016] Figure 1 It is a structural schematic diagram of the tooth shape of the internal thread of the utility model;

[0017] Figure 2 It is a structural schematic diagram of the tooth shape of the external thread of the utility model;

[0018] Figure 3 It is a schematic diagram of the external thread with shoulder structure of the utility model;

[0019] Figure 4 It is a schematic diagram of the external thread without shoulder structure of the utility model;

[0020] Figure 5 It is a schematic diagram of the internal thread with shoulder structure of the utility model;

[0021] Figure 6 It is a schematic diagram of the internal thread of the utility model without shoulder structure;

[0022] Figure 7 This is a schematic diagram of the assembly of the threaded joint with shoulder structure of the utility model;

[0023] Figure 8 This is a schematic diagram of the assembly of the threaded joint without shoulder structure of the utility model;

[0024] Markings in the figure: 1-internal thread, 2-external thread, 3-coupling, 4-tube body, 5-tube end cylinder, 6-round hole column. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the utility model provided in the accompanying drawings is not intended to limit the scope of the utility model claimed for protection, but merely represents selected embodiments of the utility model. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] It should be noted that reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0028] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the utility model product is usually placed when in use. They are only simplified descriptions for the convenience of describing the present utility model, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance.

[0029] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0030] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] An oil and casing threaded joint comprises a coupling and a pipe body, wherein the outer side of the end of the pipe body is provided with an external thread, and the inner two ends of the coupling are provided with internal threads, and the pipe body and the coupling are threadedly connected via the external thread of the pipe body and the internal thread of the coupling, the bearing surface angle of the tooth profile of the external thread is 0-5°, the guide surface angle of the tooth profile of the external thread is 40-60°, the bearing surface angle of the tooth profile of the internal thread is 0-5°, the guide surface angle of the tooth profile of the internal thread is 40-60°, the guide surface angle of the tooth profile of the external thread is the same as the guide surface angle of the tooth profile of the internal thread, and the bearing surface angle of the tooth profile of the external thread is the same as the bearing surface angle of the tooth profile of the internal thread.

[0032] Furthermore, a pipe end cylinder is provided at the end of the pipe body, and a round hole column and a shoulder matched with the pipe end cylinder are provided on the inner side of the coupling.

[0033] During the implementation of the utility model, the angle of the bearing surface of the round thread tooth profile is improved. The bearing surface and guide surface angles of the traditional API round thread are both 30°. The bearing surface angles of the tooth profiles of the internal and external threads of the utility model are 0-5°, and the guide surface angles are 40-60°, eliminating the possibility of slipping of the threaded connection due to the large bearing surface angle of the API round thread, while retaining the advantage of good sealing performance of the round thread. At the same time, the connection diameter of the end tooth bottom of the traditional API round thread is smaller than the outer diameter of the pipe body, and the end tooth bottom diameter of the external thread connection of the pipe body is changed to be larger than the outer diameter of the pipe body, so that the strength of the pipe body thread connection is consistent with the strength of the pipe body from the design point of view. After the machine is tightened, the inner diameter of the inner thread connection tooth bottom of the coupling exceeds the outer diameter of the pipe body, which structurally ensures that the connection strength of the coupling is consistent with the pipe body after being connected to the pipe body, solving the problems of low connection strength of the existing API round thread, poor sealing performance of the trapezoidal thread, and failure to meet the technical requirements of the oil extraction industry.

[0034] In addition, the shoulder of the coupling makes the inner diameter of the pipe body in a continuous transition state, eliminating the discontinuous transition state of the inner diameter of the API round thread joint connection, so that the threaded joint has the excellent sealing performance of the round thread and the pipe body connection strength of the trapezoidal thread.

[0035] Example 1

[0036] Shoulder structure:

[0037] An oil and casing threaded joint comprises a coupling and a pipe body, wherein the outer side of the end of the pipe body is provided with an external thread, and the two ends of the inner side of the coupling are provided with internal threads, and the pipe body and the coupling are threadedly connected through the external thread of the pipe body and the internal thread of the coupling, the bearing surface angle of the tooth profile of the external thread is 0-5°, the guide surface angle of the tooth profile of the external thread is 40-60°, the bearing surface angle of the tooth profile of the internal thread is 0-5°, the guide surface angle of the tooth profile of the internal thread is 40-60°, the guide surface angle of the tooth profile of the external thread is the same as the guide surface angle of the tooth profile of the internal thread, and the bearing surface angle of the tooth profile of the external thread is the same as the bearing surface angle of the tooth profile of the internal thread, the end of the pipe body is provided with a pipe end cylinder, and the inner side of the coupling is provided with a round hole column and a shoulder matched with the pipe end cylinder.

[0038] The external thread of the pipe body is screwed together with the internal thread of the coupling to form a threaded joint connection. After the threads are screwed together, sealing and connection functions are achieved. After the cylindrical end face of the pipe end is screwed together with the shoulder of the coupling, contact is achieved to achieve sealing.

[0039] Example 2

[0040] No shoulder structure:

[0041] An oil and casing threaded joint comprises a coupling and a pipe body, wherein the outer side of the end of the pipe body is provided with an external thread, and the inner two ends of the coupling are provided with internal threads, and the pipe body and the coupling are threadedly connected via the external thread of the pipe body and the internal thread of the coupling, the bearing surface angle of the tooth profile of the external thread is 0-5°, the guide surface angle of the tooth profile of the external thread is 40-60°, the bearing surface angle of the tooth profile of the internal thread is 0-5°, the guide surface angle of the tooth profile of the internal thread is 40-60°, the guide surface angle of the tooth profile of the external thread is the same as the guide surface angle of the tooth profile of the internal thread, and the bearing surface angle of the tooth profile of the external thread is the same as the bearing surface angle of the tooth profile of the internal thread.

[0042] The external thread of the pipe body is screwed together with the internal thread of the coupling to form a threaded joint connection. After the threads are screwed together, the sealing and connection functions are achieved.

[0043] The above is the embodiment of the utility model. The above is the preferred embodiment of the utility model. If the preferred implementation methods in each preferred embodiment are not obviously self-contradictory or based on a preferred implementation method, each preferred implementation method can be arbitrarily superimposed and used in combination. The embodiments and specific parameters in the embodiments are only for the purpose of clearly describing the verification process of the utility model, and are not used to limit the patent protection scope of the utility model. The patent protection scope of the utility model is still subject to its claims. All equivalent structural changes made by using the description and drawings of the utility model should be included in the protection scope of the utility model.

Claims

1. An oil and casing threaded joint, It is characterized in that The invention comprises a coupling (3) and a pipe body (4), wherein an outer end of the pipe body (4) is provided with an external thread (2), and both ends of the inner side of the coupling (3) are provided with internal threads (1); the pipe body (4) and the coupling (3) are threadedly connected via the external thread (2) of the pipe body (4) and the internal thread (1) of the coupling (3); the bearing surface angle of the tooth profile of the external thread (2) is 0-5°, the guiding surface angle of the tooth profile of the external thread (2) is 40-60°, the bearing surface angle of the tooth profile of the internal thread (1) is 0-5°, the guiding surface angle of the tooth profile of the internal thread (1) is 40-60°, the guiding surface angle of the tooth profile of the external thread (2) is the same as the guiding surface angle of the tooth profile of the internal thread (1), and the bearing surface angle of the tooth profile of the external thread (2) is the same as the bearing surface angle of the tooth profile of the internal thread (1).

2. An oil and casing threaded joint according to claim 1, It is characterized in that The end of the pipe body (4) is provided with a pipe end cylinder (5), and the inner side of the coupling (3) is provided with a round hole column (6) and a shoulder matched with the pipe end cylinder (5).

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