Threaded connection structure of oil pipe

Abstract

The utility model relates to the technical field of threaded connection structures, in particular to an oil pipe threaded connection structure which is characterized in that two threaded sections are symmetrically arranged on the inner wall of a barrel body, the two threaded sections are arranged in the circumferential direction of the barrel body, each threaded section is provided with a first end and a second end, and the diameter of the first end is smaller than that of the second end; the two threaded sections are used for being in threaded connection with two oil pipes respectively, the two annular grooves are formed in the inner wall of the barrel body in the circumferential direction of the barrel body, the two annular grooves are formed in the opposite ends of the two threaded sections respectively, and the profile curve of each annular groove is composed of three arc sections which are in transition with one another; and the annular groove is used for being matched and clamped with the end part of the oil pipe. The oil pipe joint has the advantages that the three arc sections which abut against one another serve as the top end, stress concentration of the combination portion of the oil pipe and the barrel is reduced, the anti-over-torque and anti-fatigue performance is improved, the sealing precision of the sealing end is guaranteed, and the sealing effect is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of threaded connection structures, in particular to an oil pipe threaded connection structure. Background Art

[0002] Oil casing is a steel pipe used to support the wall of oil and gas wells to ensure the normal operation of the entire oil well during the drilling process and after completion. According to the use, casing can be divided into: guide tube, surface casing, technical casing and oil layer casing. Oil special pipe is mainly used for drilling oil and gas wells and transporting oil and gas. It includes oil drill pipe, oil casing and pumping pipe. Oil drill pipe is mainly used to connect drill collars and drill bits and transmit drilling power. Pumping pipe mainly transports oil and gas at the bottom of the oil well to the ground.

[0003] In the application process of existing oil pipes, production casings and intermediate casing strings, due to the need for a relatively strict airtight sealing environment, and at the same time under the external air pressure, temperature and external force environment, the oil pipes are required to ensure that they maintain good structural characteristics.

[0004] The existing oil pipe threaded connection structure simply adopts the threaded connection method, and usually uses a large number of API standard round threads and trapezoidal thread joints for connection. However, this threaded connection structure cannot meet the requirements of oil and gas wells with harsh mining environment conditions in terms of air tightness. At the same time, under the action of external forces, it cannot play a good anti-deformation effect, resulting in weak overall sealing stability. Utility Model Content

[0005] The purpose of the utility model is to overcome the problems existing in the above-mentioned prior art and to provide an oil pipe threaded connection structure, which can solve the problem of weak stability of the overall seal in the prior art.

[0006] The technical solution of the utility model is:

[0007] A threaded connection structure for an oil pipe comprises: a cylinder, the inner wall of which is symmetrically provided with two threaded sections, the two threaded sections are arranged along the circumference of the cylinder, the threaded section has a first end and a second end, the diameter of the first end is smaller than the diameter of the second end, the two threaded sections are respectively used for threaded connection with two oil pipes, and further comprises:

[0008] Two annular grooves are opened on the inner wall of the cylinder along the circumference of the cylinder. The two annular grooves are respectively arranged at the opposite ends of the two threaded sections. The contour curve of the annular grooves is three circular arc segments that transition to each other. The annular grooves are used to match and clamp with the end of the oil pipe.

[0009] Preferably, the three arc segments transitioning to each other are respectively a first arc, a second arc and a third arc, and the central angles of the first arc, the second arc and the third arc are respectively 15°, 75° and 25°.

[0010] Preferably, the first ends of the two threaded segments are arranged opposite to each other.

[0011] Preferably, the taper of the thread segment is 1:16.

[0012] Preferably, the thread segment comprises:

[0013] A first section is located at one end of the cylinder, and the first section has a plurality of first thread teeth arranged at equal intervals;

[0014] A second section, located at one end of the annular groove, the second section having a plurality of second thread teeth arranged at equal intervals;

[0015] The third section is arranged between the first section and the second section, and the third section has a plurality of third thread teeth arranged at equal intervals. The spacing between the plurality of first thread teeth is not equal to the spacing between the plurality of second thread teeth and the plurality of third thread teeth. The side wall of the oil pipe is provided with a fourth thread section threadedly connected to the third section to match the third section. The fourth thread section has a plurality of fourth thread teeth arranged at equal intervals, and the spacing between the plurality of fourth thread teeth is equal to the spacing between the plurality of third thread teeth.

[0016] Preferably, the spacing between the plurality of second thread teeth is smaller than the spacing between the plurality of third thread teeth, and the spacing between the plurality of third thread teeth is smaller than the spacing between the plurality of first thread teeth.

[0017] Preferably, the plurality of the first thread teeth, the plurality of the second thread teeth, and the plurality of the third thread teeth are all provided with end faces abutting against the fourth thread segment, and an angle ɑ is formed between the end faces and the axial direction of the cylinder, and the ɑ is 3°.

[0018] Compared with the prior art, the oil pipe threaded connection structure provided by the utility model has the following beneficial effects:

[0019] 1. The present application sets matching sealing sections and annular grooves, and the annular groove is a three-section arc section that transitions with each other as the top, which can effectively lower and reduce the stress concentration at the joint of the oil pipe and the barrel, thereby improving the ability to resist over-torque and fatigue. On this basis, compared with the traditional double-taper design, the three arc sections that abut each other can be introduced more smoothly during the buckle process, and the axial and radial pressures at the end of the oil pipe can produce good sealing performance. The end sealing section improves the sealing performance and prevents any wear problems. Despite the use and deformation of the seal, as well as load cycles, the sealing integrity remains unchanged.

[0020] 2. This application optimizes the structure of the oil pipe and the cylinder, and adjusts the pitch of the cylinder to a three-stage structure. Compared with the traditional equally spaced pitch distributed structure, the pitch of the main thread segment is the largest, the pitch of the interval thread segment is moderate, and the pitch of the adjusted secondary thread segment is the smallest. This structural design can reduce the load on the main thread segment and the secondary thread segment due to the different bearing surface gaps when the connection structure is subjected to external force, and the interval thread segment is subjected to force first, thereby reducing the circumferential interference of the structure and reducing the risk of buckling.

[0021] 3. This application optimizes the intersection of the end face and the axial direction of the barrel, and adopts a smoother structural design. Compared with the traditional solution, this design can improve the tensile performance and has higher performance under external pressure, compression and bending. The optimized thread geometry can also reduce the risk of wear even if the thread lubricant is not applied properly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the utility model;

[0023] Figure 2 This is a cross-sectional exploded view of the connection between the cylinder and the oil pipe of the utility model;

[0024] Figure 3 It is a cross-sectional schematic diagram of the sealing section of the utility model;

[0025] Figure 4 It is a partial schematic diagram of the connection between the cylinder and the oil pipe of the utility model. DETAILED DESCRIPTION

[0026] The technical solution in the present application will be described clearly and in detail below in conjunction with the accompanying drawings. In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0027] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as suggesting or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0028] The utility model provides a threaded connection structure for an oil pipe. Figures 1 to 4 The utility model is described with reference to the structural schematic diagram, but it should be understood that the protection scope of the utility model is not limited by the specific implementation method.

[0029] Example 1

[0030] like Figure 1 As shown, the utility model provides an oil pipe threaded connection structure, comprising two oil pipes 2 and a cylinder 1, wherein the two oil pipes 2 are respectively sleeved at both ends of the cylinder 1, and the cylinder 1 is used to connect one end of the two sections of the oil pipes 2, and the inner wall of the cylinder 1 is symmetrically provided with two threaded sections, and the two threaded sections are arranged along the circumference of the cylinder 1, and the threaded sections have a first end and a second end, and the diameter of the first end is smaller than the diameter of the second end, and the two threaded sections are respectively used to be threadedly connected with the two oil pipes 2, and the outer side walls of the two oil pipes 2 are respectively provided with threaded sections in the circumferential direction, that is, the oil pipes 2 are provided with external threaded sections, that is, the threaded structure of the threaded sections and the external threaded sections of the oil pipes 2 is a cone The thread structure also includes: two annular grooves are opened on the inner wall of the cylinder 1 along the circumference of the cylinder 1, and the two annular grooves are respectively arranged at the opposite ends of the two threaded sections. The contour curve of the annular groove is three arc sections that transition to each other. The annular groove is used to match and clamp with the end of the oil pipe 2. The opposite ends of the two oil pipes 2 are also provided with a sealing section 22. The sealing section 22 is annular and matches the annular groove to achieve a sealed connection between the oil pipe 2 and the cylinder 1. When in use, the threaded sections are first opened at both ends of the inner wall of the cylinder 1. At this time, a ring similar to a step is left between the two threaded sections on the inner wall of the cylinder 1. Figure 1 It can be seen that the middle part of the inner wall of the cylinder 1 has an annular groove at both ends of the step. Figure 2 The cross-sectional shape of the annular groove can be seen; at the same time, an external threaded section that matches the threaded section is opened on the outer side wall of the two oil pipes 2, and then a sealing section 22 is set at the opposite ends of the two oil pipes 2. When the oil pipe 2 is threadedly connected to the cylinder 1, the sealing section 22 is just clamped in the annular groove and abuts against the side wall of the annular groove, thereby achieving a seal between the oil pipe 2 and the cylinder 1, and can be introduced more smoothly during the buckling process. The axial and radial pressures at the ends of the oil pipe 2 can produce good sealing performance, and the end sealing section 22 improves the sealing performance. Among them, the sealing section 22 can be made of metal material to prevent any wear problems.

[0031] like Figure 3 As shown, further, the three arc segments transitioning from each other are the first arc 221, the second arc 222, and the third arc 223, and the central angles of the first arc 221, the second arc 222, and the third arc 223 are 15°, 75°, and 25°, respectively. That is to say, the sealing section 22 and the annular groove are composed of three arc segments abutting against each other. The three arc segments abutting against each other are used as the top, which can effectively reduce the stress concentration of the joint part of the oil pipe 2 and the cylinder 1, improve the ability to resist over-torque and fatigue, and keep the sealing integrity unchanged despite the use and deformation of the seal and the load cycle. Among them, when the three arc segments are of the above-mentioned curvature, the sealing section 22 and the annular groove can achieve the best sealing performance.

[0032] Example 2

[0033] As a further improvement on the first embodiment, the first ends of the two thread segments are arranged opposite to each other (the ends with smaller diameters are arranged opposite to each other). Figure 2 , Figure 4 As shown, the cross-section of the first section and the threaded section is a right-angled trapezoid, that is, the first section is inclined from one end of the cylinder 1 toward the other end, and the threaded section is also inclined along one end of the oil pipe 2 toward the other end, and the inclination angles of the first section and the threaded section are the same.

[0034] Furthermore, the taper of the thread segment is 1:16, and the inclination angle of the thread segment is 61.5°-64.5°. With this taper, better sealing performance can be achieved.

[0035] Among them, the other structures of this embodiment are consistent with those of Embodiment 2, and are just optimizations made to Embodiment 2.

[0036] Example 3

[0037] As a further improvement on Example 2, Figure 2 As shown, the threaded section includes: a first section 11, a second section 13, and a third section 12. The first section 11 is located at one end of the cylinder 1. Figure 2 The first section 11 is a main thread section, and the first section 11 has a plurality of first thread teeth 111 arranged at equal intervals; the second section 13 is located at one end of the annular groove, Figure 2Look at the leftmost end, the second section 13 is a secondary thread section, and the second section 13 has a plurality of second thread teeth 131 arranged at equal intervals; the third section 12 is arranged between the first section 11 and the second section 13, and the third section 12 is an interval thread section, and the interval thread section is arranged between the main thread section and the secondary thread section, and the third section 12 has a plurality of third thread teeth 121 arranged at equal intervals, and the spacing between the plurality of first thread teeth 111 is not equal to the spacing between the plurality of second thread teeth 131 and the plurality of third thread teeth 121. The side wall of the oil pipe 2 is provided with a fourth thread section (external thread section) threadedly connected to the third section 12, and the fourth thread section has a plurality of fourth thread teeth 21 arranged at equal intervals, and the spacing between the plurality of fourth thread teeth 21 is equal to the spacing between the plurality of third thread teeth 121. In summary, the first section of the device is set as a three-section variable pitch thread section, and the first section 11, the second section 13, and the third section 12 are all full thread thread sections. The fourth thread segment (external thread segment) on the side wall of the oil pipe 2 has a plurality of fourth thread teeth 21 arranged at equal intervals, and the spacing between the plurality of fourth thread teeth 21 is equal to the spacing between the plurality of third thread teeth 121, which can improve the connection strength.

[0038] Furthermore, the spacing between the plurality of second thread teeth 131 is smaller than the spacing between the plurality of third thread teeth 121, and the spacing between the plurality of third thread teeth 121 is smaller than the spacing between the plurality of first thread teeth 111. The first section 11 (main thread section) has the largest pitch, the third section 12 (interval thread section) has a moderate pitch, and the second section 13 (secondary thread section) has the smallest pitch. Compared with the traditional equally spaced pitch distributed structure, the design of the device can reduce the load of the first section 11 (main thread section) and the second section 13 (secondary thread section) when the connection structure is subjected to external force, because of the different bearing surface gaps, and the third section 12 (interval thread section) is preferentially subjected to force, thereby reducing the circumferential interference of the structure and reducing the risk of sticking.

[0039] Furthermore, the first threads 111, the second threads 131, and the third threads 121 are all provided with an end face 23 that is disposed in contact with the fourth thread segment, and an angle ɑ is formed between the end face 23 and the axial direction of the cylinder 1, and ɑ is 3°. Figure 4 It can be seen that the end face 23 where the first thread 111, the second thread 131, and the third thread 121 abut against the fourth thread 21 is the right side of the connection, and the end face 23 is set at an angle of 3° to the axial direction of the cylinder 1, while the left side of the connection is set at an angle of 10° to the axial direction of the cylinder 1, which further improves the sealing performance. At the same time, the smoother structural design of this device can improve the tensile performance compared to the traditional solution, and also has higher performance under external pressure, compression and bending. The optimized thread geometry can also reduce the risk of wear even if the thread lubricant is not applied properly.

[0040] Among them, the other structures of this embodiment are consistent with those of Embodiment 2, and are just optimizations made to Embodiment 2.

[0041] The advantages of the utility model are:

[0042] 1. The present application sets matching sealing sections and annular grooves, and the annular groove is a three-section arc section that transitions with each other as the top, which can effectively lower and reduce the stress concentration at the joint of the oil pipe and the barrel, thereby improving the ability to resist over-torque and fatigue. On this basis, compared with the traditional double-taper design, the three arc sections that abut each other can be introduced more smoothly during the buckle process, and the axial and radial pressures at the end of the oil pipe can produce good sealing performance. The end sealing section improves the sealing performance and prevents any wear problems. Despite the use and deformation of the seal, as well as load cycles, the sealing integrity remains unchanged.

[0043] 2. This application optimizes the structure of the oil pipe and the cylinder, and adjusts the pitch of the cylinder to a three-stage structure. Compared with the traditional equally spaced pitch distributed structure, the pitch of the main thread segment is the largest, the pitch of the interval thread segment is moderate, and the pitch of the adjusted secondary thread segment is the smallest. This structural design can reduce the load on the main thread segment and the secondary thread segment due to the different bearing surface gaps when the connection structure is subjected to external force, and the interval thread segment is subjected to force first, thereby reducing the circumferential interference of the structure and reducing the risk of buckling.

[0044] 3. This application optimizes the intersection of the end face and the axial direction of the barrel, and adopts a smoother structural design. Compared with the traditional solution, this design can improve the tensile performance and has higher performance under external pressure, compression and bending. The optimized thread geometry can also reduce the risk of wear even if the thread lubricant is not applied properly.

[0045] The above disclosures are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A threaded connection structure for an oil pipe, comprising: A cylinder (1) has two threaded sections symmetrically arranged on its inner wall, the two threaded sections being arranged along the circumference of the cylinder (1), the threaded section having a first end and a second end, the diameter of the first end being smaller than the diameter of the second end, the two threaded sections being respectively used for threaded connection with two oil pipes (2), and characterized in that it further comprises: Two annular grooves are provided on the inner wall of the cylinder (1) along the circumference of the cylinder (1), the two annular grooves are respectively arranged at opposite ends of the two threaded sections, the contour curve of the annular grooves is three circular arc sections transitioning to each other, the annular grooves are used to match and clamp with the end of the oil pipe (2), and the first ends of the two threaded sections are arranged opposite to each other; The threaded section comprises: a first section (11), located at one end of the barrel (1), the first section (11) having a plurality of first thread teeth (111) arranged at equal intervals; a second section (13), located at one end of the annular groove, the second section (13) having a plurality of second thread teeth (131) arranged at equal intervals; a third section (12), arranged between the first section (11) and the second section (13), the third section (12) having a plurality of third thread teeth (121) arranged at equal intervals, the spacing between the plurality of first thread teeth (111) being unequal to the spacing between the plurality of second thread teeth (131) and the plurality of third thread teeth (121), a fourth threaded section threadedly connected to match the third section (12) being provided on the side wall of the oil pipe (2), the fourth threaded section having a plurality of fourth thread teeth (21) arranged at equal intervals, the spacing between the plurality of fourth thread teeth (21) being equal to the spacing between the plurality of third thread teeth (121); The spacing between the plurality of second thread teeth (131) is smaller than the spacing between the plurality of third thread teeth (121), and the spacing between the plurality of third thread teeth (121) is smaller than the spacing between the plurality of first thread teeth (111); The plurality of first thread teeth (111), the plurality of second thread teeth (131), and the plurality of third thread teeth (121) are all provided with an end face (23) disposed in contact with the fourth thread segment, an angle ɑ is formed between the end face (23) and the axial direction of the cylinder (1), and the angle ɑ is 3°, and an angle b is formed between the side surface opposite to the end face (23) and the axial direction of the cylinder (1), and the angle b is 10°.

2. The oil pipe threaded connection structure according to claim 1, characterized in that: The three arc segments transitioning to each other are respectively a first arc (221), a second arc (222), and a third arc (223); the central angles of the first arc (221), the second arc (222), and the third arc (223) are 15°, 75°, and 25°, respectively.

3. The oil pipe threaded connection structure according to claim 1, characterized in that: The taper of the thread section is 1:16.

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