Threaded joint for oil pipe

Abstract

The utility model discloses an oil pipe screwed joint, which belongs to the technical field of oil and gas well drilling and mining, and comprises an internal screwed pipe and an external screwed pipe which are meshed with each other, the end part of the external screwed pipe is provided with a nose end, the end part of the internal screwed pipe connected with the nose end is provided with a circular bead, and the nose end and the circular bead are in interference fit with each other; an external thread sealing face is arranged on the outer wall, close to the nose end, of the external thread pipe, an internal thread sealing face is arranged on the inner wall, close to the shoulder, of the internal thread pipe, and the internal thread sealing face and the external thread sealing face are both arranged to be in conical surface friction interference fit. The inner threaded pipe and the outer threaded pipe are both provided with the sealing surfaces, the sealing contact length is increased, the stability of the connector is improved, the high-pressure air sealing effect can be achieved after the sealing surfaces are in contact, meanwhile, the circular bead is arranged in the inner threaded pipe, and when the nose end of the outer threaded pipe is in abutting contact with the circular bead, the phenomenon of excessive torque thread gluing can be prevented; and an auxiliary sealing effect can also be achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of oil and gas well drilling and exploitation, and in particular relates to an oil pipe threaded joint. Background Art

[0002] With the continuous exploitation of oil and gas resources, the depth of oil and gas wells is getting deeper and deeper, and the difficulty is getting greater and greater. The traditional API standard thickened round threaded oil pipe can no longer meet the high strength and high sealing requirements of deep wells and ultra-deep wells for threaded joints; at the same time, the reusability of the traditional API standard thickened oil pipe is poor, and after the end of the thickened oil pipe is damaged, it needs to be re-upset, heat treated and other processes before it can be used again, which brings challenges to the environmental protection requirements of green manufacturing to reduce carbon emissions, and also reduces the reuse rate of thickened oil pipe materials. Therefore, there is an urgent need for a high-strength, high-sealing, wear-resistant and reusable oil pipe threaded joint that can replace thickened oil pipes in the process of oil and gas extraction. Utility Model Content

[0003] The utility model aims to provide an oil pipe threaded joint, which solves the technical problem that the threaded joint in the prior art cannot meet the high strength and high sealing requirements of deep wells and ultra-deep wells.

[0004] The technical solution adopted by the utility model is that the oil pipe threaded joint comprises an internal threaded pipe and an external threaded pipe meshing with each other, a nose end is arranged at the end of the external threaded pipe, a shoulder is arranged at the end where the internal threaded pipe is connected to the nose end, and the nose end and the shoulder are interference fit against each other;

[0005] An external thread sealing surface is provided near the nose end of the external thread pipe outer wall, and an internal thread sealing surface is provided near the shoulder of the internal thread pipe inner wall. Both the internal thread sealing surface and the external thread sealing surface are set to be a conical friction interference fit.

[0006] The utility model is also characterized in that:

[0007] The taper of the internal thread sealing surface and the external thread sealing surface is 1:8, and the length of the internal thread sealing surface and the external thread sealing surface is 3.50mm-4.00mm.

[0008] The outer wall of the external threaded pipe is provided with an external thread, and the external thread includes a complete thread segment and an incomplete thread segment, the tooth height of the complete thread segment is equal, and the tooth height of the incomplete thread segment gradually decreases from one end close to the complete thread segment to the end far away from the complete thread segment;

[0009] The inner wall of the internal threaded pipe is provided with internal threads, and the tooth height of the internal threads is equal and equal to the complete thread section of the external threads;

[0010] The external thread and the internal thread engage.

[0011] An oil storage and tool retreat groove is provided between the internal thread and the internal thread sealing surface. The depth of the oil storage and tool retreat groove does not exceed the internal thread tooth height, and the length is 1.50mm-2.00mm.

[0012] The thread tip arc R1 and tooth bottom arc R4 of the external thread and internal thread are both 0.60mm-0.70mm, and the tooth tip arc R2 and tooth bottom arc R3 are both 0.20mm-0.30mm.

[0013] The beneficial effects of the utility model are:

[0014] 1. In the utility model, both the internal threaded pipe and the external threaded pipe are provided with sealing surfaces, and a cone surface with a taper of 1:8 is used for sealing, which increases the sealing contact length and improves the stability of the joint. After the sealing surfaces are in contact, the effect of high-pressure gas sealing can be achieved. At the same time, a shoulder is provided in the internal threaded pipe. When the nose end of the external threaded pipe contacts the shoulder, the phenomenon of over-torque sticking can be prevented, and the auxiliary sealing can also be achieved.

[0015] 2. The internal threaded pipe is equipped with oil storage and backing grooves to store excess thread grease when threading and avoid interference with the thread starter, which may cause sticking.

[0016] 3. The thread tooth top arc R1 and tooth bottom arc R4 of the utility model are set to 0.60mm-0.70mm, and the tooth top arc R2 and tooth bottom arc R3 are set to 0.20-0.30mm, which avoids the sticking phenomenon caused by the contact between the tooth top and tooth bottom of the internal thread and the external thread. At the same time, compared with the traditional on-site construction, the buckle window is 14%-20% of the set arc length, which is increased to 58%-66%, which is convenient for on-site operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the oil pipe threaded joint of the utility model;

[0018] Figure 2 It is a tooth profile diagram of an internally threaded pipe or an externally threaded pipe in the oil pipe threaded joint of the utility model;

[0019] Figure 3 The utility model is a schematic diagram of the setting angle size of the guide surface of the internal threaded pipe and the external threaded pipe in the oil pipe threaded joint and the size of the buckle window.

[0020] In the figure, 1. internal threaded pipe, 11. shoulder, 12. internal thread sealing surface, 13. oil storage and back-off groove, 14. internal thread, 15. internal thread pipe inner surface, 2. external threaded pipe, 21. nose end, 22. external thread sealing surface, 23. external thread, 231. complete thread section, 232. incomplete thread section, 24. internal thread pipe inner surface. DETAILED DESCRIPTION

[0021] The utility model is described in detail below with reference to the accompanying drawings and specific implementation modes.

[0022] Example 1

[0023] like Figure 1 As shown, the utility model discloses an oil pipe threaded joint, comprising an internal threaded pipe 1 and an external threaded pipe 2 meshing with each other, a nose end 21 is arranged at the end of the external threaded pipe 2, a shoulder 11 is arranged at the end where the internal threaded pipe 1 is connected to the nose end 21, and the nose end 21 and the shoulder 11 are interference fit against each other; due to the adoption of a new type of partially trapezoidal thread and an end face shoulder against each other structure, the thread damage caused by frequent loading and unloading of the oil pipe and the needs of multiple cutting and re-roughening are met during use, and the utility model is very suitable for construction oil pipes that are frequently loaded and unloaded, reducing the cost of processing, using and repairing thickened oil pipe threads, and can significantly extend its service life and improve the reuse rate of the oil pipe.

[0024] An external thread sealing surface 22 is provided on the outer wall of the external threaded pipe 2 near the nose end 21, and an internal thread sealing surface 12 is provided on the inner wall of the internal threaded pipe 1 near the shoulder 11. Both the internal thread sealing surface 12 and the external thread sealing surface 22 are configured as conical friction interference fits.

[0025] Furthermore, the taper of the internal thread sealing surface 12 and the external thread sealing surface 22 are both 1:8, and the length of the internal thread sealing surface 12 and the external thread sealing surface 22 are both 3.50 mm-4.00 mm.

[0026] The internal thread sealing surface 12 and the external thread sealing surface 22 are used for sealing, and the air pressure of the sealing can reach 40-60MPa, and the water pressure can reach 60-70MPa; when fastening, the external thread 23 and the internal thread 14 should be evenly coated with thread grease, and ordinary thread grease should be used for the thread grease; the thread guide surface angle α of the external thread 23 and the internal thread 14 is set to 42-45°, and the load-bearing surface angle β is set to 0-3°.

[0027] Example 2

[0028] On the basis of Example 1, the outer wall of the externally threaded pipe 2 is provided with an external thread 23, and the external thread 23 includes a complete thread segment 231 and an incomplete thread segment 232. The tooth height of the complete thread segment 231 is equal, and the tooth height of the incomplete thread segment 232 gradually decreases from one end close to the complete thread segment 231 to one end away from the complete thread segment 231.

[0029] The inner wall of the internal threaded pipe 1 is provided with an internal thread 14, and the distance from the internal thread 14 to the shoulder 11 is not greater than the length of the nose end 21; the tooth height of the internal thread 14 is equal and equal to the complete thread section of the external thread 23;

[0030] Since the tooth height of the external thread 23 gradually decreases and the tooth height of the internal thread 14 remains unchanged, the external threaded pipe 2 will be squeezed by the internal threaded pipe 1 when the external threaded pipe 2 is threadedly connected with the internal threaded pipe 1, so that the meshing strength between the internal thread 14 and the external thread 23 is higher.

[0031] The external thread 23 and the internal thread 14 are meshed, and the tooth profiles of the external thread 23 and the internal thread 14 are both set to be trapezoidal, which improves the connection strength of the thread compared to the traditional round thread. The thread guide surface angle of the external thread 23 and the internal thread 14 is set to 42-45°; compared with the traditional thread guide surface setting of 10°-15°, it is convenient for buckling and guiding. The thread bearing surface angle of the external thread 23 and the internal thread 14 is set to 0-3°, which improves the strength of the thread connection and facilitates production and processing;

[0032] In this embodiment, the tooth height h is 1.10 mm, wherein h1 or h2 is 0.575 mm, and h2 or h1 is 0.525 mm, the internal thread 14 and the external thread 23 are tapered threads with a taper of 1:16; the surface treatment of the internal thread 14 is ordinary phosphating treatment, and the thickness of the phosphating film is 15 μm-25 μm; the thread guide surface angle α of the external thread 23 and the internal thread 14 is set to 45°, and the bearing surface angle β is set to 2°,

[0033] Furthermore, an oil storage and tool retreat groove 13 is provided between the internal thread 14 and the internal thread sealing surface 12, the depth of the oil storage and tool retreat groove 13 does not exceed the internal thread tooth height, and the length is 1.50mm-2.00mm;

[0034] When making up, first tighten by hand, then use a tubing pliers to tighten to the specified optimal torque value, and the speed of making up is less than 10r / min. During this process, the excess thread grease will enter the oil storage and the backing groove 13, avoiding the influence caused by excessive application of thread grease. Taking the oil pipe as an example, its make-up torque value and thread grease application amount are shown in Table 1:

[0035] Table 1

[0036]

[0037] After the make-up is completed, the inner surface 15 of the internal threaded tube is flush with the inner surface 24 of the external threaded tube.

[0038] Example 3

[0039] like Figure 2 As shown, based on Example 2, the thread top arc R1 and the tooth bottom arc R4 of the external thread 23 and the internal thread 14 are both 0.60mm-0.70mm, and the tooth top arc R2 and the tooth bottom arc R3 are both 0.20mm-0.30mm. Figure 3As shown, the arc length L of the buckle window is set to 0.8-1.0m, and the buckle window is (58%-66%)L.

[0040] Specifically, the tooth top arc R1 is 0.70 mm, the tooth bottom arc R4 is 0.60 mm, the tooth top arc R2 is 0.20 mm, and the tooth bottom arc R3 is 0.30 mm. The arc length L of the buckle window is set to 0.80 m, and the buckle window is 66% L, i.e., 0.52 m.

[0041] There may also be other settings, such as: the thread guide surface angle α of the external thread 23 and the internal thread 14 is set to 42°, the load-bearing surface angle β is set to 3°, the tooth top arc R1 is 0.65mm, the tooth bottom arc R4 is 0.60mm, the tooth top arc R2 is 0.30mm and the tooth bottom arc R3 is 0.20mm, the buckle window arc length L is set to 0.80m, and the buckle window is 58%L, i.e. 0.46m.

[0042] The above examples are preferred examples of the present invention, and the present invention is not limited to the above embodiments.

Claims

1. Oil pipe threaded joint, characterized in that: It comprises an internally threaded tube (1) and an externally threaded tube (2) meshing with each other, the end of the externally threaded tube (2) being provided with a nose end (21), the end of the internally threaded tube (1) connected to the nose end (21) being provided with a shoulder (11), and the nose end (21) and the shoulder (11) being in abutting interference fit; An external thread sealing surface (22) is provided on the outer wall of the external threaded tube (2) near the nose end (21), and an internal thread sealing surface (12) is provided on the inner wall of the internal threaded tube (1) near the shoulder (11), and both the internal thread sealing surface (12) and the external thread sealing surface (22) are configured to be a conical friction interference fit; The taper of the internal thread sealing surface (12) and the external thread sealing surface (22) are both 1:8, and the length of the internal thread sealing surface (12) and the external thread sealing surface (22) are both 3.50 mm to 4.00 mm; The outer wall of the externally threaded pipe (2) is provided with an external thread (23), the external thread (23) comprising a complete thread segment (231) and an incomplete thread segment (232), the complete thread segment (231) having the same tooth height, and the incomplete thread segment (232) having a tooth height that gradually decreases from an end close to the complete thread segment (231) to an end away from the complete thread segment (231); The inner wall of the internal threaded pipe (1) is provided with an internal thread (14), and the tooth heights of the internal thread (14) are all equal and equal to the complete thread segment (231); The external thread (23) and the internal thread (14) are meshed; An oil storage and tool retreat groove (13) is provided between the internal thread (14) and the internal thread sealing surface (12); the depth of the oil storage and tool retreat groove (13) does not exceed the tooth height of the internal thread (14), and the length is 1.50 mm to 2.00 mm; The thread tooth top arc R1 and tooth bottom arc R4 of the external thread (23) and the internal thread (14) are both 0.60 mm to 0.70 mm, and the tooth top arc R2 and tooth bottom arc R3 are both 0.20 mm to 0.30 mm.

Images