Threaded joint for oil casing

Abstract

The invention provides an oil casing pipe screwed joint. The oil casing pipe screwed joint comprises an outer screwed joint and an inner screwed joint, wherein an outer thread has the tooth height H1; the first internal thread section has the tooth height H2, the second internal thread section has the tooth height H3, and the second internal thread section is located between the end face of the first internal thread section and the end face of the external thread connector along the central axis; wherein the relation between the tooth height H1 and the tooth height H2 meets the condition that H2-H1 is equal to 0.2 mm-0. 4mm, the relation between the tooth height H1 and the tooth height H3 meets the condition that H3-H1 is equal to 0 mm-0. 0mm, and the relation between the tooth groove width L23 of the second internal thread section and the tooth thickness width L11 of the external thread meets the condition that L23-L11 is equal to 0.02 mm-0. 0mm. According to the technical scheme, the problems that in the prior art, an oil casing pipe threaded connector is prone to thread gluing, poor in sealing performance and high in machining cost are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil casing pipe thread joint, in particular to an oil casing pipe thread joint. BACKGROUND

[0002] At present, there are two types of oil casing pipe thread joints used in oil fields. One is a standard API (American Petroleum Institute) thread joint, which is prone to poor field operation performance because the tooth top and the tooth bottom are in contact and there is no gap between them. The design without a gap between them requires high machining precision. If there is a machining error during machining, the thread joint is prone to have a large difference in make-up torque when being made up to the same triangular bottom side, which leads to a large torque fluctuation during make-up operation, thereby causing thread sticking. At the same time, the gap between the inner and outer thread tooth sides of the oil casing pipe thread joint is also large, generally about 0.25 mm, which leads to a large leakage passage area, thereby causing poor sealing performance, and no gas sealing function. The above factors lead to thread sticking, pipe string leakage and other accidents in actual field use, which seriously affects the efficiency of field operation. The other is a special thread joint with a sealing surface, which has excellent anti-sticking performance and sealing performance, but the production and machining cost is high, thereby leading to a high procurement cost of the oil field. SUMMARY

[0003] The main purpose of the present application is to provide an oil casing pipe thread joint to solve the problems of thread sticking, poor sealing and high machining cost of the oil casing pipe thread joint in the prior art.

[0004] In order to achieve the above purpose, the present application provides an oil casing pipe thread joint, which has a central axis, and comprises: an outer thread joint provided with an outer thread having a tooth height H1; an inner thread joint provided with an inner thread, the outer thread and the inner thread being matched, the inner thread comprising a first inner thread section and a second inner thread section connected with the first inner thread section, the first inner thread section having a tooth height H2, and the second inner thread section having a tooth height H3, along the central axis, the second inner thread section being located between the first inner thread section and the end face of the outer thread joint; wherein the relationship between the tooth height H1 and the tooth height H2 satisfies H2-H1=0.2mm-0.4mm, the relationship between the tooth height H1 and the tooth height H3 satisfies H3-H1=0mm-0.05mm, and the relationship between the tooth groove width L23 of the second inner thread section and the tooth thickness width L11 of the outer thread satisfies L23-L11=0.02mm-0.05mm.

[0005] Further, the relationship between the tooth thickness width L11 of the external thread and the groove width L21 of the first internal thread section satisfies: L21-L11=0.02mm-0.05mm.

[0006] Further, the second internal thread section comprises 1-3 internal thread teeth.

[0007] Further, the external thread teeth of the external thread have an external load bearing surface and an external guide surface, which are located on both sides of the external thread teeth along the central axis and are both inclined relative to the central axis, the inclination angle of the external load bearing surface is in the range of-4°-3°, and the inclination angle of the external guide surface is in the range of 10°-40°.

[0008] Further, the internal thread teeth of the internal thread have an internal load bearing surface and an internal guide surface, which are located on both sides of the internal thread teeth along the central axis and are both inclined relative to the central axis, the internal load bearing surface has an inclination angle of β1, and the internal guide surface has an inclination angle of β2, wherein β1=α1, and β2=α2.

[0009] Further, the tooth height H1 of the external thread is in the range of 1.5mm-2.3mm.

[0010] Further, the pitch of the external thread and the pitch of the internal thread are both P, and the pitch P is in the range of 3.17mm-8.47mm.

[0011] Further, the thread taper of the external thread and the thread taper of the internal thread are both in the range of 1:16-1:18.

[0012] Further, the relationship between the tooth thickness width L11 of the external thread and the groove width L12 of the external thread satisfies: L11=L12.

[0013] Further, the tooth thickness width L11 of the external thread is in the range of 1.58mm-4.23mm.

[0014] The application has the following advantages. On the one hand, the tooth height H2 of the first internal thread section and the tooth height H1 of the external thread satisfy the relationship H2-H1=0.2mm-0.4mm, so that a gap is formed between the bottom of the internal thread tooth of the first internal thread section and the top of the external thread tooth of the external thread. The gap can store excess thread grease, improve the on-site operation performance, and reduce the probability of galling. Even if a processing error occurs, the gap formed between the bottom of the internal thread tooth of the first internal thread section and the top of the external thread tooth of the external thread can achieve a fault-tolerant effect, so as to reduce the problem of excessive torque fluctuation in the make-up operation, thereby reducing the probability of galling of the thread. In addition, the make-up of the oil casing thread joint is performed according to the size of the oil casing thread joint, so that the interference in the diameter direction formed between the top of the internal thread tooth of the first internal thread section and the bottom of the external thread tooth of the external thread is between 0.2mm and 0.4mm, which is much lower than the interference of the API thread joint, so that the anti-galling performance of the thread joint is greatly improved, and the stress level of the thread joint is reduced. On the other hand, the second internal thread section is arranged, and the tooth height H3 of the second internal thread section and the tooth height H1 of the external thread satisfy the relationship H3-H1=0mm-0.05mm, so that the gap between the bottom of the internal thread tooth of the second internal thread section and the top of the external thread tooth of the external thread is small or non-existent, thereby preventing the leakage of the fluid in the pipe body, so that the oil casing thread joint has good sealing performance. In addition, the make-up of the oil casing thread joint is performed according to the size of the oil casing thread joint, so that the interference in the diameter direction formed between the top of the internal thread tooth of the second internal thread section and the bottom of the external thread tooth is between 0.5mm and 0.8mm. When the make-up and tightening are about to reach the final position, the radial interference between the internal thread tooth and the external thread tooth rapidly increases, so that the make-up torque rapidly increases, which can indicate the positioning of the make-up. On the other hand, the relationship between the tooth groove width L23 of the second internal thread section and the tooth thickness width L11 of the external thread satisfies L23-L11=0.02mm-0.05mm, so that the tooth side gap between the external thread and the second internal thread section is much lower than that of the API thread joint, thereby reducing the leakage passage area and improving the sealing performance of the oil casing thread joint. In summary, the oil casing thread joint of the application divides the internal thread into the first internal thread section and the second internal thread section, and the above parameters are arranged, so that the oil casing thread joint has excellent sealing effect and even certain airtight sealing performance without additional processing of a sealing surface, and the probability of make-up galling is reduced, that is, the oil casing thread joint has excellent anti-galling performance and sealing performance, thereby reducing the production and processing cost. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification. The embodiments of the application, together with its

[0016] Figure 1 Fig. 1 shows a schematic view of the structure of the external thread of the oil casing thread joint according to the present application;

[0017] Figure 2 Fig. 2 shows a schematic view of the structure of the internal thread of the oil casing thread joint according to the present application; Figure 1

[0018] Figure 3 Fig. 3 shows a schematic view of the structure of the external thread of the oil casing thread joint according to the present application; Figure 1

[0019] Figure 4 Fig. 4 shows a partial enlarged view of the oil casing thread joint according to the present application; Figure 1

[0020] Figure 5 Fig. 5 shows an enlarged view of the first internal thread segment of the oil casing thread joint according to the present application at A; Figure 4

[0021] Figure 6 Fig. 6 shows a schematic view of the structure of the external thread tooth of the oil casing thread joint according to the present application; Figure 5

[0022] Figure 7 Fig. 7 shows a schematic view of the structure of the internal thread tooth of the first internal thread segment of the oil casing thread joint according to the present application; Figure 5

[0023] Figure 8 Fig. 8 shows an enlarged view of the second internal thread segment of the oil casing thread joint according to the present application at B; Figure 4

[0024] Figure 9 Fig. 9 shows a schematic view of the structure of the external thread tooth of the oil casing thread joint according to the present application; Figure 8

[0025] Figure 10 Fig. 10 shows a schematic view of the structure of the internal thread tooth of the second internal thread segment of the oil casing thread joint according to the present application. Figure 8 Wherein, the above drawings include the following reference signs:

[0026] 1, external thread joint; 11, external load bearing surface; 12, external guide surface; 2, internal thread joint; 21, first internal thread segment; 22, second internal thread segment; 23, internal load bearing surface; 24, internal guide surface.

[0027] DETAILED DESCRIPTION

[0028] ​​​​​​​​​It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] As shown in Figures 1 to 10 The embodiment of the present application provides an oil casing thread joint, the oil casing thread joint has a central axis L, and the oil casing thread joint comprises an outer thread joint 1 provided with an outer thread, the outer thread has a tooth height H1; an inner thread joint 2 provided with an inner thread, the outer thread and the inner thread are matched, the inner thread comprises a first inner thread section 21 and a second inner thread section 22 connected with the first inner thread section 21, the first inner thread section 21 has a tooth height H2, the second inner thread section 22 has a tooth height H3, along the central axis L, the second inner thread section 22 is located between the first inner thread section 21 and an end face of the outer thread joint 1; wherein the relationship between the tooth height H1 and the tooth height H2 satisfies: H2-H1=0.2mm-0.4mm, the relationship between the tooth height H1 and the tooth height H3 satisfies: H3-H1=0mm-0.05mm, and the relationship between a tooth groove width L23 of the second inner thread section 22 and a tooth thickness width L11 of the outer thread satisfies: L23-L11=0.02mm-0.05mm.

[0030] In the above technical solution, on the one hand, the tooth height H2 of the first inner thread section 21 and the tooth height H1 of the outer thread satisfy the relationship: H2-H1=0.2mm-0.4mm, and a certain gap can be formed between the inner thread tooth bottom of the first inner thread section 21 and the outer thread tooth top of the outer thread (as shown in Figure 4 and attached Figure 5The gap can not only store excess thread compound to improve the on-site operation performance and reduce the probability of galling, but also can achieve the effect of fault tolerance to reduce the problem of excessive torque fluctuation of the make-up operation and reduce the probability of thread galling, even if there is a processing error. In addition, according to the size of the oil casing thread joint, the diameter direction interference between the inner thread tooth top of the first inner thread section 21 and the outer thread tooth bottom of the outer thread is between 0.2mm and 0.4mm, which is much lower than the interference of the API thread joint, so that the anti-galling performance of the thread joint can be greatly improved and the stress level of the thread joint can be reduced. On the other hand, by setting the second inner thread section 22 and the relationship between the tooth height H1 of the outer thread and the tooth height H3 of the second inner thread section 22 satisfies: H3-H1=0mm~0.05mm, the gap between the inner thread tooth bottom of the second inner thread section 22 and the outer thread tooth top of the outer thread is small or no gap, so that the fluid leakage inside the pipe body can be prevented, so that the oil casing thread joint has good sealing performance. At the same time, according to the size of the oil casing thread joint, the diameter direction interference between the inner thread tooth top of the second inner thread section 22 and the outer thread tooth bottom is between 0.5mm and 0.8mm, so that the radial interference between the inner thread tooth and the outer thread tooth can be rapidly increased when the make-up and tightening is about to reach the final position, so that the make-up torque can be rapidly increased, which can indicate the positioning of the make-up to a certain extent. On the other hand, by setting the relationship between the tooth groove width L23 of the second inner thread section 22 and the tooth thickness width L11 of the outer thread satisfies: L23-L11=0.02mm~0.05mm, the tooth side gap between the outer thread and the second inner thread section 22 can be much lower than that of the API thread joint, so that the leakage passage area can be reduced to improve the sealing performance of the oil casing thread joint. In summary, in the oil casing thread joint of the present application, the inner thread is divided into the first inner thread section 21 and the second inner thread section 22, and by setting the above parameters, the oil casing thread joint can have excellent sealing effect without additional sealing surface, and even has certain airtight sealing performance, and the probability of make-up galling can be reduced, that is, the oil casing thread joint can have excellent anti-galling performance and sealing performance, so that the production and processing cost can be reduced.

[0031] In some embodiments, the oil casing thread joint is combined by the outer thread joint 1 and the inner thread joint 2, the outer thread is processed on the outside of the pipe end to form the outer thread joint 1, and the inner thread is processed on the inside of the coupling or the pipe end to form the inner thread joint 2, wherein the shapes of the thread teeth of the outer thread joint 1 and the inner thread joint 2 are all trapezoidal.

[0032] In some embodiments, asFigure 1 and Figure 4 As shown in the figure, the part of the internal thread joint 2 corresponding to the thread of the end of the external thread joint 1 is a second internal thread section 22, and the second internal thread section 22 includes at least one internal thread with a tooth height H3.

[0033] It should be noted that the diameter direction is the direction of the diameter of the oil casing thread joint, which is perpendicular to the direction of the central axis L.

[0034] It should be noted that the tooth height H1 of the external thread refers to the tooth height of the external thread of the external thread, the tooth height H2 of the first internal thread section 21 refers to the tooth height of the internal thread of the first internal thread section 21, and the tooth height H3 of the second internal thread section 22 refers to the tooth height of the internal thread of the second internal thread section 22.

[0035] As shown in the figure, Figures 5 to 7 In the embodiment of the present application, the relationship between the tooth thickness width L11 of the external thread and the tooth groove width L21 of the first internal thread section 21 satisfies: L21-L11=0.02mm~0.05mm. In this way, the tooth side gap between the external thread and the first internal thread section 21 can be much lower than that of the API thread joint, so as to further reduce the leakage passage area, thereby improving the sealing performance of the oil casing thread joint.

[0036] As shown in the figure, Figure 4 In the embodiment of the present application, the second internal thread section 22 includes 1~3 internal threads. In this way, although the gap between the tooth bottom of the internal thread of the second internal thread section 22 and the tooth top of the external thread is small or no gap, since the second internal thread section 22 includes fewer internal threads, the influence on the site operation is limited, and the occurrence of galling can be avoided.

[0037] As shown in the figure, Figure 6 and Figure 9 In the embodiment of the present application, the external thread of the external thread has an external load surface 11 and an external guide surface 12, and along the central axis L, the external load surface 11 and the external guide surface 12 are respectively located on both sides of the external thread and are both inclined relative to the central axis L, and the inclination angle α1 of the external load surface 11 ranges from-4° to 3°, and the inclination angle α2 of the external guide surface 12 ranges from 10° to 40°.

[0038] In the above technical solution, by setting the inclination angle α1 of the external load surface 11 to the above parameter, the thread profile can be optimized, and the connection strength can be improved; by setting the inclination angle α2 of the external guide surface 12 to the above parameter, the thread guiding performance during make-up can be enhanced, the internal thread joint 2 and the external thread joint 1 can be easily centered, thereby improving the make-up speed, facilitating the operation of the operator, and thereby improving the operation efficiency.

[0039] As shown in the figure, Figure 7 andFigure 10 As shown in the drawings, in the embodiments of the present application, the internal thread tooth of the internal thread has an internal load bearing surface 23 and an internal guide surface 24, and the internal load bearing surface 23 and the internal guide surface 24 are respectively located on both sides of the internal thread tooth and are both arranged to be inclined relative to the central axis L along the central axis L, the internal load bearing surface 23 has an inclination angle β1, and the internal guide surface 24 has an inclination angle β2, wherein β

[0040] 1=α1, β2=α2.

[0041] In the above technical solution, by making the load bearing surface and the guide surface of the internal and external threads have equal angles, the consistency of the angles of the internal and external threads can be maintained, the smooth docking of the threaded joint during the make-up process can be ensured, the stress concentration can be reduced, the sealing performance and the anti-sticking performance can be improved, and thus the work efficiency can be improved.

[0042] It should be noted that, as shown in Figure 6 and Figure 9 , the oil casing threaded joint has a cross section perpendicular to the central axis L, the inclination angle α1 of the external load bearing surface 11 refers to the included angle between the external load bearing surface 11 and the cross section, wherein the angle is negative, indicating that the internal and external load bearing surfaces are inclined to the left side of the cross section, and the angle is positive, indicating that the internal and external load bearing surfaces are inclined to the right side of the cross section; the inclination angle α2 of the external guide surface 12 refers to the included angle between the external guide surface 12 and the cross section, and for the same reason, as shown in Figure 7 and Figure 10 , the inclination angle β1 of the internal load bearing surface 23 refers to the included angle between the internal load bearing surface 23 and the cross section, and the inclination angle β2 of the internal guide surface 24 refers to the included angle between the internal guide surface 24 and the cross section.

[0043] As shown in Figure 6 and Figure 9 , in the embodiments of the present application, the tooth height H1 of the external thread ranges from 1.5 mm to 2.3 mm. In this way, different tooth heights H1 can be selected according to the size of the oil casing threaded joint.

[0044] Preferably, in the embodiments of the present application, the tooth height H1 of the external thread is 1.58 mm.

[0045] As shown in Figures 6 to 10 , in the embodiments of the present application, the pitch of the external thread and the pitch of the internal thread are both P, and the pitch P ranges from 3.17 mm to 8.47 mm. In this way, different pitches P can be selected according to the size of the oil casing threaded joint, and the above range of the pitch P is convenient for processing and convenient for make-up operation.

[0046] Preferably, in the embodiments of the present application, the pitch P is 5.08 mm.

[0047] It should be noted that the pitch of the first internal thread segment 21 and the second internal thread segment 22 of the internal thread is P.

[0048] In the embodiment of the present application, the range of the thread taper of the external thread and the thread taper of the internal thread is 1:16-1:18. In this way, by selecting a proper thread taper, the alignment of the threaded joint can be improved, the deviation during make-up can be reduced, and the reliability of the connection can be improved.

[0049] It should be noted that the thread taper of the first internal thread segment 21 and the second internal thread segment 22 of the internal thread is 1:16-1:18.

[0050] As shown in Figure 9 In the embodiment of the present application, the relationship between the tooth thickness width L11 of the external thread and the tooth groove width L12 of the external thread satisfies L11=L12. During make-up, if the tooth thickness width is greater than the tooth groove width, the thread tooth can be subjected to excessive shearing force at the tooth root, resulting in the thread tooth being sheared off from the root. When L11=L12, the damage of the thread caused by the size mismatch can be avoided, and the service life of the thread can be prolonged.

[0051] As shown in Figure 7 In the embodiment of the present application, the relationship between the tooth groove width L21 of the first internal thread segment 21 and the tooth thickness width L22 of the first internal thread segment 21 satisfies L21=L22.

[0052] As shown in Figure 10 In the embodiment of the present application, the relationship between the tooth groove width L23 of the second internal thread segment 22 and the tooth thickness width L24 of the second internal thread segment 22 satisfies L23=L24.

[0053] As shown in Figure 9 In the embodiment of the present application, the range of the tooth thickness width L11 of the external thread is 1.58mm-4.23mm. The above parameter range takes into account the connection requirements of different specifications of oil casing, and ensures the applicability and universality of the threaded joint. By selecting a proper L11 value, the sealing performance of the threaded joint can be ensured, and the connection strength and operation performance of the thread can be optimized.

[0054] It should be noted that the oil casing threaded joint of the present application can be used according to the requirements of specific working conditions. The same machining process as the API thread is used, the coupling and the pipe body are of the same steel grade, the threaded grease conforming to the API requirements is uniformly applied to both ends during make-up, and the make-up is performed at the triangular mark position.

[0055] It should be noted that, in order to solve the problems of easy sticking, poor sealing performance and poor operation performance of the existing API threaded joint in field operation, and the problem of high cost of the special threaded joint, the oil casing threaded joint has good anti-sticking performance and sealing performance, even has certain air sealing performance, stable make-up torque, simple structure and low processing cost, so as to ensure safe, efficient and economic development of oil and gas fields.

[0056] It should be noted that the oil casing threaded joint of the present application has simple structure, excellent anti-sticking performance and air sealing performance compared with ordinary API buttress thread, which can effectively solve the problems of low efficiency and poor sealing performance of the existing ordinary API buttress casing make-up operation, and can promote safe and efficient development of oil fields.

[0057] It should be noted that the oil casing threaded joint of the present application has simple structure, excellent anti-sticking performance and air sealing performance compared with ordinary API buttress thread, which can effectively solve the problems of low efficiency and poor sealing performance of the existing ordinary API buttress casing make-up operation, and can promote safe and efficient development of oil fields.

[0058] Test standard: ISO 13679:2002 Tubulars and Tubular Threaded Connections, Test Methods, make-up to triangular base edge by position control. Thread compound TOP 1704 is evenly applied, and the make-up speed is less than 5 turns per minute. The test sample is subjected to 3 make-ups and 2 breakouts, and no sticking phenomenon occurs. The make-up and breakout test data are shown in Table 1, and the internal pressure sealing test data are shown in Table 2.

[0059] Table 1 Make-up and Breakout Test Data

[0060]

[0061] Table 2 Internal Pressure Sealing Test Data

[0062]

[0063] According to the above content, the oil casing threaded joint of the present application has full-size full-performance test evaluation in use performance, 3 make-ups and 2 breakouts without sticking, connection strength exceeding 100% of the pipe body connection strength, and internal pressure resistance exceeding 100% of the pipe body. Compared with the prior art, the oil casing threaded joint of the present application has significant progress, which is specifically shown in that, in order to solve the problems of easy sticking, poor sealing performance and poor operation performance of the existing API threaded joint in field operation, and the problem of high cost of the special threaded joint, the oil casing threaded joint of the present application has good anti-sticking performance and sealing performance, even has certain air sealing performance, and simple structure, which can meet the safe, efficient and economic development of oil and gas fields.

[0064] Specifically, in the first embodiment of the oil casing thread joint of the present application, the pipe body adopts a φ139.7mmx12.7mm specification casing with a steel grade of P110. The thread pitch P is 5.08mm, the thread taper is 1:16, the thread load surface angle α1=β1=-3°, the thread guide surface angle α2=β2=10°, the outer thread tooth height H1=1.58mm, the tooth height H2=1.78mm of the first inner thread section of the inner thread; the second inner thread section of the inner thread has two thread teeth with a tooth height H3=1.58mm. The tooth flank clearance L21-L11=0.03mm, L23-L11=0.03mm, the diameter direction interference amount formed by the tooth top of the first inner thread section and the tooth bottom of the outer thread is 0.3mm, and the diameter direction interference amount formed by the tooth top of the second inner thread section and the tooth bottom of the outer thread is 0.6mm. The box and pin meet the 3-on-2-off non-sticking buckle, the connection strength exceeds 100% of the pipe body connection strength, the internal pressure strength exceeds 100% of the pipe body, and has certain air tightness.

[0065] In the second embodiment of the oil casing thread joint of the present application, the pipe body adopts a φ339.72x12.19mm specification casing with a steel grade of P110. The thread pitch P is 5.08mm, the thread taper is 1:16, the thread load surface angle α1=β1=-3°, the thread guide surface angle α2=β2=10°, the outer thread tooth height H1=1.78mm, the tooth height H2=1.98mm of the first inner thread section of the inner thread; the second inner thread section of the inner thread has two thread teeth with a tooth height H3=1.78mm. The tooth flank clearance L21-L11=0.04mm, L23-L11=0.04mm, the diameter direction interference amount formed by the tooth top of the first inner thread section and the tooth bottom of the outer thread is 0.35mm, and the diameter direction interference amount formed by the tooth top of the second inner thread section and the tooth bottom of the outer thread is 0.65mm. The box and pin meet the 3-on-2-off non-sticking buckle, the connection strength exceeds 100% of the pipe body connection strength, the internal pressure strength exceeds 100% of the pipe body, and has certain air tightness.

[0066] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: On the one hand, the tooth height H2 of the first internal thread segment and the tooth height H1 of the external thread are related as follows: H2-H1 = 0.2mm~0.4mm. A certain gap can be formed between the bottom of the internal thread tooth of the first internal thread segment and the top of the external thread tooth of the external thread. This gap can not only store excess thread grease to improve on-site operation performance and reduce the probability of sticking, but also, even if machining errors occur, the gap formed between the bottom of the internal thread tooth of the first internal thread segment and the top of the external thread tooth of the external thread can also achieve a fault-tolerant effect, thereby reducing the problem of excessive torque fluctuation during threading and reducing the occurrence of... The probability of thread sticking is reduced. Furthermore, depending on the specifications of the oil casing threaded joint, the thread is adjusted so that the interference in the diameter direction between the crest of the internal thread in the first internal thread segment and the root of the external thread is between 0.2mm and 0.4mm. This interference is significantly lower than that of API threaded joints, greatly improving the anti-sticking performance and reducing the stress level of the threaded joint. On the other hand, by setting a second internal thread segment, and ensuring that the relationship between the tooth height H1 of the external thread and the tooth height H3 of the second internal thread segment satisfies H3-H1=0mm~0.05mm, the interference between the root of the internal thread in the second internal thread segment and the crest of the external thread is reduced. A small or no gap prevents fluid leakage inside the pipe, ensuring good sealing performance of the oil-jacket threaded joint. Simultaneously, the oil-jacket threaded joint is threaded according to its specifications, ensuring the interference in the diameter direction between the crest of the internal thread and the root of the external thread in the second internal thread section is between 0.5mm and 0.8mm. This allows the radial interference between the internal and external threads to increase rapidly as the threading nears its final position, resulting in a rapid increase in threading torque. This provides a degree of indication for threading positioning. Furthermore, by adjusting the tooth groove width L23 of the second internal thread section to match the tooth thickness width L1 of the external thread... The relationship between L23 and L11 satisfies L23-L11 = 0.02mm to 0.05mm, which makes the tooth flank clearance between the external thread and the second internal thread section much lower than that of the API threaded joint, thereby reducing the leakage channel area and improving the sealing performance of the oil casing threaded joint. In summary, in the oil casing threaded joint of this application, the internal thread is divided into a first internal thread section and a second internal thread section. By setting the above parameters, no additional machining of the sealing surface is required, which can make the oil casing threaded joint have excellent sealing effect and even a certain gas-tight performance. At the same time, it can also reduce the probability of seizing, that is, it can achieve excellent anti-seizing performance and sealing performance, thereby reducing production and processing costs.

[0067] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A threaded joint for an oil sleeve, characterized in that, The oil casing threaded joint has a central axis (L), and the oil casing threaded joint includes: An external threaded connector (1) is provided with an external thread, wherein the external thread has a tooth height H1; An internal threaded connector (2) is provided with an internal thread, wherein the external thread and the internal thread are engaged. The internal thread includes a first internal thread segment (21) and a second internal thread segment (22) connected to the first internal thread segment (21). The first internal thread segment (21) has a tooth height H2, and the second internal thread segment (22) has a tooth height H3. Along the central axis (L), the second internal thread segment (22) is located between the end face of the first internal thread segment (21) and the external threaded connector (1). The relationship between the tooth height H1 and the tooth height H2 satisfies: H2-H1=0.2mm~0.4mm, the relationship between the tooth height H1 and the tooth height H3 satisfies: H3-H1=0mm~0.05mm, and the relationship between the tooth groove width L23 of the second internal thread segment (22) and the tooth thickness width L11 of the external thread satisfies: L23-L11=0.02mm~0.05mm.

2. The oil casing threaded joint according to claim 1, characterized in that, The relationship between the tooth thickness width L11 of the external thread and the tooth groove width L21 of the first internal thread segment (21) satisfies: L21-L11=0.02mm~0.05mm.

3. The oil casing threaded joint according to claim 1, characterized in that, The second internal thread segment (22) includes 1 to 3 internal thread teeth.

4. The oil casing threaded joint according to any one of claims 1 to 3, characterized in that, The external thread has an outer bearing surface (11) and an outer guide surface (12). Along the central axis (L), the outer bearing surface (11) and the outer guide surface (12) are located on both sides of the external thread and are inclined relative to the central axis (L). The inclination angle α1 of the outer bearing surface (11) is in the range of -4° to 3°, and the inclination angle α2 of the outer guide surface (12) is in the range of 10° to 40°.

5. The oil casing threaded joint according to claim 4, characterized in that, The internal thread has an inner bearing surface (23) and an inner guide surface (24). Along the central axis (L), the inner bearing surface (23) and the inner guide surface (24) are located on both sides of the internal thread and are inclined relative to the central axis (L). The inner bearing surface (23) has an inclination angle β1 and the inner guide surface (24) has an inclination angle β2, where β1 = α1 and β2 = α2.

6. The oil casing threaded joint according to any one of claims 1 to 3, characterized in that, The tooth height H1 of the external thread is in the range of 1.5mm to 2.3mm.

7. The oil casing threaded joint according to any one of claims 1 to 3, characterized in that, The pitch of the external thread and the pitch of the internal thread are both P, and the pitch P ranges from 3.17 mm to 8.47 mm.

8. The oil casing threaded joint according to any one of claims 1 to 3, characterized in that, The taper of the external thread and the taper of the internal thread both range from 1:16 to 1:

18.

9. The oil casing threaded joint according to any one of claims 1 to 3, characterized in that, The relationship between the tooth thickness width L11 and the tooth groove width L12 of the external thread satisfies: L11 = L12.

10. The oil casing threaded joint according to claim 9, characterized in that, The tooth thickness width L11 of the external thread ranges from 1.58 mm to 4.23 mm.

Images