A joint assembly, a casing device, an oil and gas well production system and use thereof

Abstract

The application discloses a joint assembly, a casing device, an oil and gas well exploitation system and application thereof, and relates to the technical field of oil and gas well exploitation. The joint assembly comprises a first joint and a second joint; the first joint is provided with an external thread and a first sealing part; the second joint is provided with an internal thread and a second sealing part; the length ratio of the first sealing part to the external diameter of the first joint is 0.05:1-0.06:1; the first sealing part comprises a first sealing surface and a first shoulder; the length ratio of the second sealing part to the first sealing part is 1.6:1-1.7:1; the second sealing part comprises a second sealing surface and a second shoulder; the included angle between the first sealing surface and the axis of the first joint and the included angle between the second sealing surface and the axis of the second joint are 12-16 degrees; the included angle between the first shoulder and the axis of the first joint and the included angle between the second shoulder and the axis of the second joint are 60-80 degrees; and in a sealing state of thread connection, the first shoulder and the second shoulder abut to realize precise connection and high sealing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pipes, in particular to a joint assembly, a casing device, an oil and gas well exploitation system and application thereof. BACKGROUND

[0002] A casing string is connected by threads to connect single oil well pipes, and is lowered into the ground for several kilometers to exploit oil and gas. In use, two pipes are connected by threads through a coupling. In the general API standard, the casing is connected by round threads or buttress threads. The advantage of this joint is that it is mature in technology and low in production cost. The joint connection part of the casing string is a weak key link. SUMMARY

[0003] The inventor found in work that in the development process of deep wells, ultra-deep wells, high-pressure gas wells, directional wells and acid environment wells, the existing casing and coupling with API standard threads are prone to rupture, drag and leakage, and the existing casing and coupling assembly cannot meet the production requirements. In order to enrich product types and increase selection space, the inventor made the present application. The present application provides a joint assembly, a casing device, an oil and gas well exploitation system and application thereof.

[0004] In a first aspect, the present application provides a joint assembly, which can include: a first joint and a second joint; an outer thread is formed on the outer surface of the first joint, and a first sealing part is arranged on the outer surface of the end portion thereof; an inner thread matched with the outer thread is formed on the inner surface of the second joint, and a second sealing part matched with the first sealing part is arranged on the inner surface away from the end portion thereof;

[0005] The length ratio of the first sealing part to the outer diameter of the first joint is 0.05:1-0.06:1, and the first sealing part can include a first sealing surface and a first shoulder; the length ratio of the second sealing part to the length of the first sealing part is 1.6:1-1.7:1, and the second sealing part can include a second sealing surface matched with the first sealing surface and a second shoulder matched with the first shoulder; the included angle between the first sealing surface and the axis of the first joint is 12°-16°, and the included angle between the first shoulder and the axis of the first joint is 60°-80°; the included angle between the second sealing surface and the axis of the second joint is 12°-16°, and the included angle between the second shoulder and the axis of the second joint is 60°-80°;

[0006] In the sealed state of the threaded connection of the first joint and the second joint, the first sealing surface and the second sealing surface are in interference contact, and the first shoulder and the second shoulder are in abutment.

[0007] Optionally, the length of the first sealing part and the outer diameter of the first joint are in a ratio of 0.052:1 to 0.057:1, the length of the second sealing part and the length of the first sealing part are in a ratio of 1.63:1 to 1.68:1; the included angle between the first sealing surface and the axis of the first joint is 13° to 15.5°, the included angle between the first shoulder and the axis of the first joint is 65° to 74°; the included angle between the second sealing surface and the axis of the second joint is 13° to 15.5°, and the included angle between the second shoulder and the axis of the second joint is 65° to 74°.

[0008] Optionally, the roughness of the first sealing surface is not less than Ra1.6.

[0009] and / or,

[0010] the roughness of the second sealing surface is not less than Ra1.6.

[0011] Optionally, the first sealing part can further comprise a first auxiliary shoulder matched with the first shoulder, the first auxiliary shoulder being located between the first shoulder and the first sealing surface, and the included angle between the first auxiliary shoulder and the axis of the first joint is 18° to 22°.

[0012] The second sealing part can further comprise a second auxiliary shoulder matched with the second shoulder and matched with the first auxiliary shoulder, the second auxiliary shoulder being located between the second shoulder and the second sealing surface, and the included angle between the second auxiliary shoulder and the axis of the second joint is 18° to 22°.

[0013] In the sealed state of the threaded connection of the first joint and the second joint, the first auxiliary shoulder and the second auxiliary shoulder are in interference contact; and the axial distance between the first intersection point of the extension line of the first shoulder and the extension line of the first auxiliary shoulder and the second intersection point of the extension line of the second shoulder and the extension line of the second auxiliary shoulder is zero.

[0014] Optionally, the included angle between the first auxiliary shoulder and the axis of the first joint is 18.5° to 20°, and the included angle between the second auxiliary shoulder and the axis of the second joint is 18.5° to 20°.

[0015] Optionally, the first sealing part can further comprise a first transition surface located between the first sealing surface and the first auxiliary shoulder, and the included angle between the first transition surface and the axis of the first joint is 3° to 5°.

[0016] The second sealing part can further comprise a second transition surface located between the second sealing surface and the second auxiliary shoulder, and the included angle between the second transition surface and the axis of the second joint is 3° to 5°.

[0017] Optionally, the included angle between the first transition surface and the axis of the first joint is 3.2°-4.7°, and the included angle between the second transition surface and the axis of the second joint is 3.2°-4.7°.

[0018] Optionally, the taper of the external thread segment where the external thread is located is 1:18-1:14, and the taper of the internal thread segment where the internal thread is located is 1:18-1:14.

[0019] Optionally, the taper of the external thread segment where the external thread is located is 1:17-1:15, and the taper of the internal thread segment where the internal thread is located is 1:17-1:15.

[0020] Optionally, the tooth top and the tooth bottom of the external thread are parallel to the axis of the first joint, the tooth top clearance of the external thread is 0.2±0.015mm, and the tooth side clearance of the external thread is 0.02±0.0015mm; the tooth top and the tooth bottom of the internal thread are parallel to the axis of the first joint, the tooth top clearance of the internal thread is 0.2±0.015mm, and the tooth side clearance of the internal thread is 0.02±0.0015mm.

[0021] Optionally, in the sealed state of the threaded connection of the first joint and the second joint, the external thread and the internal thread are in interference contact, and the interference amount of the external thread and the internal thread is not greater than δ.

[0022] wherein,

[0023] In the formula, A is a constant, which is 0.152×10 -3 ; σ s is the yield strength of the material, D is the outer diameter of the second joint, d is the outer diameter of the first joint, and d m is the inner diameter of the end of the first joint.

[0024] Optionally, each connection point of the first sealing part is provided with a fillet; and / or each connection point of the second sealing part is provided with a fillet.

[0025] In a second aspect, an embodiment of the present application provides a casing device, which can include a casing and a coupling, and the casing device includes the joint assembly as described in the first aspect.

[0026] In the casing device, the end of the casing is provided with the first joint, and the end of the coupling is provided with the second joint.

[0027] In a third aspect, an embodiment of the present application provides an oil and gas well exploitation system, which includes the casing device as described in the second aspect.

[0028] In a fourth aspect, the embodiments of the present application provide an application of the joint assembly as described in the first aspect in an oil and gas well exploitation system.

[0029] The beneficial effects of the above technical solutions provided in the embodiments of the present application at least include:

[0030] The embodiments of the present application provide a joint assembly, a casing device, an oil and gas well exploitation system and an application thereof. The joint assembly is adjusted through multiple tests on the sealing surface and the shoulder structure of the sealing part, so that each component can realize precise connection and high sealing under interference contact, and can meet the application in deep wells, ultra-deep wells, high-pressure gas wells, directional wells and acidic environment wells.

[0031] Further, the joint assembly in the embodiments is subjected to make-up and breakout tests, load envelope tests and ultimate load tests. The test results show that no galling phenomenon occurs in the make-up and breakout tests; the joint tensile and compression efficiency in the load envelope tests is equal to 100% of the pipe body, which meets the pressure sealing requirements specified in the standard and no structural failure occurs; and the ultimate load test result exceeds the set requirement; and the test result meets the set API requirement of the joint.

[0032] Other features and advantages of the present application will be further described in the following specification, and some will become apparent from the specification, or will be learned from the practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structure specifically pointed out in the written specification and the accompanying drawings.

[0033] The technical solutions of the present application will be further described in detail below with the help of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings are used to provide further understanding of the present application, and constitute a part of the specification, which are used to explain the present application together with the embodiments of the present application, and do not constitute a limitation to the present application. In the drawings:

[0035] Figure 1 The structure diagram of the joint assembly in the embodiments of the present application in a non-sealing state;

[0036] Figure 2 The structure diagram of the joint assembly in the embodiments of the present application in a sealing state;

[0037] Figure 3 The structure diagram of the first joint in the embodiments of the present application;

[0038] Figure 4 The structure diagram of the first sealing part in the embodiments of the present application;

[0039] Figure 5Structure diagram of the second joint provided in the embodiment of the present application;

[0040] Figure 6 Structure diagram of the second sealing part provided in the embodiment of the present application;

[0041] Wherein, 1-first joint; 2-second joint;

[0042] 11-external thread; 12-first sealing part; 121-first sealing surface; 122-first shoulder; 123-first auxiliary shoulder; 124-first transition surface;

[0043] 21-internal thread; 22-second sealing part; 221-second sealing surface; 222-second shoulder; 223-second auxiliary shoulder; 224-second transition surface. DETAILED DESCRIPTION

[0044] Exemplary embodiments of the present disclosure will be described in detail with reference to the drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art.

[0045] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "far", "near", "front", "back", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0046] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0047] The inventors found in work that with the development of the petroleum industry, especially the development of deep wells, ultra-deep wells, high-pressure gas wells, directional wells, and acid environment wells, higher requirements are put forward for the service performance of the oil casing, and the existing casing with the API standard thread connection form is prone to failure in the form of fracture, slip, leakage and the like in complex well conditions, which brings huge losses to the oil field. The threads on the existing casing joints not only bear the connection function but also bear the sealing function, and the joint stress concentration phenomenon is serious. The inventors found that the reason for the above connection failure is that the matching degree between the threads is not high, and the sealing part cannot reach the high pressure requirement, and after long-term research and development by the inventors, the present invention is made.

[0048] A joint assembly is provided in the embodiments of the present application, which can include a first joint 1 and a second joint 2, as shown in the drawings. Figures 1-6 The outer surface of the first joint 1 is provided with external threads 11, and the outer surface of the end portion thereof is provided with a first sealing portion 12. The inner surface of the second joint 2 is provided with internal threads 21 matched with the external threads 11, and the inner surface away from the end portion thereof is provided with a second sealing portion 22 matched with the first sealing portion 12. The length ratio of the first sealing portion 12 to the outer diameter of the first joint 1 is 0.05:1-0.06:1, and the first sealing portion 12 can include a first sealing surface 121 and a first shoulder 122. The length ratio of the second sealing portion 22 to the length of the first sealing portion 12 is 1.6:1-1.7:1, and the second sealing portion 22 can include a second sealing surface 221 matched with the first sealing surface 121 and a second shoulder 222 matched with the first shoulder 122. The included angle between the first sealing surface 121 and the axis of the first joint 1 is 12°-16°, and the included angle between the first shoulder 122 and the axis of the first joint 1 is 60°-80°. The included angle between the second sealing surface 221 and the axis of the second joint 2 is 12°-16°, and the included angle between the second shoulder 222 and the axis of the second joint 2 is 60°-80°. In the sealing state of the thread connection of the first joint 1 and the second joint 2, the first sealing surface 121 and the second sealing surface 221 are in interference contact, and the first shoulder 122 and the second shoulder 222 are in abutment.

[0049] In the embodiments of the present application, the length of the first sealing portion is L1, the length of the second sealing portion is L2, the outer diameter of the first joint is d, the inner diameter of the pipe end of the second joint is d m , the outer diameter of the second joint is D, and the lengths of the first sealing portion and the second sealing portion need to satisfy the following conditions: 0.05d≤L1≤0.06d, 1.6L1≤L2≤1.7L1.

[0050] The joint assembly provided in the embodiment of the present application can realize precise connection and high sealing under interference contact of each component through multiple test adjustments of the sealing surface of the sealing part and the shoulder structure, and can meet the application in deep wells, ultra-deep wells, high-pressure gas wells, directional wells and wells in acidic environment.

[0051] Further, the joint assembly in the embodiment is subjected to make-up / demolition test, load envelope test and ultimate load test according to API RP 5C5-2017 “Casing and Tubing Thread Connection Test Procedure” (CAL IV), and the test results show that no galling phenomenon occurs in the make-up / demolition test; the joint tensile and compression efficiency in the load envelope test is equal to 100% of the pipe body, which meets the standard pressure sealing requirement, and no structural failure occurs; the ultimate load test result exceeds the set requirement; the test result meets the set joint application level API RP 5C5-2017, CAL IV requirement.

[0052] In a preferred embodiment, the length of the first sealing part 12 to the outer diameter of the first joint 1 is 0.052:1-0.057:1, the length of the second sealing part 22 to the length of the first sealing part 12 is 1.63:1-1.68:1; the included angle between the first sealing surface 121 and the axis of the first joint 1 is 13°-15.5°, and the included angle between the first shoulder 122 and the axis of the first joint 1 is 65°-74°; the included angle between the second sealing surface 221 and the axis of the second joint 2 is 13°-15.5°, and the included angle between the second shoulder 222 and the axis of the second joint 2 is 65°-74°.

[0053] In a more preferred embodiment, the length of the first sealing part 12 to the outer diameter of the first joint 1 is 0.054:1-0.056:1, the length of the second sealing part 22 to the length of the first sealing part 12 is 1.64:1-1.68:1; the included angle between the first sealing surface 121 and the axis of the first joint 1 is 14°-15°, and the included angle between the first shoulder 122 and the axis of the first joint 1 is 65°-70°; the included angle between the second sealing surface 221 and the axis of the second joint 2 is 14°-15°, and the included angle between the second shoulder 222 and the axis of the second joint 2 is 65°-70°.

[0054] In another optional embodiment, the roughness of the first sealing surface is not less than Ra1.6; and / or, the roughness of the second sealing surface is not less than Ra1.6.

[0055] In another optional embodiment, with reference to Figures 1-6As shown, the first sealing part 12 can further include a first auxiliary shoulder 123 matched with the first shoulder 122, the first auxiliary shoulder 123 being located between the first shoulder 122 and the first sealing surface 121, and the included angle between the first auxiliary shoulder 123 and the axis of the first joint 1 being 18°-22°; the second sealing part 22 can further include a second auxiliary shoulder 223 matched with the second shoulder 222 and matched with the first auxiliary shoulder 123, the second auxiliary shoulder 223 being located between the second shoulder 222 and the second sealing surface 221, and the included angle between the second auxiliary shoulder 223 and the axis of the second joint 2 being 18°-22°; the first auxiliary shoulder 123 and the second auxiliary shoulder 223 are in interference contact in the sealed state of the threaded connection of the first joint 1 and the second joint 2; and the axial distance between the first intersection of the extension line of the first shoulder 122 and the extension line of the first auxiliary shoulder 123 and the second intersection of the extension line of the second shoulder 222 and the extension line of the second auxiliary shoulder 223 is zero.

[0056] In a preferred embodiment, the included angle between the first auxiliary shoulder 123 and the axis of the first joint 1 is 18.5°-20°, and the included angle between the second auxiliary shoulder 223 and the axis of the second joint 2 is 18.5°-20°.

[0057] In a more preferred embodiment, the included angle between the first auxiliary shoulder 123 and the axis of the first joint 1 is 19.5°-21°, and the included angle between the second auxiliary shoulder 223 and the axis of the second joint 2 is 19.5°-21°.

[0058] In another optional embodiment, referring to Figures 1-6 As shown, the first sealing part 12 can further include a first auxiliary shoulder 123 matched with the first shoulder 122, the first auxiliary shoulder 123 being located between the first shoulder 122 and the first sealing surface 121, and the included angle between the first auxiliary shoulder 123 and the axis of the first joint 1 being 18°-22°; the second sealing part 22 can further include a second auxiliary shoulder 223 matched with the second shoulder 222 and matched with the first auxiliary shoulder 123, the second auxiliary shoulder 223 being located between the second shoulder 222 and the second sealing surface 221, and the included angle between the second auxiliary shoulder 223 and the axis of the second joint 2 being 18°-22°; the first auxiliary shoulder 123 and the second auxiliary shoulder 223 are in interference contact in the sealed state of the threaded connection of the first joint 1 and the second joint 2; and the axial distance between the first intersection of the extension line of the first shoulder 122 and the extension line of the first auxiliary shoulder 123 and the second intersection of the extension line of the second shoulder 222 and the extension line of the second auxiliary shoulder 223 is zero.

[0059] In a preferred embodiment, the included angle between the first auxiliary shoulder 123 and the axis of the first joint 1 is 18.5°-20°, and the included angle between the second auxiliary shoulder 223 and the axis of the second joint 2 is 18.5°-20°.

[0060] In a more preferred embodiment, the included angle between the first auxiliary shoulder 123 and the axis of the first joint 1 is 19.5°-21°, and the included angle between the second auxiliary shoulder 223 and the axis of the second joint 2 is 19.5°-21°.

[0061] In another optional embodiment, referring to Figures 1-6As shown in the figure, the taper of the external thread section where the external thread 11 is located is 1:18-1:14, and the taper of the internal thread section where the internal thread 21 is located is 1:18-1:14.

[0062] In a preferred embodiment, referring to Figures 1-6 As shown in the figure, the taper of the external thread section where the external thread 11 is located is 1:17-1:15, and the taper of the internal thread section where the internal thread 21 is located is 1:17-1:15.

[0063] In a more preferred embodiment, referring to Figures 1-6 As shown in the figure, the taper of the external thread section where the external thread 11 is located is 1:16, and the taper of the internal thread section where the internal thread 21 is located is 1:16.

[0064] In another optional embodiment, referring to Figures 1-6 As shown in the figure, the tooth top and the tooth bottom of the external thread 11 are parallel to the axis of the first joint 1, and the tooth top gap of the external thread 11 is 0.2±0.015mm, and the tooth side gap of the external thread 11 is 0.02±0.0015mm; the tooth top and the tooth bottom of the internal thread 21 are parallel to the axis of the first joint, and the tooth top gap of the internal thread 21 is 0.2±0.015mm, and the tooth side gap of the internal thread 21 is 0.02±0.0015mm.

[0065] In another optional embodiment, referring to Figures 1-6 As shown in the figure, in the sealed state of the threaded connection of the first joint 1 and the second joint 2, the external thread 11 and the internal thread 21 are in interference contact, and the interference amount of the external thread 11 and the internal thread 21 is not greater than δ;

[0066] Wherein,

[0067] In the formula, A is a constant, which is 0.152×10 -3 ;σ s is the yield strength of the material, D is the outer diameter of the second joint, d is the outer diameter of the first joint, d m is the inner diameter of the end of the first joint.

[0068] In the embodiment of the application, the tooth top and the tooth bottom of the thread are parallel to the axis, which is more conducive to the engagement of the thread when the thread is screwed, and the thread is not easy to be wrongly buckled.

[0069] In another optional embodiment, referring to Figures 1-6 As shown in the figure, each connection point of the first sealing part 12 is provided with a round corner; and / or, each connection point of the second sealing part 22 is provided with a round corner.

[0070] The joint assembly in the embodiment of the present application, in the specific implementation, the second joint 2 is provided with a manual tightening point and a mechanical tightening point. First, the first joint 1 and the second joint 2 are connected manually, as shown in the reference Figure 1 , when the first joint 1 is rotated to the manual tightening point, the outer thread segment where the outer thread 11 is located and the median line where the inner thread 21 is located are coincident, and there is a gap in the axial direction between the first intersection of the extension line of the first auxiliary shoulder and the first shoulder and the second intersection of the extension line of the second auxiliary shoulder and the second shoulder. Then, the first joint 1 and the second joint 2 are further fastened by using a tool, as shown in the reference Figure 2 , when the first joint 1 is rotated to the mechanical tightening point, the first shoulder 122 and the second shoulder 222 are in abutting contact, the outer thread 11 and the inner thread 21, the first sealing surface 121 and the second sealing surface 221, the first auxiliary shoulder 123 and the second auxiliary shoulder 223 are in interference contact, and the axial distance between the first intersection of the extension line of the first shoulder 122 and the extension line of the first auxiliary shoulder 123 and the second intersection of the extension line of the second shoulder 222 and the extension line of the second auxiliary shoulder 223 is zero, thereby realizing precise connection and precise sealing.

[0071] The following is the relevant introduction and test results of the specific embodiment of the joint assembly applied to the casing device, i.e., applied to the casing and the coupling.

[0072] Embodiment 1

[0073] The casing outer diameter d is 244.89 mm, the pipe end inner diameter d m is 224.7 mm, and the casing wall thickness is 11.99 mm; the coupling outer diameter D is 269.9 mm, the taper of the outer thread (male thread) and the inner thread (female thread) is 1:16, the length L1 of the first sealing part (male sealing part) is 13.6 mm, the length L2 of the second sealing part (female sealing part) is 22.8 mm, the included angle between the first shoulder (male main shoulder) and the casing axis and the included angle between the second shoulder (female main shoulder) and the coupling axis are both 75°; the included angle between the first auxiliary shoulder (male auxiliary shoulder) and the casing axis and the included angle between the second auxiliary shoulder (female auxiliary shoulder) and the coupling axis are both 20°; the included angle between the first sealing surface (male sealing surface) and the casing axis and the included angle between the second sealing surface (female sealing surface) and the coupling axis are both 14°; the included angle between the first transition surface (male transition surface) and the casing axis and the included angle between the second transition surface (female transition surface) and the coupling axis are both 4°; the tooth top and the tooth bottom of the outer thread (male thread segment) are both parallel to the axis of the oil casing, and the tooth top and the tooth bottom of the inner thread (female thread segment) are both parallel to the axis of the coupling; the outer thread tooth height is 1.42 mm, the inner thread tooth height is 1.62 mm, the tooth side clearance after engagement is 0.02 mm, and the tooth top clearance is 0.2 mm.

[0074] In this embodiment of the invention, according to API RP 5C5-2017 "Test Procedures for Casing and Tubing Threaded Connections" (CAL IV), the joint assembly in Example 1 above was subjected to an up / down test, a load envelope test, and an ultimate load test. The test results show that:

[0075] (1) No hook-and-loop fastening was observed in the sample during the fastening / unfastening test;

[0076] (2) In the load envelope test, the tensile and compressive efficiency of the joint is equal to 100% of that of the pipe body. The test meets the pressure sealing requirements specified in the standard and no structural failure occurs.

[0077] (3) The ultimate load test results of the sample exceed the set requirements;

[0078] (4) The test results of the sample meet the requirements of API RP 5C5-2017, CAL IV level for the specified connector.

[0079] Example 2

[0080] The outer diameter d of the casing is 339.72 mm, and the inner diameter d of the pipe end is... m The casing diameter is 319.3 mm, and the casing wall thickness is 12.19 mm; the coupling outer diameter D is 365.12 mm; the taper of the external thread (male thread) and internal thread (female thread) is 1:16; the length L1 of the first sealing part (male sealing part) is 17 mm; the length L2 of the second sealing part (female sealing part) is 28 mm; the angles between the first shoulder (princess shoulder) and the casing axis, and between the second shoulder (female main shoulder) and the coupling axis are both 75°; the angles between the first auxiliary shoulder (male auxiliary shoulder) and the oil casing axis, and between the second auxiliary shoulder (female auxiliary shoulder) and the coupling axis are both 2°. 2°; the angle between the first sealing surface (male sealing surface) and the oil casing axis and the angle between the second sealing surface (female sealing surface) and the coupling axis are both 20°; the angle between the first transition surface (male transition surface) and the oil casing axis and the angle between the second transition surface (female transition surface) and the coupling axis are both 3°; the tooth tip and tooth root of the external thread (male thread section) are parallel to the oil casing axis, and the tooth tip and tooth root of the internal thread (female thread section) are parallel to the coupling axis; the tooth height of the external thread is 1.57mm, the tooth height of the internal thread is 1.77mm, the tooth flank clearance after meshing is 0.02mm, and the tooth tip clearance is 0.2mm.

[0081] When the pin end of the casing is rotated to the hand-tightened position, the pin and box threads are fully engaged, the pin and box thread centerlines coincide, and no interference occurs, at which time the axial distance between the pin and box tip points (i.e., the intersection of the extension lines of the auxiliary shoulder and the shoulder) is 3.2 mm; when the pin end is rotated to the machine-tightened position, the pin thread segment and the box thread segment fully interfere, the interference amount is 3.2 / 16 = 0.2 mm, the pin sealing portion and the box sealing portion interfere, the pin main shoulder and the box main shoulder are in abutting contact, and the axial distance between the pin and box tip points is 0.

[0082] According to API RP 5C5-2017 “Casing and Tubing Thread Connection Test Procedure” (CAL IV) and finite element simulation test results of the above embodiments are shown:

[0083] (1) The stress of the sample in the makeup test is moderate, and no stress concentration occurs;

[0084] (2) In the API 5C5 (2017) “Casing and Tubing Thread Connection Test Procedure” A series test of the sample, the pin sealing surface 121 and the box sealing surface 221 maintain a moderate contact pressure higher than the experimental load pressure.

[0085] The specific parameters and test results of the embodiments 3-8 and the comparative examples 1-4 are shown in Table 1 and Table 2:

[0086] Table 1 Parameter list of embodiments 3-8 and comparative examples 1-4

[0087]

[0088]

[0089] It should be noted that the above thread tapers in Table 1 of the present embodiment represent the external thread taper and the internal thread taper respectively, the above shoulder and axis angles represent the angle between the first shoulder and the axis of the first joint (casing) and the angle between the second shoulder and the axis of the second joint (coupling), the above auxiliary shoulder and axis angles represent the angle between the first auxiliary shoulder and the axis of the first joint (casing) and the angle between the second auxiliary shoulder and the axis of the second joint (coupling), the above sealing surface and axis angles represent the angle between the first sealing surface and the axis of the first joint (casing) and the angle between the second sealing surface and the axis of the second joint (coupling), and the above transition surface and axis angles represent the angle between the first transition surface and the axis of the first joint (casing) and the angle between the second transition surface and the axis of the second joint (coupling).

[0090] Table 2 Test result list of embodiments 3-8 and comparative examples 1-4

[0091]

[0092]

[0093] It should be noted that the example 3 to example 5, the comparative example 1 and the comparative example 2 in the embodiment of the present application all have the make-up and break-out test, the load envelope test and the ultimate load test; the example 6 to example 8, the comparative example 3 and the comparative example 4 have the finite element simulation test.

[0094] Based on the same inventive concept, the embodiment of the present application further provides a casing device, which can comprise: a casing and a coupling, and the joint assembly described above in the casing device; wherein the end of the casing is provided with a first joint, and the end of the coupling is provided with a second joint.

[0095] The first joint described above in the embodiment of the present application can be a part of the casing, or welded or threaded on one end of the casing; similarly, the second joint described above can be a part of the coupling, or welded or threaded on one end of the coupling. In the specific implementation, both ends of the casing are provided with the first joint, and both ends of the coupling are also provided with the second joint, so that the casing can be connected by the coupling for use in the downhole.

[0096] Based on the same inventive concept, the embodiment of the present application further provides an oil and gas well exploitation system, which can comprise the casing device described above.

[0097] Based on the same inventive concept, the embodiment of the present application further provides an application of the joint assembly described above in the oil and gas well exploitation system.

[0098] The casing device, the oil and gas well exploitation system and the application of the joint assembly in the oil and gas well exploitation system in the embodiment of the present application have the similar principles to solve the problems as the joint assembly described above, so the implementation can refer to the implementation of the joint assembly described above, and the repeated parts will not be described herein.

[0099] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. The present disclosure is not limited to the precise construction which has been described above and illustrated in the accompanying drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present disclosure is only limited by the appended claims. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A joint assembly, characterized by The utility model relates to a kind of threaded joints, including: First joint and second joint;The outer surface of the first joint is provided with external thread, and the outer surface of its end is provided with first sealing part;The inner surface of the second joint is provided with internal thread matched with the external thread, and the inner surface away from its end is provided with second sealing part matched with the first sealing part; The length ratio of the first sealing part and the first joint outer diameter is 0.052:1~0.057:1, and the first sealing part includes first sealing surface and first shoulder;The length ratio of the second sealing part and the first sealing part is 1.63:1~1.68:1, and the second sealing part includes second sealing surface matched with the first sealing surface and second shoulder matched with the first shoulder;The included angle between the first sealing surface and the axis of the first joint is 13°~15.5°, and the included angle between the first shoulder and the axis of the first joint is 65°~74°;The included angle between the second sealing surface and the axis of the second joint is 13°~15.5°, and the included angle between the second shoulder and the axis of the second joint is 65°~74°; The first joint and the second joint are in sealed state in threaded connection, the first sealing surface and the second sealing surface are in interference contact, and the first shoulder and the second shoulder are in abutment.

2. The joint assembly of claim 1, wherein, The roughness of the first sealing surface is not less than Ra1.6; And / or, The roughness of the second sealing surface is not less than Ra1.

6.

3. The joint assembly of claim 1, wherein, The first sealing part further includes: first auxiliary shoulder matched with the first shoulder, the first auxiliary shoulder is located between the first shoulder and the first sealing surface, and the included angle between the first auxiliary shoulder and the axis of the first joint is 18°~22°; The second sealing part further includes: second auxiliary shoulder matched with the second shoulder and matched with the first auxiliary shoulder, the second auxiliary shoulder is located between the second shoulder and the second sealing surface, and the included angle between the second auxiliary shoulder and the axis of the second joint is 18°~22°; The first auxiliary shoulder and the second auxiliary shoulder are in interference contact in the sealed state of threaded connection of the first joint and the second joint, and the axial distance between the first intersection point of the extension line of the first shoulder and the first auxiliary shoulder and the second intersection point of the extension line of the second shoulder and the second auxiliary shoulder is zero.

4. The joint assembly of claim 3, wherein, The included angle between the first auxiliary shoulder and the axis of the first joint is 18.5°~20°, and the included angle between the second auxiliary shoulder and the axis of the second joint is 18.5°~20°.

5. The fitting assembly of claim 3, wherein, The first sealing part further includes first transition surface between the first sealing surface and the first auxiliary shoulder, and the included angle between the first transition surface and the axis of the first joint is 3°~5°; The second sealing part further includes second transition surface between the second sealing surface and the second auxiliary shoulder, and the included angle between the second transition surface and the axis of the second joint is 3°~5°.

6. The joint assembly of claim 5, wherein, An angle between the first transition surface and an axis of the first joint is 3.2°-4.7°, and an angle between the second transition surface and an axis of the second joint is 3.2°-4.7°.

7. The joint assembly of any one of claims 1-5, wherein, A taper of an outer thread segment where the outer thread is located is 1:18-1:14, and a taper of an inner thread segment where the inner thread is located is 1:18-1:

14.

8. The joint assembly of claim 7, wherein, A taper of an outer thread segment where the outer thread is located is 1:17-1:15, and a taper of an inner thread segment where the inner thread is located is 1:17-1:

15.

9. The joint assembly of claim 7, wherein, A tooth top and a tooth bottom of the outer thread are parallel to the axis of the first joint, a tooth top clearance of the outer thread is 0.2±0.015mm, and a tooth side clearance of the outer thread is 0.02±0.0015mm; a tooth top and a tooth bottom of the inner thread are parallel to the axis of the first joint, a tooth top clearance of the inner thread is 0.2±0.015mm, and a tooth side clearance of the inner thread is 0.02±0.0015mm.

10. The joint assembly of claim 9, wherein, The first joint and the second joint are in a sealed state in a threaded connection, the outer thread and the inner thread are in interference contact, and an interference amount of the outer thread and the inner thread is not greater than δ. wherein ; where A is a constant, 0.152 x 10 -3 ; σ s is the yield strength of the material, D is the outside diameter of the second joint, d is the outside diameter of the first joint, and d m is the inside diameter of the end of the first joint.

11. The joint assembly of any one of claims 1-5, wherein, Each connection point of the first sealing part is provided with a round corner, and / or each connection point of the second sealing part is provided with a round corner.

12. A cannula device, characterized by The casing device comprises: The casing device comprises: The casing device comprises:

13. An oil and gas well production system characterized by, 14. Use of the joint assembly according to any one of claims 1-11 in an oil and gas well production system. ​ ​

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