Sleeve joint suitable for surface casing well drilling

Abstract

The invention belongs to the technical field of oil and gas drilling and completion, and discloses a casing joint suitable for surface casing drilling. The casing joint comprises a male end and a female end matched with the male end. The male end comprises a first tubular column, the end portion of one end of the first tubular column is a first torque shoulder, and external threads are arranged on the outer side of the first tubular column. The female end comprises a second tubular column, a second torque shoulder is arranged in the middle of the interior of the second tubular column, and internal threads matched with the external threads are arranged on the two sides of the second torque shoulder in the second tubular column; the first pipe column is provided with a first high-torsion-resistance right-angle structure between the first torque shoulder and the external threads, the second pipe column is provided with second high-torsion-resistance right-angle structures between the two sides of the second torque shoulder and the internal threads, and the first high-torsion-resistance right-angle structure and the second high-torsion-resistance right-angle structures are in interference fit. According to the casing joint, the phenomena of thread gluing and releasing at the casing joint during casing drilling can be avoided, and the casing joint has the advantages of being high in torsion resistance and easy to buckle.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas drilling and completion, and in particular relates to a casing joint suitable for surface casing drilling. Background Art

[0002] Shale gas drilling is difficult due to the loose and easily collapsed strata, widespread development of underground cracks and caves, the existence of underground rivers and abundant groundwater. Due to the complex surface geological conditions, conventional drilling construction often encounters complex problems underground, resulting in difficulties in lowering the casing and even forcing the well to be relocated due to the scrapping of the wellbore, causing huge economic losses.

[0003] Casing drilling is a new drilling technology that can effectively solve the complex problems of underground accidents such as well kick, well wall collapse, diameter reduction, drilling fluid leakage, and drill bit sticking in unstable formations. Especially when drilling large-scale wells in surface layers with complex geological conditions, this technology can lower the casing more quickly and carry out cementing operations.

[0004] The casing currently used in casing drilling has a thinner wall than conventional drill pipes, and the strength of the casing threaded joints is relatively weak. The torque that can be transmitted is far less than that of conventional drill pipes. The torque transmission direction is only unidirectional, and it needs to withstand higher torque than ordinary casing, while also withstanding the longitudinal torsional vibration and lateral oscillation caused by the drill bit breaking the rock.

[0005] The most widely used connection method for casing is threaded connection. The thread is subjected to complex composite stress, and the force on each thread tooth is very uneven. The threaded joint part is always the most vulnerable part of the entire pipe string, which makes the casing more prone to expansion and sticking failure at the threaded connection. In addition, the wellbore drilled in the surface layer is often large in size (above Ф406.4mm), which makes it inconvenient to buckle the casing, and the buckling time is long, affecting the efficiency of on-site construction.

[0006] In summary, the casing used in the existing casing drilling is prone to failure at the threaded connection, and the connection is inconvenient. Summary of the invention

[0007] In view of the above problems, the present invention provides a casing joint suitable for surface casing drilling, which adopts the following technical solutions:

[0008] A casing joint suitable for surface casing drilling, comprising a male end and a female end matching the male end; wherein the male end comprises a first pipe string, the end of one end of the first pipe string is a first torque shoulder, and the middle position of the first pipe string is circumferentially provided with an external thread on the outside; the female end comprises a second pipe string, the interior of the second pipe string is provided with a second torque shoulder at a middle position, the interior of the second pipe string is provided with internal threads matching the external threads on both sides of the second torque shoulder, and the internal threads extend from one side of the second torque shoulder to the outer end of the second pipe string; the first pipe string is provided with a first high torsion-resistant right-angle structure between the first torque shoulder and the external thread, and the second pipe string is provided with a second high torsion-resistant right-angle structure between both sides of the second torque shoulder and the internal thread, and the first high torsion-resistant right-angle structure and the second high torsion-resistant right-angle structure are interference fit.

[0009] Furthermore, the external thread and the internal thread are both tapered threads.

[0010] Furthermore, the tooth profiles of the external thread and the internal thread are right-angled trapezoids.

[0011] Furthermore, the right-angled trapezoidal tooth profile includes a first straight line segment at the tooth top, and a second straight line segment and a third straight line segment at both sides of the tooth profile;

[0012] The two ends of the second straight line segment are respectively connected to the tooth bottom and the first end of the first straight line segment, the second straight line segment, the tooth bottom and the first straight line segment form right-angle sides, and the angle between the second straight line segment and the perpendicular line of the thread axis forms a load-bearing angle; the first end of the third straight line segment is connected to the second end of the first straight line segment, the second end of the third straight line segment is connected to the tooth bottom, and the angle between the third straight line segment and the perpendicular line of the thread axis forms a guide angle.

[0013] Furthermore, the right-angled side edge of the right-angled trapezoidal tooth profile of the external thread is located on a side away from the first torque shoulder, and the right-angled side edge of the right-angled trapezoidal tooth profile of the internal thread is located on a side away from the second torque shoulder.

[0014] Furthermore, a first chamfer is provided at a connection between one end of the second straight line segment and the tooth bottom, a second chamfer is provided at a connection between the other end of the second straight line segment and the first end of the first straight line segment, a third chamfer is provided at a connection between the second end of the first straight line segment and the first end of the third straight line segment, and a fourth chamfer is provided at a connection between the second end of the third straight line segment and the tooth bottom.

[0015] Furthermore, the load angle of the external thread and the internal thread is 0°.

[0016] Furthermore, the pitch of the external thread is the same as the pitch of the internal thread, and the difference between the tooth height h2 of the internal thread and the tooth height h1 of the external thread is 0.1 mm.

[0017] Furthermore, the outer diameter D of the first pipe column ranges from 40 to 400 mm, and the wall thickness t of the first pipe column satisfies t / D≤12%, and t≤22 mm.

[0018] Furthermore, the difference between the inner diameter of the first torque shoulder and the second torque shoulder and D-2t is between -2.0 and 1.0.

[0019] Furthermore, the taper of the first tapered mother body of the external thread and the second tapered mother body of the internal thread is 1:10.

[0020] Furthermore, the guide angle between the external thread and the internal thread is 30°.

[0021] Beneficial effects of the present invention:

[0022] 1. The casing joint of the present invention can avoid sticking and stripping phenomena at the casing joint when casing drilling is adopted, has the characteristics of high torsion resistance and easy buckling, can adapt to complex stress conditions in the well, and ensure safe and efficient drilling of casing drilling.

[0023] 2. The casing joint of the present invention increases the casing threading speed during surface casing drilling and improves construction efficiency.

[0024] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic structural diagram of a casing joint suitable for surface casing drilling according to an embodiment of the present invention is shown;

[0027] Figure 2 A schematic structural diagram of a male end according to an embodiment of the present invention is shown;

[0028] Figure 3A schematic structural diagram of a first high torsion-resistant right-angle structure according to an embodiment of the present invention is shown;

[0029] Figure 4 A schematic diagram of the structure of a female end according to an embodiment of the present invention is shown;

[0030] Figure 5 A schematic structural diagram of a second high torsion-resistant right-angle structure according to an embodiment of the present invention is shown;

[0031] Figure 6 A schematic diagram showing the coordination of a first high torsion-resistant right-angle structure and a second high torsion-resistant right-angle structure according to an embodiment of the present invention is shown;

[0032] Figure 7 A schematic diagram of parameters of an external thread and an internal thread according to an embodiment of the present invention is shown;

[0033] Figure 8 A schematic diagram of load-bearing surface parameters of an external thread and an internal thread according to an embodiment of the present invention is shown;

[0034] Fig. 9 A schematic diagram of guide surface parameters of an external thread and an internal thread according to an embodiment of the present invention is shown;

[0035] Fig.10 A schematic diagram of the fitting clearance between the external thread and the internal thread according to an embodiment of the present invention is shown.

[0036] In the figure: 1. male end; 2. female end; 11. first pipe column; 12. first torque shoulder; 13. external thread; 14. first high torsion-resistant right-angle structure; 21. second pipe column; 22. second torque shoulder; 23. internal thread; 24. second high torsion-resistant right-angle structure; 3. first straight line segment; 4. second straight line segment; 5. third straight line segment; 6. first chamfer; 7. second chamfer; 8. third chamfer; 9. fourth chamfer; 10. fitting clearance. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0039] The invention provides a casing joint suitable for surface casing drilling, which has the characteristics of high torsion resistance and easy make-up, and is used for improving the casing make-up speed and torsion resistance during the surface casing drilling process.

[0040] like Figure 1 As shown, a casing joint suitable for surface casing drilling comprises a male end 1 and a female end 2 matching with the male end 1 .

[0041] like Figure 2 As shown, the male end 1 includes a first pipe column 11, one end of the first pipe column 11 is a first torque shoulder 12, and the middle position of the first pipe column 11 is provided with an external thread 13 along the circumferential direction on the outside; Figure 4 As shown, the female end 2 includes a second tubular column 21, a second torque shoulder 22 is provided at a middle position inside the second tubular column 21, and internal threads 23 cooperating with the external threads 13 are provided on both sides of the second torque shoulder 22 inside the second tubular column 21, and the internal threads 23 extend from one side of the second torque shoulder 22 to the outer end of the second tubular column 21.

[0042] like Figure 2 and Figure 3 As shown, the first pipe column 11 is provided with a first high torsion resistance right angle structure 14 between the first torque shoulder 12 and the external thread 13. Figure 4 and Figure 5 As shown, the second pipe column 21 is provided with a second high torsion resistance right-angle structure 24 between both sides of the second torque shoulder 22 and the internal thread 23 .

[0043] The torque bearing capacity of the sleeve joint of the present invention is mainly provided by the first torque shoulder 12 and the second torque shoulder 22 of the male end 1. Figure 6 As shown, the first high torsion-resistant right-angle structure 14 and the second high torsion-resistant right-angle structure 24 are interference-fitted to achieve high torsion-resistant performance.

[0044] During the connection process, the external thread 13 of the male end 1 is connected to the internal thread 23 of the female end 2, and the end of the male end 1 abuts against one side of the annular boss.

[0045] For example, Figure 7As shown, both the external thread 13 and the internal thread 23 are tapered threads. The first pipe column 11 is provided with a first tapered matrix at the middle position. Continuous protrusions and grooves with a set cross section are formed on the first tapered matrix along the spiral line to form a tapered external thread 13.

[0046] A second conical matrix is ​​provided on both sides of the second torque shoulder 22 inside the second pipe column 21 , and continuous protrusions and grooves with a set cross section are formed on the second conical matrix along the spiral line to form a conical internal thread 23 .

[0047] Both the male end 1 and the female end 2 are connected by tapered threads to achieve sealing. The shape of the tapered threads generates pressure on both sides of the threads, thereby achieving sealing. When the threads rotate, due to the shape of the threads, inward pressure is generated, and this pressure causes the two sides of the threads to fit tightly, thereby achieving thread sealing. At the same time, due to the shape of the tapered threads, the pressure on both sides of the threads increases as the threads rotate, thereby further enhancing the sealing effect.

[0048] The male end 1 and the female end 2 adopt tapered thread seal to ensure reliable sealing effect and stable sealing performance, which is suitable for harsh working conditions such as high-pressure drilling and high speed. At the same time, the tapered thread seal has a simple structure, is easy to manufacture and install, and has a low cost.

[0049] For example, Figure 7 As shown, the tooth profiles of the external thread 13 on the first pipe column 11 and the internal thread 23 on the second pipe column 21 are right-angled trapezoids, and the external thread 13 and the internal thread 23 are meshed.

[0050] For example, Figure 8 and Fig. 9 As shown, the right-angled trapezoidal tooth profile includes a first straight line segment 3 at the tooth top, and a second straight line segment 4 and a third straight line segment 5 at both sides of the tooth profile.

[0051] Among them, the two ends of the second straight line segment 4 are respectively connected to the tooth bottom and the first end of the first straight line segment 3, the second straight line segment 4 and the tooth bottom and the first straight line segment 3 form a right-angle side, and the angle between the second straight line segment 4 and the perpendicular line of the thread axis forms a load-bearing angle; the first end of the third straight line segment 5 is connected to the second end of the first straight line segment 3, the second end of the third straight line segment 5 is connected to the tooth bottom, and the angle between the third straight line segment 5 and the perpendicular line of the thread axis forms a guide angle.

[0052] For example, the right-angled side of the right-angled trapezoidal tooth profile of the external thread 13 is located at a side away from the first torque shoulder 12 , and the right-angled side of the right-angled trapezoidal tooth profile of the internal thread 23 is located at a side away from the second torque shoulder 22 .

[0053] A first chamfer 6 is provided at the connection between one end of the second straight line segment 4 and the tooth bottom, a second chamfer 7 is provided at the connection between the other end of the second straight line segment 4 and the first end of the first straight line segment 3, a third chamfer 8 is provided at the connection between the second end of the first straight line segment 3 and the first end of the third straight line segment 5, and a fourth chamfer 9 is provided at the connection between the second end of the third straight line segment 5 and the tooth bottom.

[0054] For example, the load angle of the external thread 13 and the internal thread 23 is 0°, the taper of the first conical matrix of the external thread 13 and the second conical matrix of the internal thread 23 is 1:10, and the guide angle of the external thread 13 and the internal thread 23 is 30°. Increasing the guide angle of the external thread 13 and the internal thread 23 to 30° makes it easy to buckle the casing.

[0055] For example, the pitch of the external thread 13 is the same as the pitch of the internal thread 23, and the difference between the tooth height h2 of the internal thread 23 and the tooth height h1 of the external thread 13 is 0.1 mm. Fig.10 As shown, there is a matching gap 10 between the internal thread 23 and the external thread 13, which facilitates the buckling of the casing.

[0056] For example, the outer diameter D of the first tube column 11 of the male end 1 ranges from 40 to 400 mm, and the wall thickness t of the first tube column 11 satisfies t / D≤12%, and t≤22 mm.

[0057] The difference between the inner diameter of the first torque shoulder 12 and the second torque shoulder 22 and D-2t is between -2.0 and 1.0.

[0058] For example, the outer diameter D of the first tube column 11 of the male end 1 is 365.13 mm, the pitch of the external thread 13 on the first tube column 11 is 6.35 mm, the tooth height h1 is 1.575 mm, and the tooth height h2 of the internal thread 23 on the second tube column 21 of the female end 2 is 1.675 mm.

[0059] The taper of the tapered mother body of the external thread 13 and the internal thread 23 is 1:10, and the guide angle of the external thread 13 and the internal thread 23 is 30°, making it easy to thread on a casing of Ф339.7mm specification.

[0060] The maximum yield torque of the casing joint of the present invention is 43700N.m, which meets the requirement of 30000N.m during the construction of 339.7mm casing drilling. The tensile, internal pressure and external extrusion performance of the casing joint of the present invention are not lower than the pipe body itself, meeting the requirements of the joint sealing ability and the internal pressure of the pipe body, and the joint bending can reach 20° / 30m; the casing joint of the present invention can pass the evaluation requirements of API RP5C5-2017.

[0061] During surface casing drilling, the casing is connected through casing joints, and the torque of the wellhead equipment is transmitted to the casing drill bit through the casing. It is necessary to meet the high torsion resistance during the drilling process, and the casing joints need to be easy to operate at the wellhead. During the drilling process of surface casing, it is common to encounter underground rivers and other collapsed formations, and drill stuck, top drive stopped and other situations occur frequently. The casing torque value can reach 30000N.m.

[0062] The casing joint of the present invention can avoid sticking and stripping phenomena at the casing joint thread when casing drilling is adopted, can adapt to complex formation conditions underground, and ensure safe and efficient drilling of casing drilling.

[0063] The pitch design of the external thread 13 of the casing joint of the present invention can effectively improve the accuracy of thread fastening and avoid wrong fastening when the casing threads are fastened. The maximum yield torque of the first high torsion-resistant right-angle structure 14 and the second high torsion-resistant right-angle structure 24 reaches 43700N.m, which exceeds the construction torque of 30000N.m during surface drilling, and is 2 to 3 times higher than the torque of conventional stepped casing.

[0064] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A casing joint suitable for surface casing drilling, characterized in that: It comprises a male end (1) and a female end (2) matching with the male end (1); The male end (1) comprises a first pipe column (11), one end of which is a first torque shoulder (12), and an external thread (13) is circumferentially arranged on the outside of the middle position of the first pipe column (11); the female end (2) comprises a second pipe column (21), a second torque shoulder (22) is arranged at the middle position of the inside of the second pipe column (21), and internal threads (23) matching the external threads (13) are arranged on both sides of the second torque shoulder (22) inside the second pipe column (21), and the female end (2) comprises a second pipe column (21), a second torque shoulder (22) is arranged at the middle position of the inside of the second pipe column (21), and the internal threads (23) matching the external threads (13) are arranged on both sides of the second torque shoulder (22). The internal thread (23) extends from one side of the second torque shoulder (22) to the outer end of the second pipe column (21); the first pipe column (11) is provided with a first high-torque resistance right-angle structure (14) between the first torque shoulder (12) and the external thread (13); the second pipe column (21) is provided with a second high-torque resistance right-angle structure (24) between both sides of the second torque shoulder (22) and the internal thread (23); the first high-torque resistance right-angle structure (14) and the second high-torque resistance right-angle structure (24) are interference fit.

2. The casing joint suitable for surface casing drilling according to claim 1, characterized in that: The external thread (13) and the internal thread (23) are both tapered threads.

3. The casing joint suitable for surface casing drilling according to claim 1, characterized in that: The tooth profiles of the external thread (13) and the internal thread (23) are right-angled trapezoids.

4. The casing joint suitable for surface casing drilling according to claim 3, characterized in that: The right-angled trapezoidal tooth profile comprises a first straight line segment (3) at the tooth top, and a second straight line segment (4) and a third straight line segment (5) at both sides of the tooth profile; The two ends of the second straight line segment (4) are respectively connected to the tooth bottom and the first end of the first straight line segment (3), the second straight line segment (4) and the tooth bottom and the first straight line segment (3) form right-angled sides, and the angle between the second straight line segment (4) and the perpendicular line of the thread axis forms a load-bearing angle; the first end of the third straight line segment (5) is connected to the second end of the first straight line segment (3), the second end of the third straight line segment (5) is connected to the tooth bottom, and the angle between the third straight line segment (5) and the perpendicular line of the thread axis forms a guide angle.

5. The casing joint suitable for surface casing drilling according to claim 4, characterized in that: The right-angled side of the right-angled trapezoidal tooth profile of the external thread (13) is located on a side away from the first torque shoulder (12), and the right-angled side of the right-angled trapezoidal tooth profile of the internal thread (23) is located on a side away from the second torque shoulder (22).

6. The casing joint suitable for surface casing drilling according to claim 4, characterized in that: A first chamfer (6) is provided at a connection between one end of the second straight line segment (4) and the tooth bottom, a second chamfer (7) is provided at a connection between the other end of the second straight line segment (4) and the first end of the first straight line segment (3), a third chamfer (8) is provided at a connection between the second end of the first straight line segment (3) and the first end of the third straight line segment (5), and a fourth chamfer (9) is provided at a connection between the second end of the third straight line segment (5) and the tooth bottom.

7. The casing joint suitable for surface casing drilling according to any one of claims 4 to 6, characterized in that: The load angle of the external thread (13) and the internal thread (23) is 0°.

8. The casing joint suitable for surface casing drilling according to any one of claims 1 to 6, characterized in that: The pitch of the external thread (13) is the same as the pitch of the internal thread (23), and the difference between the tooth height h2 of the internal thread (23) and the tooth height h1 of the external thread (13) is 0.1 mm.

9. The casing joint suitable for surface casing drilling according to claim 1, characterized in that: The outer diameter D of the first pipe column (11) ranges from 40 to 400 mm, and the wall thickness t of the first pipe column (11) satisfies t / D≤12%, and t≤22 mm.

10. The casing joint suitable for surface casing drilling according to claim 9, characterized in that: The difference between the inner diameter of the first torque shoulder (12) and the second torque shoulder (22) and D-2t is between -2.0 and 1.

0.

11. The casing joint suitable for surface casing drilling according to claim 2, characterized in that: The taper of the first tapered matrix of the external thread (13) and the second tapered matrix of the internal thread (23) is 1:

10.

12. The casing joint suitable for surface casing drilling according to claim 4, characterized in that: The guide angle between the external thread (13) and the internal thread (23) is 30°.

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