A thickened direct-connection gas-tight oil sleeve joint

Abstract

This utility model relates to the field of oil casing threaded connection technology, and in particular to a thickened direct-connection gas-tight oil casing joint, comprising an external thread end and an internal thread end. The external thread end consists of a locking block mounting groove, a slanted torque shoulder, a sealing groove, a sawtooth external thread, an external thread relief groove, a sealing outer conical surface, and a straight end face; the internal thread end consists of a slanted end face, a cylindrical hole, a sawtooth internal thread, a sealing inner conical surface, and a right-angled inner shoulder. Through the cooperation between the sealing groove, locking block, sawtooth, external thread end, and internal thread end, the joint plays a role in connection and sealing, ensuring the structural integrity and sealing integrity of the entire tubing string. 1) The large end of the joint is equipped with an elastic sealing structure of an O-ring to prevent external fluid from entering the thread. 2) The locking block structure effectively prevents the joint from loosening. When it is necessary to disassemble the joint, the screws fixing the locking block can be broken with a hammer or other tools to easily unscrew the threads.

Description

Technical Field

[0001] This utility model relates to the field of oil casing threaded connection technology, specifically a thickened direct connection type gas-tight oil casing joint. Background Technology

[0002] The casing and tubing are connected by threaded joints to form a casing string, primarily used for oil and natural gas extraction. When extracting high-pressure gas wells, ultra-deep wells, and horizontal wells, the requirements for the casing and tubing are extremely high. Using ordinary casing and tubing presents the following problems: 1) These wells typically have 5-6 layers of casing, and the gap between the casing couplings and the inner wall of the outer casing is very small. Even slight well inclination can make casing installation difficult; 2) When encountering obstructions during casing installation, loosening of the joints often occurs; 3) If API casing is used, the cement sheath at the coupling connection is very thin, compromising cementing quality and often leading to premature casing failure; 4) These wells place higher demands on the connection strength of the casing and tubing joints. Reducing the outer diameter of the couplings decreases the connection strength of the tubing string, failing to meet extraction requirements; 5) These wells have very high requirements for the gas-tight performance of the joints, and ordinary casing and tubing joints cannot achieve the desired sealing effect.

[0003] To address these challenges, some casing and tubing manufacturers have designed direct-connection gas-tight casing and tubing joints to solve the technical difficulties of difficult casing and tubing installation, small cementing clearance, and poor sealing performance. Utility Model Content

[0004] The purpose of this invention is to solve the problem of this device by proposing a thickened direct-connection gas-tight oil sleeve joint.

[0005] To achieve the above objectives, this utility model provides the following technical solution: Design a thickened direct-connection gas-tight oil sleeve joint, comprising an external thread end and an internal thread end. The external thread end and the internal thread end are respectively machined at both ends of a steel pipe. Before machining, the pipe ends need to be thickened internally and externally. The external thread end consists of a locking block mounting groove, a slanted torque shoulder, a sealing groove, a sawtooth external thread, an external thread relief groove, a sealing external conical surface, and a straight end face. The internal thread end consists of a slanted end face, a cylindrical hole, a sawtooth internal thread, a sealing internal conical surface, and a right-angle internal shoulder.

[0006] Preferably, there are a total of 4 lock block mounting slots, which are evenly distributed on the entire circumference, i.e., 4×90°. Each lock block mounting slot is provided with 2 screw holes, which can be used to fix the lock block. One side of the lock block is machined with fine serrations.

[0007] Preferably, a lock block is installed in the lock block mounting groove, and one side of the lock block has fine serrations. The fine serrations protrude δ beyond the inclined torque shoulder by a distance δ=0.2-0.4mm.

[0008] Preferably, the sealing groove is dovetail-shaped, with a groove depth B = 4.5-5.0 mm, a groove bottom width A = 7.7-8.4 mm, and a dovetail surface inclination angle α = 7-8°. An O-ring with a radius R = 3.3-3.6 mm is placed inside the sealing groove.

[0009] Preferably, the inclined torque shoulder and the inclined end face can be axially interference-fitted, and the inclined angles of the two are the same, both being β, where β = 7-9°.

[0010] Preferably, the outer sealing conical surface and the inner sealing conical surface can be radially interference-fitted, with an interference amount of 0.30-0.85mm.

[0011] Preferably, the taper of both the outer sealing conical surface and the inner sealing conical surface is 1:8.

[0012] Preferably, there is a gap of 0.1-0.2 mm between the straight end face and the right-angled inner shoulder.

[0013] The thickened direct-connection gas-tight oil sleeve joint proposed in this utility model has the following advantages: Through the cooperation of the sealing groove, locking block, saw teeth, external thread end, and internal thread end, the external thread end and internal thread end are screwed together with a certain torque. After the joints at both ends of the pipe are screwed together, they form an oil casing string that is thousands or even tens of thousands of meters long. The joint plays the role of connection and sealing, ensuring the structural integrity and sealing integrity of the entire string. 1) The large end of the joint is equipped with an elastic sealing structure with an O-ring to prevent fluid from outside the pipe from entering the thread. At the same time, the small end of the joint is equipped with a conical / conical metal sealing structure to prevent fluid from inside the pipe from entering the thread. This gives the joint a good internal and external sealing effect. 2) A locking block structure is set up to effectively prevent the joint from loosening. When it is necessary to disassemble the joint, the screws fixing the locking block can be broken with a hammer or other tools to easily unscrew the joint. Attached Figure Description

[0014] Figure 1 Schematic diagram of the external thread end and internal thread end of this utility model; Figure 2 A schematic diagram of the external thread end and the internal thread end of this utility model after they are screwed together; Figure 3 Layout diagram of the external threaded end and locking block mounting groove of this utility model; Figure 4 Cross-sectional view of the lock block mounting groove of this utility model; Figure 5 A schematic diagram of the locking block structure of this utility model; Figure 6 Dimensions and installation diagram of sealing groove and sealing ring.

[0015] In the diagram: 1. External thread end, 2. Lock block mounting groove, 3. Inclined torque shoulder, 4. Sealing groove, 5. Serrated external thread, 6. External thread relief groove, 7. Sealing external conical surface, 8. Straight end face, 9. Screw hole, 10. Lock block, 11. Inclined end face, 12. Cylindrical hole, 13. Serrated internal thread, 14. Sealing internal conical surface, 15. Right-angle internal shoulder, 16. Internal thread end, 17. Serration, 18. O-ring seal. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings: β, the inclination angle of the inclined torque shoulder 3 and the inclined end face 11; δ, the distance by which the serration 17 on the locking block protrudes beyond the inclined torque shoulder 3; L, the depth of the locking block mounting groove; H, the depth of the screw in the locking block mounting groove; A, the width of the dovetail sealing groove; B, the depth of the dovetail sealing groove; α, the inclination angle of the dovetail surface of the dovetail sealing groove; S, the gap between the straight end face 8 and the right-angle inner shoulder 15.

[0017] See attached document Figure 1-6 In this embodiment, a thickened direct-connection gas-tight oil sleeve joint includes two parts: an external thread end 1 and an internal thread end 16. The external thread end and the internal thread end are respectively machined at both ends of a steel pipe. Before machining, the pipe ends need to be thickened internally and externally. The external thread end 1 consists of a locking block mounting groove 2, a slanted torque shoulder 3, a sealing groove 4, a sawtooth external thread 5, an external thread relief groove 6, a sealing external conical surface 7, and a straight end face 8; the internal thread end 16 consists of a slanted end face 11, a cylindrical hole 12, a sawtooth internal thread 13, a sealing internal conical surface 14, and a right-angled internal shoulder 15.

[0018] There are a total of 4 locking block mounting slots 2 on the external thread end 1, which are evenly distributed on the entire circumference, i.e., 4×90°. Each locking block mounting slot is provided with 2 screw holes 9 for fixing the locking block 10. One side of the locking block 10 is machined with small serrations 17, and 2 screw holes 18 are provided for easy fixing.

[0019] After passing through screw hole 18, the screw is screwed into screw hole 9 and tightened, thereby fixing the locking block in the locking block mounting groove 2. One side of the locking block 10 has fine serrations 17, which protrude δ beyond the inclined torque shoulder 3 by a distance δ=0.2-0.4mm. When fixing the locking block, the side with fine serrations faces outward. After the joint is screwed in, the fine serrations 17 engage with the inclined end face 11, preventing the joint from loosening.

[0020] The sealing groove 4 on the external thread end 1 is dovetail-shaped, with a groove depth B = 4.5-5.0 mm, a groove bottom width A = 7.7-8.4 mm, and a dovetail face inclination angle α = 7-8°. An O-ring 19, made of rubber, with a radius R = 3.3-3.6 mm, is placed inside the sealing groove. The sealing groove is designed as a dovetail shape, wider at the bottom and narrower at the top, and its depth is slightly greater than the radius of the O-ring, effectively preventing the O-ring from being squeezed out during tightening.

[0021] After the connector is installed, the O-ring 19 undergoes elastic deformation under the action of the cylindrical hole 12, which plays a sealing role and prevents external fluid from entering the thread.

[0022] After the joint is screwed in, the inclined torque shoulder 3 and the inclined end face 11 are axially interference-fitted, and the inclination angles of the two surfaces are the same, both being β, where β = 7-9°. The purpose of setting 3 and 11 as inclined surfaces is to improve the joint's resistance to bending and torsion.

[0023] After the joint is screwed in, the outer sealing cone surface 7 and the inner sealing cone surface 14 undergo a radial interference fit with an interference amount of 0.30-0.85mm.

[0024] The taper of both the sealing outer conical surface 7 and the sealing inner conical surface 14 is 1:8.

[0025] After the joint is screwed in, there is a gap of 0.1-0.2mm between the straight end face 8 and the right-angle inner shoulder 15. The straight end face 8 and the right-angle inner shoulder 15 will only come into contact when the inclined torque shoulder 3 and the inclined end face 11 are subjected to large deformation or wear, so as to resist excessive torque.

[0026] Working principle: The external thread end 1 and the internal thread end 16 are screwed together with a certain torque for use, see Figure 2 After the joints at both ends of the pipe are screwed together, they form an oil casing string that can be thousands or even tens of thousands of meters long. The joints serve to connect and seal, ensuring the structural integrity and sealing integrity of the entire string.

[0027] like Figure 3 As shown, there are a total of 4 locking block mounting slots 2 on the external thread end 1, evenly distributed on the entire circumference, i.e., 4×90°. Each locking block mounting slot is provided with 2 screw holes 9 for fixing the locking block.

[0028] The installation of the locking block 10 is very simple. The screw passes through the screw hole 18 and is screwed into the screw hole 9 to tighten, thus fixing the locking block in the locking block mounting groove 2. One side of the locking block 10 has fine serrations 17, which protrude δ beyond the inclined torque shoulder 3 by a distance δ = 0.2-0.4 mm. When fixing the locking block, the side with the fine serrations faces outwards. After the joint is screwed in, the fine serrations 17 engage with the inclined end face 11, preventing the joint from loosening.

[0029] The sealing groove 4 on the external thread end 1 is dovetail-shaped, with a groove depth B = 4.5-5.0 mm, a groove bottom width A = 7.7-8.4 mm, and a dovetail face inclination angle α = 7-8°. An O-ring 19, made of rubber, with a radius R = 3.3-3.6 mm, is placed inside the sealing groove. The sealing groove is designed as a dovetail shape, wider at the bottom and narrower at the top, and its depth is slightly greater than the radius of the O-ring, effectively preventing the O-ring from being squeezed out during tightening.

[0030] After the connector is installed, the O-ring 19 undergoes elastic deformation under the action of the cylindrical hole 12, forming an elastic sealing structure to prevent external fluid from entering the thread.

[0031] from Figure 1 and Figure 2 It can also be seen that after the joint is screwed in, the inclined torque shoulder 3 and the inclined end face 11 have an axial interference fit, and the inclination angles of the two are the same, both being β, where β = 7-9°. The purpose of setting 3 and 11 as inclined surfaces is to improve the bending and torsional resistance of the joint.

[0032] After the joint is screwed in, the outer sealing cone 7 and the inner sealing cone 14 undergo a radial interference fit with an interference amount of 0.30-0.85mm, forming a metal / metal sealing structure to prevent fluid from entering the thread.

[0033] To achieve the best sealing effect, the taper of both the outer sealing cone 7 and the inner sealing cone 14 is set to 1:8.

[0034] from Figure 2 It can be seen that after the joint is screwed in, there is a certain gap S between the straight end face 8 and the right-angle inner shoulder 15, with S=0.1-0.2mm. The purpose of this setting is to protect the metal / metal seal. Only when the inclined torque shoulder 3 and the inclined end face 11 undergo significant deformation or wear will the straight end face 8 and the right-angle inner shoulder 15 come into contact, thus resisting excessive torque.

[0035] This utility model is simple and convenient to process, has high connection strength, good sealing performance, large cementing gap, and is not easy to loosen after being attached. It is suitable for use in high-pressure gas wells, ultra-deep wells, and horizontal wells with harsh mining conditions.

[0036] Although the present invention has been illustrated and described with reference to preferred embodiments, those skilled in the art should understand that various changes in form and detail are possible within the scope of the claims.

Claims

1. A thickened direct-connection gas-tight oil sleeve joint, comprising an external threaded end (1) and an internal threaded end (16), wherein the external threaded end (1) and the internal threaded end (16) are respectively machined at both ends of a steel pipe, and the pipe ends need to be thickened internally and externally before machining, characterized in that: The external thread end (1) is composed of a locking block mounting groove (2), a slanted torque shoulder (3), a sealing groove (4), a sawtooth external thread (5), an external thread relief groove (6), a sealing outer conical surface (7), and a straight end face (8). The internal thread end (16) is composed of a slanted end face (11), a cylindrical hole (12), a sawtooth internal thread (13), a sealing inner conical surface (14), and a right-angle inner shoulder (15).

2. The thickened direct-connection gas-tight oil sleeve joint according to claim 1, characterized in that: There are a total of 4 lock block mounting slots (2), which are evenly distributed on the entire circumference, i.e., 4×90°. Each lock block mounting slot is provided with 2 screw holes (9). The screw holes (9) can be used to fix the lock block (10). The lock block (10) has small serrations (17) on one side.

3. The thickened direct-connection gas-tight oil sleeve joint according to claim 1, characterized in that: A lock block (10) is installed in the lock block mounting groove (2). One side of the lock block (10) has small serrations (17). The small serrations (17) protrude δ beyond the inclined torque shoulder (3) by a distance δ=0.2-0.4mm.

4. The thickened direct-connection gas-tight oil sleeve joint according to claim 1, characterized in that: The sealing groove (4) is dovetail-shaped, with a groove depth B = 4.5-5.0 mm, a groove bottom width A = 7.7-8.4 mm, and a dovetail surface inclination angle α = 7-8°. An O-ring (18) with a radius R = 3.3-3.6 mm is placed inside the sealing groove (4).

5. The thickened direct-connection gas-tight oil sleeve joint according to claim 1, characterized in that: The inclined torque shoulder (3) and the inclined end face (11) can be axially interference-fitted, and the inclined angles of the two are the same, both being β, β=7-9°.

6. The thickened direct-connection gas-tight oil sleeve joint according to claim 1, characterized in that: The sealing outer conical surface (7) and the sealing inner conical surface (14) can be radially interference-fitted with an interference amount of 0.30-0.85mm.

7. The thickened direct-connection gas-tight oil sleeve joint according to claim 1, characterized in that: The taper of the outer sealing cone (7) and the inner sealing cone (14) is 1:

8.

8. The thickened direct-connection gas-tight oil sleeve joint according to claim 1, characterized in that: There is a gap of 0.1-0.2mm between the straight end face (8) and the right-angle inner shoulder (15).

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