Hydraulic safety joint

Abstract

The utility model discloses a hydraulic safety connector which comprises an upper connector and a lower connector, a lining screw thread rod with male threads is fixedly arranged at the lower end of the upper connector, and female threads corresponding to the male threads are arranged in the lower connector. A plurality of through grooves are formed in the side wall of the lining screw thread rod in the circumferential direction and extend upwards from the lower end of the lining screw thread rod in the axial direction. The central pipe extends into the upper joint and the lower joint; the annular supporting sliding sleeve is assembled between the central pipe and the lining screw thread rod and is used for expanding the lower end of the lining screw thread rod so as to enable the male thread to be tightly matched with the female thread; the annular piston is assembled between the central pipe and the lower connector, and the working end of the annular piston faces the end face of the annular supporting sliding sleeve; an annular piston cavity is formed between the central pipe and the lower joint, and a bypass hole is formed in the central pipe to be communicated with the annular piston cavity; and a limiting seat for preventing the sealing ball from falling is arranged below the bypass hole in the central pipe. The device is safe in structure, easy to assemble, flexible to operate and easy to master, is suitable for various well types such as highly-deviated wells and horizontal wells, is used for being connected to the lowermost part of a drill pipe string, is the link which is the most easy to detach in the whole drill pipe string, and can also be connected to a fishing tool, and after the fishing tool is stuck, the drill pipe can be detached from the device and lifted out of the device.

Description

Technical Field

[0001] The utility model relates to a downhole operation tool used in oil and gas well workover fishing operations, specifically a hydraulic safety joint connected to a fishing tool. Background Technique

[0002] During oil and gas field workover fishing operations, to prevent the fishing tool from being stuck when the fishing and unjamming are unsuccessful after fishing, a safety joint is generally connected to the bottom of the fishing tool, so that when the above situation occurs, the fishing tool above the safety joint can be retrieved by disconnecting at the safety joint. However, traditional safety joints all have certain drawbacks in use:

[0003] One is a serrated safety joint. The upper and lower mating wide serrated thread surfaces of this safety joint are in contact and tightened under the action of tension, and can withstand tension and transmit torque. The "eight"-shaped convex and concave structure in the upper and lower mating generates a pre-tension and maintains a constant locking force. In actual applications, this safety joint can transmit positive and negative torques, but often cannot be unfastened normally when it is necessary to retrieve the fishing tool above the safety joint, and it may unfasten and loosen by itself when it is not necessary to retrieve in special cases;

[0004] Another is a square-threaded safety joint. This structure relies on the mutually cooperating inclined flanges to withstand axial tensile and compressive loads and single-direction torque. When it is necessary to retrieve the fishing tool above the safety joint, reverse the drill string, and the square-thread can be unfastened and loosened first. In actual applications, the reverse torque generated during drill string threading is likely to cause this safety joint to be reversed and loosened, causing the fishing tool to fall into the well;

[0005] The third is a pin-type safety joint. The upper joint and the lower joint of this safety joint are fixed by pins and can withstand axial tensile and compressive loads and torque. However, this safety joint has poor anti-torque performance and is prone to disconnect during operation: during the process of running in the hole, it will disconnect due to the torque generated by the distortion of the downhole casing, causing the fishing tool to fall into the well.

[0006] In addition, most of the above safety joints need to rotate the pipe string of the fishing tool to unfasten and loosen, and it is relatively difficult to rotate the pipe string in highly deviated wells and horizontal wells, so the use effect is not good. Content of the Utility Model

[0007] To solve the above deficiencies in the prior art, the utility model aims to provide a hydraulic safety joint to achieve the purpose of avoiding the inability to unfasten and loosen after entering the well and avoiding the fishing tool falling into the well due to failure during operation.

[0008] To achieve the above object, the technical solution adopted by the present utility model is as follows: A hydraulic safety joint includes an upper joint and a lower joint. A lining screw rod with male threads is fixedly provided at the lower end of the upper joint, and female threads corresponding to the male threads are provided inside the lower joint; a plurality of through grooves are circumferentially formed on the side wall of the lining screw rod, and the through grooves extend axially upward from the lower end of the lining screw rod;

[0009] It further includes a central tube extending into the upper joint and the lower joint, a ring-shaped support sliding sleeve assembled between the central tube and the lining screw rod for expanding the lower end of the lining screw rod to make the male threads and the female threads fit tightly, a ring-shaped piston assembled between the central tube and the lower joint with the working end facing the end face of the ring-shaped support sliding sleeve, and a sealing ball for injecting pressure into the central tube;

[0010] A ring-shaped piston cavity is formed between the central tube and the lower joint, and a side through hole is provided on the central tube to communicate with the ring-shaped piston cavity; a limit seat for preventing the sealing ball from falling is provided below the side through hole inside the central tube.

[0011] As a limitation of the present utility model, the ring-shaped support sliding sleeve is fixed on the central tube by a safety pin.

[0012] As a further limitation of the present utility model, a receiving cavity is formed between the central tube and the lining screw rod, and the receiving cavity is located above the ring-shaped support sliding sleeve for accommodating the ring-shaped support sliding sleeve pushed upward by the ring-shaped piston;

[0013] The thickness of the receiving cavity is greater than the thickness of the ring-shaped support sliding sleeve.

[0014] As another limitation of the present utility model, the ring-shaped piston is fixed on the central tube by a safety pin.

[0015] As a further limitation of the present utility model, a sealing ring is provided between the ring-shaped piston and the inner wall of the ring-shaped piston cavity.

[0016] Due to the adoption of the above technical solution, compared with the prior art, the beneficial effects obtained by the present utility model are:

[0017] The present utility model adopts the method of throwing a ball to inject pressure and release the connection. After throwing the ball and injecting pressure, the ring-shaped piston pushes the ring-shaped support sliding sleeve away from its original position. The multi-lobe male threads at the lower end of the lining screw rod lose support and deform and contract under the action of elastic force, so as to disengage from the female threads of the lower joint, thus completing the release of the safety joint. In the present utility model, the release of the upper joint and the lower joint does not rely on rotation, so it has more advantages in the application of highly deviated wells and horizontal wells, and can greatly improve the construction efficiency and economic benefits.

[0018] Compared with the traditional safety joint, the present utility model has good anti-torque performance, can transmit bidirectional torque, can withstand axial tensile and compressive loads, is not easy to unthread and loosen, and has high safety performance.

[0019] In summary, the structure of the utility model is safe and easy to assemble, and the operation is flexible and easy to master. It is applicable to various well types such as highly deviated wells and horizontal wells. It is used to connect to the bottom of the drill pipe string and is the most easily disassembled part of the entire drill pipe string. It can also be used to connect to fishing tools. After the fishing tool is stuck, it can be disassembled from the utility model and the drill pipe can be lifted out. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present utility model will be further described in detail below in conjunction with the drawings and specific embodiments.

[0021] Figure 1 is a schematic structural diagram of an embodiment of the present utility model;

[0022] Figure 2 is a schematic diagram of the split structure of an embodiment of the present utility model;

[0023] Figure 3 is a longitudinal sectional view of the structural relationship of an embodiment of the present utility model;

[0024] Figure 4 is a schematic structural diagram of the upper sub of an embodiment of the present utility model;

[0025] In the figure: 1, upper sub; 2, lower sub; 3, central tube; 4, sealing ball; 5, annular support sliding sleeve; 6, annular piston; 7, inner lining screw rod; 8, male thread; 9, through groove; 10, accommodation cavity; 11, annular piston cavity; 12, side through hole; 13, limit seat; 14, safety pin. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The preferred embodiments of the present utility model will be described below in conjunction with the drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and understanding the present utility model, and are not used to limit the present utility model.

[0027] This embodiment discloses a hydraulic safety joint, which is mainly used in oil and gas field workover fishing operations to connect the drill pipe and the fishing tool. When the fishing tool is stuck and cannot be lifted out, the hydraulic safety joint can be released by dropping a ball and building pressure, so that the drill pipe above the hydraulic safety joint can be safely lifted out.

[0028] It should be noted in advance that in this embodiment, "upper" is defined as the side close to the wellhead after the equipment is lowered into the well, and "lower" is defined as the side far from the wellhead after the equipment is lowered into the well.

[0029] As Figures 1 to 4 shown, this embodiment includes an upper sub 1, a lower sub 2, a central tube 3, a sealing ball 4, an annular support sliding sleeve 5 and an annular piston 6. Among them, the upper end of the upper sub 1 is used to connect the upper feeding tool (usually a drill pipe), as Figure 4As shown, a lining screw rod 7 that can extend into the interior of the lower joint 2 is fixedly provided at the lower end of the upper joint 1. A male thread 8 is provided at the lower end of the lining screw rod 7, and a plurality of through grooves 9 are circumferentially provided on the side wall of the lining screw rod 7. The through grooves 9 extend axially upward from the lower end face of the lining screw rod 7, dividing the male thread 8 into multiple segments, enabling the male thread 8 to expand or contract.

[0030] During workover fishing operations, the lower end of the lower joint 2 is usually used to connect the fishing tool. A female thread is provided inside the lower joint 2, and this female thread is adapted to the above-mentioned male thread 8. With the cooperation of the female thread and the male thread 8, the lower joint 2 and the upper joint 1 are assembled into one body. As Figure 3 shown, the female thread is provided at the part where the inner wall of the lower joint 2 contacts the lining screw rod 7.

[0031] The central pipe 3 is assembled inside the upper joint 1 and the lower joint 2 for transporting drilling fluid from top to bottom. As Figure 3 shown, an accommodation cavity 10 is formed between the central pipe 3 and the lining screw rod 7; an annular piston cavity 11 is formed between the central pipe 3 and the lower joint 2, and a side through hole 12 is provided on the central pipe 3 to communicate with the annular piston cavity 11. In this embodiment, a limit seat 13 for preventing the sealing ball 4 from falling is provided below the side through hole 12 inside the central pipe 3, and a through hole for the drilling fluid to pass through is provided on the limit seat 13.

[0032] The sealing ball 4 is a steel ball, and its diameter is smaller than the inner diameter of the central pipe 3 but larger than the diameter of the through hole on the limit seat 13. When the sealing ball 4 is dropped into the central pipe 3 and falls to the limit seat 13, it will block the through hole to build pressure, and then the drilling fluid in the central pipe 3 will enter the annular piston cavity 11 through the side through hole 12.

[0033] The annular support sliding sleeve 5 is assembled between the central pipe 3 and the lining screw rod 7 for expanding the multiple segments of the male thread 8 at the lower end of the lining screw rod 7 outward, enabling the male thread 8 to be closely fitted with the female thread of the lower joint 2. As Figure 3 shown, the annular support sliding sleeve 5 is fixed on the central pipe 3 through a safety pin 14, located below the above-mentioned accommodation cavity 10. The thickness of the annular support sliding sleeve 5 is smaller than the thickness of the accommodation cavity 10, so that after the annular piston 6 pushes the annular support sliding sleeve 5 into the accommodation cavity 10, the annular support sliding sleeve 5 loses the support for the multiple segments of the male thread 8, enabling the multiple segments of the male thread 8 to deform and retract.

[0034] The annular piston 6 is assembled between the central pipe 3 and the lower joint 2, as Figure 3As shown in the figure, it is located inside the above-mentioned annular piston chamber 11. The working end of the annular piston 6 faces the lower end surface of the above-mentioned annular support sliding sleeve 5. By contacting the lower end surface of the annular support sliding sleeve 5, the annular support sliding sleeve 5 can be pushed upward. In this embodiment, the annular piston 6 is also fixed to the central tube 3 by a safety pin 14, and a sealing ring is provided between the annular piston 6 and the inner wall of the annular piston chamber 11.

[0035] Here, it should be supplemented that the connection between the male thread 8 at the end of the inner lining screw rod 7 of the upper joint 1 and the female thread inside the lower joint 2 does not rely on rotation. Instead, after inserting the two into place, the annular support sliding sleeve 5 is added inside the inner lining screw rod 7, and the multi-lobe male thread 8 is expanded outward to be in close contact with the female thread.

[0036] In actual application, when it is necessary to release the connection, the sealing ball 4 is put into the central tube 3. The sealing ball 4 drops to the limit seat 13 to block the through-hole for pressure buildup. The drilling fluid in the central tube 3 enters the annular piston chamber 11 through the side through-hole 12. As the hydraulic pressure continuously increases, the safety pin 14 between the annular piston 6 and the central tube 3 is cut off; after cutting off the safety pin 14, the annular piston 6 moves upward to push the annular support sliding sleeve 5. When the safety pin 14 between the annular support sliding sleeve 5 and the central tube 3 is also cut off, the annular support sliding sleeve 5 will be pushed into the accommodation cavity 10 by the annular piston 6; at this time, the multi-lobe male thread 8 on the inner lining screw rod 7 loses the support of the annular support sliding sleeve 5, and will retract and deform to disengage from the female thread. Then, by lifting the drill pipe, the release operation can be completed, and the upper drill pipe sent in can be safely removed.

[0037] It should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, for those skilled in the art, they can still modify the technical solutions described in the above embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hydraulic safety joint, comprising an upper joint and a lower joint, characterized in that: The lower end of the upper joint is fixedly provided with a lining screw rod with male threads, and the lower joint has female threads corresponding to the male threads; a plurality of through grooves are circumferentially formed on the side wall of the lining screw rod, and the through grooves extend axially upward from the lower end of the lining screw rod; It further includes a central tube extending into the upper joint and the lower joint, an annular support sliding sleeve assembled between the central tube and the lining screw rod for expanding the lower end of the lining screw rod to make the male threads and the female threads fit tightly, an annular piston assembled between the central tube and the lower joint with the working end facing the end face of the annular support sliding sleeve, and a sealing ball for injecting pressure into the central tube; An annular piston cavity is formed between the central tube and the lower joint, and the central tube is provided with a side through hole to communicate with the annular piston cavity; a limit seat for preventing the sealing ball from falling is arranged below the side through hole in the central tube.

2. The hydraulic safety joint according to claim 1, wherein: The annular support sliding sleeve is fixed on the central tube by a safety pin.

3. The hydraulic safety joint according to claim 2, characterized in that: A receiving cavity is formed between the central tube and the lining screw rod, and the receiving cavity is located above the annular support sliding sleeve for accommodating the annular support sliding sleeve pushed upward by the annular piston; The thickness of the receiving cavity is greater than the thickness of the annular support sliding sleeve.

4. A hydraulic safety joint according to any one of claims 1-3, characterized in that: The annular piston is fixed on the central tube by a safety pin.

5. The hydraulic safety joint according to claim 4, characterized in that: A sealing ring is arranged between the annular piston and the inner wall of the annular piston cavity.

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