Composite safety joint

Abstract

The invention discloses a composite safety joint, which relates to the technical field of sand prevention in oil well exploitation and completion, and comprises an upper joint, a lower joint, a connecting rod, a reverse nut, a plurality of shear pins and a plurality of anti-rotation pins, wherein the upper part of the connecting rod is threadedly installed at the lower end inside the upper joint, a reverse nut is sleeved on the outer side of the middle part of the connecting rod, and the reverse nut can slide along the axial direction of the connecting rod, and at least two pin grooves are circumferentially arranged on the upper outer wall of the lower part of the connecting rod, and the pin grooves are extended along the axial direction of the connecting rod, and a raised step is arranged at the lower part of the connecting rod; the lower joint is sleeved on the connecting rod and the outer part of the upper joint from bottom to top, the lower joint is threadedly connected with the reverse nut, the upper part of the lower joint is fixedly connected with the upper joint through a plurality of shear pins, and the lower part of the lower joint is connected with the connecting rod through at least two anti-rotation pins, and one anti-rotation pin extends into one pin groove. The device is simple to operate, has high safety, and has a wide range of applications, and greatly improves the efficiency and success rate of recovery of completion pipe strings.

Description

Technical Field

[0001] The invention relates to the technical field of sand prevention in petroleum exploitation and completion, and in particular to a composite safety joint. Background Art

[0002] The safety joint is connected to the lower part of the completion string. When the recovery string is stuck, it can be easily released here and recovered again in sections, reducing the difficulty of recovery.

[0003] At present, the commonly used safety joints for completion strings include reverse-threaded, pin-type, and ball-dropping types, but each type has limitations: the reverse-threaded safety joint needs to be released by forward rotation, but in some cases, when the completion string is difficult to run, it needs to be released by forward rotation, but there is a risk of premature release of the safety joint; although the pin-type safety joint can transmit torque, if a drill stop occurs during running or there is a perforating gun under the string, the string vibrates during perforating, which can easily cause premature shearing; the ball-dropping safety joint needs to be sealed, but it cannot be released by pressure when connected to the bottom of the screen. These existing technical problems seriously restrict the efficiency of late recovery of the completion string. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a composite safety joint, which is simple to operate, highly safe, and has a wide range of applications, and greatly improves the efficiency and success rate of completion string recovery.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a composite safety joint, comprising an upper joint, a lower joint, a connecting rod, a buckle nut, a plurality of shear pins and a plurality of anti-rotation pins, wherein the upper joint, the lower joint and the connecting rod are all hollow structures, the upper portion of the connecting rod is threadedly mounted on the lower end inside the upper joint, the buckle nut is sleeved on the outer side of the middle portion of the connecting rod, a non-circular hole is arranged inside the buckle nut, the structure of the outer wall of the middle portion of the connecting rod matches the structure of the non-circular hole, the buckle nut can slide along the axial direction of the connecting rod, at least two pin grooves are arranged circumferentially on the outer wall of the lower portion of the connecting rod, The pin groove is extended along the axial direction of the connecting rod, and a raised step is provided at the lower part of the connecting rod, and the raised step is arranged above the pin groove; the lower joint is sleeved on the outside of the connecting rod and the upper joint from bottom to top, the lower joint is threadedly connected with the reverse thread nut, the upper part of the lower joint is fixedly connected to the upper joint through a plurality of shear pins, and the lower part of the lower joint is connected to the connecting rod through at least two anti-rotation pins, one anti-rotation pin extends into one of the pin grooves, and the upper and lower ends of the connecting rod are sealed with the upper joint and the lower joint respectively.

[0007] Preferably, it also includes a spring, which is sleeved on the middle part of the connecting rod and is arranged above the buckle nut.

[0008] Preferably, it further comprises a first O-ring, and the upper end of the connecting rod forms a sealing connection with the upper joint through the first O-ring.

[0009] Preferably, two second O-rings are further included, and the lower end of the connecting rod forms a sealing connection with the lower joint through the two second O-rings.

[0010] Preferably, a plurality of first grooves are circumferentially arranged on the outer side of the lower part of the upper joint, and a first protrusion is formed between any two adjacent first grooves; a plurality of second grooves are circumferentially arranged on the upper part of the lower joint, and a second protrusion is formed between any two adjacent second grooves; the second protrusion matches the first groove structure, and one second protrusion is installed in one first groove; the first protrusion matches the second groove structure, and one first protrusion is installed in one second groove.

[0011] Preferably, the non-circular hole comprises a plurality of arc segments and a plurality of straight segments, and the plurality of arc segments and the plurality of straight segments are arranged at intervals.

[0012] Preferably, the connecting rod includes an upper rod section, a middle rod section and a lower rod section which are sequentially connected from top to bottom, the outer diameter of the upper rod section is smaller than the outer diameter of the middle rod section, the outer diameter of the middle rod section is smaller than the outer diameter of the lower rod section, the raised step is formed between the middle rod section and the lower rod section, the upper rod section is threadedly connected to the upper joint, the reverse threaded nut is sleeved on the middle rod section, and the pin groove is arranged on the lower rod section.

[0013] Preferably, the pin groove is a waist-shaped groove, a plurality of the pin grooves are evenly distributed along the circumference of the connecting rod, and the number of the pin grooves is four.

[0014] Compared with the prior art, the present invention has achieved the following technical effects:

[0015] The composite safety joint provided by the present invention comprises an upper joint, a lower joint, a connecting rod, a reverse nut, a plurality of shear pins and a plurality of anti-rotation pins, the reverse nut is slidably sleeved on the connecting rod, the lower joint is threadedly connected with the reverse nut, the upper part of the lower joint is fixedly connected with the upper joint through a plurality of shear pins, and the lower part of the lower joint is connected with the connecting rod through at least two anti-rotation pins. Torque can be transmitted when lowering. If the drill is stopped or the pipe string vibrates the shear pins in advance during the lowering process, the reverse nut continues to play a connecting and sealing role. Due to the presence of the anti-rotation pin below, a certain torque can also be transmitted. It can be seen that the composite safety joint in the present invention has a dual protection effect. When the pipe string is recovered later, it only needs to be rotated forward by a certain torque, the anti-rotation pin is sheared, and the reverse rotation is more than 8 turns to realize the final release of the composite safety joint. The specially designed reverse release mechanism has reliable performance, simple operation, high safety, and a wide range of applications. The composite safety joint in the present invention makes up for the defects of the existing safety joints and greatly improves the efficiency and success rate of recovery of the completion pipe string. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only 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.

[0017] Figure 1 A schematic diagram of the structure of the composite safety joint provided by the present invention;

[0018] Figure 2 A schematic structural diagram of the upper joint of the composite safety joint provided by the present invention;

[0019] Figure 3 A schematic structural diagram of the lower joint of the composite safety joint provided by the present invention;

[0020] Figure 4 A schematic structural diagram of a connecting rod of a composite safety joint provided by the present invention;

[0021] Figure 5 for Figure 4 Sectional view along AA direction;

[0022] Figure 6 for Figure 4 Cross-sectional view along the BB direction;

[0023] Figure 7 for Figure 4 Schematic diagram of the C direction;

[0024] Figure 8A front view of the reverse thread nut of the composite safety joint provided by the present invention;

[0025] Fig. 9 A side view of the reverse thread nut of the composite safety joint provided by the present invention.

[0026] Explanation of the accompanying drawings: 1. upper joint; 2. shear pin; 3. spring; 4. buckle nut; 5. connecting rod; 51. upper rod section; 52. middle rod section; 53. lower rod section; 54. pin groove; 55. raised step; 6. anti-rotation pin; 7. lower joint; 8. first O-ring; 9. second O-ring; 10. first groove; 11. first protrusion; 12. second groove; 13. second protrusion; 14. non-circular hole. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0028] The purpose of the present invention is to provide a composite safety joint which is simple to operate, highly safe, and has a wide range of applications, thereby greatly improving the efficiency and success rate of recovery of completion tubulars.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1As shown, this embodiment provides a composite safety joint, including an upper joint 1, a lower joint 7, a connecting rod 5, a reverse nut 4, a plurality of shear pins 2 and a plurality of anti-rotation pins 6. The upper joint 1, the lower joint 7 and the connecting rod 5 are all hollow structures. The upper part of the connecting rod 5 is threadedly installed on the lower end inside the upper joint 1. The outer side of the middle part of the connecting rod 5 is sleeved with a reverse nut 4. A non-circular hole 14 is arranged inside the reverse nut 4. The structure of the outer wall of the middle part of the connecting rod 5 matches the structure of the non-circular hole 14. The reverse nut 4 can slide along the axial direction of the connecting rod 5. By setting the non-circular hole 14, the reverse nut 4 cannot rotate along the circumferential direction of the connecting rod 5. At least two pins are arranged circumferentially on the outer wall of the lower part of the connecting rod 5 Groove 54, the pin groove 54 is extended along the axial direction of the connecting rod 5, and a raised step 55 is arranged at the lower part of the connecting rod 5, and the raised step 55 is arranged above the pin groove 54. The raised step 55 is used to block the reverse nut 4 and bear the connection of the pipe column after the upper joint 1 and the lower joint 7 are separated; the lower joint 7 is sleeved on the outside of the connecting rod 5 and the upper joint 1 from bottom to top, and the lower joint 7 is threadedly connected with the reverse nut 4. The upper part of the lower joint 7 is fixedly connected with the upper joint 1 through a plurality of shear pins 2, and the lower part of the lower joint 7 is connected with the connecting rod 5 through at least two anti-rotation pins 6. One anti-rotation pin 6 extends into a pin groove 54, and the anti-rotation pin 6 can move up and down in the pin groove 54, but cannot rotate in the circumferential direction. The upper and lower ends of the connecting rod 5 are sealed with the upper joint 1 and the lower joint 7 respectively.

[0031] The present embodiment further includes a spring 3, which is sleeved in the middle of the connecting rod 5 and is arranged above the buckle nut 4. The spring 3 can tighten the buckle nut 4 when the lower joint 7 is installed, so that the buckle nut 4 is more easily connected to the thread of the lower joint 7.

[0032] This embodiment also includes a first O-ring 8, and the upper end of the connecting rod 5 forms a sealing connection with the upper joint 1 through the first O-ring 8. Specifically, the installation groove of the first O-ring 8 is set on the inner side wall of the upper joint 1.

[0033] This embodiment also includes two second O-rings 9, and the lower end of the connecting rod 5 forms a sealing connection with the lower joint 7 through the two second O-rings 9. Specifically, the mounting groove of the second O-ring 9 is set on the outer side wall of the connecting rod 5.

[0034] like Figure 2 As shown, a plurality of first grooves 10 are arranged on the outer side of the lower part of the upper joint 1 along the circumferential direction, and a first protrusion 11 is formed between any two adjacent first grooves 10. Specifically, the first grooves 10 are milled on the outer side of the upper joint 1. Figure 3The upper part of the lower joint 7 is provided with a plurality of second grooves 12 along the circumferential direction, and a second protrusion 13 is formed between any two adjacent second grooves 12. Specifically, the second protrusion 13 matches the structure of the first groove 10, and one second protrusion 13 is installed in one first groove 10, and the first protrusion 11 matches the structure of the second groove 12, and one first protrusion 11 is installed in one second groove 12. It can be seen that the upper joint 1 and the lower joint 7 in this embodiment have a plug-in structure, and during the lowering of the pipe string, torque can be transmitted to facilitate the safe lowering of the pipe string.

[0035] In this specific embodiment, three of each of the first groove 10 , the first protrusion 11 , the second groove 12 and the second protrusion 13 are provided.

[0036] like Figure 4 As shown, the connecting rod 5 includes an upper rod section 51, a middle rod section 52 and a lower rod section 53 connected in sequence from top to bottom. The outer diameter of the upper rod section 51 is smaller than the outer diameter of the middle rod section 52, and the outer diameter of the middle rod section 52 is smaller than the outer diameter of the lower rod section 53. A raised step 55 is formed between the middle rod section 52 and the lower rod section 53. The upper rod section 51 is threadedly connected to the upper joint 1, the reverse thread nut 4 is sleeved on the middle rod section 52, and the pin groove 54 is provided on the lower rod section 53. Figure 5 As shown, a plane is milled on the outer surface of the middle portion of the connecting rod 5 (i.e., the middle rod section 52), and the plane matches with the inner hole of the buckle nut 4.

[0037] like Figure 6 and Figure 7 As shown, the pin groove 54 is a waist-shaped groove, and a plurality of pin grooves 54 are evenly distributed along the circumference of the connecting rod 5 , and the number of pin grooves 54 is four.

[0038] like Figure 8 and Fig. 9 As shown, the non-circular hole 14 includes a plurality of arc segments and a plurality of straight segments, and the plurality of arc segments and the plurality of straight segments are arranged at intervals. Specifically, a plane is processed on the inner surface of the reverse nut 4, and the plane is the straight segment of the non-circular hole 14, which matches the plane in the middle of the connecting rod 5; the reverse nut 4 is processed with a reverse thread on the outer circle for connecting with the lower joint 7. In this embodiment, the reverse nut 4 adopts a special thread structure to ensure the success rate of the forward release, and the specially designed reverse release mechanism has reliable performance and is easy to operate.

[0039] When assembling the composite safety joint in this embodiment, the connecting rod 5 is first threadedly connected to the upper joint 1, and the sealing is achieved through the first O-ring 8. The lower joint 7 is threadedly connected to the reverse nut 4, and the second protrusion 13 of the lower joint 7 is inserted into the corresponding first groove 10 of the upper joint 1. The two are fixed by the shear pin 2, and the internal and external sealing is achieved by the second O-ring 9. After the upper joint 1 and the lower joint 7 are connected, the reverse nut 4 is not subjected to force, and is only subjected to force after the upper joint 1 and the lower joint 7 are disconnected.

[0040] When the completion string is lowered, the composite safety joint in this embodiment can be connected to different positions of the string. When lowered, the upper joint 1 and the lower joint 7 are plugged together and connected by the shear pin 2. Torque can be transmitted during the lowering process. If the shear pin 2 is sheared in advance due to the drilling or vibration of the string during lowering, the reverse nut 4 continues to play a connecting and sealing role. Due to the presence of the anti-rotation pin 6, a certain torque can still be transmitted. It can be seen that the composite safety joint in this embodiment has a dual protection effect. If the string needs to be recovered later, the string is rotated forward with a certain torque, the anti-rotation pin 6 is sheared, and it continues to rotate forward for more than 8 circles. The upper joint 1 will be separated from the lower joint 7, which is convenient for the recovery of other strings later, and the efficiency and success rate of the string recovery are improved. The composite safety joint in this embodiment makes up for the defects of the existing safety joints, is simple to operate, has high safety, and has a wide range of applications, which greatly improves the efficiency and success rate of the recovery of the completion string.

[0041] The present specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A composite safety joint, characterized in that: The invention comprises an upper joint, a lower joint, a connecting rod, a buckle nut, a plurality of shear pins and a plurality of anti-rotation pins, wherein the upper joint, the lower joint and the connecting rod are all hollow structures, the upper portion of the connecting rod is threadedly mounted on the lower end inside the upper joint, the buckle nut is sleeved on the outer side of the middle portion of the connecting rod, a non-circular hole is arranged inside the buckle nut, the structure of the outer wall of the middle portion of the connecting rod matches the non-circular hole structure, the buckle nut can slide along the axial direction of the connecting rod, at least two pin grooves are arranged on the circumferential direction of the lower outer wall of the connecting rod, and the pin grooves are arranged along the connecting rod. The connecting rod is axially extended, and a raised step is provided at the lower part of the connecting rod, and the raised step is provided above the pin groove; the lower joint is sleeved on the outside of the connecting rod and the upper joint from bottom to top, and the lower joint is threadedly connected to the reverse nut, and the upper part of the lower joint is fixedly connected to the upper joint through a plurality of shear pins, and the lower part of the lower joint is connected to the connecting rod through at least two anti-rotation pins, and one anti-rotation pin extends into one of the pin grooves, and the upper and lower ends of the connecting rod are sealed with the upper joint and the lower joint respectively.

2. The composite safety joint according to claim 1, characterized in that: It also includes a spring, which is sleeved on the middle part of the connecting rod and is arranged above the buckle nut.

3. The composite safety joint according to claim 1, characterized in that: It also includes a first O-ring, through which the upper end of the connecting rod forms a sealing connection with the upper joint.

4. The composite safety joint according to claim 1, characterized in that: It also includes two second O-rings, and the lower end of the connecting rod forms a sealing connection with the lower joint through the two second O-rings.

5. The composite safety joint according to claim 1, characterized in that: A plurality of first grooves are circumferentially arranged on the outer side of the lower part of the upper joint, and a first protrusion is formed between any two adjacent first grooves; a plurality of second grooves are circumferentially arranged on the upper part of the lower joint, and a second protrusion is formed between any two adjacent second grooves; the second protrusion matches the first groove structure, and one second protrusion is installed in one first groove; the first protrusion matches the second groove structure, and one first protrusion is installed in one second groove.

6. The composite safety joint according to claim 1, characterized in that: The non-circular hole comprises a plurality of arc segments and a plurality of straight segments, and the plurality of arc segments and the plurality of straight segments are arranged at intervals.

7. The composite safety joint according to claim 1, characterized in that: The connecting rod includes an upper rod section, a middle rod section and a lower rod section connected in sequence from top to bottom, the outer diameter of the upper rod section is smaller than the outer diameter of the middle rod section, the outer diameter of the middle rod section is smaller than the outer diameter of the lower rod section, the raised step is formed between the middle rod section and the lower rod section, the upper rod section is threadedly connected to the upper joint, the buckle nut is sleeved on the middle rod section, and the pin groove is arranged on the lower rod section.

8. The composite safety joint according to claim 1, characterized in that: The pin groove is a waist-shaped groove, and a plurality of the pin grooves are evenly distributed along the circumference of the connecting rod, and the number of the pin grooves is four.

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