Breaking-off type carbon fiber sucker rod safety joint for oil field

Abstract

The utility model relates to the technical field of oil-gas exploration and exploitation, in particular to a breaking-off type carbon fiber sucker rod safety joint for an oil field, which comprises a first joint main body and a second joint main body, the first connector body is of a cylinder structure, and a first inner threaded hole is formed in one side of the first connector body. A protective sleeve is arranged on the other side; one side of the second joint main body is a snapping part, and the other side of the second joint main body is provided with a second internal threaded hole; the protective sleeve is sleeved outside the snapping part of the second joint main body and is in sealed connection with the snapping part; and the protective sleeve isolates the snapping part from the external environment. The sealing space formed between the protection part and the breaking part seals and protects key components such as the breaking groove and the like, so that the key components are prevented from being eroded by well fluid. The safety connector can be normally broken and disengaged when needed, the working reliability and stability of the safety connector are improved, the risk that the safety connector fails due to scaling is reduced, and the occurrence rate of oil well operation faults is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of oil and gas exploration and exploitation, in particular to a breakaway carbon fiber sucker rod safety joint for oil fields. Background Art

[0002] During oilfield production, a pumping unit uses a carbon fiber sucker rod to reciprocate within the well, pumping crude oil to the surface. However, during the production process, oil wells often face problems such as sand production and wax buildup in the tubing. Sand production can cause the piston in the pump to become blocked by sand particles, resulting in jamming. This can seriously hinder the normal operation of the pump and make it impossible to remove the carbon fiber sucker rod and piston from the surface for inspection according to standard procedures.

[0003] Currently, the common solution is to use equipment such as a workover rig to lift the carbon fiber sucker rod to overcome the sticking. This involves connecting the workover rig's lifting system to the carbon fiber sucker rod and gradually increasing the lifting load until the sticking is overcome. However, during this process, if the lifting load exceeds the tensile strength of the carbon fiber sucker rod, the rod will break. This necessitates salvage operations to retrieve the broken carbon fiber sucker rod string from the well, which not only damages the rod but also consumes significant time, significantly impacting production efficiency.

[0004] To prevent this, oilfields install safety joints on their carbon fiber sucker rod strings. When the string is pulled upward and the safety joint's breakaway load is reached, the joint disconnects, preventing the rod from breaking. Furthermore, since multiple sucker rods are connected in series downhole, disconnecting the safety joint separates the stuck rod from the upper rod, eliminating the need for complex handling of the entire rod string and improving construction timelines.

[0005] However, existing sucker rod safety joints have problems with being difficult to disengage or prematurely disengaging. This is because the various parts of the safety joint, immersed in the liquid medium in the well for a long time, scale and solidify, increasing the breaking load. Premature disengagement occurs because the safety joint body vibrates and oscillates as it reciprocates with the sucker rod in the well, subjecting it to severe stress and easily bending and deforming under external forces. This causes stress concentration fatigue at the trapezoidal break point, reducing tensile strength and causing premature breaking when the sucker rod is pulled, thus defeating the purpose of the safety joint.

[0006] Therefore, it is necessary to design a carbon fiber sucker rod safety joint to reliably complete the disconnection work. Utility Model Content

[0007] The utility model aims to provide a breakaway type carbon fiber sucker rod safety joint for oil fields, which can reliably complete the breakaway work, thereby solving the technical problems in the background technology.

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a breakaway carbon fiber sucker rod safety joint for oil fields, comprising: a first joint body and a second joint body;

[0009] The first joint body is a cylindrical structure, with a first internal threaded hole on one side and a protective sleeve on the other side; the second joint body has a breaking portion on one side and a second internal threaded hole on the other side;

[0010] The protective sleeve is sleeved on the outside of the breaking portion of the second joint body and is sealed with the breaking portion; the protective sleeve isolates the breaking portion from the external environment.

[0011] Furthermore, the breaking portion includes a screw portion, a breaking groove and a positioning step arranged in sequence from left to right;

[0012] The screw portion is a threaded rod structure, which cooperates with the protective sleeve to connect the first joint body and the second joint body;

[0013] The breaking groove is an annular groove surrounding the outer surface of the second joint body, and the cross-section of the breaking groove is a trapezoid;

[0014] The positioning step is an annular protruding structure on the second joint body, and the outer circumference of the positioning step is sealed with the inner wall of the protective sleeve.

[0015] Furthermore, the protective sleeve is in the form of a sleeve structure, and an internal thread is provided on one side of the protective sleeve close to the first internal threaded hole, which is connected to the screw portion of the second joint body through the internal thread; the other side of the protective sleeve is in the form of a sleeve structure, which is sleeved on the positioning step of the breaking portion through the sleeve structure and is sealed with the positioning step; the protective sleeve cooperates with the positioning step of the breaking portion to form a sealed space.

[0016] Furthermore, a sealing groove is provided at the position where the protective sleeve contacts the positioning step, and a sealing ring is provided in the sealing groove; the sealing groove is opened on the inner wall of the protective sleeve.

[0017] Furthermore, a partition is provided inside the first joint body, and the partition is provided between the protective sleeve and the first internal threaded hole to isolate the protective sleeve from the first internal threaded hole.

[0018] Furthermore, it also includes a locking bolt; a threaded hole is opened in the radial direction of the corresponding first joint body and the second joint body; the locking bolt passes through the first joint body and is screwed into the second joint body; the locking bolt fixes the two together and limits the freedom of relative rotation between the two.

[0019] Beneficial effects

[0020] The sealed space formed between the protective portion and the breaking portion of this utility model seals and protects key components such as the breaking groove from well fluid erosion. This ensures that the safety joint can break and disconnect normally when needed, improves the reliability and stability of the safety joint, reduces the risk of safety joint failure due to scaling, and reduces the incidence of oil well operation failures.

[0021] The breaking portion of the utility model, especially the trapezoidal breaking groove, can accurately break under the designed breaking load when subjected to the lifting load. This effectively avoids the risk of carbon fiber sucker rod fracture and damage caused by continued lifting, protects the upper sucker rod, and reduces maintenance and replacement costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a half-section view of the safety joint disclosed by the utility model.

[0024] In the picture:

[0025] The names of the reference numerals in the figure are: 1. first joint body; 2. second joint body; 3. breaking groove; 4. first internal threaded hole; 5. second internal threaded hole; 6. screw portion; 7. locking bolt; 8. positioning step; 9. sealing groove; 10. protective cover. DETAILED DESCRIPTION

[0026] 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0027] In order to achieve the above purpose, the present invention provides the following technical solutions: Figure 1 As shown, a breakaway carbon fiber sucker rod safety joint for oil fields comprises: a first joint body 1 and a second joint body 2;

[0028] The first joint body 1 is a cylindrical structure, with a first internal threaded hole 4 formed on one side and a protective sleeve 10 formed on the other side.

[0029] The first internal threaded hole 4 is used for threaded connection with a carbon fiber sucker rod or a connecting rod of a workover rig; the protective sleeve 10 is sleeved on the outside of the breaking portion of the second joint body 2 and is sealed with the breaking portion; the protective sleeve 10 isolates the breaking portion from the external environment;

[0030] One side of the second joint body 2 is a breaking portion, and the other side is provided with a second internal threaded hole 5;

[0031] The breaking part is the main force-bearing component. When the sucker rod is pulled up to reach the breaking load force, the breaking part breaks due to stress concentration, realizing the safety joint breaking function and protecting the sucker rod from being damaged by excessive stretching.

[0032] The second internal threaded hole 5 is used for threaded connection with a carbon fiber sucker rod or a connecting rod of a workover rig.

[0033] Furthermore, the breaking portion includes a screw portion 6, a breaking groove 3 and a positioning step 8 arranged in sequence from left to right;

[0034] The screw portion 6 is a threaded rod structure having a certain length and pitch, and has a thread on its outer surface, which cooperates with the protective sleeve 10 to connect the first joint body 1 and the second joint body 2. Specifically, the screw portion 6 extends into the interior of the protective sleeve 10 and is threadedly connected to the internal thread of the protective sleeve 10;

[0035] Breakaway groove 3 is an annular groove extending 360 degrees around the outer surface of the second joint body 2. Its cross-section is trapezoidal; when subjected to an upward load, its trapezoidal cross-section creates a stress concentration point. When the load reaches the designed value, breakaway groove 3 preferentially opens, allowing the safety joint to disconnect as intended, separating the stuck portion from the upper sucker rod. Furthermore, because it is located within the enclosed interior of the safety joint body, it is protected from well fluid corrosion and scaling that could affect the disconnection function.

[0036] The positioning step 8 is an annular protrusion structure on the second joint body 2. The outer circumference of the positioning step 8 is sealed with the inner wall of the protective sleeve 10. The positioning step 8 has a certain width. When the protective sleeve 10 is mounted on the outside of the positioning step 8, it limits the axial relative movement of the first joint body 1 and the second joint body 2 when subjected to external force, prevents twisting while the protective sleeve 10 is maintained, and avoids the premature breaking of the breaking groove 3 in the sealed space due to stress concentration fatigue, ensuring that the safety joint can be disconnected at rated load.

[0037] Furthermore, the protective sleeve 10 is in a sleeve structure, with an internal thread provided on one side of the protective sleeve 10 close to the first internal threaded hole 4, and a sleeve structure on the other side; it is connected to the screw portion 6 of the second joint body 2 through the internal thread; the protective sleeve 10 is sleeved on the positioning step 8 of the breaking part through the sleeve structure, and is sealed with the positioning step 8; the protective sleeve 10 cooperates with the positioning step 8 of the breaking part to form a sealed space; the breaking part is protected from erosion by well fluid, and scaling of the breaking groove 3 is prevented from affecting the normal operation of the safety joint.

[0038] The breaking parts are all in a sealed space; the sealed space protects the internal components from being corroded by well fluid, ensures that the breaking groove 3 is in a stable environment, and prevents scaling of the breaking groove 3 from affecting the normal operation of the safety joint.

[0039] Furthermore, a sealing groove 9 is provided where the protective sleeve 10 contacts the positioning step 8. Multiple sealing grooves 9 may be provided, depending on the situation. A sealing ring is provided within the sealing groove 9, further enhancing the sealing effect and preventing well fluids and other substances from entering the sealed space. The sealing groove 9 is provided on the inner wall of the protective sleeve 10, rather than on the positioning step 8, so it does not affect the strength of the positioning step 8 or the breakaway portion.

[0040] Furthermore, a partition is provided inside the first joint body 1, and the partition is provided between the protective sleeve 10 and the first internal threaded hole 4; the protective sleeve 10 is isolated from the first internal threaded hole 4; the partition is a planar plate structure, which is used to prevent impurities such as well fluid from entering the space between the protective sleeve 10 and the breaking part from the first internal threaded hole 4, thereby ensuring that the sealing space is clean and stable and maintaining the performance of the breaking part.

[0041] Furthermore, a locking bolt 7 is included; threaded holes are provided in the radial direction of the corresponding first joint body 1 and the second joint body 2; the locking bolt 7 passes through the first joint body 1 and is screwed into the second joint body 2;

[0042] The locking bolt 7 securely connects the two together, limiting the freedom of relative rotation between the two; this further enhances the stability of the connection between the first joint body 1 and the second joint body 2, and further ensures the reliability of the safety joint during normal operation.

[0043] The working principle and process are as follows:

[0044] During the oil field pumping operation, the safety joint of the present application is connected to the carbon fiber sucker rod column. The carbon fiber sucker rod reciprocates under the drive of the pumping unit. The first joint body 1 and the second joint body 2 of the safety joint are tightly matched through the threaded connection of the screw part 6. At the same time, the threaded connection between the protective sleeve 10 and the second joint body 2 and the sealing connection between the positioning step 8 and the protective sleeve 10 ensure the stability of the entire safety joint structure. The locking bolt 7 further limits the relative rotation between the two joint bodies to ensure that there will be no accidental loosening during the torque transmission process. At this time, the breaking groove 3 is in a sealed space, free from well fluid erosion and impurity interference, maintaining its structural integrity and performance stability. The safety joint, like an ordinary joint, smoothly transmits the tension and torque of the sucker rod, allowing the pumping operation to proceed normally.

[0045] When a downhole pump becomes stuck, a workover rig is activated to lift the sucker rod to overcome the jam and restore normal operation. As the lifting force applied by the workover rig's lifting system gradually increases, tension is transmitted through the carbon fiber sucker rod to the safety joint. The safety joint's breaking section begins to experience increasing tension, and the trapezoidal cross-section of the breaking groove 3 gradually creates stress concentration under the action of this tension.

[0046] When the lifting force applied by the workover rig reaches the breaking load designed for the safety joint, the stress concentration at the breaking groove 3 reaches the limit, and the breaking groove 3 will break along its annular structure; after the breaking groove 3 breaks, the safety joint realizes the breaking function, separating the sucker rod at the stuck part from the upper sucker rod.

[0047] The embodiments of the present invention are provided for purposes of illustration and description and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention and to enable those skilled in the art to understand the present invention and design various embodiments with various modifications suitable for specific applications.

Claims

1. A breakaway carbon fiber sucker rod safety joint for oil fields, characterized in that: include: A first joint body (1) and a second joint body (2); The first joint body (1) is a cylindrical structure, with a first internal threaded hole (4) provided on one side of the first joint body (1); a protective sleeve (10) is provided on the other side; one side of the second joint body (2) is a breaking portion, and the other side is provided with a second internal threaded hole (5); The protective sleeve (10) is sleeved on the outside of the breaking portion of the second joint body (2) and is sealed to the breaking portion; the protective sleeve (10) isolates the breaking portion from the external environment.

2. The breakaway carbon fiber sucker rod safety joint for oil fields according to claim 1, characterized in that: The breaking portion comprises a screw portion (6), a breaking groove (3) and a positioning step (8) which are arranged in sequence from left to right; The screw portion (6) is a threaded rod structure, and cooperates with the protective sleeve (10) to connect the first joint body (1) and the second joint body (2); The breaking groove (3) is an annular groove surrounding the outer surface of the second joint body (2), and the cross-sectional shape of the breaking groove (3) is a trapezoid; The positioning step (8) is an annular protruding structure on the second joint body (2), and the outer circumference of the positioning step (8) is sealedly connected to the inner wall of the protective sleeve (10).

3. The breakaway carbon fiber sucker rod safety joint for oil fields according to claim 2, characterized in that: The protective sleeve (10) is in a sleeve structure, and an internal thread is provided on one side of the protective sleeve (10) near the first internal threaded hole (4), and is connected to the screw portion (6) of the second joint body (2) through the internal thread; the other side of the protective sleeve (10) is in a sleeve structure, and is sleeved on the positioning step (8) of the breaking portion through the sleeve structure, and is sealed with the positioning step (8); the protective sleeve (10) cooperates with the positioning step (8) of the breaking portion to form a sealed space.

4. The breakaway carbon fiber sucker rod safety joint for oil fields according to claim 3, characterized in that: A sealing groove (9) is also provided at the position where the protective sleeve (10) contacts the positioning step (8), and a sealing ring is provided in the sealing groove (9); the sealing groove (9) is opened on the inner wall of the protective sleeve (10).

5. The breakaway carbon fiber sucker rod safety joint for oil fields according to claim 1, characterized in that: A partition is provided inside the first joint body (1), and the partition is provided between the protective sleeve (10) and the first internal threaded hole (4), isolating the protective sleeve (10) from the first internal threaded hole (4).

6. The breakaway carbon fiber sucker rod safety joint for oil fields according to claim 1, characterized in that: It also includes a locking bolt (7); threaded holes are provided in the radial direction of the corresponding first joint body (1) and the second joint body (2); the locking bolt (7) passes through the first joint body (1) and is screwed into the second joint body (2); the locking bolt (7) fixes the two together, limiting the freedom of relative rotation between the two.

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