Non-rotating safety joint and hand releasing method

Abstract

The non-rotating safety connector comprises an upper connector body and a transposition mandrel which are connected through threads, a transposition mechanism and a left-hand transposition nut which are movably connected with each other are arranged on the surface of the transposition mandrel, and one end of the left-hand transposition nut is connected with a spline outer cylinder through a left-hand thread; the end, away from the left-hand transposition nut, of the spline outer cylinder is connected with a sealing outer cylinder. A sealing mandrel is arranged in the sealing outer cylinder. A pull sleeve is arranged at the opposite connecting position of the inner sides of the sealing outer cylinder and the lower connector, and one end of the pull sleeve is connected with the sealing mandrel. The method comprises the steps that the non-rotating safety connector is lowered into a well, the pulling force of the pipe column is increased to enable the pulling sleeve to be broken, the pipe column is repeatedly lifted and lowered to drive the mandrel to move till the left-handed nut is completely disengaged from the connecting thread of the outer cylinder, and hand releasing is achieved. Under the condition that manual rotating operation is not carried out and the internal and external pressure difference of a tubular column does not need to be met, hand releasing can be achieved, the operation efficiency is improved, and the operation risk and cost are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum equipment, and in particular relates to a non-rotating safety joint. The invention also relates to a method for releasing the non-rotating safety joint. Background Art

[0002] At present, the safety joints used in oil downhole tools mainly include: rotary safety joints and pressure differential safety joints.

[0003] The rotating safety joint needs to rotate the pipe column when it is released. The widely used RTTS safety joint needs to be released by lifting up, rotating the pipe column, lowering, and rotating the pipe column, and repeating this operation about 24 times to release it. The more rotations, the longer the release time, and the higher the operation cost.

[0004] When releasing the differential pressure safety joint, it is necessary to establish a pressure difference between the inside and outside of the pipe. When releasing the internal differential pressure safety joint, the pressure inside the pipe must be higher than the pressure outside the pipe. During operation, the inside of the pipe must be in a closed state, and the pressure inside the pipe must be pressurized to make it higher than the pressure outside the pipe, and the safety joint can be released. When releasing the external differential pressure safety joint, it is necessary to establish a pressure difference between the outside of the pipe and the inside of the pipe. During operation, it is necessary to establish a pressure difference between the outside of the pipe and the casing, and the outside of the pipe can be pressurized to release the safety joint. Although the differential pressure safety joint does not need to rotate the pipe when used, it is necessary to establish a pressure difference between the inside and outside of the pipe when releasing it. The safety joint is a safety tool and may need to be released at any stage of the operation. Its application has limitations.

[0005] With the widespread application of non-rotating tubing operations, although the differential pressure safety joint does not require rotating the tubing, it is difficult to ensure that the current well conditions can establish a pressure difference between the inside and outside of the tubing when the safety joint is activated. Summary of the invention

[0006] The purpose of the present invention is to provide a non-rotating safety joint that can be released without manual rotation operation and without satisfying the pressure difference between the inside and outside of the pipe column, thereby improving operation efficiency and reducing operation risks and costs.

[0007] Another object of the present invention is to provide a method for releasing a non-rotating safety joint.

[0008] The first technical solution adopted by the present invention is to include an upper joint and a transposition spindle connected to each other by threads, a transposition mechanism is provided on the surface of the transposition spindle, a left-handed transposition nut is sleeved on the outer side of the transposition spindle, a lug which is movably connected with the transposition mechanism is connected on the inner side of the left-handed transposition nut, the lug drives the left-handed transposition nut to rotate rightward when it moves in the transposition mechanism, one end of the left-handed transposition nut is connected to a spline outer cylinder through a left-handed thread, and the spline outer cylinder is sleeved on the outer side of the transposition spindle; The end of the transposition shaft away from the upper joint is connected to the sealing shaft, the end of the spline outer cylinder away from the left-handed transposition nut is connected to the sealing outer cylinder, and the sealing outer cylinder is sleeved on the outside of the sealing shaft; the other end of the sealing outer cylinder is connected to the lower joint, and a pull sleeve is provided at the relative connection position between the inner side of the sealing outer cylinder and the lower joint, and one end of the pull sleeve is connected to the sealing shaft.

[0009] The first technical solution of the present invention is also characterized in that: The transposition mechanism comprises a plurality of linear grooves uniformly arranged along the axial direction on the outer tube wall of the transposition mandrel, and the plurality of linear grooves are uniformly distributed along the circumference of the transposition mandrel; Every two straight travel grooves and the upper transposition grooves and lower transposition grooves arranged at both ends constitute a group of transposition grooves; One end of the upper linear groove in a group of transposition grooves is communicated with the lower linear groove through the lower transposition groove, and the other end of the lower linear groove is communicated with the next group of transposition grooves through the upper transposition groove.

[0010] The upper transposition groove is composed of an inclined groove a and an inclined groove b which are interconnected, and the lower transposition groove is composed of an inclined groove c and an inclined groove d which are interconnected.

[0011] A limiting step is arranged at one end of the pull sleeve close to the sealing outer cylinder, and the other end of the pull sleeve is connected with the sealing mandrel through a thread.

[0012] An inner spline groove is formed inside the spline outer cylinder, and an outer spline is fixedly connected to the outer tube wall of the transposition mandrel at a position corresponding to the inner spline groove. The outer spline is clamped in the inner spline groove to prevent the transposition mandrel from rotating relative to the spline outer cylinder.

[0013] A guide groove a is provided on the external spline along the axial direction of the transposition spindle, and a 15° guide groove is provided at the position of the external spline relative to the transposition mechanism; A radial hole is provided on the spline outer cylinder relative to the external spline, and a guide groove b is provided on the spline outer cylinder relative to the transposition mechanism.

[0014] The lugs are a pair and are symmetrically fixed to the inner wall of the left-handed transposition nut along the central axis of the left-handed transposition nut.

[0015] The second technical solution adopted by the present invention is a method for releasing a non-rotating safety joint, which specifically comprises the following steps: Step 1, lower the non-rotating safety joint into the well, and the joint is in a locked state; Step 2, increasing the pulling force of the pipe string to break the pull sleeve, and realizing relative movement among the upper joint, the transposition mandrel, the sealing mandrel and the left-hand transposition nut, the spline outer cylinder, the sealing outer cylinder, and the lower joint; Step 3, lifting and lowering the pipe string drives the transposition mandrel to move, and the lug moves in the transposition mechanism, driving the left-hand transposition nut to rotate relative to the spline outer cylinder; Step 4, repeat lifting and lowering the pipe column until the connecting thread of the left-hand transposition nut and the spline outer cylinder is completely disengaged to achieve release.

[0016] The beneficial effects of the present invention are: (1) The non-rotating safety joint of the present invention is provided with a transposition mechanism on the outer pipe wall of the transposition mandrel. The transposition mechanism and the lug on the inner side of the left-handed transposition nut slide with each other, so that when performing the lifting-lowering operation, the lug of the left-handed transposition nut slides on the inner side of the transposition mechanism. Each time the lifting-lowering operation is performed, the connecting thread of the left-handed transposition nut and the spline outer cylinder can be disengaged by about 1 / 2 turn. The lifting-lowering operation can be repeated to achieve the release. The linear motion is converted into rotational motion by the transposition mechanism, and there is no need for on-site operators to rotate the pipe column, thereby reducing the operating intensity of the operators and improving work efficiency.

[0017] (2) The non-rotating safety joint of the present invention is capable of transmitting the torque of the pipe column when the non-rotating safety joint is in a locked state and a free state by arranging an external spline on the outer side of the central shaft and arranging a matching internal spline groove on the inner side of the spline outer cylinder. When the non-rotating safety joint is in a released state, the transposed central shaft and the spline outer cylinder will not rotate relative to each other.

[0018] (3) The non-rotating safety joint of the present invention is provided with a guide groove and a radial hole with an inclination angle of 60° at a position of the spline outer cylinder relative to the spline, a guide groove structure is provided on the spline, and a 15° guide groove is provided at the end of the transposition mechanism; when in motion, mud and impurity sediments in the spline groove and the transposition mechanism can be discharged from the radial hole of the spline outer cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the non-rotating safety joint of the present invention; Figure 2 It is a structural schematic diagram of the transposition mechanism in the non-rotating safety joint of the present invention; Figure 3 It is a schematic structural diagram of the non-rotating safety joint of the present invention when it is lifted up in the state of being released from the hand; Figure 4 It is a schematic diagram of the structure of the non-rotating safety joint of the present invention when it has completed the 1 / 2 release state; Figure 5 It is a structural schematic diagram of the non-rotating safety joint of the present invention, in which the left-handed transposition nut and the spline outer cylinder are loosely connected when the non-rotating safety joint has been released from the hands; Figure 6 It is a schematic diagram of the connection between the pull sleeve, the lower joint and the sealing mandrel in the non-rotating safety joint of the present invention; Figure 7 It is a cross-sectional view of a left-handed transposition nut in a non-rotating safety joint of the present invention; Figure 8It is a schematic structural diagram of the cooperative connection between the transposed mandrel and the spline outer cylinder in the non-rotating safety joint of the present invention; Fig. 9 yes Figure 8 Cross-sectional view from perspective A; Fig.10 It is a cross-sectional view of a spline outer cylinder in a non-rotating safety joint of the present invention.

[0020] In the figure, 1. upper joint, 2. transposition spindle, 3. left-handed transposition nut, 4. spline outer cylinder, 5. sealing outer cylinder, 6. sealing spindle, 7. pulling sleeve, 8. lower joint, 9. transposition mechanism, 10. lug, 11. external spline, 12. internal spline groove, 13. left-handed thread, 14. radial hole, 15. linear stroke groove, 16. upper transposition groove, 17. lower transposition groove, 18. inclined groove a, 19. inclined groove b, 20. inclined groove c, 21. inclined groove d, 22. limiting step, 23. guide groove a, 24.15° guide groove, 25. guide groove b. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] Example 1 The non-rotating safety joint of the present invention, such as Figure 1 As shown, it includes an upper joint 1 and a transposition spindle 2 that are mutually connected by threads, a transposition mechanism 9 is provided on the surface of the transposition spindle 2, a left-handed transposition nut 3 is sleeved on the outer side of the transposition spindle 2, a lug 10 that is movably connected with the transposition mechanism 9 is fixedly connected to the inner side of the left-handed transposition nut 3, and the lug 10 drives the left-handed transposition nut 3 to rotate rightward when it moves in the transposition mechanism 9, one end of the left-handed transposition nut 3 is connected to a spline outer cylinder 4 through a left-handed thread 13, and the spline outer cylinder 4 is sleeved on the outer side of the transposition spindle 2; by adopting the left-handed transposition nut 3, the right-handed thread on the pipe string will not be loosened during the right-handed disengagement process.

[0023] The end of the transposition shaft 2 away from the upper joint 1 is connected to the sealing shaft 6, the end of the spline outer cylinder 4 away from the left-handed transposition nut 3 is connected to the sealing outer cylinder 5, and the sealing outer cylinder 5 is sleeved on the outside of the sealing shaft 6; one end of the sealing outer cylinder 5 is connected to the lower joint 8, and a pulling sleeve 7 is provided at the relative connection position of the inner sides of the sealing outer cylinder 5 and the lower joint 8, and one end of the pulling sleeve 7 is connected to the sealing shaft 6.

[0024] Example 2 On the basis of Example 1, further, Figure 2As shown, the transposition mechanism 9 of the non-rotating safety joint of the present invention comprises a plurality of linear grooves 15 uniformly opened along the axial direction on the outer tube wall of the transposition mandrel 2, and the plurality of linear grooves 15 are uniformly distributed along the circumference of the transposition mandrel 2; Each two straight travel grooves 15 and the upper transposition grooves 16 and the lower transposition grooves 17 adjacent to each other at both ends form a group of transposition grooves, the upper transposition groove 16 is composed of an inclined groove a18 and an inclined groove b19, and the lower transposition groove 17 is composed of an inclined groove c20 and an inclined groove d21; One end of the upper linear groove 15 in a group of transposition grooves is connected to the lower linear groove 15 through the inclined groove c20 and the inclined groove d21, and the other end of the lower linear groove 15 is connected to the next group of transposition grooves through the inclined groove a18 and the inclined groove b19.

[0025] That is, when the operator is lifting the pipe string, Figure 3 As shown in FIG. 1 , the lug 10 on the inner wall of the left-handed transposition nut 3 moves in the transposition mechanism 9 by first reaching the upper transposition groove 16, passing through the inclined groove b19 to enter the first linear groove 15, and then sliding along the linear groove 15 to the lower transposition groove 17, passing through the inclined groove c20, and when the pipe string is lowered again, as shown in FIG. Figure 4 As shown, the lug 10 passes through the inclined groove d21 and slides along the second linear groove 15 to the position of the inclined groove a18, and then enters the second group of transposition grooves. After completing a set of lifting-lowering operations, the left-handed transposition nut 3 rotates rightward by a certain angle relative to the transposition spindle 2. Figure 5 As shown, as the lifting-lowering operation is repeated, the left-handed transposition nut 3 and the spline outer cylinder 4 become loose, allowing the nut to be released.

[0026] Example 3 The non-rotating safety joint of the present invention comprises an upper joint 1 and a transposition spindle 2 which are mutually connected by threads. A transposition mechanism 9 is provided on the surface of the transposition spindle 2. A left-handed transposition nut 3 is sleeved on the outer side of the transposition spindle 2. A lug 10 which is movably connected with the transposition mechanism 9 is fixedly connected on the inner side of the left-handed transposition nut 3. When the lug 10 is located in the transposition mechanism 9 and moves, it drives the left-handed transposition nut 3 to rotate rightward. One end of the left-handed transposition nut 3 is connected to a spline outer cylinder 4 through a left-handed thread 13. The spline outer cylinder 4 is sleeved on the outer side of the transposition spindle 2. By adopting the left-handed transposition nut 3, the right-handed thread on the pipe column will not be loosened during the right-handed disengagement process.

[0027] The end of the transposition shaft 2 away from the upper joint 1 is connected to the sealing shaft 6, the end of the spline outer cylinder 4 away from the left-handed transposition nut 3 is connected to the sealing outer cylinder 5, and the sealing outer cylinder 5 is sleeved on the outside of the sealing shaft 6; one end of the sealing outer cylinder 5 is connected to the lower joint 8, and a pulling sleeve 7 is provided at the relative connection position of the inner sides of the sealing outer cylinder 5 and the lower joint 8, and one end of the pulling sleeve 7 is connected to the sealing shaft 6.

[0028] In the initial state, the entire safety joint is locked by the pull sleeve 7. Figure 6 As shown, the pull sleeve 7 is provided with a limiting step 22 near one end of the sealing outer cylinder 5, and the other end of the pull sleeve 7 is connected to the sealing mandrel 6 by a thread. When the sealing mandrel 6 is subjected to a pulling force to the left and the lower joint 8 is subjected to a pulling force to the right, there is no relative movement between the sealing mandrel 6, the pull sleeve 7 and the sealing outer cylinder 5 and the lower joint 8.

[0029] That is, the non-rotating safety joint bears the tension of the lower pipe string when it is lowered into the well. The tension acts on the limiting step 22 of the pull sleeve 7 through the lower joint 8 and the sealing outer tube 5, and the pull sleeve 7 bears the weight of the pipe string below the non-rotating safety joint.

[0030] The non-rotating safety joint bears the tension applied by the upper pipe column during operation. The tension acts on the thread of the pull sleeve 7 through the upper joint 1, the transposition mandrel 2 and the sealing mandrel 6. When the tension on the pipe column is greater than the predetermined breaking force of the pull sleeve 7, the pull sleeve 7 breaks, so that the upper joint 1, the transposition mandrel 2, the sealing mandrel 6 and the left-hand transposition nut 3, the spline outer cylinder 4, the sealing outer cylinder 5, and the lower joint 8 can realize relative movement.

[0031] At this time, the non-rotating safety joint of the present invention is in a free state. As long as the movement stroke of the lug 10 inside the left-handed transposition nut 3 does not reach 1.5m, the long stroke-two-end transposition structure can ensure that the non-rotating safety joint of the present invention is in a free state and will not directly enter a slip-out state.

[0032] When it is necessary to enter the hands-free state, the lifting and lowering of the pipe column drives the transposition spindle 2 to move, and the lug 10 of the left-handed transposition nut 3 moves in the transposition mechanism 9, so that the connecting thread of the left-handed transposition nut 3 and the spline outer cylinder 4 is disengaged about 1 / 2 turn, and the lifting and lowering operation is repeated until the left-handed transposition nut 3 and the left-handed thread 13 of the spline outer cylinder 4 are completely disengaged to achieve hands-free state.

[0033] Preferably, the number of lifting and lowering is ≥ 24 times. The multiple lifting and lowering design can prevent the non-rotating safety joint from accidentally falling off. The number of meshing teeth of the left-handed thread 13 can be increased according to the on-site use requirements to adjust the number of lifting and lowering.

[0034] After the hands are released, the upper joint 1, the transposition mandrel 2, the sealing mandrel 6, and the left-hand transposition nut 3 are lifted out to the surface along with the pipe string, and the spline outer cylinder 4, the sealing outer cylinder 5, and the lower joint 8 remain in the well.

[0035] Example 4 On the basis of Example 3, Figure 7As shown, the lugs 10 of the non-rotating safety joint of the present invention are a pair, which are symmetrically fixed to the inner wall of the left-handed transposition nut 3 along the central axis of the left-handed transposition nut 3. The double lug structure doubles the force when the left-handed transposition nut 3 is rotated and released, and the symmetrical structure makes the force uniform during the rotation and release of the left-handed transposition nut 3.

[0036] Example 5 On the basis of Example 3, Figure 8 and Fig. 9 As shown, an inner spline groove 12 is formed at a relative position on the inner side of the spline outer cylinder 4 of the non-rotating safety joint of the present invention, and an outer spline 11 is fixedly connected to the outer tube wall of the transposition spindle 2 at a position relative to the inner spline groove 12. The outer spline 11 is clamped in the inner spline groove 12, and the column torque can be transmitted when the non-rotating safety joint is in a locked state and a free state. When the non-rotating safety joint is in a released state, the transposition spindle 2 and the spline outer cylinder 4 will not rotate relative to each other.

[0037] Furthermore, if Figure 8 and Fig.10 As shown, a guide groove a23 is provided on the external spline 11 along the axial direction of the transposition spindle 2, and a 15° guide groove 24 is provided at the position of the external spline 11 relative to the transposition mechanism 9; A radial hole 14 is formed at a position of the spline outer cylinder 4 relative to the external spline 11 , and a guide groove b25 is formed at a position of the spline outer cylinder 4 relative to the transposition mechanism 9 .

[0038] Since mud and impurity precipitation may appear in the transposition mechanism 9 of the transposition spindle 2 during the use of the non-rotating safety joint, when the lug 10 of the left-handed transposition nut 3 moves in the transposition mechanism 9 of the transposition spindle 2, the mud and impurity precipitation can be discharged from the radial hole 14 through the guide groove a23, the 15° guide groove 24 and the guide groove b25.

[0039] Example 6 The non-rotating safety joint release method of the present invention, as a safety tool in oil and gas downhole tools, can be widely used in non-rotating pipe string operations, and can be used in current deep water wells and horizontal wells. The tools that can be used in conjunction include non-rotating packers, pressure-set packers, etc. The present invention adopts the non-rotating safety joint of the above-mentioned embodiment 2, and specifically includes the following steps: Step 1, assemble the non-rotating safety joint, lower the assembled non-rotating safety joint into the well, and the joint is in a locked state; Step 2, increasing the pulling force of the pipe string to break the pull sleeve 7, and realizing relative movement among the upper joint 1, the transposition mandrel 2, the sealing mandrel 6, the left-hand transposition nut 3, the spline outer cylinder 4, the sealing outer cylinder 5, and the lower joint 8; Step 3, lifting and lowering the pipe column drives the transposition mandrel 2 to move, so that the lug 10 moves in the transposition mechanism 9, driving the left-handed transposition nut 3 to rotate relative to the spline outer cylinder 4; Furthermore, when the pull sleeve 7 breaks, the non-rotating safety joint enters a free state, and whether to enter a release state can be selected by controlling the lifting stroke.

[0040] Step 4, repeatedly lift up and lower the pipe column until the connecting thread of the left-handed transposition nut 3 and the spline outer cylinder 4 is completely disengaged, and the pipe column is released.

[0041] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0042] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Non-rotating safety joint, characterized in that: It comprises an upper joint (1) and a transposition spindle (2) which are connected to each other by threads, a transposition mechanism (9) is provided on the surface of the transposition spindle (2), a left-handed transposition nut (3) is sleeved on the outer side of the transposition spindle (2), a lug (10) which is movably connected to the transposition mechanism (9) is connected on the inner side of the left-handed transposition nut (3), and the lug (10) drives the left-handed transposition nut (3) to rotate rightward when it moves in the transposition mechanism (9), one end of the left-handed transposition nut (3) is connected to a spline outer cylinder (4) via a left-handed thread (13), and the spline outer cylinder (4) is sleeved on the outer side of the transposition spindle (2); The end of the transposition spindle (2) away from the upper joint (1) is connected to a sealing spindle (6); the end of the spline outer cylinder (4) away from the left-handed transposition nut (3) is connected to a sealing outer cylinder (5); the sealing outer cylinder (5) is sleeved on the outside of the sealing spindle (6); the other end of the sealing outer cylinder (5) is connected to the lower joint (8); a pull sleeve (7) is provided at a relative connection position on the inner side of the sealing outer cylinder (5) and the lower joint (8); one end of the pull sleeve (7) is connected to the sealing spindle (6).

2. The non-rotating safety joint according to claim 1, characterized in that: The transposition mechanism (9) comprises a plurality of linear grooves (15) uniformly arranged along the axial direction on the outer tube wall of the transposition spindle (2), wherein the plurality of linear grooves (15) are uniformly distributed along the circumference of the transposition spindle (2); Every two straight travel grooves (15) and the upper transposition grooves (16) and the lower transposition grooves (17) arranged at both ends form a group of transposition grooves; One end of the upper linear groove (15) in a group of transposition grooves is connected to the lower linear groove (15) through the lower transposition groove (17), and the other end of the lower linear groove (15) is connected to the next group of transposition grooves through the upper transposition groove (16).

3. The non-rotating safety joint according to claim 2, characterized in that: The upper transposition groove (16) is composed of an inclined groove a (18) and an inclined groove b (19) which are interconnected, and the lower transposition groove (17) is composed of an inclined groove c (20) and an inclined groove d (21) which are interconnected.

4. The non-rotating safety joint according to claim 1, characterized in that: A limiting step (22) is provided at one end of the pull sleeve (7) close to the sealing outer cylinder (5), and the other end of the pull sleeve (7) is connected to the sealing core shaft (6) via a thread.

5. The non-rotating safety joint according to claim 1, characterized in that: An inner spline groove (12) is formed on the inner side of the spline outer cylinder (4); an outer spline (11) is fixedly connected to the outer tube wall of the transposition spindle (2) at a position relative to the inner spline groove (12); the outer spline (11) is clamped in the inner spline groove (12) to prevent the transposition spindle (2) from rotating relative to the spline outer cylinder (4).

6. The non-rotating safety joint according to claim 1, characterized in that: A guide groove a (23) is provided on the external spline (11) along the axial direction of the transposition spindle (2), and a 15° guide groove (24) is provided at a position of the external spline (11) relative to the transposition mechanism (9); The spline outer cylinder (4) is provided with a radial hole (14) at a position relative to the external spline (11), and the spline outer cylinder (4) is provided with a guide groove b (25) at a position relative to the transposition mechanism (9).

7. The non-rotating safety joint according to claim 1, characterized in that: The lugs (10) are a pair and are symmetrically fixed to the inner wall of the left-handed transposition nut (3) along the central axis of the left-handed transposition nut (3).

8. A method for releasing a non-rotating safety joint, characterized in that: The non-rotating safety joint according to any one of claims 1 to 7 is used, and specifically comprises the following steps: Step 1, lower the non-rotating safety joint into the well, and the joint is in a locked state; Step 2, increasing the pulling force of the pipe string to break the pull sleeve (7), and realizing relative movement among the upper joint (1), the transposition mandrel (2), the sealing mandrel (6), the left-hand transposition nut (3), the spline outer cylinder (4), the sealing outer cylinder (5), and the lower joint (8); Step 3, lifting and lowering the pipe column drives the transposition mandrel (2) to move, and the lug (10) moves in the transposition mechanism (9), driving the left-handed transposition nut (3) to rotate relative to the spline outer cylinder (4); Step 4, repeatedly lift up and lower the pipe column until the connecting thread of the left-handed transposition nut (3) and the spline outer cylinder (4) are completely disengaged, and the pipe column is released.

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