A loosening spring for a downhole pipe coupling

Abstract

The present invention discloses a loosening bullet for underground tubular couplings, comprising a connecting joint, a partition detonating joint, a porous charge shell and a bullet tail which are coaxially arranged from top to bottom; a coaxial detonating cord is arranged in the central through hole of the connecting joint; the partition detonating joint comprises a cylindrical side wall and a bottom plate, a sealed cavity is formed between the bottom end of the connecting joint and the bottom plate, a perforating bullet is arranged in the sealed cavity, and the top of the perforating bullet is in contact with the detonating cord; a circumferential pre-splitting groove is arranged on the outer wall of the cylindrical side wall; a plurality of through holes are arranged on the side wall of the porous charge shell, and a main charge column and a simulated charge column are arranged in the porous charge shell from top to bottom, and the amount of the main charge column can be adjusted by adjusting the height of the simulated charge column; the bullet tail is a conical hollow structure, and a groove arranged circumferentially is arranged on the outer wall of the bullet tail. The loosening bullet of the present invention adopts a partition detonating technology and an exposed charge, and is used for loosening underground tubular couplings.

Description

Technical Field

[0001] The invention belongs to the field of handling underground pipe string stuck accidents, and specifically relates to a loosening bullet for underground pipe string couplings. The loosening bullet adopts a partition detonation technology and exposed charge, and is used for loosening underground pipe string couplings. Background Art

[0002] In the construction of oil and gas wells and other fields, downhole tubulars often get stuck. Common methods to solve the stuck accidents include loosening the tubular and cutting the tubular. Cutting the tubular cannot achieve the recovery of the entire tubular and has a destructive effect on the tubular. Loosening the tubular coupling will not damage the tubular and can achieve the reuse function of the tubular.

[0003] The structure of the existing loose-fitting bomb is a detonating cord-wrapped structure, which has poor pressure-bearing and sealing performance, and the construction operation is complicated and needs to be customized according to different wells, which increases the construction period and construction difficulty. Summary of the invention

[0004] In view of the defects and shortcomings in the prior art, the present invention provides a loosening bullet for underground tubular couplings, which adopts partition detonation technology, exposed charging, a shell designed as a screen tube and an adjustable charge type loosening bullet to achieve the purpose of loosening underground tubular couplings.

[0005] To achieve the above object, the present invention adopts the following technical scheme:

[0006] A loose buckle bullet for a downhole pipe string coupling comprises a connecting joint, a partition detonating joint, a porous charge shell and a bullet tail which are coaxially arranged in sequence from top to bottom;

[0007] A coaxial detonating cord is arranged in the central through hole of the connecting joint; the connecting joint is connected to the partition detonating joint, and a plurality of sealing rings are arranged between the lower outer wall of the connecting joint and the upper inner wall of the partition detonating joint;

[0008] The partition detonating joint comprises a cylindrical side wall and a bottom plate, a sealed cavity is formed between the bottom end of the connection joint and the bottom plate, a perforating bullet is arranged in the sealed cavity, and the top of the perforating bullet is in contact with the detonating cord; a circumferential pre-crack groove is arranged on the outer wall of the cylindrical side wall, and the pre-crack groove is located between the lower end surface of the connection joint and the lowest sealing ring;

[0009] A plurality of through holes are arranged on the side wall of the porous charge shell, and a main charge column and a simulated charge column are arranged in the porous charge shell from top to bottom, and the charge amount of the main charge column can be adjusted by adjusting the height of the simulated charge column; the upper end of the porous charge shell is connected to the lower outer wall of the partition detonation joint, and a stop screw is arranged on the side wall at the contact position between the two;

[0010] The tail of the bullet is a conical hollow structure, and grooves arranged along the circumferential direction are provided on the outer wall of the tail of the bullet. The tail of the bullet is threadedly connected to the lower end of the porous charge shell and is provided with a stop screw.

[0011] The present invention also includes the following technical features:

[0012] Specifically, the perforated bullet includes a perforated bullet shell, an explosive located at the upper end of the perforated bullet shell, a main charge and a charge cap located in the shell; the explosive is in contact with the lower end of the detonating cord.

[0013] Specifically, the bottom plate thickness of the partition detonating joint is 3 mm.

[0014] Specifically, among the multiple through holes on the porous charge shell, four top through holes are located at the top, and the four top through holes are evenly distributed along the circumference of the porous charge shell. Below each top through hole is a group of through holes distributed at equal intervals along a 60° spiral, and the spiral directions of the spirally arranged through holes in each group below the four top through holes are consistent.

[0015] Specifically, the diameter of the through hole is 10 mm; the distance between the top through hole and the upper stop screw is 20 mm; and the vertical spacing between the through holes is 10 mm.

[0016] Specifically, the diameter of the groove on the outer wall of the tail is 4 mm, and the circumferentially arranged grooves have two circles, one upper and one lower.

[0017] Specifically, the connecting joint and the partition detonating joint are threadedly connected; the upper end of the porous charge shell is threadedly connected to the lower outer wall of the partition detonating joint.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] The buckle-loosening bullet of the invention adopts a partition detonation technology and an exposed charge and is used for loosening a coupling of a downhole pipe column.

[0020] In the present invention, the main charge column in the shell is a heat-resistant and pressure-resistant charge column, which has been waterproofed and passed the pressure test in the exposed state. It is combined with a polymer material simulation charge column to achieve adjustable charge quantity according to actual charge quantity requirements.

[0021] The porous charge shell material is a soluble high-performance metal material, and the structure is designed as a porous tubular screen tube structure. Through a special treatment process, the surface hardness of the porous charge shell is improved. On the one hand, the pressure-bearing performance of the porous charge shell in the well is increased. On the other hand, after loosening, the porous charge shell is broken into small pieces and quickly dissolved, achieving the purpose of no falling objects in the well.

[0022] The porous charge shell is a porous pipe screen structure, which can fully release the explosive energy of the charge and improve the loosening effect of the pipe coupling; the porous structure on the porous charge shell ensures that the porous charge shell itself can be broken into small fragments after loosening.

[0023] In the present invention, a perforating bullet is loaded inside the partition detonation joint to realize the detonation function of the main charge column.

[0024] A circumferential pre-splitting groove is provided on the outer wall of the cylindrical side wall of the partition detonating joint. The function of the pre-splitting groove is that after the main charge is detonated, it can be neatly broken from the pre-splitting groove to avoid deformation of the partition detonating joint and cause the tool string to get stuck underground.

[0025] In the present invention, grooves arranged along the circumferential direction are provided on the outer wall of the tail of the bullet. The function of the grooves is to break the tail of the bullet into small pieces after being detonated underground, and will not cause blockage of the underground water hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the porous charge shell structure of the present invention;

[0028] Figure 3 It is a schematic diagram of the connection between the connecting joint and the partition detonating joint of the present invention.

[0029] The numbers in the figure are as follows: 1-connecting joint, 2-partition detonating joint, 2-1-bottom plate, 2-2-pre-crack groove, 3-porous charge shell, 3-1-through hole, 4-tail, 5-detonating cord, 6-sealing ring, 7-piercing bullet, 8-main charge column, 9-simulated charge column, 10-first stop screw. DETAILED DESCRIPTION

[0030] The present invention provides a loosening spring for a downhole pipe string coupling, such as Figures 1 to 3As shown, it includes a connecting joint 1, a partition detonating joint 2, a porous charge shell 3 and a bullet tail 4 which are coaxially arranged from top to bottom; a coaxial detonating cord 5 is arranged in the central through hole of the connecting joint 1; the connecting joint 1 and the partition detonating joint 2 are threadedly connected, and a plurality of sealing rings 6 are arranged between the lower outer wall of the connecting joint 1 and the upper inner wall of the partition detonating joint 2; the partition detonating joint 2 includes a cylindrical side wall and a bottom plate 2-1, a sealed cavity is formed between the bottom end of the connecting joint 1 and the bottom plate 2-1, a perforating bullet 7 is arranged in the sealed cavity, and the top of the perforating bullet 7 is in contact with the detonating cord 5; a circumferential pre-crack groove 2-2 is arranged on the outer wall of the cylindrical side wall, and the function of the pre-crack groove 2-2 is that after the main charge is detonated, it can be neatly broken from the pre-crack groove 2-2 to avoid causing the partition detonating joint 2 Deformation causes the tool string to get stuck underground. The pre-crack groove 2-2 is located between the lower end face of the connecting joint 1 and the lowest sealing ring 6; a plurality of through holes 3-1 are provided on the side wall of the porous charge shell 3, and a main charge column 8 and a simulated charge column 9 are installed in the porous charge shell 3 from top to bottom. The amount of the main charge column 8 can be adjusted by adjusting the height of the simulated charge column 9; the upper end of the porous charge shell 3 is threadedly connected to the lower outer wall of the partition detonating joint 2, and a first stop screw 10 is provided on the side wall at the contact position between the two; the tail 4 is a conical hollow structure, and a groove arranged along the circumferential direction is provided on the outer wall of the tail 4. The function of the groove is that the tail 4 can be broken into small pieces after underground detonation, and will not cause blockage of the underground water eye; the tail 4 is threadedly connected to the lower end of the porous charge shell 3 and is provided with a second stop screw. The loosening bullet of the present invention adopts a partition detonation technology and exposed charging, and is used for loosening the coupling of a downhole pipe column; the main charging column in the shell is a heat-resistant and pressure-resistant charging column, which has been waterproofed and passed the pressure test in the exposed state, and is combined with a polymer material simulation charging column to achieve adjustable charging amount according to actual charging amount requirements.

[0031] The perforated bullet 7 comprises a perforated bullet shell, a detonating charge at the upper end of the perforated bullet shell, a main charge and a charge cap located in the shell; the detonating charge contacts the lower end of the detonating cord 5, and the detonation function of the main charge column is realized.

[0032] The thickness of the bottom plate 2-1 of the partition detonating joint 2 is 3 mm.

[0033] Among the multiple through holes 3-1 on the porous charge shell 3, the topmost ones are four top through holes, which are evenly distributed along the circumference of the porous charge shell 3. Below each top through hole is a group of through holes 3-1 distributed at equal intervals along a 60° spiral, and the spiral directions of the through holes 3-1 arranged in spirals in each group below the four top through holes are consistent. The porous charge shell 3 is made of a soluble high-performance metal material, and the structure is designed as a porous tubular sieve tube structure. The surface hardness of the porous charge shell 3 is improved through a special treatment process, which increases the pressure-bearing performance of the porous charge shell 3 underground, and on the other hand, the porous charge shell 3 is broken into small pieces after loosening, and is quickly dissolved, so as to achieve the purpose of no falling objects underground. The porous charge shell 3 is a porous pipe string sieve tube structure, which can fully release the explosive energy of the charge and improve the effect of loosening the pipe string coupling; the porous structure on the porous charge shell 3 ensures that the porous charge shell 3 itself can be broken into small pieces after loosening.

[0034] The diameter of the through hole 3-1 is 10 mm; the distance between the top through hole and the first stop screw 10 above it is 20 mm; the vertical spacing of the through holes 3-1 is 10 mm.

[0035] The diameter of the groove on the outer wall of the tail 4 is 4 mm, and the circumferentially arranged groove has two circles, one upper and one lower.

[0036] The working principle of the present invention is as follows:

[0037] The detonating index detonates the perforating bullet. The explosive in the perforating bullet is detonated and crushes the charge liner to produce a metal jet. The metal jet penetrates the partition and detonates the main charge column in the shell. The main charge column acts on the pipe coupling and shakes the coupling loose, thereby achieving the purpose of loosening the pipe coupling.

[0038] The test process is as follows: firstly, a coupling pipe string the same as that used in the underground well is selected, and the coupling is fastened; secondly, the bottom is sealed to simulate the underground environment, the pipe string is filled with water, the loosening bomb of the present invention is placed at the coupling position, and finally the loosening bomb is detonated to observe whether the coupling position of the pipe string is intact and whether the coupling can be removed normally.

[0039] Test result: The coupling is intact, has no deformation and can be disassembled normally. The test result meets the requirements.

[0040] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0041] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0042] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A loosening spring for a downhole pipe coupling, characterized in that: It comprises a connecting joint (1), a partition detonating joint (2), a porous charge shell (3) and a bullet tail (4) which are coaxially arranged in sequence from top to bottom; A coaxial detonating cord (5) is arranged in the central through hole of the connecting joint (1); the connecting joint (1) is connected to the partition detonating joint (2), and a plurality of sealing rings (6) are arranged between the lower outer wall of the connecting joint (1) and the upper inner wall of the partition detonating joint (2); The partition detonating joint (2) comprises a cylindrical side wall and a bottom plate (2-1), a sealed cavity is formed between the bottom end of the connecting joint (1) and the bottom plate (2-1), a perforating bullet (7) is arranged in the sealed cavity, and the top of the perforating bullet (7) is in contact with the detonating cord (5); a circumferential pre-splitting groove (2-2) is arranged on the outer wall of the cylindrical side wall, the function of the pre-splitting groove (2-2) is to neatly break the main charge from the pre-splitting groove (2-2) after the main charge is detonated, so as to avoid deformation of the partition detonating joint (2) and cause the tool string to get stuck underground, and the pre-splitting groove (2-2) is located between the lower end surface of the connecting joint (1) and the lowest sealing ring (6); A plurality of through holes (3-1) are provided on the side wall of the porous charge shell (3); a main charge column (8) and a simulated charge column (9) are installed in the porous charge shell (3) from top to bottom; the charge amount of the main charge column (8) can be adjusted by adjusting the height of the simulated charge column (9); the upper end of the porous charge shell (3) is connected to the lower outer wall of the partition detonating joint (2); a first stop screw (10) is provided on the side wall at the contact position between the two; The tail (4) is a conical hollow structure, and a groove arranged along the circumferential direction is provided on the outer wall of the tail (4). The function of the groove is that after being detonated underground, the tail (4) can be broken into small pieces, and will not cause clogging of the underground water hole; the tail (4) is threadedly connected to the lower end of the porous charge shell (3) and is provided with a second stop screw; The buckle-loosening bullet adopts the partition detonation technology and exposed charge, which is used for loosening the coupling of downhole pipe string; the main charge column in the shell is a heat-resistant and pressure-resistant charge column, which has been waterproofed and passed the pressure test in the exposed state. It is matched with the polymer material simulation charge column to realize the adjustable charge amount according to the actual charge amount requirements; The perforated bullet (7) comprises a perforated bullet shell, a detonating charge located at the upper end of the perforated bullet shell, a main charge and a charge liner located in the shell; the detonating charge is in contact with the lower end of the detonating cord (5); The bottom plate (2-1) of the partition detonating joint (2) has a thickness of 3 mm; Among the multiple through holes (3-1) on the porous charge shell (3), four top through holes are located at the top, and the four top through holes are evenly distributed along the circumference of the porous charge shell (3), and below each top through hole is a group of through holes (3-1) distributed at equal intervals along a 60° spiral, and the spiral directions of the groups of spirally arranged through holes (3-1) below the four top through holes are consistent; The porous charge shell (3) is made of a soluble high-performance metal material, and is designed as a porous tubular screen structure, which can fully release the explosive energy of the charge and improve the effect of loosening the pipe string coupling. The porous structure on the porous charge shell (3) ensures that after loosening, the porous charge shell (3) itself can be broken into small fragments. The diameter of the through hole (3-1) is 10 mm; the distance between the top through hole and the first stop screw (10) above it is 20 mm; the vertical spacing of the through holes (3-1) is 10 mm; The diameter of the groove on the outer wall of the tail (4) is 4 mm, and the groove arranged circumferentially has two circles, one upper and one lower; The connecting joint (1) and the partition detonating joint (2) are threadedly connected; The upper end of the porous charge shell (3) is threadedly connected to the lower outer wall of the partition detonating joint (2).

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