A dissolvable bridge plug

Abstract

The invention relates to a soluble bridge plug, which belongs to the technical field of oilfield downhole tools. The soluble bridge plug comprises a center pipe, a boss arranged on the upper part of the center pipe, a tool hole arranged on the boss for setting, a ball seat hole arranged in the boss, a thrust sleeve, a rubber tube, a propelling sleeve and a slip arranged on the center pipe in sequence below the boss, and the lower part of the slip is abutted against the upper part of a guide shoe which is connected with the center pipe through threads. The invention has the beneficial effects that the slips are driven to expand outward respectively after setting by using the pressure of fracturing, and the expansion degree depends on the pressure of fracturing instead of being completed uniformly by the setting tool, so that the soluble bridge plug has the ability to adapt to irregular well walls, and is reliably anchored in the well walls and safe and reliable.

Description

Technical Field

[0001] This invention relates to the field of oilfield downhole tool technology, and more particularly to a soluble bridge plug. Background Technology

[0002] Soluble bridge plugs are a technological innovation in the field of oil drilling. They are mainly used to control water flow in oil and gas wells, especially during hydraulic fracturing operations. Unlike traditional permanent bridge plugs, these bridge plugs can dissolve or disappear under certain conditions, thus providing a temporary sealing solution.

[0003] The roughness and irregularity of the well wall after drilling means that the slips of the bridge plug are currently opened by a single cone, and the degree of opening of the slips is the same. When the slips of the bridge plug are opened, they may not be fully anchored to the irregular well wall, which may affect the fixing effect. This may cause the bridge plug to loosen or even fall off when it is subjected to subsequent pressure.

[0004] Due to their complex structure, current soluble bridge plugs have varying dissolution efficiencies at different locations. In particular, since the rubber cartridge is not yet unsealed, there is a dead zone for liquid flow in the soluble rubber cartridge area, resulting in a long dissolution time for the bridge plug. Summary of the Invention

[0005] To address the problems of unreliable anchoring of soluble bridge plugs to the wellbore and long dissolution time, this invention provides a soluble bridge plug.

[0006] The technical solution provided by the present invention is: a soluble bridge plug, including a central tube, a boss on the upper part of the central tube, a tool hole for setting on the boss, a ball seat hole inside the boss, and a thrust sleeve, a rubber sleeve, a push sleeve and a slip are sequentially sleeved on the central tube below the boss, the lower part of the slip abuts against the upper part of the guide shoe, and the guide shoe is connected to the central tube by a thread.

[0007] An opening pin is provided between the thrust sleeve and the central tube. The thrust sleeve and the central tube are connected by a one-way tooth. The one-way tooth allows the thrust sleeve to descend along the outer circle of the central tube but not to rise. The thrust sleeve extends downward to a locking sleeve. The rubber sleeve is sleeved on the outside of the locking sleeve. The locking sleeve extends downward and is inserted into the thrust sleeve. A stepping pin is provided between the thrust sleeve and the locking sleeve. The thrust sleeve is blocked under the rubber sleeve.

[0008] The lower part of the push sleeve is provided with a cone body, and the push sleeve presses on the cone body. There are three cone bodies evenly distributed around the circumference of the central tube. The lower end face of the boss has three evenly distributed blind holes machined downward on the outside of the ball seat hole. There are three evenly distributed notches on the outer circle of the central tube. There are through holes between the blind holes and the notches. A piston B is provided in the blind hole. The piston B is fitted with the blind hole through the gap of the sealing ring. The lower part of the piston B is fixedly connected to the push rod, and the push rod extends out of the through hole.

[0009] The push sleeve extends downwards with a retaining ring. The inner hole of the vertebral body has a large-diameter stepped hole D. The bottom of the stepped hole D has an annular end face. A stop block is provided in the notch of the central tube. The outer side of the stop block is blocked on the annular end face of the vertebral body. The upper part of the stop block is connected to the lever through an ear plate and a shaft hinge. The inner side of the lever is located at the lower end of the push rod, and the outer side of the lever is located below the retaining ring of the push sleeve.

[0010] The lower part of the vertebral body is a cone-shaped structure with a reduced diameter. The lower part of the vertebral body is inserted into the slips. There are three slips, which are arranged around the outer circumference of the central tube. The inner hole formed by the three slips has the same conical hole as the vertebral body. The slips are fitted with elastic bands on the outside.

[0011] The lower end face of the boss is machined with a stepped hole A on the outside of the ball seat hole. A stepped hole B with a smaller diameter than the stepped hole A is machined below the stepped hole A. A stepped hole C with a smaller diameter than the stepped hole B is machined below the stepped hole B. A piston A is installed inside the stepped hole A. The piston A is clearance-fitted with the stepped hole A through a sealing ring. A compression spring is installed between the piston A and the bottom of the stepped hole A. A valve stem is fixedly connected to the lower part of the piston A. The lower part of the valve stem has a conical tip structure. The conical tip of the valve stem seals the stepped annular surface between the stepped hole B and the stepped hole C. An inner through-hole communicating with the inner hole of the central tube is provided on the inside of the stepped hole C. An outer through-hole communicating with the outer circle of the central tube is provided on the outside of the stepped hole B. The outer through-hole is located at the one-way toothed connection part between the locking sleeve and the central tube.

[0012] The outer circumference of the shoe has a groove, and a cleaning sleeve is fitted inside the groove. The cleaning sleeve is made of water-absorbing and expanding material.

[0013] The bottom of the outer circle of the push sleeve has three circumferentially distributed limiting grooves B. The upper part of the cone body is inserted into the inner circumferential limiting groove B for circumferential limiting. The upper end face of the guide shoe has three circumferentially distributed limiting grooves A. The lower part of the slipper extends into the inner circumferential limiting groove A for circumferential limiting.

[0014] The central tube, guide shoe, slip, propulsion sleeve, cone, thrust sleeve, stepping pin, opening pin, valve stem, piston A, piston B, push rod, stop block, lever, ear plate and shaft are all made of soluble metal, and the elastic hoop and rubber sleeve are made of soluble rubber.

[0015] The beneficial effects of this invention are as follows: 1. The use of an opening pin prevents premature setting of the soluble bridge plug. A rubber sleeve is placed outside the thrust sleeve, and a stepping pin is installed between the thrust sleeve and the advance sleeve to achieve step-by-step setting, i.e., the slips are anchored first, followed by the rubber sleeve setting. This avoids damage to the rubber sleeve surface caused by simultaneous action, which would affect the sealing effect. 2. By utilizing the pressure of fracturing, after the slips are set, each slip is driven to expand outwards independently, while the advance sleeve does not descend, thus preserving the sealing performance of the rubber sleeve. The degree of expansion depends on the fracturing pressure rather than being uniformly achieved by the setting tools, enabling the soluble bridge plug to adapt to irregular wellbore walls and reliably anchor within the wellbore wall, ensuring safety and reliability. 3. By setting a switch channel on the wall of the central tube, the channel inside and outside the central tube is opened after fracturing. The fluid in the well flows into the one-way tooth section between the central tube and the thrust sleeve. Since the one-way tooth has a very small structural size, it can dissolve in a short time. The axial restraint between the thrust sleeve and the central tube is released, and all the components outside the central tube are in a free state. The rubber sleeve retracts under its own elasticity, and the annulus of the oil sleeve outside the central tube can be filled with fluid, thereby accelerating the dissolution rate of the overall soluble bridge plug. Attached Figure Description

[0016] Appendix Figure 1 This is a schematic diagram of the structure of the present invention;

[0017] Appendix Figure 2 This is a cross-sectional view of the present invention;

[0018] Appendix Figure 3 It is attached Figure 2 Enlarged view of point A;

[0019] Appendix Figure 4 It is attached Figure 2 Enlarged view of point B;

[0020] Appendix Figure 5 This is a schematic diagram of the central tube structure;

[0021] Appendix Figure 6 It is a 3D diagram of the central tube;

[0022] Appendix Figure 7 This is a schematic diagram of the propulsion sleeve;

[0023] Appendix Figure 8 This is a schematic diagram of the vertebral body.

[0024] In the diagram: 1-Center tube, 101-Boss, 102-Tool hole, 103-Spherical seat hole, 104-Stepped hole A, 105-Stepped hole B, 106-Stepped hole C, 107-Outer opening, 108-Inner opening, 109-Blind hole, 1010-Notch, 1011-Through hole, 2-Guide shoe, 201-Limiting groove A, 3-Latch, 4-Rubber sleeve, 5-Propeller sleeve, 501-Limiting groove B, 502-Retaining ring. 6-Thrust sleeve, 601-Locking sleeve, 7-Stepping pin, 8-Cleaning sleeve, 9-One-way tooth, 10-Valve stem, 11-Piston A, 12-Elastic clamp, 13-Pelvis, 1301-Step hole D, 1302-Annular end face, 14-Opening pin, 15-Soluble ball, 16-Piston B, 17-Push rod, 18-Stop block, 19-Lever, 20-Shaft, 21-Ear plate. Detailed Implementation

[0025] like Figures 1-8 As shown, a soluble bridge plug includes a central tube 1. A boss 101 is provided on the upper part of the central tube 1. A tool hole 102 for setting is provided on the boss 101. A ball seat hole 103 is provided inside the boss 101. A thrust sleeve 6, a rubber sleeve 4, a push sleeve 5 and a slip 3 are sequentially fitted on the central tube 1 below the boss 101. The lower part of the slip 3 abuts against the upper part of the guide shoe 2. The guide shoe 2 is connected to the central tube 1 by threads.

[0026] An opening pin 14 is provided between the thrust sleeve 6 and the central tube 1 to prevent the soluble bridge plug from being prematurely set. The thrust sleeve 6 and the central tube 1 are connected by a one-way tooth 9. The one-way tooth 9 allows the thrust sleeve 6 to descend along the outer circle of the central tube 1 but not to rise. The thrust sleeve 6 extends downward to a locking sleeve 601. The rubber sleeve 4 is sleeved on the outside of the locking sleeve 601. The locking sleeve 601 extends downward and is inserted into the push sleeve 5. A stepping pin 7 is provided between the push sleeve 5 and the locking sleeve 601. The push sleeve 5 is blocked under the rubber sleeve 4.

[0027] The lower part of the push sleeve 5 is provided with a cone 13. The push sleeve 5 presses on the cone 13. There are three cones 13 evenly distributed around the circumference of the central tube 1. The lower end face of the boss 101 has three circumferentially distributed blind holes 109 machined downward outside the ball seat hole 103. Three circumferentially distributed notches 1010 are opened on the outer circle of the central tube 1. A through hole 1011 is opened between the blind holes 109 and the notches 1010. A piston B16 is provided in the blind hole 109. The piston B16 is fitted with the blind hole 109 through a sealing ring. The lower part of the piston B16 is fixedly connected to the push rod 17. The push rod 17 extends out of the through hole 1011.

[0028] The push sleeve 5 extends downward with a retaining ring 502. The inner hole of the cone 13 has a large-diameter stepped hole D1301. The bottom of the stepped hole D1301 has an annular end face 1302. The notch 1010 of the central tube 1 is provided with a stop block 18. The outer side of the stop block 18 blocks the annular end face 1302 of the cone 13. The upper part of the stop block 18 is connected to the lever 19 through the ear plate 21 and the shaft 20. The inner side of the lever 19 is located at the lower end of the push rod 17, and the outer side of the lever 19 is located below the retaining ring 502 of the push sleeve 5.

[0029] The lower part of the vertebral body 13 is a cone-shaped structure with a reduced diameter. The lower part of the vertebral body 13 is inserted into the slip 3. There are three slips 3. The slips 3 are arranged around the outer circumference of the central tube 1. The inner hole formed by the three slips 3 has the same conical hole as the vertebral body 13. The slips 3 are fitted with an elastic hoop 12.

[0030] When the soluble bridge plug is set, the setting tool restricts the downward movement of the guide shoe 2 and pushes the thrust sleeve 6 down. The opening pin 14 is sheared off. Since there is a stepping pin 7 between the push sleeve 5 and the thrust sleeve 6, the push sleeve 5 and the thrust sleeve 6 cannot move up and down. The push sleeve 5 pushes the cone 13 down. The cone 13 pushes the slip 3 to expand outward and anchor it in the sleeve. The setting tool continues to apply pressure. The stepping pin 7 is sheared off. The thrust sleeve 6 moves downward and approaches the push sleeve 5. Under the action of the one-way tooth 9, the thrust sleeve 6 no longer rises. The rubber sleeve 4 is compressed and expands to stick to the inner wall of the sleeve for sealing.

[0031] The opening pin 14 is set to prevent the soluble bridge plug from setting prematurely. The rubber sleeve 4 is set on the outside of the thrust sleeve 6, and the stepping pin 7 is set between the thrust sleeve 6 and the push sleeve 5 to achieve step setting. That is, the slip 3 is anchored first, and the rubber sleeve 4 is set later. This avoids the surface of the rubber sleeve 4 being pulled and damaged when they act simultaneously, which would affect the sealing effect.

[0032] After the soluble bridge plug is set, a soluble ball 15 is inserted into the soluble bridge plug. The soluble ball 15 lands on the ball seat hole 103 and seals it, thereby separating the upper and lower parts of the soluble bridge plug. The pressure of the fracturing causes the piston B16 to descend. The piston B16 and the push rod 17 descend and press against the inside of the lever 19, causing the stop block 18 to descend. At the same time, the outside of the lever 19 rises, preventing the push sleeve 5 from descending. The descent of the stop block 18 pushes the cone 13 to descend.

[0033] Since each cone 13 is equipped with a stop 18, the pressure during fracturing can drive the stop 18 to descend, pushing the cone 13 down. When the anchoring force between a slip 3 and the well wall is insufficient, the fracturing pressure can push the cone 13 down and anchor the slip 3 to the well wall. By utilizing the fracturing pressure, after the slip 3 is set, each slip 3 is driven to expand outward. The degree of expansion depends on the fracturing pressure rather than being uniformly completed by the setting tool, so that the soluble bridge plug has the ability to adapt to irregular well walls and is reliably anchored in the well wall, which is safe and reliable.

[0034] The lower end face of the boss 101 has a stepped hole A104 machined downwards outside the ball seat hole 103. Below the stepped hole A104, a stepped hole B105 with a smaller diameter than the stepped hole A104 is machined. Below the stepped hole B105, a stepped hole C106 with a smaller diameter than the stepped hole B105 is machined. A piston A11 is installed inside the stepped hole A104. The piston A11 is clearance-fitted with the stepped hole A104 through a sealing ring. A compression spring is installed between the piston A11 and the bottom of the stepped hole A104. The lower part of the piston A11 is fixedly connected to the valve stem 10. The lower part of the valve stem 10 has a conical tip structure. The conical tip of the valve stem 10 is sealed on the stepped annular surface between the stepped hole B105 and the stepped hole C106. The inner side of the stepped hole C106 is provided with an inner port 108 that communicates with the inner hole of the central tube 1. The outer side of the stepped hole B105 is provided with an outer port 107 that communicates with the outer circle of the central tube 1. The outer port 107 is located at the connection part of the locking sleeve 601 and the one-way tooth 9 of the central tube 1.

[0035] During fracturing, the fracturing pressure causes piston A11 to descend, and valve stem 10 closes the inner and outer channels of the central tube 1. When fracturing ends, the pressure above is released. At this time, regardless of whether the soluble ball 15 is away from the ball seat hole 103, piston A11 rises under the action of the compression spring, and the inner and outer channels of the central tube 1 are opened. The fluid in the well flows into the one-way tooth 9 between the central tube 1 and the thrust sleeve 6. Because the one-way tooth 9 has a very small structural size, it can dissolve in a short time. The vertical constraint between the thrust sleeve 6 and the central tube 1 is released, and all the components outside the central tube 1 are in a free state. The rubber sleeve 4 retracts under its own elasticity, and the annulus of the oil sleeve outside the central tube 1 is filled with fluid, thereby accelerating the dissolution rate of the overall soluble bridge plug.

[0036] The outer circumference of the guide shoe 2 is machined with an annular groove, and a cleaning sleeve 8 is fitted inside the annular groove of the guide shoe 2. The cleaning sleeve 8 is made of water-absorbing and expanding material, which can clean the inner wall of the sleeve and improve the anchoring force and sealing effect.

[0037] The bottom of the outer circle of the push sleeve 5 has three circumferentially distributed limiting grooves B501. The upper part of the cone body 13 is inserted into the inner circumferential limiting groove B501 for limiting. The upper surface of the guide shoe 2 has three circumferentially distributed limiting grooves A201. The lower part of the slipper 3 extends into the inner circumferential limiting groove A201 for limiting.

[0038] The central tube 1, guide shoe 2, slip 3, propulsion sleeve 5, cone 13, thrust sleeve 6, stepping pin 7, opening pin 14, valve stem 10, piston A11, piston B16, push rod 17, stop block 18, lever 19, ear plate 21 and shaft 20 are all made of soluble metal, and the elastic hoop 12 and rubber sleeve 4 are made of soluble rubber.

Claims

1. A soluble bridge plug comprising a central tube (1), characterized in that: The center tube (1) upper part is provided with a boss (101), the boss (101) is provided with a tool hole (102) for setting, the boss (101) is provided with a ball seat hole (103), the center tube (1) is sequentially sleeved with a thrust sleeve (6), a rubber tube (4), a propelling sleeve (5) and a slip (3) below the boss (101), the slip (3) lower part abuts against the upper part of the guide shoe (2), the guide shoe (2) is connected with the center tube (1) through threads; The thrust sleeve (6) and the center tube (1) are provided with an opening pin (14), the thrust sleeve (6) and the center tube (1) are connected through a one-way tooth (9), the one-way tooth (9) makes the thrust sleeve (6) can descend along the outer circle of the center tube (1) and cannot rise, the thrust sleeve (6) extends downward by a locking sleeve (601), the rubber tube (4) is sleeved outside the locking sleeve (601), the locking sleeve (601) extends downward and is inserted into the propelling sleeve (5), the propelling sleeve (5) and the locking sleeve (601) are provided with a step pin (7), the propelling sleeve (5) is blocked below the rubber tube (4); The propelling sleeve (5) lower part is provided with a vertebral body (13), the propelling sleeve (5) is pressed on the upper surface of the vertebral body (13), the vertebral body (13) is three in number and is uniformly distributed along the circumference of the center tube (1), the boss (101) lower end surface is downwardly machined with three circumferentially distributed blind holes (109) outside the ball seat hole (103), the outer circle of the center tube (1) is opened with three circumferentially distributed notches (1010), a through hole (1011) is opened between the blind hole (109) and the notch (1010), the blind hole (109) is provided with a piston B (16), the piston B (16) is gap fitted with the blind hole (109) through a sealing ring, the piston B (16) lower part is fixedly connected with a jacking rod (17), the jacking rod (17) extends out of the through hole (1011); The propelling sleeve (5) extends downward by a blocking ring (502), the vertebral body (13) inner hole is opened with a large-diameter stepped hole D (1301), the stepped hole D (1301) bottom has an annular end face (1302), the notch (1010) of the center tube (1) is provided with a stop block (18), the stop block (18) is blocked on the annular end face (1302) of the vertebral body (13) outside, the stop block (18) upper part is hingedly connected with a lever (19) through an ear plate (21) and a shaft (20), the lever (19) inner side is located at the lower end of the jacking rod (17), the outer side of the lever (19) is located below the blocking ring (502) of the propelling sleeve (5); The vertebral body (13) lower part is a conical structure with reduced diameter, the vertebral body (13) lower part is inserted into the slip (3), the number of the slip (3) is three, the slip (3) is arranged along the outer circumference of the center tube (1), the inner hole surrounded by the three slips (3) has the same conical hole as the vertebral body (13), the slip (3) outside is sleeved with an elastic hoop (12).

2. A dissolvable bridge plug according to claim 1, wherein: The lower end face of the boss (101) is downwardly machined with a stepped hole A (104) outside the ball seat hole (103), the lower part of the stepped hole A (104) is machined with a stepped hole B (105) smaller in diameter than the stepped hole A (104), the lower part of the stepped hole B (105) is machined with a stepped hole C (106) smaller in diameter than the stepped hole B (105), the stepped hole A (104) is provided with a piston A (11), the piston A (11) is in gap fit with the stepped hole A (104) through a sealing ring, a compression spring is arranged between the piston A (11) and the bottom of the stepped hole A (104), the lower part of the piston A (11) is fixedly connected with a valve rod (10), the lower part of the valve rod (10) is in conical pointed structure, the conical pointed head of the valve rod (10) is sealed in the stepped annular surface between the stepped hole B (105) and the stepped hole C (106), the inner side of the stepped hole C (106) is provided with an inner through hole (108) in communication with the inner hole of the center pipe (1), the outer side of the stepped hole B (105) is provided with an outer through hole (107) in communication with the outer circle of the center pipe (1), and the outer through hole (107) is located at the connection position of the locking sleeve (601) and the one-way tooth (9) of the center pipe (1).

3. The dissolvable bridge plug of claim 1, wherein: The outer circle of the guide shoe (2) is machined with an annular groove, and the guide shoe (2) is sleeved with a cleaning sleeve (8) in the annular groove, and the cleaning sleeve (8) is made of water-absorbing and expanding material.

4. The dissolvable bridge plug of claim 1, wherein: The outer circle bottom of the pushing sleeve (5) is provided with three circumferentially distributed limiting grooves B (501), the upper part of the vertebra (13) is inserted into the circumferential limiting of the limiting grooves B (501), and the upper end face of the guide shoe (2) is provided with three circumferentially distributed limiting grooves A (201), and the lower part of the slip (3) is inserted into the circumferential limiting of the limiting grooves A (201).

5. The dissolvable bridge plug of claim 1, wherein: The center pipe (1), the guide shoe (2), the slip (3), the pushing sleeve (5), the vertebra (13), the thrust sleeve (6), the step pin (7), the opening pin (14), the piston B (16), the jacking rod (17), the stop block (18), the lever (19), the ear plate (21) and the shaft (20) are all made of soluble metal, and the elastic hoop (12) and the rubber cylinder (4) are made of soluble rubber.

6. The dissolvable bridge plug of claim 2, wherein: The center pipe (1), the guide shoe (2), the slip (3), the pushing sleeve (5), the vertebra (13), the thrust sleeve (6), the step pin (7), the opening pin (14), the valve rod (10), the piston A (11), the piston B (16), the jacking rod (17), the stop block (18), the lever (19), the ear plate (21) and the shaft (20) are all made of soluble metal, and the elastic hoop (12) and the rubber cylinder (4) are made of soluble rubber.

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