CN111502595B - All-metal sealed soluble bridge plug - Google Patents

Abstract

The invention belongs to the field of oilfield downhole tools, and particularly relates to an all-metal sealed soluble bridge plug, which comprises a central pipe, wherein an upper outer pipe and a lower outer pipe are sequentially sleeved on the central pipe, an annular space is reserved between the upper outer pipe and the central pipe, an upper piston and a lower piston are arranged in the annular space and are respectively a piston A and a piston B, wherein the piston A is fixedly and hermetically connected with the central pipe and is in sliding and sealing connection with the upper outer pipe, the inner side of the upper outer pipe of a piston B section is provided with an expanding step, the expanding step plays a limiting role on the piston B, the piston B is in sliding and sealing connection with the upper outer pipe, and the piston B is in sliding and sealing connection with the central pipe.

Description

All-metal seal soluble bridge plug

Technical Field

The invention belongs to the field of oil field downhole tools, and in particular relates to a full metal sealing soluble bridge plug.

Background technique

Bridge plugs are downhole tools used to temporarily isolate wellbores in staged fracturing technology for horizontal wells. According to different ways of unsealing, bridge plugs can be divided into retrievable bridge plugs, drillable bridge plugs and soluble bridge plugs. The cost of retrievable bridge plugs is high and the risk of failure is high; when drilling and milling drillable bridge plugs, the amount of debris generated will accumulate and block the casing, which will have an adverse effect on subsequent operations; soluble bridge plugs are a new type of bridge plug made of magnesium-aluminum alloy, which can dissolve in a certain liquid environment after the fracturing operation is completed, thereby realizing full-bore production of the wellbore.

In the prior art, the rubber tube in the bridge plug is relatively thick, while the diameter of the bridge plug is fixed. Therefore, the rubber tube seriously restricts the expansion of the bridge plug diameter, thereby limiting the performance of the bridge plug. In addition, when installing the bridge plug, a special setting tool for the bridge plug needs to be connected above the bridge plug. The tool section formed by the setting tool and the bridge plug being connected as one is relatively long, which is prone to jamming during the downhole process. Therefore, it is necessary to design a soluble bridge plug that does not require a setting tool.

Summary of the invention

In order to solve the problem in the background technology that the sealing component of the bridge plug is too thick, which affects the expansion of the bridge plug diameter, and the problem in the background technology that the bridge plug needs a sealing tool when setting, which leads to an excessively long pipe string, the present invention provides a full metal sealed soluble bridge plug. The sealing component of the present invention is a thinner metal sealing ring, and the present invention does not require a sealing tool after reaching a predetermined position, so the length of the pipe string is shorter and the probability of sticking is reduced.

The technical solution provided by the present invention is: a full metal sealed soluble bridge plug, comprising a central tube, a vertebral body and a slip, wherein the central tube is threadedly connected to the vertebral body, the slip is sleeved on the outer side of the central tube and the vertebral body, the vertebral body and the slip move toward each other so that the claws of the slip expand and finally get stuck on the inner wall of the casing, and the outer side of the claw is provided with a ceramic column, and the present invention is characterized in that: the present invention also comprises a metal sealing ring, the metal sealing ring is sleeved on the vertebral body, and the upper end of the slip abuts against the metal sealing ring;

The central tube below the slip is provided with a directional ring, a support ring, an upper outer tube and a lower outer tube in sequence, and the four are threadedly connected in sequence;

A retaining spring is arranged on the inner side of the lower part of the directional ring, and the support ring is located below the retaining spring for supporting the retaining spring. The outer side of the center tube corresponding to the retaining spring section is processed with a retaining tooth for limiting the downward movement of the retaining spring relative to the center tube, so that the support ring, retaining spring and directional ring as a whole can only move upward relative to the center tube;

An annular space is left between the upper outer tube and the central tube, and two pistons are arranged in the annular space, namely piston A and piston B. Piston A is fixedly and sealedly connected to the central tube and is slidably and sealedly connected to the upper outer tube. The inner side of the upper outer tube in the piston B section is provided with a diameter expansion step, which serves as a limit for piston B. Piston B is slidably and sealedly connected to the upper outer tube, and piston B is slidably and sealedly connected to the central tube, so that piston A, piston B, central tube and upper outer tube form a gas chamber, which is called an upper gas chamber.

An annular space is left between the lower outer tube and the central tube, and two pistons are arranged in the annular space, namely piston C and piston D, wherein piston C is fixedly sealed and connected to the central tube, and is slidably sealed and connected to the lower outer tube, and piston D is fixedly sealed and connected to the lower outer tube, and is slidably sealed and connected to the central tube, so that piston C, piston D, central tube and lower outer tube form a gas chamber, which is called a lower gas chamber;

The inner side of the central tube is divided into an upper enlarged diameter section and a lower reduced diameter section. A hydrodynamic rotary propeller is installed in the enlarged diameter section. The hydrodynamic rotary propeller is coaxial with the central tube. A helical gear is connected to the shaft of the hydrodynamic rotary propeller. Two coaxial holes are opened on the central tube between the piston B and the piston C. Valve cores are respectively installed in the two holes. A screw engaged with the helical gears is connected between the two valve cores, so that the rotational motion of the helical gears is converted into the axial motion of the screw. An axial blind hole and a radial through hole are opened on one of the valve cores. The axial blind hole and the radial through hole are connected to form a liquid passage connecting the inside and outside of the central tube. The axial movement of the valve core controls the opening and closing of the liquid passage.

A soluble rubber soft layer is vulcanized on the valve core;

The outer side of the upper end of the vertebral body is provided with a reduced diameter section, the outer side of the reduced diameter section is slidably sealed with the continuous oil pipe, and the two are connected by a drop-out shear nail.

Furthermore, retaining rings are provided on both sides of the hydrodynamic rotary propeller to limit the propeller.

Furthermore, a sealing spacer ring is mounted on the vertebral body above the metal sealing ring to limit the position of the metal sealing ring.

Furthermore, the piston A and the piston C are both formed by splicing two half rings, and an annular groove is processed on the outer side of the central tube of the section where the piston A and the piston C are located, and the piston A and the piston C are installed in the annular groove.

The beneficial effects of the present invention are:

The sealing component in the present invention is a metal sealing ring. Compared with the traditional rubber sealing component, the metal sealing ring is thinner, thereby improving the expandability of the bridge plug diameter.

After the present invention reaches the predetermined position, the continuous oil pipe is used to pressurize the water-powered rotary paddle to rotate, and the rotary motion of the bevel gear is converted into the axial motion of the screw, thereby opening the liquid passage. Under the action of the strong hydraulic pressure downhole, the two air chambers are compressed, thereby forming a reverse force on the two pistons of each air chamber, and the reaction force pulls the central pipe and the two outer pipes in the opposite direction, thereby expanding the slips and anchoring them on the casing wall. Therefore, after the present invention reaches the predetermined position, it can achieve self-sealing without the need to use a sealing tool, thereby shortening the length of the pipe string, thereby avoiding the occurrence of jamming due to the long pipe string when lowered into the horizontal well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of the present invention.

FIG2 is a cross-sectional view taken along line A-A in FIG1.

FIG3 is a cross-sectional view taken along line B-B in FIG1.

FIG. 4 is a partial enlarged view of point C in FIG. 1 .

In the figure: 1-coiled tubing, 2-hand-release shear nail, 3-vertebral body, 4-sealing spacer ring, 5-metal sealing ring, 6-center tube, 7-slip, 8-directional ring, 9-support ring, 10-circlip, 11-upper outer tube, 12-lower outer tube, 13-piston D, 14-lower air cavity, 15-piston C, 16-piston B, 17-upper air cavity, 18-piston A, 19-blocking ring, 20-hydrodynamic rotary propeller, 21-bevel gear, 22-screw, 23-valve core, 24-liquid passage.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

The present invention includes a central tube 6, a vertebral body 3 and a slip 7. The central tube 6 is threadedly connected to the vertebral body 3. The slip 7 is sleeved on the outside of the central tube 6 and the vertebral body 3. The vertebral body 3 and the slip 7 move toward each other so that the claws of the slip 7 expand and finally get stuck on the inner wall of the casing. The outside of the claws is provided with a ceramic column. The above is a common structure in the prior art and will not be repeated here.

The main innovation of the present invention is:

The present invention also includes a metal sealing ring 5, which is sleeved on the vertebral body 3, and the upper end of the slip 7 is against the metal sealing ring 5. The metal sealing ring 5 in the present invention replaces the traditional soluble rubber sealing component. The thickness of the metal sealing ring 5 is smaller than that of the rubber sealing component, so it is more conducive to improving the expandability of the bridge plug diameter.

The central tube 6 below the slips 7 is sequentially sleeved with an orientation ring 8, a support ring 9, an upper outer tube 11 and a lower outer tube 12, which are threadedly connected in sequence.

A retaining spring 10 is arranged on the inner side of the lower part of the directional ring 8, and the support ring 9 is located below the retaining spring 10 to support the retaining spring 10. The outer side of the center tube 6 corresponding to the retaining spring 10 is processed with a tooth for limiting the downward movement of the retaining spring 10 relative to the center tube 6, so that the support ring 9, the retaining spring 10 and the directional ring 8 as a whole can only move upward relative to the center tube 6.

An annular space is left between the upper outer tube 11 and the center tube 6, and two pistons are arranged in the annular space, namely piston A18 and piston B16. The piston A18 is fixedly and sealedly connected to the center tube 6, and is slidably and sealedly connected to the upper outer tube 11. The inner side of the upper outer tube 11 in the piston B16 section is provided with a diameter expansion step, which serves as a limit for the piston B16. The piston B16 is slidably and sealedly connected to the upper outer tube 11, and the piston B16 is slidably and sealedly connected to the center tube 6, so that the piston A18, the piston B16, the center tube 6, and the upper outer tube 11 form a gas chamber, which is called the upper gas chamber 17.

When the upper air cavity 17 is subjected to liquid pressure from downhole, the upper air cavity 17 is compressed, and pistons A18 and B16 approach each other. The movement of piston A18 applies a downward thrust to the central tube 6, and the movement of piston B16 applies an upward thrust to the upper outer tube 11, so that the two reaction forces finally act between the slip 7 and the vertebral body 3, causing the slip 7 to expand and finally get stuck on the inner wall of the casing.

An annular space is left between the lower outer tube 12 and the center tube 6, and two pistons are arranged in the annular space, namely piston C15 and piston D13. The piston C15 is fixedly sealed and connected to the center tube 6, and is slidably sealed and connected to the lower outer tube 12. The piston D13 is fixedly sealed and connected to the lower outer tube 12, and is slidably sealed and connected to the center tube 6. Therefore, the piston C15, the piston D13, the center tube 6, and the lower outer tube 12 form a gas chamber, which is called the lower gas chamber 14.

When the lower air cavity 14 is subjected to the liquid pressure from the well, the lower air cavity 14 is compressed, and generates the same reverse force as the upper air cavity 17 to seal the bridge plug. The reaction forces generated by the two air cavities are superimposed to increase the sealing force and provide a better sealing effect.

The inner side of the central tube 6 is divided into an upper enlarged diameter section and a lower reduced diameter section. A hydrodynamic rotary propeller 20 is installed in the enlarged diameter section. The hydrodynamic rotary propeller 20 is coaxial with the central tube 6. When the bridge plug is in place, the continuous oil pipe 1 is pressed, and the liquid flows through to rotate the hydrodynamic rotary propeller 20. The shaft of the hydrodynamic rotary propeller 20 is connected with a bevel gear 21, so that the bevel gear 21 rotates synchronously with the shaft of the hydrodynamic rotary propeller 20. Two coaxial holes are opened on the central tube 6 between the piston B16 and the piston C15. Valve cores 23 are installed in the two holes respectively. A screw 22 meshing with the bevel gear 21 is connected between the two valve cores 23, so that the rotational motion of the bevel gear 21 is converted into the axial motion of the screw 22. The thread length of the screw 22 meshing with the bevel gear 21 is limited, so even if the bevel gear 21 is always in unidirectional rotation, the axial displacement of the screw 22 is fixed, but the bevel gear 21 loses meshing with the screw 22 and rotates idly. One of the valve cores 23 is provided with an axial blind hole and a radial through hole, the axial blind hole and the radial through hole are connected to form a liquid passage 24 , and the axial movement of the valve core 23 controls the opening and closing of the liquid passage 24 .

In order to ensure the sealing performance between the valve core 23 and the hole, a soluble rubber soft layer is vulcanized on the valve core 23 .

The outer side of the upper end of the vertebral body 3 is provided with a reduced diameter section, and the outer side of the reduced diameter section is slidably sealed with the coiled tubing 1, and the two are connected by the release shear pins 2. After the bridge plug is set, the coiled tubing 1 is lifted up, and the low-strength release shear pins 2 are sheared off, that is, the release is achieved. The present invention does not need to connect a special setting tool when setting, so the length of the pipe string is short, and the occurrence of jamming accidents is effectively reduced when it is lowered into a horizontal well. When the bridge plug is lowered, the coiled tubing 1 pushes the bridge plug downward, and the release shear pins 2 are not subjected to force, so they will not break accidentally.

The two sides of the hydrodynamic rotary propeller 20 are respectively provided with retaining rings 19 for limiting the position of the hydrodynamic rotary propeller 20 .

A sealing spacer ring 4 is sleeved on the vertebral body 3 above the metal sealing ring 5 to limit the position of the metal sealing ring.

The piston A18 and the piston C15 are both formed by splicing two half rings. The outer side of the central tube 6 of the section where the piston A18 and the piston C15 are located is processed with an annular groove, and the piston A18 and the piston C15 are installed in the annular groove.

All components except the ceramic column in the present invention are made of soluble materials. After fracturing, the present invention dissolves by itself to restore the full diameter of the casing.

The present invention is particularly suitable for horizontal well fracturing. Before fracturing, the present invention is connected to the lower end of the coiled tubing 1 and inserted into the well. During the insertion process, the well fluid passes through the hydrodynamic rotary paddle 20 from bottom to top, causing the hydrodynamic rotary paddle 20 to rotate counterclockwise, and the bevel gear 21 follows and rotates counterclockwise, driving the screw 22 to move axially, thereby blocking the liquid passage 24. As the bridge plug is continuously lowered, the hydrodynamic rotary paddle 20 continues to rotate counterclockwise, but due to the limited length of the thread on the screw 22, the bevel gear 21 loses engagement with the screw 22 and rotates idly, so that the screw 22 will not continue to move axially. After the bridge plug is sent to the predetermined position, the coiled tubing 1 is pressurized, and liquid passes through the hydrodynamic rotary paddle 20 from top to bottom, causing the hydrodynamic rotary paddle 20 to rotate clockwise, and the bevel gear 21 rotates clockwise accordingly, driving the screw 22 to move axially, and opening the liquid passage 24. With continuous pressure, the hydrodynamic rotary paddle 20 continues to rotate clockwise. Also, because the thread length on the screw 22 is limited, the screw 22 will not continue to move axially, and the liquid passage 24 is kept open.

The present invention utilizes fluid to drive the hydrodynamic rotary paddle 20 to convert the rotary motion into axial movement, thereby opening the fluid passage 24, causing the two air chambers to be compressed by the strong hydraulic pressure downhole, thereby generating a reverse force to seal the bridge plug.

Claims (4)

1. A fully metal sealed soluble bridge plug, comprising a central tube (6), a vertebral body (3) and a slip (7), wherein the central tube (6) is threadedly connected to the vertebral body (3), the slip (7) is sleeved on the outer sides of the central tube (6) and the vertebral body (3), the vertebral body (3) and the slip (7) move toward each other so that the claws of the slip (7) expand and finally get stuck on the inner wall of the casing, and the outer sides of the claws are provided with a ceramic column, characterized in that: the present invention also comprises a metal sealing ring (5), the metal sealing ring (5) is sleeved on the vertebral body (3), and the upper end of the slip (7) abuts against the metal sealing ring (5); A central tube (6) below the slip (7) is provided with a directional ring (8), a support ring (9), an upper outer tube (11) and a lower outer tube (12) in sequence, and the four are threadedly connected in sequence; A retaining spring (10) is arranged on the inner side of the lower part of the directional ring (8); the supporting ring (9) is located below the retaining spring (10) and is used to support the retaining spring (10); and a retaining tooth for limiting the downward movement of the retaining spring (10) relative to the central tube (6) is processed on the outer side of the central tube (6) corresponding to the retaining spring (10) section, so that the supporting ring (9), the retaining spring (10) and the directional ring (8) as a whole can only move upward relative to the central tube (6); An annular space is reserved between the upper outer tube (11) and the central tube (6), and two pistons are arranged in the annular space, namely, piston A (18) and piston B (16), wherein piston A (18) is fixedly sealedly connected to the central tube (6) and is slidably sealedly connected to the upper outer tube (11), and the inner side of the upper outer tube (11) section of the piston B (16) is provided with a diameter expansion step, and the diameter expansion step serves as a limit for the piston B (16), the piston B (16) is slidably sealedly connected to the upper outer tube (11), and the piston B (16) is slidably sealedly connected to the central tube (6), so that the piston A (18), the piston B (16), the central tube (6) and the upper outer tube (11) form a gas chamber, which is called an upper gas chamber (17); An annular space is reserved between the lower outer tube (12) and the central tube (6), and two pistons are arranged in the annular space, namely, piston C (15) and piston D (13), wherein piston C (15) is fixedly sealed connected to the central tube (6) and is slidably sealed connected to the lower outer tube (12), and piston D (13) is fixedly sealed connected to the lower outer tube (12) and is slidably sealed connected to the central tube (6), so that piston C (15), piston D (13), central tube (6) and lower outer tube (12) form a gas chamber, which is called a lower gas chamber (14); The inner side of the central tube (6) is divided into an upper expanded diameter section and a lower reduced diameter section. A hydrodynamic rotary paddle (20) is installed in the expanded diameter section. The hydrodynamic rotary paddle (20) is coaxial with the central tube (6). A bevel gear (21) is connected to the shaft of the hydrodynamic rotary paddle (20). Two coaxial holes are opened on the central tube (6) between the piston B (16) and the piston C (15). Valve cores (23) are respectively installed in the two holes. A screw (22) meshing with the bevel gear (21) is connected between the two valve cores (23), so that the rotational motion of the bevel gear (21) is converted into the axial motion of the screw (22). An axial blind hole and a radial through hole are opened on one of the valve cores (23). The axial blind hole and the radial through hole are connected to form a liquid passage (24) connecting the inside and outside of the central tube (6). The axial movement of the valve core (23) controls the opening and closing of the liquid passage (24). A soluble rubber soft layer is vulcanized on the valve core (23); The outer side of the upper end of the vertebral body (3) is provided with a reduced diameter section, the outer side of the reduced diameter section is slidably sealed with the continuous oil pipe, and the two are connected by a drop-out shear nail (2). 2. A fully metal sealed soluble bridge plug according to claim 1, characterized in that retaining rings (19) are respectively provided on both sides of the hydrodynamic rotary paddle (20) to limit the position of the paddle. 3. The all-metal sealed soluble bridge plug according to claim 1 is characterized in that a sealing spacer ring (4) is mounted on the cone (3) above the metal sealing ring (5) to limit its position. 4. The all-metal sealed soluble bridge plug according to claim 1 is characterized in that: the piston A (18) and the piston C (15) are both formed by splicing two half rings, and an annular groove is processed on the outer side of the center tube (6) of the section where the piston A (18) and the piston C (15) are located, and the piston A (18) and the piston C (15) are installed in the annular groove.