Removable-connectable bridge plug and operation method

Abstract

The invention discloses a removable-connectable bridge plug and an operation method, and belongs to the technical field of oil and gas well downhole tools. The bridge plug comprises a main body, a fixing device, a linkage mechanism and a connecting device. A slip of the fixing device is hinged to a main body, and a tile supporting cone moves downwards to drive the slip to expand in the radial direction so as to anchor the well wall. A sliding body of the linkage mechanism is fixed in the main body through a shear pin, and two ends of the sliding body are conical slopes; when the slips expand, the hinged plates are pulled by the steel cables to swing inwards in the radial direction and extrude the sliding bodies, and the sliding bodies are driven to move downwards after the shear pins are damaged. Mushroom nails of the connecting device are radially arranged on the side wall of the base, and reset springs enable the mushroom nails to have a retraction trend. When the sliding body moves downwards, the lower end conical surface overcomes the spring force to eject out the mushroom nails to provide a connecting structure. According to the invention, active recovery and underground series connection functions of the bridge plug are realized, the staged fracturing operation efficiency is greatly improved, and the cost and the wellbore risk are reduced.

Description

Technical Field

[0001] This invention relates to the field of efficient development technology for unconventional oil and gas reservoirs, specifically a removable-connectable bridge plug and its operation method. Background Technology

[0002] In horizontal well fracturing operations in unconventional oil and gas reservoirs, bridge plugs are key tools for sealing the wellbore and achieving staged fracturing.

[0003] Existing technologies generally adopt a process mode of single bridge plug step-by-step setting and perforation. The bridge plug tool is usually designed for single use. That is, after being set by hydraulic or mechanical means, the bridge plug slips and rubber sleeve are permanently anchored and sealed on the casing. After the fracturing of this section is completed, a drilling tool needs to be lowered to remove it before the next section can be carried out.

[0004] However, this technical approach has a fundamental bottleneck: because the bridge plug, once set, lacks the ability to actively unseal and reset downhole, it cannot be retrieved or repositioned once set. Therefore, each stage of fracturing requires a complete cycle of "downloading the bridge plug - setting - perforation - fracturing - drilling," resulting in lengthy operation cycles, frequent tripping operations, and high drilling costs when performing 15-25 fracturing stages in horizontal sections thousands of meters long. Furthermore, the drilling process poses a potential risk to casing integrity. More critically, existing bridge plugs have a single function, only capable of isolating the current well section and unable to form a reliable mechanical connection with other bridge plugs downhole. This prevents the construction of a more integrated multi-stage isolation system, hindering the efficient implementation of ultra-long horizontal sections and high-volume fracturing processes. Summary of the Invention

[0005] The purpose of this invention is to provide a removable-connectable bridge plug and its operation method, which has the functions of active recovery and reliable connection and disassembly between multiple bridge plugs downhole.

[0006] The technical solution of this invention is: A removable-connectable bridge plug includes a body; a fixing device including: a slip, arranged axially along the body, one end of which is hinged to the body and the other end is a free end; a support cone, sleeved on the outside of the body and located at the free end of the slip, the support cone engaging with the inner surface of the slip to allow the slip to expand radially outward with its hinged end as the axis; and a linkage mechanism including: a sliding body, axially fixed to the body by a shear pin, both ends of the sliding body being configured as tapered inclined surfaces; and a hinge plate, one end of which is hinged to the body, the other end of which moves radially inward into the body from the hinge point, and moves radially with the sliding body during the radial movement. The conical inclined surface at one end slides against the sliding body; the traction mechanism includes: a steel cable connected between the free end of the slip and the hinge plate, and a pulley for guiding the steel cable, the pulley being fixedly installed inside the main body; the path of the steel cable is configured such that when the slip expands outward, it can pull the hinge plate to move radially inward and abut against the top of the sliding body; the connecting device is provided at the base end of the main body, including: a mushroom nail, which is radially inserted through the side wall of the base, the head of the mushroom nail sliding against the conical inclined surface at the other end of the sliding body; a return spring, one end acting on the inner wall of the main body, and the other end acting on the head of the mushroom nail.

[0007] Furthermore, the inner surface of the bearing cone engages with the outer surface of the main body via a keyway or spline, allowing the bearing cone to move only along the axial direction of the main body and preventing relative rotation. This prevents the bearing cone from rotating or shifting circumferentially during the setting process, ensuring a precise downward trajectory. Consequently, the radial expansion of the slip is uniform and reliable, improving the setting success rate and anchoring stability.

[0008] Furthermore, it also includes a sealing and force transmission device, which comprises: a drum-shaped sealing sleeve fitted outside the main body; a pressure-bearing ring fitted outside the main body and located between the drum-shaped sealing sleeve and the bearing cone; an upper pressure ring and a lower pressure ring located at the upper and lower ends of the drum-shaped sealing sleeve, respectively; the lower pressure ring is connected to the pressure-bearing ring, and the pressure-bearing ring is driven into contact or fixedly connected to the upper end of the bearing cone. While the bridge plug is anchored, a high-pressure sealing ring is formed in the adjacent area of ​​the slips, achieving synchronous and reliable completion of anchoring and sealing functions during the setting process, ensuring the sealing effectiveness of the fracturing operation.

[0009] Furthermore, the sealing and force transmission device also includes: a sealing cap, fixedly connected to the top of the main body, for receiving the setting force from the external setting tool; and a pressure transmission ring, sleeved on the outside of the main body and located between the sealing cap and the upper pressure ring, for transmitting the setting force from the sealing cap to the upper pressure ring. This smoothly and efficiently converts the concentrated force applied by the external setting tool into a squeezing force on the drum seal and a thrust force on the bearing cone, optimizing the transmission efficiency of the setting force.

[0010] Furthermore, the end faces of the upper and lower pressure rings are tapered, which is used to radially compress the drum seal sleeve under axial pressure. This efficiently converts the axial setting force into radial compressive force, allowing the drum seal sleeve to produce large radial deformation under low axial load, quickly forming a tight fit with the well wall, and improving the sealing response speed and reliability.

[0011] Furthermore, multiple slips are provided, along with corresponding multiple hinge plates and multiple traction mechanisms that match the slips. All slips and hinge plates are equidistantly arranged along the circumference of the main body. The combination of multiple circumferentially distributed slips and hinge plates ensures a uniform radial anchoring force distribution on the bridge plug during setting, significantly enhancing the bridge plug's resistance to torsion and axial slippage in the wellbore, and improving its overall stability under high-pressure fracturing conditions.

[0012] Furthermore, each of the slips has an anchor tooth on its outer surface, and the cone-shaped surface of the slip cone has a first anchor tooth. The first anchor tooth and the second anchor tooth form a double interlocking structure, which enhances the mechanical interlock between the slip cone and the slip, and between the slip and the well wall, respectively, significantly improving the pressure resistance and anti-slip performance of the anchoring system, making it particularly suitable for deep, high-stress formations.

[0013] A method for operating a removable-connectable bridge plug, based on the aforementioned bridge plug, includes the following steps: An axial setting force is applied to the bridge plug, driving the support cone downward to radially open the slips and anchor them to the well wall; the expansion of the slips pulls the hinge plate radially inward through the traction mechanism, and provides a driving force for the sliding body to move downward. When the driving force reaches a certain level, the shear pin is cut off, the sliding body continues to move downward, and the mushroom pin is radially pushed out through the conical inclined surface at its other end, so that the mushroom pin extends out of the base to provide a connection structure for interconnection with the top of the second bridge plug; The unsealing tool is lowered into the bridge plug from the wellhead. The unsealing tool is then used to pull the sliding body upwards. As the sliding body moves upwards, the conical slope at the other end releases pressure on the mushroom plug. The return spring drives the mushroom plug to retract radially, disconnecting it from the second bridge plug. Simultaneously, the conical slope at one end of the sliding body radially expands the hinge plate, thereby pulling the slip radially to release the anchoring via the traction mechanism. Finally, the bridge plug, now unsealed, is pulled out of the wellbore.

[0014] By using a single axial setting force, the three actions of anchoring, sealing, and connection extension are completed automatically and sequentially, achieving one-click setting connection. During unsealing, the connection and anchoring can be released simultaneously by simply lifting the sliding body, achieving complete and damage-free recovery of the bridge plug, significantly improving operational efficiency and protecting the integrity of the wellbore.

[0015] Furthermore, the applied axial setting force simultaneously drives the drum seal to expand radially, forming a seal at the anchoring position of the slip. Integrating the sealing process into the setting linkage ensures that the setting of the sealing ring and the anchoring of the slip are mechanically homogeneous and synchronous, guaranteeing a precise correspondence between the sealing position and the anchoring position, thus avoiding seal failure problems that may occur in traditional processes.

[0016] A series-connectable bridge plug system includes at least two of the aforementioned removable-connectable bridge plugs. A mushroom-shaped stud extending from the base of one bridge plug connects to the top of the body of the next bridge plug, allowing multiple bridge plugs to be series-connected and fixed within the wellbore. Through the mechanical interconnection between the mushroom-shaped studs and the body of the bridge plugs, multiple bridge plugs are connected in series downhole to form a single pressure-bearing structure, significantly improving the overall axial pressure resistance and impact resistance of the bridge plug string during staged fracturing, and achieving reliable isolation for multi-stage fracturing in long well sections.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes a support cone to drive the radial expansion of the slips, while a traction mechanism converts this expansion into the release of the axial lock on the sliding body. This drives the sliding body downwards, using its lower conical surface to push out the mushroom-shaped pin at the base. This allows the bridge plug to not only anchor to the wellbore via the slips during a single setting process but also automatically and synchronously extend the connecting device, connecting with the top of the bridge plug below. This enables a single bridge plug to become a series-connected node downhole. Furthermore, during retrieval, simply lifting the sliding body with external tools—a reverse operation—synchronously drives the mushroom-shaped pin to retract and the slips to shrink, achieving complete unsealing and lossless retrieval of the bridge plug. This invention solves the problems of existing bridge plugs being unrecoverable after setting and unable to be connected in series downhole. It allows multiple interconnected bridge plugs to be set sequentially in one tubing run, and all can be retrieved at once after fracturing, significantly reducing the number of tripping and drilling operations. This significantly improves the efficiency, economy, and wellbore safety of staged fracturing in unconventional oil and gas long horizontal wells. Attached Figure Description

[0018] Figure 1 This is a front view of the internal structure of the present invention.

[0019] Figure 2 for Figure 1 A schematic diagram of a local structure.

[0020] Figure 3 This is a front view of the external structure of the present invention.

[0021] Figure 4 This is a schematic diagram showing the structural relationship between the sliding body and the base.

[0022] The components are as follows: 1. Main body; 2. Opening cap; 3. Upper pressure ring; 4. Drum seal sleeve; 5. Lower pressure ring; 6. Pressure transmission ring; 7. Pressure bearing ring; 8. Support cone; 9. First anchor tooth; 10. Slip; 11. Second anchor tooth; 12. Pulley; 13. Steel cable; 14. Slip seat; 15. Hinge plate; 16. Sliding body; 17. Shear pin; 18. Mushroom nail; 19. Spring; 20. Base. Detailed Implementation

[0023] The following is combined Figures 1 to 4 The specific embodiments of the present invention will be described in detail below. In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0025] Example like Figure 1 and Figure 3 As shown, a removable-connectable bridge plug includes a main body 1, and further includes a fixing device, a linkage mechanism, and a connecting device.

[0026] The fixing device includes a slip 10 and a support cone 8. The slip 10 is arranged along the axial direction of the main body 1, with one end hinged to the main body 1 and the other end being a free end. A slip seat 14 is disposed on the outside of the main body 1, and the hinged end of the slip 10 is hinged to the slip seat 14. The support cone 8 is sleeved on the outside of the main body 1 and located at the free end of the slip 10. The support cone 8 mates with the inner surface of the slip 10 so that the slip 10 expands radially outward with its hinged end as the axis.

[0027] The linkage mechanism includes: a sliding body 16, a hinge plate 15, and a traction mechanism; such as Figure 2 and Figure 4As shown, the sliding body 16 is axially fixed to the main body 1 by shear pins 17, and both ends of the sliding body 16 are configured as tapered inclined surfaces; one end of the hinge plate 15 is hinged to the main body 1, and the other end moves radially inward toward the interior of the main body at the hinge point, and slides against the tapered inclined surface at one end of the sliding body 16 during radial movement; the traction mechanism includes: a steel cable 13 connected between the free end of the slip 10 and the hinge plate 15 and a pulley 12 for guiding the steel cable 13, the pulley 12 being fixedly installed inside the main body 1; the path of the steel cable 13 is configured such that when the slip 10 expands outward, it can pull the hinge plate 15 to move radially inward and abut against the top of the linkage sleeve 16.

[0028] The connecting device is set at the base 20 end of the main body 1, including: mushroom nail 18 and return spring 19; the mushroom nail 18 is radially inserted through the side wall of the base 20, the base 20 has a through hole, the tail end of the mushroom nail 18 is inserted in the through hole, and the head of the mushroom nail 18 slides against the tapered inclined surface of the other end of the sliding body 16; one end of the return spring 19 acts on the inner wall of the main body 1, and the other end acts on the head of the mushroom nail 18 for resetting the mushroom nail 18.

[0029] The inner surface of the bearing cone 8 is fitted to the outer surface of the main body 1 via a keyway or spline, allowing the bearing cone 8 to move only along the axial direction of the main body 1 and preventing relative rotation. This prevents the bearing cone from rotating or shifting circumferentially during the setting process, ensuring its downward trajectory is accurate. Consequently, the radial expansion of the slip 10 is uniform and reliable, improving the setting success rate and anchoring stability.

[0030] like Figure 1 As shown, the sealing and force transmission device includes: a drum-shaped sealing sleeve 4, a pressure-bearing ring 7, an upper pressure ring 3, and a lower pressure ring 5; the drum-shaped sealing sleeve 4 is fitted outside the main body 1; the pressure-bearing ring 7 is fitted outside the main body 1 and located between the drum-shaped sealing sleeve 4 and the supporting cone 8; the upper pressure ring 3 and the lower pressure ring 5 are located at the upper and lower ends of the drum-shaped sealing sleeve 4, respectively; the lower pressure ring 5 is connected to the pressure-bearing ring 7, and the pressure-bearing ring 7 is driven into contact or fixedly connected to the upper end of the supporting cone 8. While the bridge plug is anchored, a high-pressure sealing ring is formed in the adjacent area of ​​the slip 10, realizing the synchronous and reliable completion of the anchoring and sealing functions during the setting process, ensuring the sealing effectiveness of the fracturing operation.

[0031] The sealing and force transmission device also includes: a sealing cap 2 and a pressure transmitting ring 6; the sealing cap 2 is fixedly connected to the top of the main body 1 and is used to receive the setting force of the external setting tool; the pressure transmitting ring 6 is sleeved on the outside of the main body 1 and located between the sealing cap 2 and the upper pressure ring 3, and is used to transmit the setting force from the sealing cap 2 to the upper pressure ring 3. The sealing cap 2 and the pressure transmitting ring 6 form a clear axial force transmission path, smoothly and efficiently converting the concentrated force applied by the external setting tool into the squeezing of the drum sleeve 4 and the thrust of the bearing cone 8, thus optimizing the transmission efficiency of the setting force.

[0032] like Figure 1As shown, the opposite end faces of the upper pressure ring 3 and the lower pressure ring 5 are tapered, which is used to radially compress the drum seal sleeve 4 under axial pressure. This efficiently converts the axial setting force into radial compressive force, allowing the drum seal sleeve 4 to produce large radial deformation under low axial load, quickly forming a tight fit with the well wall, and improving the sealing response speed and reliability.

[0033] Multiple slips 10 are installed, along with multiple hinge plates 15 that match the slips 10 and multiple traction mechanisms. All slips 10 and hinge plates 15 are equidistantly arranged along the periphery of the main body 1. The combination of multiple circumferentially distributed slips 10 and hinge plates 15 ensures a uniform radial anchoring force distribution on the bridge plug during setting, significantly enhancing the bridge plug's resistance to torsion and axial slippage in the wellbore, and improving its overall stability under high-pressure fracturing conditions.

[0034] like Figure 1 As shown, each slip 10 has a second anchor tooth 11 on its outer surface, and the supporting cone 8 has a first anchor tooth on its conical surface. The first anchor tooth 9 and the second anchor tooth 11 form a double interlocking structure, which enhances the mechanical interlock between the supporting cone 8 and the slip 10, and between the slip 10 and the well wall, respectively, significantly improving the pressure resistance and anti-slip performance of the anchoring system, and is especially suitable for deep, high-stress formations.

[0035] A method for operating a removable-connectable bridge plug, based on the aforementioned bridge plug, includes the following steps: An axial setting force is applied to the bridge plug, driving the support cone 8 downward to radially open the slip 10 and anchor it to the well wall; the expansion of the slip 10 pulls the hinge plate 15 radially inward through the traction mechanism and gives the sliding body 16 a downward driving force. When the driving force reaches a certain level, the shear pin 17 is cut off, the sliding body 16 continues to move downward and radially pushes out the mushroom nail 18 through the conical inclined surface at its other end, so that the mushroom nail 18 extends out of the base 20 to provide a connection structure for interconnection with the top of the second bridge plug; The unsealing tool is lowered into the bridge plug from the wellhead. The unsealing tool is then used to pull the sliding body 16 upward. As the sliding body 16 moves upward, the conical slope at the other end releases the pressure on the mushroom nail 18. The return spring 19 drives the mushroom nail 18 to retract radially to disconnect it from the second bridge plug. At the same time, the conical slope at one end of the sliding body 16 radially expands the hinge plate 15, which in turn pulls the slip 10 radially to release the anchoring through the traction mechanism. Finally, the bridge plug in the unsealed state is pulled out of the wellbore.

[0036] By using a single axial setting force, the three key actions of anchoring, sealing, and connection extension are completed automatically and sequentially, achieving one-click setting and connection. During unsealing, the connection and anchoring can be simultaneously released by simply lifting the sliding body 16, achieving complete and damage-free recovery of the bridge plug, significantly improving operational efficiency and protecting the integrity of the wellbore.

[0037] The axial setting force applied during setting and connection simultaneously drives the drum sleeve 4 to expand radially, forming a seal at the anchoring position of the slip 10. Integrating the sealing process into the setting linkage chain ensures that the setting of the sealing ring and the anchoring of the slip are mechanically homogeneous and synchronous, guaranteeing a precise correspondence between the sealing position and the anchoring position, thus avoiding seal failure problems that may occur in traditional processes.

[0038] A series-connectable bridge plug system includes at least two of the aforementioned removable-connectable bridge plugs. A mushroom-shaped stud 18 extending from the base 20 of the previous bridge plug connects to the top of the body 1 of the next bridge plug, thus fixing multiple bridge plugs in series within the wellbore. Through the mechanical interconnection between the mushroom-shaped studs 18 and the body 1, multiple bridge plugs are connected in series downhole to form a single pressure-bearing structure, significantly improving the overall axial pressure resistance and impact resistance of the bridge plug string during staged fracturing, and achieving reliable isolation for multi-stage fracturing in long well sections.

[0039] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A removable-connectable bridge plug, comprising a body, characterized in that, Also includes: The fixing device includes: a slip, which is arranged along the axial direction of the main body, with one end hinged to the main body and the other end being a free end; and a support cone, which is sleeved on the outside of the main body and located at the free end of the slip, the support cone engaging with the inner surface of the slip so that the slip expands radially outward with its hinged end as the axis. The linkage mechanism includes: a sliding body axially fixed to the main body by shear pins, both ends of the sliding body being configured as tapered inclined surfaces; a hinge plate, one end of which is hinged to the main body, and the other end of which moves radially inward toward the interior of the main body at the hinge point, and slides against the tapered inclined surface at one end of the sliding body during radial movement; and a traction mechanism including: a steel cable connecting the free end of the slip and the hinge plate, and a pulley for guiding the steel cable; the path of the steel cable is configured such that when the slip expands outward, it can pull the hinge plate to move radially inward and abut against the top of the sliding body; A connecting device, disposed at the base end of the main body, includes: a mushroom-shaped nail, which is radially inserted through the side wall of the base, and the head of the mushroom-shaped nail slides against the tapered inclined surface at the other end of the sliding body; and a return spring, one end of which acts on the inner wall of the main body and the other end of which acts on the head of the mushroom-shaped nail.

2. The removable-connectable bridge plug according to claim 1, characterized in that, The inner surface of the support cone is engaged with the outer surface of the main body via a keyway or spline, allowing the support cone to move only along the axial direction of the main body.

3. A removable-connectable bridge plug according to claim 2, characterized in that, It also includes a sealing and force transmission device, which includes: a drum-shaped sleeve fitted outside the main body; a pressure-bearing ring fitted outside the main body and located between the drum-shaped sleeve and the support cone; an upper pressure ring and a lower pressure ring located at the upper and lower ends of the drum-shaped sleeve, respectively; the lower pressure ring is connected to the pressure-bearing ring, and the pressure-bearing ring is driven to contact or fixedly connected to the upper end of the support cone.

4. A removable-connectable bridge plug according to claim 3, characterized in that, The sealing and force transmission device further includes: a sealing cap, fixedly connected to the top of the main body, for receiving the setting force of an external setting tool; and a pressure transmission ring, sleeved on the outside of the main body and located between the sealing cap and the upper pressure ring, for transmitting the setting force from the sealing cap to the upper pressure ring.

5. A removable-connectable bridge plug according to claim 3, characterized in that, The end faces of the upper pressure ring and the lower pressure ring are tapered, which are used to radially compress the drum sleeve when subjected to axial pressure.

6. A removable-connectable bridge plug according to claim 1, characterized in that, Multiple slips are provided, and correspondingly multiple hinge plates and multiple traction mechanisms are provided to match the slips. The slips and hinge plates are all arranged at equal intervals along the periphery of the main body.

7. A removable-connectable bridge plug according to claim 6, characterized in that, Each of the card tiles has a second anchor tooth on its outer surface, and the support cone has a first anchor tooth on its conical surface.

8. A method of operating a removable-connectable bridge plug, based on the bridge plug according to any one of claims 1-7, characterized in that, Includes the following steps: An axial setting force is applied to the bridge plug, driving the support cone downward to radially open the slips and anchor them to the well wall; the expansion of the slips pulls the hinge plate radially inward through the traction mechanism, and provides a driving force for the sliding body to move downward. When the driving force reaches a certain level, the shear pin is cut off, the sliding body continues to move downward, and the mushroom pin is radially pushed out through the conical inclined surface at its other end, so that the mushroom pin extends out of the base to provide a connection structure for interconnection with the top of the second bridge plug; The unsealing tool is lowered into the bridge plug from the wellhead. The unsealing tool is then used to pull the sliding body upwards. As the sliding body moves upwards, the conical slope at the other end releases pressure on the mushroom plug. The return spring drives the mushroom plug to retract radially, disconnecting it from the second bridge plug. Simultaneously, the conical slope at one end of the sliding body radially expands the hinge plate, thereby pulling the slip radially to release the anchoring via the traction mechanism. Finally, the bridge plug, now unsealed, is pulled out of the wellbore.

9. The operating method according to claim 8, characterized in that, The applied axial setting force simultaneously drives the drum sleeve to expand radially, thereby forming a seal at the anchoring position of the slip.

10. A series-connected bridge plug system, characterized in that, It includes at least two removable-connectable bridge plugs as described in any one of claims 1-7, wherein a mushroom-shaped pin extending from the base of the previous bridge plug is connected to the top of the body of the next bridge plug, so that multiple bridge plugs are fixed in series within the wellbore.

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