US20110017475A1

US20110017475A1 - Nitinol Spring Through Tubing Bridge Plug

Info

Publication number: US20110017475A1
Application number: US12/752,879
Authority: US
Inventors: Gary Cresswell; Freeman Hill; William Befeld; Gregory Rinberg; Dan Raz; Michael Goldstein
Original assignee: Baker Hughes Inc
Current assignee: Baker Hughes Holdings LLC
Priority date: 2009-04-03
Filing date: 2010-04-01
Publication date: 2011-01-27
Also published as: WO2010115188A3; WO2010115188A2

Abstract

A bridge plug assembly that can be set in a wellbore tubular using wellbore pressure to form a pressure differential on a piston that actuates sliding members. A resilient member, such as a spring, is compressed from a downhole pressure differential. The bridge plug assembly can be removed by equalizing pressure across the piston and the spring. The spring can expand and re-stow the expanded plug. The plug can be formed from a nickel titanium alloy flexible member that can be selectively radially expanded so its outer surface sealingly engages a surrounding tubular. The percentage of weight of nickel can range up to about 40 to about 58%, 55% or to about 60%.

Description

RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Application No. 61/166,489, filed on Apr. 3, 2009, the full disclosure of which is hereby incorporated by reference herein.

BACKGROUND

1. Field of Invention
The invention relates generally to the field of oil and gas production. More specifically, the present invention relates to a system and method for plugging tubing within a borehole.
2. Description of Prior Art
Downhole plugs are used to block flow through a wellbore tubular and can be formed from an elastomeric membrane on a mandrel or coaxially stacked members. Downhole plugs can be selectively set into place by expanding the membrane or collapsing the stacked members to block the annular space within the mandrel. Plug or packer setting can occur by axially compressing the mandrel or by filling the membrane with a pressurized fluid. The tubulars can be casing or production tubing.

SUMMARY OF INVENTION

Disclosed herein is a bridge plug that can be set to block flow in a tubular, or to block flow in an annulus between two tubulars. In one example, the plug includes a nickel titanium alloy flexible member that can be selectively radially expanded so its outer surface sealingly engages a surrounding tubular. In an example embodiment a bridge plug assembly for plugging a tubular within a wellbore is described herein that includes an elongate mandrel, an actuation sleeve circumscribing the mandrel, a first reservoir within the actuation sleeve, a plug section on the mandrel and adjacent the actuation sleeve and selectively moveable from a substantially cylindrical insertion configuration to a radially bulging plugging configuration, a second reservoir disposed between the first reservoir and the plug section, and a sealing barrier between the first and second reservoir and coupled to the actuation sleeve. When pressure in the first reservoir is greater than the second reservoir pressure it pushes the barrier into the second reservoir, this in turn urges the actuation sleeve into compressive engagement with the plug section and convert the plug section to the radially bulging plugging configuration. Valves that selectively open and close may be included that each have an end in fluid communication with the wellbore and an opposite end in fluid communication with the first reservoir, other valves may have an end in fluid communication with the wellbore and an opposite end in fluid communication with the second reservoir. A flow circuit can be in the mandrel that is made up of interconnected axial and radial passages, a valve actuator can be included that is coupled with the mandrel and selectively provides fluid communication between the flow circuit and the second reservoir. Another flow circuit may be set in the mandrel that is made up of axial and radial passages that interconnect, a valve actuator can be coupled with the mandrel that selectively provides fluid communication between the first reservoir and the second reservoir. A deployment module can be included that is attachable to an end of the actuation sleeve. The bridge plug assembly may further include a spring coaxially disposed in the mandrel and selectively compressible. Equalizing fluid pressure across the barrier allows the spring to axially expand and selectively move the plug section back to the substantially cylindrical insertion configuration from the radially protruding configuration. An outer shell made of a nickel titanium alloy can be optionally included on the outer periphery of the plug section.
Also included and described herein is a method of plugging a tubular within a wellbore. In an example the method includes providing a bridge plug assembly in the tubular. The bridge plug assembly can have a mandrel, an actuation sleeve circumscribing the mandrel. Adjacent the sleeve can be a plug element on the mandrel that is selectively configurable between a substantially cylindrical configuration to a bulbous configuration. By axially urging the actuation sleeve against the plug element the plug element changes from the substantially cylindrical configuration into the bulbous configuration to plug the tubular. Urging the sleeve can be done by directing pressure from the wellbore along the axis of the bridge plug assembly. The bridge plug assembly can further include a reservoir and a piston that is axially slidable into the reservoir; the piston can be coupled with the actuation sleeve. A resilient member can be axially disposed in the mandrel, an example embodiment of a step of the method includes compressing the spring by forming a pressure differential along the spring. Removing the pressure differential along the spring enables the spring to exert an expansive force. Directing the spring force across the plug element can return the plug element to the substantially cylindrical configuration from the bulbous configuration. In an example embodiment, the plug element is made of an outer shell formed from a nickel titanium alloy, optionally, the plug element is made from an outer shell formed from an elastomer. A flow circuit may optionally be provided in the mandrel formed from axial and radial passages that interconnect. Also included may be a valve actuator that is coupled with the mandrel for selectively providing fluid communication between the first reservoir and the second reservoir. In an example step, the method described herein includes actuating the valve actuator to provide fluid communication between the first and second reservoirs. Another flow circuit may be included in the mandrel also made up of interconnected axial and radial passages. A valve actuator can optionally be included that is coupled with the mandrel for selectively provides fluid communication between the flow circuit and the second reservoir. In an example, the valve actuator is actuated to provide fluid communication between the flow circuit and the second reservoir. An actuation module can be included with the bridge plug assembly and a step of removing the actuation module from the bridge plug assembly can be performed with the actuation module. The actuation module can be reattached to the bridge plug assembly and a valve in the bridge plug assembly actuated to equalize pressure to the actuation sleeve. This moves the plug element so that the plug element changes to the substantially cylindrical configuration from the bulbous configuration. The bridge plug assembly can then be removed from the tubular. In an alternative example, the plug element is changed to the substantially cylindrical configuration from the bulbous configuration by compressing a spring within the mandrel with a pressure differential, then removing the pressure differential along the spring. This releases the spring to exert an expansion force, by directing the expansive force from the spring along an axis of the plug element the plug element is returned to the substantially cylindrical configuration.

BRIEF DESCRIPTION OF DRAWINGS

Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:

FIGS. 1A-1C are side views an example of a through tubing bridge plug being set in a wellbore in accordance with embodiments of the present disclosure.

FIGS. 2A-2D are schematic views of an alternative through tubing bridge plug.

FIGS. 3A-3D are side and sectional views of a plug for use in a bridge plug assembly in an insertion configuration and expanded plugging configuration.

FIGS. 4A-4C are sectional views an example of a through tubing bridge plug being set in a wellbore in accordance with embodiments of the present disclosure.

While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF INVENTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. For the convenience in referring to the accompanying figures, directional terms are used for reference and illustration only. For example, the directional terms such as “upper”, “lower”, “above”, “below”, and the like are being used to illustrate a relational location.
It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.
The present disclosure is directed to a system that blocks or plugs the inside of a tubular, such as tubing, wherein the tubular is in a wellbore. FIGS. 1A-1C illustrate in side view an example of a bridge plug assembly 10 being set within a wellbore tubular. FIG. 1A illustrates the bridge plug assembly 10 in an insertion or deploying mode, i.e., when being inserted from surface into the tubular. In this embodiment, the bridge plug assembly 10 includes a series of elongate sections or modules coaxially coupled to one another. An annular deployment module 12 is shown circumscribing a deployment mandrel 13 that protrudes from within the deployment module 12 to define an end of the bridge plug assembly 10. An annular plunger module 16 telescopingly circumscribes the deployment module 12 on an end distal the deployment mandrel 13. The end of the plunger module 16 opposite the deployment module 12 connects to an annular actuation module 24. A plug section 30 couples on the end of the actuation module 24 distal from the plunger module 16. A cylindrically shaped base sub 38 is shown attached on an end of the plug section 30. An inner mandrel 42 extends outward from the shaped base sub 38 in a direction opposite the plug section 30.
Illustrated in FIG. 1B is a side view example of the bridge plug assembly 10 being set within a tubular 8. As shown, the plug section 30 is axially compressed causing its mid portion to expand radially outward into sealing contact with the tubular 8 inner circumference. The plunger module 16 is shown in FIG. 1B having telescoped away from the deployment mandrel 13 thereby exposing more surface area of the deployment module 12. In one example embodiment, the inner mandrel 42 couples with the deployment mandrel 13, and the base sub 38 anchors onto the inner mandrel 42. Axially motivating the plunger module 16 against the plug section 30 produces the outward radial deformation of the plug section 30. In FIG. 1C, the bridge plug assembly 10 is shown in a fully set mode with the deployment module 12 having been removed from the rest of the assembly 10. When in the set mode, the bridge plug assembly 10 can remain within a tubular indefinitely.
FIGS. 2A-2D provide schematic views of an example of a bridge plug assembly 10A being used within a wellbore W. In this example fluid reservoirs R₁and R₂are provided within the plunger module 16A and actuation module 24A that are separated by a barrier B. The barrier B may be coupled with one of the plunger module 16A or actuation module 24A Fluid is shown in the reservoirs R₁and R₂, in an example the fluid is at a pressure less than the pressure ambient in the wellbore W. A resilient member, such as a spring S is shown coaxially set within the bridge plug assembly 10A. Within the wellbore W, a valve V₁can be actuated that ports higher pressure fluid from the wellbore W to the reservoir R₁, the barrier B seals between the reservoirs R₁and R₂so that a force is applied to the barrier B and transferred to the plunger module 16A and/or actuation module 24A. The plunger and actuation modules 16A, 24A may telescope along the length of the plunger assembly 10A, thus the axially applied force from the barrier B slides the plunger and actuation modules 16A, 24A towards the plug section 30A. The plug section 30A, which includes a resilient outer shell 41, does not telescope along the bridge plug assembly 10A, but is compressed causing the resilient outer shell 41 to protrude radially outward as shown in FIG. 2B into contact with the tubular 8. Ports (not shown) may direct fluid from reservoir R₂to within the protruding outer shell 41.
Referring to FIG. 2C, the deployment module 12A, which in an example embodiment operates as a setting tool to actuate the bridge plug assembly 10A, has been removed thus allowing the bridge plug assembly 10A to remain in the wellbore W and plug the tubular 8. By removing the deployment module 12A, fluid pressure from the wellbore W communicates to the spring S to form a compressed spring S_C. Valves and/or ports connected to the reservoirs R₁and R₂remain closed to seal the fluid in the reservoirs R₁and R₂. In FIG. 2D, deployment module 12A is being reset into the bridge plug assembly 10A for retrieval of the bridge plug assembly 10A from within the wellbore W. Through the deployment module 12A, or an alternative remote telemetry system, valve V₂is opened so that wellbore pressure can communicate into the plug section 30A and reservoir R₂to equalize pressure between the barrier B. Without the pressure differential across the barrier B, the spring S can expand, when expanding the spring S exerts an axial force to the inner mandrel 42A that is transferred to the base sub 38A. The deployment module 12A couples into the plunger module 16A, so that the expanding spring axially stretches the plug section 30A to draw the outer shell 41 radially inward as shown in FIG. 2D.
In an example, material for forming the outer shell 41 may include a nickel titanium alloy, wherein the percentage of weight of nickel ranges up to about 60%, in one embodiment where it ranges from about 40 to about 58% and in another embodiment about 55%. This alloy can be either an austenite or martensite phase. In an unstressed environment, the nickel titanium alloy can be in an austenite structure. It should be noted that in the configuration of FIGS. 2B and 2C, the outer shell 41 has a planar section proximate to its midsection. Retaining the expanded midsection as a planar configuration, enhances the sealing contact between the plug section 30A and tubular 8. Optionally, the outer shell 41 can be made from an elastomeric material, a memory metal, or combinations thereof.
FIGS. 3C and 3D illustrate examples of the plug section 30 in an initially produced and expanded configuration that is used for sealing within the tubular 8 and are shown respectively in side perspective views and a side partial sectional view. Referring now to FIG. 3C, the plug section 30 is shown having an outer flexible member 31 that encases a helically-wound spring 32. The spring 32 is made up of a wound elastic spring member 36 encased in a laminate 37. Material for forming the spring member 36 may include a nickel titanium alloy, wherein the percentage of weight of nickel ranges up to about 60%, in one embodiment where it ranges from about 40 to about 58% and in another embodiment about 55%. This alloy can be either an austenite or martensite phase. The laminate 37 can be any elastic material including elastomers and polymeric compounds. In this initial configuration the nickel titanium alloy can be in an austenite structure. It should be noted that in the configuration of FIGS. 3C and 3D, the plug section 30 includes a planar section proximate to its midsection. Retaining the expanded midsection as a planar configuration, enhances the sealing contact between the plug section 30 and tubular.
In an alternative example, the plug section 30 can be changed from the bulbous configuration of FIGS. 3C and 3D for insertion into a tubular 8 by axially applying a torque about the axis A_Xof the spring 32; as illustrated by the arrow in FIG. 3C. Converting the plug section 30 for tubular insertion forms the substantially cylindrical configuration depicted in FIGS. 3A and 3B; where the insertion mode configuration of the plug section 30 is illustrated respectively in a side perspective view and a side partial sectional view. Fixing opposing ends of the spring 32 can retain the plug section 30 in the insertion configuration. The axial torque can be applied to the spring 32 before or after it is coupled with the plug assembly 10. In the insertion configuration the nickel titanium alloy has an austenite-martensite structure. In an example embodiment, the maximum deformation of the nickel titanium does not exceed 8%, optionally, the maximum deformation does not exceed 6%. By releasing one end of the spring 32, while in the insertion configuration, allows the spring 32 to unwind and return to the sealing configuration of FIGS. 2A and 2B.
FIGS. 4A-4C illustrate an example embodiment of the bridge plug assembly 10 in a sectional view and depict sequences of setting the assembly 10 within the tubular 8. Referring now to FIG. 4A, a sectional view of the deployment module 12 is shown having inserted therein the deployment mandrel 13. A deployment manifold 14 is formed through the mandrel 13. A housing 15 circumscribes the mandrel 13 to define an annular space between the mandrel 13 and housing 15. The plunger module 16 includes an elongated plunger body 18 having a manifold 19 formed within the body 18. The plunger module 16 includes an annular sleeve 17 disposed along its outer periphery that is set radially outward from the body 18 to define an annular plunger reservoir 20 between the body 18 and sleeve 17. The plunger body 18 includes a mandrel-type portion having an outer attachment that lines the mandrel portion and radially transitions outward to provide a flange along the mandrel mid portion. The inner radius of the sleeve 17 is profiled to form an inwardly depending shoulder 21 on an end of the sleeve proximate the actuation module 24. The reservoir 20 is disposed axially between the shoulder 21 and the flange on the plunger body 18.
A spring body 22 between the plunger module 16 and actuation module 24 attaches coaxially with the plunger body 18. The spring body 22 includes a cylindrical cavity coaxially aligned with an axis A_Xof the assembly 10; a spring 23 is shown disposed within the cavity. A passage 29 provides fluid communication between the cavity and the spring body 22 lower end. Included within the actuation module 24 is an actuation mandrel 27 shown substantially coaxial with the bridge plug assembly 10 and having its upper end coupled to the spring body 22 lower end. The actuation mandrel 27 includes a manifold 28 made up of an elongated axial passage formed through the mandrel 27 and passages lateral to the axial passage. The axial passage of the manifold 28 is in fluid communication with the passage 29 on its upper end. Circumscribing the actuation mandrel 24 is an actuation sleeve 25 that couples with the plunger sleeve 17 on its upper end and extends into coupling arrangement with the plug section 30 on its lower end. The actuation mandrel 27 extends downward into the plug section 30 transitioning into a plug mandrel 33 within the plug section 30. The plug mandrel 33 extends through the plug section 30 and transitions into the inner mandrel 42. A plug manifold 34 extends through the plug and inner mandrels 33, 42 and includes a lateral passage connecting with the space surrounding the plug mandrel 33 upper end. The base sub 38 includes a housing 40 on its outer surface and is held to the inner mandrel by a spring nut 39. An actuation reservoir 26 is provided in the annular space between the spring body 22 lower end and actuation mandrel upper end and the actuation sleeve 25. Prior to the bridge plug assembly 10 being deployed into a wellbore, fluid can be provided in the plunger reservoir 20 and actuation reservoir 26. The fluid can be at the substantially the same pressure. In an example, the pressure in the reservoirs 20, 26 is less than pressure within a wellbore.
Referring now to FIG. 4B, the plunger module 16 has moved from its position in FIG. 4A and toward the plug section 30. As noted above, this can occur by actuating valving (not shown) that communicates fluid from the wellbore to the plunger reservoir 20. As further depicted in FIG. 4B, the plunger sleeve 17 has moved downward due to a pressure differential against the shoulder 21 caused by the higher pressure wellbore fluid. This movement enlarges the plunger reservoir 20 and significantly reducing the volume in the actuation reservoir 26. In an alternative, this can be caused by selectively actuating valving within the manifolds 19, 28, 34 or pressurizing the plunger reservoir 20 thereby expanding its volume to allow the actuation sleeve 25 to axially slide as shown.
Fluid from the actuation reservoir 26 may flow into an annular reservoir 43 shown defined between the actuation sleeve 25 and plug mandrel 33. This fluid can also fill the expanded plug section. Once the bridge plug assembly 10 is set and blocks flow in the tubular 8, the deployment module 12 can be removed thereby exposing a side of a spring piston 53 to pressure in the wellbore. Below the spring piston 53 is the spring 23A, shown in a compressed configuration due to a pressure differential between the upper end of the spring piston 53 and lower end of the spring 23A. The bridge plug assembly 10 can be removed by reinserting the deployment module 12 and actuating valving or ports to eliminate any pressure differentials across the shoulder 21. In an example, a valve actuator 45 is shown circumscribing the plug mandrel 33 and adjacent lateral ports in the plug mandrel 33. Wellbore fluid may be introduced into the reservoir 43 by actuation of the valve actuator 45 to register the lateral ports to a flow path (not shown) in communication with the reservoir 43. Further communicating the higher pressure fluid to the actuation reservoir 26 eliminates the pressure differential on the shoulder 21. A valve sleeve 47 shown circumscribing the actuation mandrel 27 adjacent the valve actuator 45 can be axially manipulated to register lateral ports in the mandrels 33, 27 for fluid communication to the reservoirs 43, 26. Removing the pressure differential allows the spring 23 to expand and exert an axial force that is ultimately transmitted to the base sub 38 for returning the plug section 30 to its original configuration of FIG. 4A. A valve V^Pis shown in the spring piston 53 that may optionally be opened to equalize fluid pressure between the wellbore and adjacent the spring 23.
In an alternative example embodiment, the plug section 30 includes the spring 32 shown helically wound around the plug mandrel 33 and covered with the flexible member 31. As discussed above, the spring 32 is torqued into the insertion or cylindrically shaped configuration (FIGS. 3A and 3B) and held in place in the embodiment of FIG. 4A. Without the resistance of the fluid trapped in the actuation reservoir 26, force in the torqued spring 32, unwinds the spring 32 allowing to radially expand as it slides the actuation sleeve 2 downward. After the flexible member 31 has radially expanded to sealingly engage the tubular 8, the valving within the manifolds 19, 28, 34 can be shut and the deployment module 12 removed as illustrated in FIG. 4C.
The present invention described herein, therefore; is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.

Claims

1. A bridge plug assembly for plugging a tubular within a wellbore comprising:

an elongate mandrel;

an actuation sleeve circumscribing the mandrel;

a first reservoir within the actuation sleeve;

a plug section on the mandrel and adjacent the actuation sleeve and selectively moveable from a substantially cylindrical insertion configuration to a radially bulging plugging configuration;

a second reservoir disposed between the first reservoir and the plug section; and

a sealing barrier between the first and second reservoir and coupled to the actuation sleeve, so that when pressure in the first reservoir exceeds the second reservoir, the barrier is urged into the second reservoir and the actuation sleeve is urged into compressive engagement with the plug section to move the plug section to the radially bulging plugging configuration.

2. The bridge plug of claim 1, further comprising a selectively open and closed valve having an end in fluid communication with the wellbore and an opposite end in fluid communication with the first reservoir.

3. The bridge plug of claim 1, further comprising a selectively open and closed valve having an end in fluid communication with the wellbore and an opposite end in fluid communication with the second reservoir.

4. The bridge plug of claim 1, further comprising a flow circuit in the mandrel made up of axial and radial passages that interconnect and a valve actuator coupled with the mandrel that selectively provides fluid communication between the flow circuit and the second reservoir.

5. The bridge plug of claim 1, further comprising a flow circuit in the mandrel made up of axial and radial passages that interconnect and a valve actuator coupled with the mandrel that selectively provides fluid communication between the first reservoir and the second reservoir.

6. The bridge plug of claim 1, further comprising a deployment module attachable to an end of the actuation sleeve.

7. The bridge plug of claim 1, further comprising a spring coaxially disposed in the mandrel and selectively compressible, so that when fluid pressure across the barrier is equalized, the spring axially expands and selectively moves the plug section to the substantially cylindrical insertion configuration.

8. The bridge plug of claim 1, further comprising an outer shell on the outer periphery of the plug section comprising a nickel titanium alloy.

9. A method of plugging a tubular within a wellbore comprising:

providing in the tubular a bridge plug assembly having a mandrel, an actuation sleeve circumscribing the mandrel, and adjacent the sleeve a plug element on the mandrel that is selectively configurable between a substantially cylindrical configuration to a bulbous configuration; and

axially urging the actuation sleeve against the plug element by directing pressure from the wellbore along the axis of the bridge plug assembly so that the plug element changes from the substantially cylindrical configuration into the bulbous configuration to plug the tubular.

10. The method of claim 9, wherein the bridge plug assembly further comprises a reservoir and a piston axially slidable into the reservoir and that is coupled with the actuation sleeve.

11. The method of claim 9, wherein the bridge plug assembly further comprises a resilient member axially disposed in the mandrel, the method further comprising compressing the spring by forming a pressure differential along the spring.

12. The method of claim 11, further comprising removing the pressure differential along the spring so that the spring exerts a force to expand and directing the spring force across the plug element so that the plug element returns to the substantially cylindrical configuration from the bulbous configuration.

13. The method of claim 9, wherein the plug element comprises an outer shell formed from a nickel titanium alloy.

14. The method of claim 9, wherein the plug element comprises an outer shell formed from an elastomer.

15. The method of claim 9, wherein a flow circuit is provided in the mandrel and made up of axial and radial passages that interconnect and a valve actuator coupled with the mandrel that selectively provides fluid communication between the first reservoir and the second reservoir, the method further comprising actuating the valve actuator to provide fluid communication between the first and second reservoirs.

16. The method of claim 9, wherein the bridge plug assembly further comprises a flow circuit in the mandrel made up of axial and radial passages that interconnect and a valve actuator coupled with the mandrel that selectively provides fluid communication between the flow circuit and the second reservoir, the method further comprising actuating the valve actuator to provide fluid communication between the flow circuit and the second reservoir.

17. The method of claim 9, wherein the bridge plug assembly further comprises an actuation module, the method further comprising removing the actuation module from the bridge plug assembly.

18. The method of claim 17, the method further comprising reattaching the actuation module to the bridge plug assembly, actuating a valve in the bridge plug assembly to equalize pressure to the actuation sleeve, and moving the plug element so that the plug element changes to the substantially cylindrical configuration from the bulbous configuration, and removing the bridge plug assembly from the tubular.

19. The method of claim 17, wherein the step of moving the plug element so that the plug element changes to the substantially cylindrical configuration from the bulbous configuration comprising compressing a spring within the mandrel with a pressure differential, then removing the pressure differential along the spring so that the spring exerts a force to expand and directing the spring force across the plug element so that the plug element returns to the substantially cylindrical configuration from the bulbous configuration.