PACKER APPARATUS

Abstract

A packer apparatus is disclosed. Packer apparatus comprises a body configured to be disposed in a wellbore and a deformable packer element disposed on the body. The deformable packer element comprises a deformable metallic outer cover. An actuation apparatus is configured to move relative to the body to deform said deformable packer element outwardly from the body to cause the deformable metallic outer cover to contact the surface of the wellbore or casing in which the apparatus is located. Deactivation of the actuation apparatus causes the deformable packer element and deformable metallic outer cover to return to a retracted condition.

Claims

1. A packer apparatus for engaging a surface of a wellbore or wellbore casing to create an annular seal or deform the wellbore casing, the apparatus comprising: a body configured to be disposed in a wellbore; a deformable packer element disposed on the body, the deformable packer element comprising a deformable metallic outer cover; and actuation apparatus configured to move relative to the body to deform said deformable packer element outwardly from the body to cause said deformable metallic outer cover to contact the surface of the wellbore or casing in which the apparatus is located; wherein deactivation of the actuation apparatus causes the deformable packer element and deformable metallic outer cover to return to a retracted condition.

2. An apparatus according to claim 1, wherein said deformable packer element further comprises a chamber configured to contain fluid, such that when the actuation apparatus is activated, said fluid is pressurised to deform said deformable metallic outer cover outwardly.

3. An apparatus according to claim 2, further comprising at least one floating piston disposed at an end of said chamber, wherein said actuation apparatus is configured to move said floating piston to pressurise said fluid disposed in the chamber.

4. An apparatus according to claim 2, wherein said fluid is compressible such that when the actuation apparatus is deactivated, said fluid expands to return the deformable packer element to a retracted condition.

5. An apparatus according to claim 2, wherein said fluid is incompressible and said deformable packer element further comprises a return spring or elastomeric element disposed in said chamber such that deactivation of the actuation apparatus causes the return spring or elastomeric element to expand to return the deformable packer element to a retracted condition.

6. An apparatus according to claim 1, wherein said deformable packer element further comprises an elastomeric element such that when the actuation apparatus is activated, said elastomeric deforms said deformable metallic outer cover outwardly, and when said actuation apparatus is deactivated, said elastomeric element expands to return the deformable packer element to a retracted condition.

7. An apparatus according to claim 6, wherein said elastomeric element is disposed in a chamber having a floating piston disposed at an end of said chamber, and wherein said actuation apparatus is configured to move said floating piston to compress said elastomeric element disposed in the chamber.

8. An apparatus according to claim 7, further comprising fluid disposed in said chamber.

9. An apparatus according to claim 1, wherein deformable packer element is rotatably mounted on said body.

10. An apparatus according to claim 1, wherein said actuation apparatus comprises a plurality of hydraulic cylinders configured to compress said deformable packer element in response to an increase in fluid pressure in each of said hydraulic cylinders.

11. An apparatus according to claim 10, wherein said actuation apparatus further comprises at least one mandrel element at least partially defining a longitudinal bore of the apparatus, said at least one hydraulic cylinder slidably disposed on said at least one mandrel element and being in fluid communication with said longitudinal bore.

12. An apparatus according to claim 11, further comprising a locking apparatus configured to prevent said at least one hydraulic cylinder moving relative to said at least one mandrel element, the locking apparatus comprising: at least one shear pin configured to prevent relative movement between said at least one hydraulic cylinder and said at least one mandrel element; and a restriction disposed in said longitudinal bore for engaging a ball or dart dropped into the longitudinal bore to block the longitudinal bore to enable fluid pressure to increase to shear said at least one shear pin and enable relative movement between said at least one hydraulic cylinder and said at least one mandrel element.

13. An apparatus according to claim 1, wherein said body portion at least partially defines a longitudinal bore of the apparatus, and wherein the apparatus further comprises at least one valve assembly disposed in said longitudinal bore, said at least one valve assembly configured to permit fluid to enter said longitudinal bore when the apparatus is moved into a wellbore containing fluid.

14. An apparatus according to claim 13, wherein said at least one valve assembly is configured to close when fluid is pumped into the longitudinal bore to enable fluid pressure to increase in the apparatus.

15. A workstring comprising: a first packer apparatus according to claim 1; a second packer apparatus according to claim 1; and a ported sub comprising ports, the ported sub connected between said first and second packer apparatuses.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Preferred embodiments of the present disclosure will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings in which:

[0037] FIG. 1a is a longitudinal cross-section of a packer apparatus for engaging a surface of a wellbore or wellbore casing to create an annular seal or deform the wellbore casing in accordance with a first embodiment of the present disclosure, in which the deformable packer element is shown in an undeformed retracted condition;

[0038] FIG. 1b is a longitudinal cross-sectional drawing of the apparatus of FIG. 1a showing the deformable packer element in the outwardly deployed condition;

[0039] FIG. 2a is a longitudinal cross-section of a packer apparatus of a second embodiment of the present disclosure;

[0040] FIG. 2b is a longitudinal cross-sectional view of the packer apparatus of FIG. 2a showing the deformable packer element in the outwardly deployed condition;

[0041] FIG. 3a is a longitudinal cross-sectional view of a packer apparatus of a third embodiment of the present disclosure;

[0042] FIG. 3b is a longitudinal cross-section corresponding to FIG. 3a showing the deformable packer element in the outwardly deployed condition;

[0043] FIG. 3c is a cross-sectional view taken along line G-G of FIG. 3a;

[0044] FIG. 4a is a longitudinal cross-section of the packer apparatus of FIG. 1a comprising a locking mechanism;

[0045] FIG. 4b is a longitudinal cross-section corresponding to FIG. 4a showing the locking mechanism in the released condition;

[0046] FIG. 4c is a cross-sectional view taken along line C-C of FIG. 4a;

[0047] FIG. 4d is a cross-sectional view taken along line D-D of FIG. 4b;

[0048] FIG. 4e is a close-up of section E of FIG. 4a;

[0049] FIG. 4f is a close-up of section F of FIG. 4b;

[0050] FIG. 5 is a longitudinal cross-section of a workstring comprising two of the packers of FIGS. 1a and 1b connected either side of a ported sub;

[0051] FIG. 6 is a longitudinal cross-section of a workstring incorporating two packer apparatuses of FIG. 1a disposed either side of a ported sub, the workstring also comprising a surge valve system;

[0052] FIG. 7a is a cross-sectional view of the packer apparatus of FIG. 1a shown disposed in wellbore casing; and

[0053] FIG. 7b is a cross-sectional view corresponding to FIG. 7a showing the packer apparatus in use to deform wellbore casing.

DETAILED DESCRIPTION OF THE INVENTION

[0054] Referring to FIGS. 1a and 1b, a packer apparatus 2 for engaging a surface of a wellbore or wellbore casing to create an annular seal or deform the wellbore casing comprises a body 4 configured to be disposed in a wellbore and a deformable packer element 6 disposed on the body 4. The deformable packer element 6 comprises a deformable metallic outer cover 8.

[0055] An actuation apparatus 10 is configured to move relative to the body 4 to deform said deformable packer element 6 outwardly from the body 4 (FIG. 1b) to cause the deformable metallic outer cover 8 to contact the surface of the wellbore or casing in which the apparatus is located. Deactivation of the actuation apparatus 10 causes the deformable packer element 6 and deformable metallic outer cover 8 to return to a retracted condition.

[0056] Depending on the alloy used to form the deformable metallic outer cover 8, after deactivation of the actuation means, the deformable metallic outer cover might not completely return to the undeformed state of FIG. 1a, but will retract sufficiently to release any seal and disengage from the surface of the casing or wellbore to prevent drag and enable repeated re-deployment. A nickel based high-performance alloy such as Inconel 625 is preferred to form the deformable metallic outer cover 8 as such materials have a high nickel content for corrosion resistance and are relatively soft and ductile.

[0057] The actuation apparatus 10 comprises a plurality of hydraulic cylinders 12 disposed on mandrel elements 14 which define a longitudinal bore 16 of the packer apparatus 2. A plurality of internal ports 18 enables fluid communication between the longitudinal bore 16 and the hydraulic cylinders 12. Each hydraulic cylinder 12 comprises a piston element 20, a housing portion 22 and an annular port 24 on one side of the piston element 20 opposite to the hydraulic cylinder to provide fluid communication with the outside of the packer apparatus 2. When hydraulic fluid pressure increases in longitudinal bore 16, fluid pressure is communication through internal ports 18 to hydraulic chambers 12 to increase fluid pressure in the hydraulic chambers 12. This creates a pressure differential to the volume on the opposite side of piston elements 20 which if sufficient pushes actuation apparatus 10 and causes annular fluid to vent through annular ports 24 to enable the actuation apparatus 10 to move to compress the deformable packer element 6.

[0058] Deformable packer element 6 comprises a deformable metallic outer cover 8 defining a chamber 30. A floating piston 32 closes off chamber 30 which is filled with fluid which might for example be oil or water. Movement of actuation apparatus 10 from the position of FIG. 1a to FIG. 1b moves floating piston 32 to compress the fluid in chamber 30 and deform the deformable metallic cover 8 outwardly to the position of FIG. 1b. This causes deformable metallic outer cover 8 to engage the surface of the wellbore and form a seal.

[0059] The deformable packer element 6 is rotatably mounted on body 4 by means of ball bearings 36. Referring to FIGS. 1a, 3a and 3c, although FIGS. 3a and 3c refer to the second embodiment of the packer apparatus which will be described in further detail below, the means of enabling rotation of the deformable packer element 6 relative to the body 4 is the same for all embodiments such that FIG. 3c is relevant to the first embodiment of FIGS. 1a and 1b. Ball bearings 36 are held in a channel 39 defined between an outer retaining sleeve 5 of the deformable packer element 6 and the body 4. A plurality of ball bearings 36 fills channel 39 and are retained by NPT plug 37. In all embodiments, three sets of ball bearings are shown which enable rotation and also act as thrust bearings. In addition to ball bearings 36, to assist rotation a bearing 33 is located between the end of the actuation apparatus 10 and the floating piston 32.

[0060] A return spring 34 is mounted in the chamber 30 such that when the actuation apparatus is deactivated, the deformable packer element 6 is returned to a retracted condition. Deactivation of the actuation apparatus 10 is accomplished by the operator reducing fluid pressure in longitudinal bore 16 to equalise with the outside annulus such that there is no pressure differential between hydraulic chambers 12 and the annulus outside of the apparatus 2.

[0061] Instead of a return spring 34, another biasing means such as an elastomeric element could be used. If the fluid in chamber 30 is an incompressible fluid such as water or an incompressible oil, the return spring 34 (or other biasing means) is required to ensure that the deformable packer element returns to a retracted condition after use. However, if the chamber 30 is filled with a compressible fluid such as a compressible oil, the natural resilience of the compressible fluid will be sufficient to expand after the actuation apparatus 10 is deactivated to return the deformable packer element to a retracted condition after use for redeployment at a different position along the wellbore. It should also be noted that the packer apparatus 2 will generally be operated in a workstring by locating the packer apparatus at the farthest point along a wellbore from the surface for an initial sealing operation. Once that sealing operation has been completed, the workstring is pulled to the next point along the wellbore for sealing. The action of pulling the packer apparatus also aids in returning the deformable packer element 106 and therefore the deformable metallic outer cover to a retracted condition.

[0062] In some circumstances, it is desirable to have the deformable packer element 6 very close to the surface of the casing or the wellbore on which the apparatus 2 is disposed. However, this creates a problem that the fluid already in the wellbore or casing must be displaced to enable the workstring containing the packer apparatus 2 to be moved into the wellbore. Moving a close tolerance workstring into a fluid filled wellbore can cause a fluid surge leading to an uncontrolled release of fluid at the surface. For this reason, a first valve 40 comprising a spring-loaded ball 42 is mounted in longitudinal bore 16. When the apparatus 2 is moved into a wellbore containing fluid, the fluid pushes ball 42 against spring 44 to enable a fluid path up through longitudinal bore 16.

[0063] A second valve assembly 50 comprises a spring-loaded sleeve 52 having internal ports 54 configured to align with external ports 56 formed through the body portion 4 when ball 58 pushes the sleeve 52 against the force of spring 60. This creates a second fluid path to allow wellbore fluid to move. When the operator wishes to pressure up the apparatus 2 to deploy the deformable packer elements 6, fluid pumped from the surface pushes the balls 42 and 58 back to the positions shown in FIGS. 1a and 1b to enable fluid pumped from the surface to flow through longitudinal bore 16 which is sealed from the annulus.

[0064] Operation of the packer apparatus 2 to form a seal in a wellbore or wellbore casing will now be described. Referring to FIGS. 1a and 1b, the packer apparatus 2 is moved to a position in a wellbore or a casing at which an annular seal is required. Hydraulic fluid is then pumped from the surface into longitudinal bore 16 which closes valves 40 and 50 to enable fluid to flow freely along the internal bore 16. This increases pressure in hydraulic cylinders 12 and when the pressure in hydraulic cylinders 12 is greater than the fluid pressure in the annulus outside of the apparatus 2 which is communicated through annular ports 24, the hydraulic cylinders push actuation apparatus 10 against floating piston 32 to compress fluid in chamber 30 against the action of spring 34. This deforms the deformable metallic outer cover 8 into the expanded condition as shown in FIG. 1b which seals against the open wellbore or casing in which the apparatus 2 is located.

[0065] When the seal formed by expanded deformable metallic outer cover 8 is no longer required, fluid pressure is reduced in the longitudinal bore 16 which enables return spring 34 to push the floating piston 32 and actuation apparatus 10 back along the tool to the condition of FIG. 1a. This returns the deformable metallic outer cover 8 to the retracted condition of FIG. 1a.

[0066] Referring to FIG. 6, packer apparatuses 2 and their annular sealing capability is useful for example in hydraulic fracturing. A ported sub 60 (also known as a nozzle stimulation sub) comprises a plurality of ports 62 to enable fluid to be pumped into the formation in which workstring 64 is located. Workstring 64 also includes first and second packer apparatuses 2 connected on opposite sides of the ported sub 60.

[0067] When a portion of the formation through which the wellbore is drilled is to be stimulated in hydraulic fracturing by pumping fracturing fluid into the formation, the operator increases the fluid pressure in longitudinal bore 16 to deploy the deformable packer elements and deformable metallic outer covers 8 to form two annular seals which creates an isolated section of wellbore containing the ported sub 60. This enables fluid being pumped through ports 62 to be contained in a volume between the seals formed by the deformable metallic outer covers 8 to increase pressure sufficiently to cause hydraulic fracturing.

[0068] An alternative use for the packer apparatus 2 will be described in reference to FIGS. 7a and 7b. The packer apparatus 2 is located in a wellbore 70 lined with steel casing 72. In some circumstances, it is desirable to create seals in the annulus 74 between the casing 72 and the wellbore surface 70 for example to prevent fluid pressure migrating up the wellbore to the surface. This can cause water table pollution and leakage of chemicals into the environment after a wellbore is abandoned when hydrocarbon production is ceased.

[0069] Packer apparatus 2 is located at a position at which such an annular seal is required. An elastomeric sleeve 76 has been mounted on the casing 72 but this is not always required, and the following procedure can be also conducted on steel casing 72 without any form of elastomeric or other sleeve. The actuation apparatus 10 is then operated in the manner described above to pressurise hydraulic chambers 12 and compress the deformable packer element 6 to push the deformable metallic outer cover 8 against the casing 72. If sufficient force is applied, steel casing 72 deforms past its elastic limit to form a permanent deformed portion of casing and therefore a seal 78 compressing the elastomeric sleeve 76 against the surface of wellbore 70. The packer apparatus can then be deactivated leaving the seal 78 in place and the packer apparatus to move to a different point in the casing 72 to form another seal.

[0070] Referring to FIGS. 4a, 4b, 4c, 4d, 4e, 4f and 5, in some circumstances it is desirable to prevent the packer apparatus 2 operating in response to fluid pressure changes until such time as other workstring operations have been conducted. For example, the operator may wish to circulate in the wellbore for cleaning purposes or run another pressure operated tool in the workstring such as a perforating tool to perforate wellbore casing to enable stimulation and hydraulic fracturing.

[0071] If a packer apparatus 2 is mounted in such a workstring, it is desirable to prevent the deformable packer element 6 from deploying to create unwanted seals. A locking mechanism 80 is therefore provided to hold the actuation apparatus 10 static when the pressure is changed in longitudinal bore 16. Locking mechanism 80 comprises at least one sheer pin 82 which projects through the body into an internal sleeve 84 which comprises a restriction 86 for catching a deformable ball 92 or a dart. A recessed portion 88 is formed in sleeve 84 for holding keys 90. Keys 90 increase the force required to release the locking mechanism 80.

[0072] In the configuration of FIGS. 4a, 4c and 4e the keys 90 prevent the actuation apparatus 10 from moving relative to body 4. When ball 92 is dropped, it sits against restriction 86 to enable the pressure to be increased sufficiently to break sheer pins 82. Keys 90 then fall into recessed portion 88 in the sleeve 84 (FIGS. 4b, 4d, 4f) to enable movement of the actuation apparatus 10 to enable the deformable packer element 6 and therefore deformable metallic outer cover 8 to be deployed.

[0073] FIG. 5 shows a ported sub 60 disposed in a workstring comprising packer apparatuses 2 in which such a locking mechanism 80 is mounted. Additional pressure deforms the ball 92 forcing it past restriction 86. The ball will then fall down the workstring to sit on the next restriction 86 to release a further packer apparatus 2 until the ball eventually lands in ball catcher 94.

[0074] A packer apparatus 102 of a second embodiment of the invention is shown in FIGS. 2a and 2b with parts common to the embodiment of FIGS. 1a and 1b shown with like reference numerals, but increased by 100.

[0075] Packer apparatus 102 comprises actuation apparatus 110 and hydraulic cylinders 112 and other pressure operated components that operate in exactly the same way as the embodiment of FIGS. 1a and 1b, such that the hydraulic actuation of the packer will not be described in any further detail with reference to the second embodiment. In this embodiment, deformable packer element 106 comprises deformable metallic outer cover 108 and a deformable elastomeric element 109. When the actuation apparatus 110 is activated, it moves to compress deformable elastomeric element 109 which in turn pushes deformable metallic outer cover 108 against the wellbore or casing to form a seal. To facilitate rotation of the deformable packer element 106 and prevent the elastomeric element 109 sticking on the body 104, the apparatus includes rotating sleeve 111 mounted on O-rings 113.

[0076] Once the actuation apparatus 110 is deactivated, the resilience of the deformable elastomeric element 109 pushes back against the actuation apparatus 110 to return the deformable packer elements 106 and therefore deformable metallic outer cover 108 to a retracted.

[0077] A packer apparatus 202 of a third embodiment of the invention is shown in FIGS. 3a and 3b, with parts common to the embodiment of FIGS. 1a and 1b shown with like reference numerals but increased by 200.

[0078] In this embodiment, packer apparatus 202 comprises a deformable packer element 206 having a deformable metallic cover 208 under which deformable elastomeric element 209 is disposed in common with the embodiment of FIGS. 2a and 2b. Also, the hydraulic operation of the apparatus 202 is identical to that of the embodiments of FIGS. 1 and 2 and will not be described in any further detail.

[0079] The difference between the embodiment of FIGS. 3a and 3b with that of FIGS. 2a and 2b is the inclusion of floating piston 232 in contact with actuation apparatus 210. When the actuation apparatus 210 is moved, it pushes floating piston 232 to compress deformable elastomeric element 209. The floating piston 232 is used to seal the elastomeric element 209 against the ingress of wellbore fluid which can contain corrosive chemicals such as hydrogen sulphide and carbon dioxide. In less corrosive environments, the floating piston 232 is not required and the embodiment of FIGS. 2a and 2b can be used.

[0080] In all embodiments, the deformable metallic outer cover 8, 108 and 208 has been found to effectively form seals and be able to deform wellbore casing in corrosive environments whilst prevent corrosion and protecting other components of the packer apparatus.

[0081] It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.