GB2296520A - Improvements in or relating to down-hole tools - Google Patents

Abstract

This invention relates to oil/gas well tools conveyed downhole on wireline, electric line, or as part of production tubing string, and particularly relates to sealing/packing tool which provide a pressure/fluid barrier. The invention provides a downhole tool 5 comprising at least one ring 12 with petaloid extensions 15, said ring 12 being disposed about a longitudinal axis of said tool 5, and means for controllably deforming said petaloid extensions 15 such that said extensions 15 may be controllably moved in use. The downhole tool 5 may be a sealing/packing tool used to provide a pressure/fluid barrier. Said controllable movement may cause the extensions 15 to be brought into close proximity with an inner surface of a conduit 55. Said tool 5 may further comprise an elastically deformable packing element 10. The extensions 15 are expanded by a wedge surface 50 on ring 20 and help to centre the tool in the conduit 55. The extensions 15 may also be arranged to act as anti-extrusion means for the packing element. <IMAGE>

Description

Improvements In or Relating to Down-Hole Tools Background to the Invention This invention relates to oil/gas well tools conveyed downhole on wireline, electric line, or as part of production tubing string, and in particular, though not exclusively, relates to sealing or packing tools which provide a pressure or fluid barrier.

Retrievable pack-off tools which require a high expansion of the packing element system and which, upon retrieval, have to pass through a restriction only slightly greater than the tools original outer diameter, are known.

Problems exist with such known tools. For example a problem exists in maintaining the centralisation of such a tool during the setting sequence. If the tool is set "squint" then failure of the packing element may occur when a differential pressure is held across the tool.

It is an object of the present invention to obviate or mitigate this and other problems associated with such tools.

Summary of the Invention According to a first aspect of the present invention there is provided a downhole tool comprising at least one ring with petalloid extensions, said ring being disposed about a longitudinal axis of said tool, and means for controllably deforming said petalloid extensions such that said extensions may be controllably moved, in use.

The downhole tool may be a sealing/packing tool used to provide a pressure/fluid barrier.

Said controllable movement may cause the extensions to be brought into contact with an inner surface of a conduit.

However, preferably and advantageously said controllable movement may cause the extensions to be brought into close proximity with an inner surface of a conduit.

Preferably also, in use, having been controllably deformed at least one, and preferably all, of said petalloid extensions are held between first and second substantially opposing surfaces.

Said downhole tool may further comprise an elastically deformable packing element, and also may comprise means to controllably deform said petalloid extensions radially outward from said tool.

The packing element may be made from a high expansion elastomer.

Preferably said ring is provided above the packing element when the tool is deployed downhole.

There may be provided two sets of rings with petalloid extensions, said rings being rotationally offset by one half of the pitch of an individual petalloid extension.

Said ring(s) may (each) be formed from a cylindrical sleeve, said sleeve being split at one end so as to form a cylindrical arrangement of petalloid extensions.

Said petalloid extensions of said ring(s) may be caused to be brought into close proximity with the conduit by means of relative movement between said ring(s) and a frusto-conical wedge. Said wedge, upon being introduced within the cylinder formed by the petalloid extensions, may cause said extensions to move radially outward from the downhole tool.

Preferably the petalloid extensions, when deployed radially outward, serve to align/centralise the tool within the conduit.

In a preferred embodiment the packing element incorporates anti-extrusion springs in its upper and lower edges.

In said preferred embodiment the petalloid extensions, when deployed radially outward, may serve to support the anti-extrusion spring in the upper edge.

According to a second aspect of the present invention there is provided a means for supporting a packing element for use in a down-hole tool comprising at least one ring with petalloid extensions, said ring being disposed about a longitudinal axis of said tool, and means for controllably deforming said petalloid extensions such that said extensions may be controllably brought into contact with the packing element, in use.

The downhole tool may be a sealing/packing tool used to provide a pressure/fluid barrier.

Preferably also, in use, having been controllably deformed at least one, and preferably all, of said petalloid extensions are held between first and second opposing surfaces.

Preferably said ring is provided adjacent to one end of the packing element.

Preferably a further ring with petalloid extensions is provided adjacent to the other end of the packing element, said further ring being disposed about a longitudinal axis of said tool, and means for controllably deforming said petalloid extensions of said further ring such that said petalloid extensions may be brought into contact with the packing element, in use.

Said tool may further comprise means to controllably deform said petalloid extensions radially outward from said tool.

Preferably the/each ring comprises two nested rings with petalloid extensions, said nested rings being rotationally offset by one half of the pitch of an individual petalloid extension.

Preferably also said rings may be formed from a cylindrical sleeve, said sleeve being split at one end so as to form a cylindrical arrangement of petalloid extensions.

Said petalloid extensions may, in use, be caused to deform radially outward by means of a frusto-conical wedge. Said wedge, upon being introduced within the cylinder formed by the petalloid extensions, causing said extensions to move radially outward from the downhole tool.

Preferably also the radially deployed petalloid extensions may rest against an edge of the elastomeric packing element and serve to reinforce the sealing properties of said packing element when a differential pressure is held across the tool.

It should be understood that sets of rings carrying petalloid extensions may be provided above the packing element, below the packing element, both above and below the packing element, or in any other suitable configuration.

Preferably the packing element comprises a plurality of sub-elements wherein, in use, longitudinal compression of the element causes a portion of a sub-element to be axially moved over another sub-element.

Preferably the packing element may comprise three sub-elements positioned sequentially along the length of the tool, wherein, in use, the uppermost and lowermost sub-elements may be caused to be axially moved over the central sub-element.

According to a third aspect of the present invention there is provided a packing element for use in a downhole packing tool, the element comprising a plurality of sub-elements wherein, in use, longitudinal compression of the element causes a portion of a sub-element to be axially moved over another sub-element.

The downhole tool may be a sealing or packing tool used to provide a pressure or fluid barrier.

Preferably the packing element may comprise three sub-elements positioned sequentially along the length of the tool, wherein, in use, the uppermost and lowermost sub-elements may be caused to be axially moved over the central sub-element.

According to a fourth aspect of the present invention there is provided a method of setting a downhole tool, the downhole tool being a sealing/packing tool used to provide a pressure/fluid barrier, the tool comprising: one or more slips; at least one ring with petalloid extensions, said ring being disposed about a longitudinal axis of said tool; means for controllably deforming said petalloid extensions such that said extensions may be controllably moved; and an elastically deformable packing element; the method comprising the steps of: locating the tool at a desired location within a conduit; anchoring the slip(s); controllably deforming said petalloid extensions thereby causing the extensions to be brought into close proximity with an inner surface of the conduit, in so doing centralising the tool within the conduit; activating the packing element thereby forming a pressure/fluid barrier.

Description of the Drawings Embodiments of the present invention will now be given, by way of example only, with reference to the accompanying drawings which are: Fig 1 a partial cross-sectional view of a downhole tool, in accordance with an embodiment of the present invention, in a running position; Fig 2 a partial cross-sectional view of the tool of Fig 1 with the petalloid extensions deployed in order to align the tool; Fig 3 a partial cross-sectional view of the tool of Fig 1 with the element in the pack-off position; Fig 4 a partial cross-sectional view of an alternative embodiment of the tool of Fig 1 with the petalloid extensions supporting the packing element; Fig 5 a partial cross-sectional view of the tool of Fig 1 in a retrieval position;; Fig 6 a side view in partial cross-section of a packing element in accordance with an embodiment of the present invention; Fig 7 a side view of the element of Fig 6 while being set; Fig 8 a side view of the element of Fig 6 in a set position; Fig 9 a side view of a support means in accordance with an embodiment of the present invention; Fig 10 a side view of the support means of Fig 9 in the set position; Fig 11 a side view of the packing element of Fig 6 and the support means of Fig 9 in a set position; Fig 12 a releasable zone isolation packer (ZIP) including the element of Fig 6 and support means of Fig 9.

Detailed Description Referring firstly to Fig 1 there is shown a downhole packing tool, generally designated 5, according to an embodiment of the present invention. Said tool 5 is shown in a running position, and comprises an elastomeric packing element 10, a centralisation ring 12 incorporating petalloid shaped elements or extensions 15, a first (upper) gauge ring 20, a second lower gauge ring 25 and a cylindrical petal housing 30. Said petal housing 30 serves also to constrain a return spring 35 against an inner cylindrical member 40 of the tool 5.

The packing element 10 is further provided with antiextrusion springs 45, 45' positioned at its upper and lower edges. The centralisation ring 12 is held between the petal housing 30 and a frusto-conical face 50 of the upper gauge ring 20.

During the setting of the tool 5 within a well bore, well casing, tubing string or other conduit 55, the petal housing 30 is caused to advance longitudinally down the length of the tool 5 as indicated by arrow A in Fig 2.

Said movement results in the compression of return spring 35, and further causes an end face 65 of the petal housing 30 to contact the petalloid extensions 15. The petalloid extensions 15 contacted thus are caused to move against the frusto-conical face 50 of the upper gauge ring 20 and hence are displaced radially outwards from the tool 5. This radial displacement of the petalloid extensions 15 results in their contact with, or preferably movement into close proximity with the inner surface of the conduit 55 and the subsequent alignment/centralisation of the tool 5.

Compression of the packing element 10 (see Fig 3) by the upper and lower gauge rings 20, 25 causes the outer diameter of the packing element 10 to increase and hence seal the conduit 55.

Fig 4 shows an alternative embodiment of the present invention wherein the petalloid extensions 15a serve to support an outer edge of the packing element 10a. This provides added reinforcement to the anti-extrusion spring 45'a which, if the tool 5a is sitting squint within the hole, may be liable to failure.

Fig 5 shows the tool 5 of Fig 1 in a position to be run in the retrieval direction indicated by arrow B. The upper and lower gauge rings 20, 25 are moved apart to allow the packing element 10 to return to its original shape. Extension of the return spring 35 disengages the frusto-conical face 50 of the upper gauge ring 20 from the petalloid extensions 15. Movement of the upper gauge ring 20 by the return spring 35 is limited by set screw 80. The petalloid extensions 15 initially remain in their deployed positions. However upon encountering an obstruction, for example a constriction in the conduit diameter, the petalloid extensions 15 are caused to contract into space 70 between the upper gauge ring 20 and the petal housing 30. The petalloid extensions 15 are able to contract so due to a pre-determined weak point designed into their geometry.

Referring now to Fig 6 there is shown a packing element lOb according to an embodiment of the present invention. The element system consists of a three piece sub-assembly of two end elements 85b, 85'b and one centre element 90b all made from an elastomeric compound.

During activation of the packing element lOb the two end elements 85b, 85'b are axially driven up over the top of the centre element 90b thus changing the formation of the three piece structure (see Fig 7). With further axial compression the element structure is wedged between its carrying mandrel 95b and the wall of the conduit 101b thus creating an effective pressure barrier (see Fig 8).

Referring now to Figs 9 to 11 there is illustrated a support means according to an embodiment of the present invention for a packing element for use in a downhole tool. The support means relates to the back-up system utilised to support an element after setting to prevent axial movement or extrusion of the element, such as that described hereinbefore with reference to Figs 6 to 8.

The support means utilises a ring comprising outer and inner rings 102b, 103b with outer and inner metal petal extensions 1l0b, 105b respectively housed in a support ring housing 115b (see Fig 9). The inner metal petal ring 102b and petal extensions 105b are formed from a thin sleeve accurately split at one end to form a cylinder of fingers referred to as petal extensions 105b.

The outer metal petal ring 103b slides over the inner metal petal ring 102b and the petal extensions 110b thereof are rotationally offset by one half of the pitch of an extension with respect to the extensions 105b.

When the tool is run into the well bore the extensions 105b, 110b are collapsed so that they are below the maximum diameter of the tool (see Fig 9).

During the setting process the extensions 105b, 110b are driven up at a metal cone 120b causing them to fan out until such time as the outer metal petal extensions 110b hit a face of the housing 115b and is wedged between that and the metal cone 120b (see Fig 10). As illustrated in Fig 11 support means as described above may advantageously be provided at both ends of the element.

The back-up system hereinbefore described is unique in that: The outer ring is uniquely formed to enhance its load bearing strength enough to support the inner ring when under axial load.

The petal extensions are further supported by being clamped between the housing and metal cone when fully expanded to enhance its axial load bearing capability.

This containment between the housing and the metal cone is key to the load bearing performance of the back-up system and subsequent pressure retaining capability of the aforementioned packing element system (see Fig 11).

The metal petal basket system is made from two machined sleeves, one fitting inside the other and offset rotationally by one half of a finger pitch to provide maximised axial load bearing capability.

Referring now to Fig 12 there is shown a releasable zone isolation plug/packer (ZIP) generally designated 5b including an element lOb and a support means according to the present invention. The parts of the packer 5b are as follows: Item Qty Part Description 95b 1 element body 21b 1 lock ring housing 31b 1 upper body lock ring 41b 1 brass set screw 51b 12 soc head cap screw 115b 1 stop ring 105b 1 anti extrusion ring (petals, 8 off) 110b 1 anti extrusion ring (petals, 8 off) 85b 1 upper end element 101b 1 brass shear screw 111b 2 o-ring 90b 1 centre element 85b 1 lower end element 141b 8 monel shear screw 151b 1 key 161b 4 brass shear screw 171b 1 upper cone 181b 1 set slip (set of 4) 191b 1 slip retainer ring 201b 16 spirol pin 211b 3 garter spring 221b 1 lower cone 231b 1 lower body lock ring 241b 1 brass set screw 251b 4 guide pin 261b 4 shaft fastener 271b 1 cone extension 281b 2 hex. soc. set screw 291b 2 o-ring 301b 1 o-ring 311b 1 bottom sub 321b 2 50K shear ring 331b 2 25K shear ring 341b 8 annld stl shear screw 351b 4 brass shear screw 361b 1 lower stop ring 371b 1 lower extrusion ring 381b 1 lower extrusion ring 391b 1 wiper ring 401b 1 element lock ring 411b 1 element lock ring housing 421b 1 fishing neck 431b 1 fishing neck extn 441b 1 shear sub extension 451b 1 shear sub 461b 1 lock ring hsg retnr 471b 2 hex. soc. set screw The Zonal Isolation Plug 5b is a high expansion device designed to prevent fluid crossflow between multiple production zones in an oil well formation.

Typically the tool 5b can expand to diameters in excess of 170% of its existing "Run in Hole" diameter.

The ZIP 5b is set by a sequence of anchoring, centralise then pack off. The ZIP 5b is set by the following procedure: a. Run tool 5b to depth in the well bore.

b. Activate "Slip" Anchoring device (slips 181b) thus preventing crossflow from washing the device 5b away from a desired setting point in well bore.

c. Expand Back-up petals 20b such that they centralise the tool 5b above and below the Packing Element 85b, 85'b, 90b prior to energising the pack-off. The petals 20b expand out to close proximity with the casing I.D.

but are designed so as to not create an interference fit which due to frictional effects may otherwise affect the tools 5b ability to successfully complete the element pack-off sequence.

d. Complete the setting sequence by axially compressing the three-piece element 85b, 85'b, 90b which is designed in such a way as to force the end elements 85b, 85'b to ramp up over the centre Element 90b in order to form an effective fluid/pressure barrier.

The embodiments of the present invention hereinbefore described are given by way of example only, and are not meant to limit the scope of the invention in any way. The following points should be particularly noted: 1. The three-piece element geometry is uniquely designed such that on setting the end elements ramp up and over the centre element so as to effectively fill the annular space where otherwise fluid could migrate across the tool.

2. The unique setting sequence whereby the tool is anchored by the slips, then centralised by the petals without the petals positively interfering with the casing I.D, then the element system is packed off. The centralising petals then form the main anti-extrusion barrier for the element system.

3. The petal back-up can also be used as a means to centralise retrievable pack-off devices and can support the element anti-extrusion springs to increase anti extrusion resistance of the retrievable packing elements.

Claims (33)

1. A downhole tool comprising at least one ring with petalloid extensions, said ring being disposed about a longitudinal axis of said tool, and means for controllably deforming said petalloid extensions such that said extensions may be controllably moved, in use.

2. A downhole tool as claimed in claim 1, wherein the downhole tool is a sealing/packing tool used to provide a pressure/fluid barrier.

3. A downhole tool as claimed in any preceding claims, wherein said controllable movement causes the extensions to be brought into contact with an inner surface of a conduit.

4. A downhole tool as claimed in either of claims 1 or 2, wherein said controllable movement causes the extensions to be brought into close proximity with an inner surface of a conduit.

5. A downhole tool as claimed in any preceding claim, wherein in use, having been controllably deformed at least one, and preferably all, of said petalloid extensions are held between first and second opposing surfaces.

6. A downhole tool as claimed in any preceding claim, wherein said downhole tool further comprises an elastically deformable packing element.

7. A downhole tool as claimed in any preceding claim, wherein said downhole tool further comprises means to controllably deform said petalloid extensions radially outward from said tool.

8. A downhole tool as claimed in any preceding claim, wherein said ring is provided above the packing element when the tool is deployed downhole.

9. A downhole tool as claimed in any preceding claim, wherein there are provided two sets of rings with petalloid extensions, said rings being rotationally offset by one half of the pitch of an individual petalloid extension.

10. A downhole tool as claimed in any preceding claim, wherein said ring(s) is/are formed from a cylindrical sleeve, said sleeve being split at one end so as to form a cylindrical arrangement of petalloid extensions.

11. A downhole tool as claimed in any preceding claim, wherein said petalloid extensions of said ring(s) are, in use, caused to be brought into close proximity with the conduit by means of relative movement between said ring(s) and a frusto-conical wedge, said wedge, upon being introduced within the cylinder formed by the petalloid extensions, causing said extensions to move radially outward from the downhole tool.

12. A downhole tool as claimed in any preceding claim, wherein, in use, the petalloid extensions, when deployed radially outward, serve to align/centralise the tool within the conduit.

13. A downhole tool as claimed in claim 6 or any of claims 7 to 12 dependent on claim 5, wherein the packing element incorporates anti-extrusion springs in its upper and lower edges.

14. A downhole tool as claimed in claim 13, wherein the petalloid extensions, when deployed radially outward, serve to support the anti-extrusion spring in the upper edge.

15. A means for supporting a packing element for use in a downhole tool comprising at least one ring with petalloid extensions, said ring being disposed about a longitudinal axis of said tool, and means for controllably deforming said petalloid extensions such that said extensions may be controllably brought into contact with the packing element, in use.

16. A support means as claimed in claim 15, wherein the downhole tool is a sealing/packing tool used to provide a pressure/fluid barrier.

17. A support means as claimed in either of claims 15 or 16, wherein, in use, having been controllably deformed at least one, and preferably all, of said petalloid extensions are held between first and second opposing surfaces.

18. A support means as claimed in any of claims 15 to 17, wherein said ring is provided adjacent to one end of the packing element.

19. A support means as claimed in claim 18, wherein a further ring with petalloid extensions is provided adjacent to the other end of the packing element, said further ring being disposed about a longitudinal axis of said tool, and means for controllably deforming said petalloid extensions of said further ring such that said petalloid extensions may be brought into contact with the packing element, in use.

20. A support means as claimed in any of claims 15 to 19, wherein said tool further comprises means to controllably deform said petalloid extensions radially outward from said tool.

21. A support means as claimed in any of claims 15 to 20, wherein the/each ring comprises two nested rings with petalloid extensions, said nested rings being rotationally offset by one half of the pitch of an individual petalloid extension.

22. A support means as claimed in any of claims 15 to 21, wherein preferably also said ring(s) is/are formed from a cylindrical sleeve, said sleeve being split at one end so as to form a cylindrical arrangement of petalloid extensions.

23. A support means as claimed in any of claims 5 to 22, wherein said petalloid extensions, in use, are caused to deform radially outward by means of a frusto-conical wedge, said wedge, upon being introduced within the cylinder formed by the petalloid extensions, causing said extensions to move radially outward from the downhole tool.

24. A support means as claimed in any of claims 15 to 23, wherein the radially deployed petalloid extensions rest against an edge of the elastomeric packing element and serve to reinforce the sealing properties of said packing element when a differential pressure is held across the tool.

25. A support means as claimed in any of claims 15 to 24, wherein the packing element comprises a plurality of sub-elements wherein, in use, longitudinal compression of the element causes a portion of a sub-element to be axially moved over another sub-element.

26. A support means as claimed in claim 25, wherein the packing element comprises three sub-elements positioned sequentially along the length of the tool, wherein, in use, the uppermost and lowermost sub-elements may be caused to be axially moved over the central sub-element.

27. A packing element for use in a down-hole packing tool, the packing element comprising a plurality of subelements wherein, in use, longitudinal compression of the element causes a portion of a sub-element to be axially moved over another sub-element.

28. A packing element as claimed in claim 27, wherein the downhole tool is a sealing/packing tool used to provide a pressure/fluid barrier.

29. A packing element as claimed in either of claims 27 or 28, wherein the packing element comprises three subelements positioned sequentially along the length of the tool, wherein, in use, the uppermost and lowermost subelements may be caused to be axially moved over the central sub-element.

30. A method of setting a downhole tool, the downhole tool being a sealing/packing tool used to provide a pressure/fluid barrier, the tool comprising: one or more slips; at least one ring with petalloid extensions, said ring being disposed about a longitudinal axis of said tool; means for controllably deforming said petalloid extensions such that said extensions may be controllably moved; an elastically deformable packing element, the method comprising the steps of: located the tool at a desired location within a conduit; anchoring the slip(s); controllably deforming said petalloid extensions thereby causing the extensions to be brought into close proximity with an inner surface of the conduit, in so doing centralising the tool within the conduit; activating the packing element thereby forming a pressure/fluid barrier.

31. A downhole tool as hereinbefore described with reference to Figs. 1, 2, 3, 5, Fig. 4, Figs. 6, 7, 8, Figs. 9, 10, 11 or Fig. 12.

32. A support means as hereinbefore described with reference to Figs. 1, 2, 3, 5, Fig. 4, Figs. 6, 7, 8, Figs. 9, 10, 11 or Fig. 12.

33. A method of setting a downhole tool as hereinbefore described with reference to Figs. 1, 2, 3, 5, Fig. 4, Figs. 6, 7, 8, Figs. 9, 10, 11 or Fig. 12.