GB2435486A

GB2435486A - A downhole packer

Info

Publication number: GB2435486A
Application number: GB0614693A
Authority: GB
Inventors: Graeme Kenneth Speirs; Ernest Stopani
Original assignee: POLYMER HOLDINGS Ltd
Current assignee: POLYMER HOLDINGS Ltd
Priority date: 2005-07-26
Filing date: 2006-07-25
Publication date: 2007-08-29
Also published as: GB0614693D0; GB0515267D0

Abstract

A downhole packer 10 adapted to expand from a non-expanded configuration to an expanded configuration comprises compression members 12, 14 that compress an expandable element 16 to expand it in a radial direction 10x,y. The compression members 12, 14 comprise contacting surfaces 12s, 14s that are inclined relative to the radial expansion direction of the expandable element 16, wherein the contacting surfaces 12s, 14s may be arcuate in shape. The compression member 16 may be manufactured from an elastomeric rubber material and further comprise a double cored spring 34 around the circumference of the rubber element acting as a reinforcing member to prevent or at least reduce creep. The reinforcing member returns the expandable member 16 to its original non-expanded from on release of the compression members 12, 14. Shearing elements in the form of tapered plugs 30 may also be used to facilitate movement between the compression member and expandable member 16 following expansion.

Description

"Packer" The invention relates to a packer, particularly but not

exclusively a downhole packer.

A packer is a device that can be run into a downhole bore to seal an annulus of the bore. The packer may be mounted on a tubular or on a sleeve which is placed over a tubular. The bore typically comprises a cased wellbore. Packers are adapted to expand from a non-expanded position (so they can enter and be removed from the bore) to an expanded position for sealing the annulus.

A packer may also be used within pipes extending from one surface location to another and are not limited to use on submerged or downhole pipes.

A known packer comprises two rings and an elastomeric element located between the rings and bonded to both rings. The packer has a longitudinal axis and a radial plane orthogonal to the longitudinal axis.

The contacting surfaces of the rings are flat and lie in a plane parallel to the radial plane. In use, once the packer has been run into the bore on a tubular, the packer is expanded by moving the two rings in the longitudinal direction towards each other to squeeze the elastomeric element therebetween. This causes the sides of the elastomeric element to expand outwards against a wall of the bore, to seal the annulus between the bore and the tubular. The differential pressure above and below the packer can typically be around 20 -3sMegapascals and so in use the packer is under constant strain.

One disadvantage of these known packers is that they do not expand uniformly. Upper and lower ends of the elastorneric element expand the least, a central part expands the most, and parts of the elastomeric element between the ends and the central part expand to an intermediate extent.

Hence, only a relatively small surface area around the central part of the elastomeric element actually contacts the wall of the bore; this produces a seal that can fail, particularly at elevated temperatures and pressures of greater than 20 Megapascals.

Additionally, the elastomeric element can be highly-stressed by the compression of the rings, which also makes the seal more likely to fail.

According to a first aspect of the present invention there is provided a packer adapted to expand from a non-expanded configuration to an expanded configuration, the packer comprising: at least one compression member and an expandable element; the at least one compression member being adapted to compress the expandable element to expand the expandable element in a radial direction; wherein the at least one compression member has a contacting surface which is adapted to contact the expandable element, at least a portion of the contacting surface being inclined relative to the radial direction.

Typically the packer is a downhole packer.

The term "expand" is used to include the meaning "increase in size in any dimension"; thus the term "expand" is not limited to the meaning "to increase in volume".

The term "inclined" includes any angle that is greater than zero degrees.

Thus, "inclined" means any direction that is not parallel to the radial plane, and may also include a surface that is perpendicular to the radial direction.

"Inclined" includes slopes having a uniform gradient, and also slopes having varying gradients.

Typically, the packer has a longitudinal axis and a radial plane normal to the longitudinal axis, and at least a portion of the contacting surface is inclined relative to the radial plane.

Throughout the specification, unless otherwise explicitly stated, "radial direction" means radial with respect to the packer, and not with respect to any bore in which the packer may be located. Hence, a "radial direction" is typically a direction lying in, or parallel to, the radial plane.

The inclined part of the contacting surface ensures that when the compression member compresses the expandable element, a component of the compression force acts directly in a radial direction. This provides a more uniform expansion of the packer. In preferred embodiments, even the parts of the expandable element adjacent to the contacting surface of the compression member expand, in use in a bore, to contact a wall of the bore. Hence, such embodiments provide a packer with an increased contact area between the expandable element and the wall of the bore.

This provides an improved seal, which can hold at higher pressures than certain known packers. Typically packers of embodiments of the invention are adapted to maintain a seal at pressures of greater than 35 Megapascals, preferably greater than 50 Megapascals, even more preferably greater than 70 Megapascals.

The term "bore" includes any downhole bore. For example this may include the wall of the wellbore itself, if the welibore is not cased. This also includes a bore of a cased wellbore, and a pipeline such as a pipeline provided at a surface or subsurface location.

Due to this improved seal provided by preferred embodiments of the invention, the choice of material for the expandable element is not limited to elastomers which have a very high tensile strength at ambient temperature which tend to be used in certain known packers. Such elastomers may not be ideal for high temperature use due to degradation.

Instead, embodiments of the invention provide the advantage of a greater choice of material for the expandable element. Hence, an expandable element comprising elastomers more suitable for high temperature use but without such a high tensile strength can be used including fluoroelastomers (especially per-fluoroelastomers) (designated FPM under ISO 1629) such as VitonTM or AflasTM or fluorosilicone elastomers (designated MFQ under ISO 1629) for example.

Thus, packers of embodiments of the present invention are more suitable for use at higher temperatures than certain known packers.

Further advantages of some embodiments of the invention are a high conversion of axial load to radial expansion, and a reduction in the required compression force to expand the packer, as compared to known packers.

Preferably, two compression members are provided, a respective compression member being adapted to compress an upper end and a lower end of the expandable element.

Preferably, the direction of inclination is radially inwards from an upper end towards a centre of the packer. Typically an inclined surface is also provided from a lower end radially inwards towards said centre of the packer.

Preferably, a part of the inclined contacting surface has a constant angle in order to efficiently move or wedge the expandable element into the radial direction.

Preferably, a part of the inclined contacting surface comprises a portion that is perpendicular to the radial plane.

Embodiments of the present invention benefit in that an end region and central region of the expandable element are extended into the radial direction simultaneously or almost simultaneously. The perpendicular portion in particular provides this benefit since in use it transmits the axial pressure to the central region of the expandable element in contrast to certain known packers which rely solely on an expandable element to transmit axial pressure to a central region of the expandable element.

Preferably, a part of the inclined contacting surface is arcuate. An arcuate portion can facilitate smooth relative movement of the expandable element and the compression member.

The arcuate portion of the contacting surface of the compression member provides a higher degree of expansion as compared with certain known packers, and in particular ensures that an axially central region of the packer is expanded more efficiently.

Preferably, the packer also comprises a shear element that connects the compression member to the expandable element in the non-expanded configuration, and, on compression of the expandable element, the shear element is adapted to shear to facilitate movement between the compression member and the expandable element.

Preferably, the compression member and the expandable element are not connected together after the shear element has sheared, although they will typically be abutting with each other during use.

The use of a shear element means that the compression member does not have to be adhesively bonded to the expandable element. Once sheared, the compression member and the expandable element can move freely with respect to each other. Hence, embodiments in which the compression member is not adhesively bonded to the expandable element helps to improve still further the free expansion of the expandable element. The temporary (or pre-installation) connection between the expandable element and the compression member provided by the shear element can provide a one-piece packer which is more convenient for handling and assembly of the packer before use.

Preferably, the shear element comprises at least one tapered plug that engages an aperture or recess in the compression member.

The shear element and the expandable element are typically formed or moulded as one-piece.

Preferably the or each shear element is tapered so that it has a relatively narrow neck portion and the neck is shaped to shear in use.

Typically, the expandable element comprises an elastomeric material.

Preferably, the expandable element comprises rubber.

Preferably, the expandable element is provided with at least one reinforcing element.

The reinforcing element typically comprises a ring member that is located within the expandable element. The ring member extends circumferentially around the expandable element and thus defines an axis which is parallel to, preferably co-axial with the longitudinal axis of the packer.

The reinforcing element is typically resilient, such that on expansion of the expandable element, the reinforcing element acts to urge the expandable element to return to its original, non-expanded form. Hence, on a release of the compression on the expandable element, the packer returns to its non-expanded configuration (e.g. for retrieval).

The reinforcing element is typically located adjacent to an end of the expandable element.

Preferably, the outer diameter of the reinforcing element is greater than the distance, in use, between an outside edge of the compression member and the wall of the bore when the compression member is concentric with the bore. If, in addition, the reinforcing element is located in the expandable element, close to a radially outer part of the expandable element, such embodiments may prevent extrusion of the expandable element in the longitudinal direction. In use in a bore, expansion of the expandable element "sets" the reinforcing element fairly quickly against the wall of the bore, positioning the reinforcing element between the wall of the bore and the compression member (typically, abutting or nearly abutting the inclined contacting surface of the compression member). In the expanded configuration, over-pressurisation of the expandable element in the longitudinal direction may be prevented by the reinforcing element blocking the gap between the wall of the bore and the compression member also to prevent extrusion of the expandable element in the longitudinal direction. In this way, loss of pressure over time of the packer can be prevented or minimised to ensure that a strong seal is maintained.

Preferably, the reinforcing element comprises a spring; most preferably a double-cored spring. A double-cored spring is a first spring provided within a bore of a second, larger spring. One suitable double-cored spring may be obtained from Skegness Springs, Skegness, UK.

Preferably the outer diameter of the first inner spring forms an interference fit with the inner diameter of the second larger spring.

Optionally in use, the outer diameter of the first inner spring may be larger than the gap between an outside edge of the compression member and the wall of the bore.

Preferably the inner spring resists compression of the outer spring so that the outer diameter of the outer spring is not compressed sufficiently for it to fit through the said gap.

Optionally the expandable element may comprise portions of differing elastomeric strength and hardness. In particular, the expandable element proximate to the ends of the packer may be harder than the centre of the expandable element. The hardness of the rubber may be varied, typically stepwise, from relatively soft in the centre to relatively hard at the ends.

According to a second aspect of the invention there is provided a packer adapted to expand from a non-expanded configuration to an expanded configuration, the packer comprising: at least one compression member and an expandable element; the at least one compression member being adapted to compress the expandable element to expand the expandable element in a radial direction; wherein a shear element is provided that connects the compression member to the expandable element before compression, and, on compression of the expandable element by the compression member, the shear element is adapted to shear to facilitate movement between the compression member and the expandable element.

Facilitating movement between the compression member and the expandable element allows, in use in a bore, the expandable element to quickly set in the bore which helps provide a good seal. In particular, such movement allows the portion of the expandable element proximate to the compression member to expand radially and set in the bore.

Preferably, after compression, the compression member and the expandable element are not bonded together.

According to a third aspect of the present invention there is provided a packer adapted to expand from a non-expanded configuration to an expanded configuration, the packer comprising: at least one compression member and an expandable element; the at least one compression member being adapted to compress the expandable element to expand the expandable element in a radial direction; wherein the expandable element is provided with at least one reinforcing member in the form of a double-cored spring.

The packers according to the second and third aspects of the invention may include any feature of the packer according to the first aspect of the invention.

In particular, preferably the double-cored spring is a double cored-spring as described herein.

An embodiment of the invention will now be described, by way of example only, with reference to the following drawings, in which: Figs la, lb and ic show cross-sectional views of a known packer in a non-expanded configuration, a part-expanded configuration and an expanded configuration respectively; Figs 2a, 2b and 2c show partial cross-sectional views of a packer of the invention in a non-expanded configuration, a part-expanded configuration and an expanded configuration respectively; and Fig 3 shows a cutaway perspective view of the packer of Fig 2, in the non-expanded configuration.

Fig 1 shows a known packer 100 which includes annular members in the form of upper and lower rings 102, 104, and an elastomeric element 106 located between the upper and lower rings 102, 104. The upper and lower rings 102, 104 each have a contacting surface 1 02s, 1 04s at which they are bonded to the elastomeric element 106.

The packer 100 has a longitudinal axis 1 OOz. Two orthogonal axes 1 OOx, bOy define a radial plane bOxy normal to the longitudinal axis lOOz.

The contacting surfaces 102s, 104s of the upper and lower rings 102, 104, lie in, or are parallel to, the radial plane bOxy.

The packer 100 is mounted on a tubular 110 that is located in a bore 120.

The bore 120 comprises a cased wellbore.

In the non-expanded configuration of Fig 1 a, there is a gap between the elastomeric element 106 and the bore 120. In the part- expanded configuration of Fig ib, the upper and lower rings 102, 104 have been moved towards each other to axially compress the elastomeric element 106, which expands radially to contact the bore 120, leaving a gap G between part of the elastomeric element 106 and the tubular 110. In the expanded configuration of Fig ic, the upper and lower rings 102, 104 have moved even closer together to axially compress the elastomeric element 106 further. At the limit of compression the elastomeric element 106 has deformed to fill the gap G of Fig lb. As can be seen from Fig 1, the expansion of the elastomeric element 106 is non-uniform. In the expanded configuration of Fig ic, only part of an outer surface of the elastomeric element 106 contacts the wall of the bore 120. Hence, the packer 100 provides a relatively weak seal that is susceptible to fail if subjected to high pressures.

Moreover, the gap remaining at either end of the packer 100 adjacent to the end rings 102, 104 can allow the elastomeric element 106 to extrude past the rings 102, 104 under pressure, thereby causing a loss of sealing stress between the elastomeric element 106 and bore 120.

Referring now to Fig 2, there is shown an embodiment of the invention.

Fig 2 shows a packer 10 which comprises two compression members in the form of upper and lower annular members 12, 14. Packer 10 also includes an expandable element 16 located between the upper and lower annular members 12, 14. The upper and lower annular members 12, 14 each have a respective contacting surface 1 2s, 1 4s at which they contact the expandable element 16.

The upper and lower annular members 12, 14 comprise metal, whilst the expandable element 16 comprises rubber.

The packer 10 is mounted on a tubular 15 that is located in a bore 20.

The bore 20 comprises a cased weilbore.

The packer 10 has a longitudinal axis 1 Oz. Two orthogonal axes 1 Ox, 1 Oy define a radial plane lOxy normal to the longitudinal axis lOz.

In use, the packer 10 has an upper end lOU and a lower end 1 OL.

The contacting surfaces 12s, 14s of the upper and lower annular members 12, 14, are inclined relative to the radial plane lOxy. The inclination is inwards in directions away from the ends lOU, 1OL of the packer 10.

Each contacting surface 12s, 14s comprises three distinct portions, as best shown in Fig 3.

Considering the contacting surface 12s, starting from the outside and moving radially inwards, the contacting surface 12s includes a uniformly tapered portion 12u, a perpendicular portion 12p that is perpendicular to the radial plane xy, and an arcuate portion 12a. Likewise, the contacting surface 14s includes a uniformly tapered portion 14u, a perpendicular portion 1 4p and an arcuate portion 1 4a.

The angle of inclination of the uniformly tapered portions 12u, 14u is typically around 40 degrees to 50 degrees relative to the radial plane xy.

The angle of inclination is optionally around 45 degrees relative to the radial plane xy.

In the non-expanded configuration, the profile of the expandable element 16 co-operates with the profile of the contacting surface 1 2s, except that the expandable element 16 has end portions 16e that lie in planes that are parallel to the radial plane xy.

The contacting surface 14s is a mirror image of the contacting surface 1 2s.

Also shown in Figs 2 and 3 are shear elements in the form of tapered plugs 30. In this embodiment, four tapered plugs 30 are provided for each annular member 12, 14. The four tapered plugs 30 are located within respective longitudinal passages 32 positioned equidistantly around the circumference of each annular member 12, 14 (i.e. at every 90 degrees).

The longitudinal passages 32 in the annular member 12 extend between an upper face thereof and the uniformly tapered portion 1 2u of the contacting surface 1 2s. The longitudinal passages 32 are located close to the outer circumference of the annular member 12. The annular member 14 is a mirror image of the annular member 12.

Before use, each tapered plug 30 is bonded to the expandable element 16 at one end thereof.

The expandable element 16 is also provided with two reinforcing members such as double-cored springs 34 which are located within the expandable element 16. A respective spring 34 is located at each end of the expandable element 16, close to the outer circumference of the expandable element 16.

The double-cored springs 34 each comprise a first outer spring 340 having a bore and a second spring 341 provided within the bore of the first spring 340. The outer diameter of each spring 34 is greater than the distance between outside edges of the annular members 12, 14 and the wall of the bore 20.

The double-cored springs 34 extend circumferentially around the expandable element 16 which defines a central axis which is co-axial with the longitudinal axis 1 Oz of the packer 10. Their function is two-fold.

Primarily, they serve (along with the uniform expansion of the expandable element 16) to resist expansion or extrusion under pressure of the expandable element 16 into an annular gap 21 (shown in Fig. 2c) in a direction parallel to the longitudinal axis 1 Oz. Secondly, they also serve to

S

disengage the expandable element 16 from the bore 20 when the setting pressure on the annular members 12, 14 is released.

The use of an inner spring resists compression of the outer spring which could otherwise lead to the spring being deformed into an oval shape and moving past the gap between the compression members 12, 14 and the bore 20. In alternative embodiments a single strengthened spring may be used although this is less preferred since it may increase the amount of force required to set the packer beyond that preferred. The use of the double cored spring increases the spring's resistance to such deformation without a commensurate increase in the radial force exerted (although some increase does result).

In use, the packer 10 is assembled in the non-expanded configuration of Figs 2a and 3. The packer 10 is then mounted on the tubular 15 and lowered into the bore 20. There is a gap between the expandable element 16 and the wall of the bore 20.

When sealing of the annulus between the bore 20 and the tubular 15 is desired, the packer 10 is expanded by moving the annular members 12, 14 closer together. This compresses the expandable element 16, which expands radially outwards to contact the wall of the bore 20.

Because the contacting surfaces 12s, 14s of the annular members 12, 14 are inclined relative to the radial plane 1 Oxy, at least a component of the compression force acts directly in a direction parallel to, or coplanar with, the radial plane 1 Oxy. Hence, axial movement of the annular members 12, 14 is directly transferred to lateral expansion of the expandable element 16. This configuration has the advantage that is provides more efficient expansion, with a smaller axial force being required to engage the expandable element 16 with the bore 20.

The expansion of the expandable element 16 shears the bond between the tapered plugs 30 and the expandable element 16, so that the expandable element 16 can move more freely with respect to the annular members 12, 14.

Expansion of the expandable element 16 "sets" the springs 34 against the wall of the bore 20, positioning the springs 34 between the wall of the bore and the annular members 12, 14. The setting of the springs 34 against the wall of the bore 20 occurs fairly quickly due to the inclined profile of the contacting surfaces 12s, 14s of the annular members 12, 14; this has already happened in the part-expanded configuration of Fig 2b. Thus, expansion and extrusion of the expandable element 16 into the annular gap 21 in a direction parallel to the longitudinal axis 1 Oz is resisted by the quick setting of the springs 34.

In the part-expanded configuration of Fig 2b, a gap G is formed between part of the expandable element 16 and the tubular 15.

In the fully expanded configuration of Fig 2c, the upper and lower annular members 12, 14 have moved even closer together, and the expandable element 16 has deformed to fill the gap G of Fig 2b.

As can be seen from Fig 2, the expansion of the expandable element 16 is essentially uniform. In the expanded configuration of Fig 2c, an entire radially-outer surface of the expandable element 16 contacts the wall of the bore 20. Hence, the packer 10 provides a strong seal that is less likely to fail if subjected to high pressures.

Extrusion of the expandable element 16 in the longitudinal direction lOz is prevented by the springs 34 blocking the gap between the wall of the bore and the annular members 12, 14. In this way, loss of sealing stress of the packer 10 is prevented. This ensures a strong seal.

Due to this improved seal provided by the packer 10, as compared to the known packer 100, the choice of material for the expandable element 16 is not limited to elastomers which have a very high tensile strength. Instead, a greater choice of material for the expandable element 16 can be used, including "high temperature" elastomers which generally have low tensile strength at elevated temperatures. Thus, in such embodiments, the packer 10 can be used at higher temperatures than the known packer 100 since they do not require high tensile strength materials to operate.

If it is desired to release the seal formed by the expanded packer (e.g. to remove the tubular 15 from the bore 20), the annular members 12, 14 are moved apart from each other. This releases the compression on the expandable element 16 and the springs 34 act to return the expandable element 16 to its original, non-expanded form. The packer 10 and tubular can now be retrieved from the bore 20.

Modifications and improvements may be incorporated without departing from the scope of the invention. For example, the contacting surface may have many different shapes. The contacting surface does not necessarily include three distinct portions (e.g. uniform, perpendicular and arcuate as described above). The contacting surface may include more or fewer distinct portions.

Optionally the expandable element may comprise portions of differing elastomeric strength. In particular, the expandable element proximate to the ends of the packer may be harder, that is have a higher modulus of elasticity. The modulus! hardness of the rubber may be varied stepwise from relatively soft in the centre to relatively hard at the ends. This also helps resist extrusion of the packer into the annular gap between the bore and the ends of the packer.

Optionally, only one compression member is provided.

The invention is not limited to the use of rubber as the expandable element; any suitable material can be used. Optionally, an expandable element that is adapted to increase in volume could be used.

There may be more or fewer than four shear elements (e.g. tapered plugs) for each compression member. In some embodiments, no shear element is provided. In some embodiments, no form of attachment between the compression member and the expandable element is provided, even in the non-expanded configuration.

Some embodiments do not include a reinforcing element.

Optionally, the expandable member may have a surface that does not co-operate with the profile of the contacting surface of the compression member.

Claims

Claims 1. A packer adapted to expand from a non-expanded configuration

to an expanded configuration, the packer comprising: at least one compression member and an expandable element; the at least one compression member being adapted to compress the expandable element to expand the expandable element in a radial direction; wherein the at least one compression member has a contacting surface which is adapted to contact the expandable element, at least a portion of the contacting surface being inclined relative to the radial direction.

2. A packer as claimed in claim 1, wherein the packer is a downhole packer.

3. A packer as claimed in either preceding claim, wherein the direction of inclination is at least one of: -radially inwards from an upper end towards a centre of the packer, -radially inwards from a lower end towards said centre of the packer.

4. A packer as claimed in any preceding claim, wherein at least a part of the inclined contacting surface has a constant angle of inclination.

5. A packer as claimed in any preceding claim, wherein at least a part of the inclined contacting surface is arcuate.

6. A packer as claimed in any preceding claim, wherein at least a part of the inclined contacting surface comprises a portion that is perpendicular to the radial plane.

7. A packer as claimed in claim 6, wherein the inclined contacting surface includes the part which is perpendicular to the radial plane and a part which has a constant angle of inclination and a further part which is arcuate.

8. A packer as claimed in any preceding claim, wherein the packer also comprises a shear element that connects the compression member to the expandable element in the non-expanded configuration, and, on compression of the expandable element, the shear element is adapted to shear to facilitate movement between the compression member and the expandable element.

9. A packer as claimed in claim 8, wherein the compression member and the expandable element are not connected together after the shear element has sheared.

10. A packer as claimed in claim 8 or 9, wherein the shear element and the expandable element are formed as one-piece.

11. A packer as claimed in any preceding claim, wherein the expandable element comprises an elastomeric material.

12. A packer as claimed in claim 11, wherein the expandable element is manufactured from a material selected form the group consisting of per-fluoroelastomers, fluoroelastomers and fluorosilicone.

13. A packer as claimed in any preceding claim, wherein the expandable element is provided with at least one reinforcing element that is located within the expandable element and extends circumferentially therearound.

14. A packer as claimed in claim 13, wherein the reinforcing element is resilient, such that on expansion of the expandable element, the reinforcing element acts to urge the expandable element to return to its original, non-expanded form.

15. A packer as claimed in claim 13 or claim 14, wherein the reinforcing element is located adjacent to an end of the expandable element.

16. A packer as claimed in any one of claims 12 to 15, wherein the outer diameter of the reinforcing element is greater than the distance, in use, between an outside edge of the compression member and the wall of the bore when the compression member is concentric with the bore.

17. A packer as claimed in any preceding claim, wherein the expandable element comprises portions of differing elastomeric strength and hardness.

18. A packer as claimed in claim 17, wherein the expandable element proximate to the ends of the packer are harder than the centre of the expandable element.

19. A packer as claimed in any preceding claim, which is adapted to maintain a seal at pressures of greater than 70 Megapascals.

20. A packer adapted to expand from a non-expanded configuration to an expanded configuration, the packer comprising: at least one compression member and an expandable element; the at least one compression member being adapted to compress the expandable element to expand the expandable element in a radial direction; wherein a shear element is prOvided that connects the compression member to the expandable element before compression, and, on compression of the expandable element by the compression member, the shear element is adapted to shear to facilitate movement between the compression member and the expandable element.

21. A packer as claimed in claim 20, wherein after compression, the compression member and the expandable element are not bonded together.

22. A packer adapted to expand from a non-expanded configuration to an expanded configuration, the packer comprising: at least one compression member and an expandable element; the at least one compression member being adapted to compress the expandable element to expand the expandable element in a radial direction; wherein the expandable element is provided with at least one reinforcing member in the form of a double-cored spring.