Patent Publication Number: US-10316610-B2

Title: Downhole packer and associated methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/EP2015/051143 which has an International filing date of Jan. 21, 2015, which claims priority to Great Britain Application No. GB 1400975.7, filed Jan. 21, 2014, the entire contents of each of which are hereby incorporated by reference. 
     FIELD 
     Embodiments described herein relate generally to a downhole seal device such as a packer and an associated end member and methods for producing and installing downhole seal devices. 
     BACKGROUND 
     Downhole packers are commonly used for applications such as isolating zones in a wellbore. Such packers are typically in the form of sheathes that can be mounted on pipelines or other structures found in the wellbore. The packers may comprise swellable components that swell under the action of fluid to form a seal between the pipeline and the inside diameter of the wellbore or bore casing. 
     Important considerations in packer design include ease of installation and the quality and reliability of sealing provided by the packer, particularly in high pressure and deep bore operations. 
     STATEMENTS OF INVENTION 
     According to a first aspect of the invention is a downhole seal device such as a packer. The seal device may be configured to be mounted on a pipeline or other elongate structure. The seal device may be configured to seal between the pipeline or other structure and walls or casing of a borehole, hole, liner, tubular or conduit in which it is located. 
     The seal device may comprise a support member. The seal device may comprise at least one and preferably two end members, e.g. first and second end members. The first and second end members may be fixed or fixable to opposing ends of the support member. The opposing ends may comprise opposing ends in a longitudinal direction of the support member. The support member and/or end member(s) may be rigid. The support member may be rigidly fixed to the end member(s). 
     The seal device may comprise a unitary or one piece device. The support member and/or one or more end members may be comprised in a unitary or one-piece chassis. The support member may be welded, bonded, integral with, or otherwise fixed to the end member(s). For example, the support member may be welded to the end member(s) using a full circle weld. 
     By providing the seal device as a one-piece or unitary device, then the device may be made stronger and more robust and the risk of the device failing, for example when being run through a tortuous well path or during operation, may be reduced. 
     The seal device may comprise one or more outer seals. The outer seal(s) may be mounted on the support member and particularly may be mounted on an outer surface of the support member. The outer seal(s) may be bonded or otherwise fixed to the support member and/or end member(s), for example, by vulcanization. The outer seal(s) may be arranged to face toward and seal against the borehole walls, liner, conduit, tubular or casing in use. 
     The seal device may comprise one or more and preferably at least two seals, such as inner seal(s), which may be arranged to face toward and/or seal against the pipeline or other elongate structure in use. 
     At least one or more or each of the seals, e.g. the inner and/or outer seals may be annular and/or cylindrical. At least one and preferably each of the seals, e.g. the outer and/or inner seals, may comprise an expandable or swellable seal. The swellable seal may be selectively or preferentially swellable in selected fluids, which may comprise fluids found downhole, such as oil and/or water. The outer seal may be swellable or expandable to seal against the bore wall, casing or conduit when swollen or expanded. At least one of the seals, e.g. inner seal(s), may be swellable or expandable to seal against the pipeline or other structure when swollen or expanded. 
     By providing both inner and outer swellable seals, the seal device may be easily placed in a position on the pipeline whilst at the same time may provide a satisfactory seal against both the pipeline or other structure upon which the seal device is mounted and the inner diameter of the bore wall or casing or conduit in which the seal device is placed. 
     By providing swellable seals that are selectively or preferentially swellable in fluids found downhole, the likelihood of unwanted swelling of the seals is reduced. If permanent seals such as Viton ‘o’-rings are provided, the seals are formed at the surface when the device is exposed to air, thereby risking air being trapped between the seals. In contrast, by providing swellable seals, the seals may only be activated when the seals are in situ and exposed to downhole fluids. In this way, the chances of air or other gasses being trapped between the seals is reduced. This in turn may reduce the risk of the seals being bypassed due to high pressure differentials between gas pockets trapped between seals and the downhole environment in use. 
     Although at least one or each of the seals, e.g. the outer and/or inner seals, may advantageously comprise a swellable seal, it will be appreciated that, in some applications, a non-swellable seal may be used for at least one or each of the inner and/or outer seals, for example, advantageously as the inner seal. The seals, e.g. the inner and/or outer seal, may comprise a U-seal. The seals, e.g. the inner and/or outer seal, may comprise a unidirectional seal. This may be beneficial, for example, when the well fluid is unknown. 
     The end members may be in the form of or comprise end rings. The end members may comprise cylindrical or annular members. The end members may comprise inner and outer surfaces, the inner surface at least partially defining a passage having openings at opposing ends of the end member. 
     The support member may comprise a core and/or sleeve. The support member may comprise a cylindrical or annular support member. The support member may comprise inner and outer surfaces. The inner surface may at least partially define a passage having openings at opposing ends of the support member. 
     The passages in the support member and/or end member(s) may be in communication and may at least partially define a through passage of the seal device for receiving the pipeline or other elongate structure, i.e. such that the seal device may be mountable on the pipeline or other elongate structure. In other words, the seal device may be provided in the form of a sleeve that can be fitted onto the pipeline or elongate structure at an operator desired location. 
     The support member and/or the end member(s) may comprise or be formed from a metallic material such as steel. 
     The support member may be provided between the end members. One or more of the seals, e.g. the inner seals, may be provided on an inner surface of at least one and preferably each end member. 
     The end members may extend radially outwardly of the support member, e.g. an outer diameter of the end members may be greater than that of the support member. The end members may form protruding shoulders adjacent the support member. At least part of the outer seal(s) may be provided between the end members. The shoulder may protrude by between 0.5 cm and 10 cm, preferably between 1 cm and 5 cms and most preferably between 2 and 3 cms outwardly of the support member. The outside diameter of the end rings may be between 10% and 50% and preferably between 20 and 30% larger than that of the support member. 
     In this way, in use, at least part of the outer seal(s) may butt against one or each end member such that the end members may act to inhibit extrusion or unwanted movement of the outer seal(s) due to pressure differential across the seal in the well. 
     The end member(s) may comprise at least one fixer for fixing the end members to the pipeline or elongate structure upon which the seal device is mountable. For example, the or each end member may comprise at least one first fixer and at least one second fixer, wherein the second fixers may be of a different type to the first fixers. 
     At least one of the fixers may comprise or be configured to receive at least one threaded member such as a set screw or grub screw, which may be configured to secure the end member on the pipeline or other elongate structure. For example, a plurality of threaded members, e.g. grub screws, may be provided or providable in threaded holes in one or more or each end member, such that the threaded members can be tightened to bear against the pipe or other elongate structure upon which the seal device is mounted, thereby fixing the end members in place. The threaded members may be distributed circumferentially around the end member. 
     At least one of the fixers may comprise a collet. For example, the end member may comprise a collet member, which may be or comprise a collet ring or annular collet member, that comprises the collet. The collet member may define a bore or passage for receiving the pipeline or other elongate member. 
     The collet may comprise one or more, e.g. a plurality of, collet fingers. The collet member may comprise a collet member body. The collet fingers may extend from the collet member body. The collet fingers may extend in parallel with the bore or through passage. The collet fingers may be connected to the collet member body via a bendable or flexible connection. The bendable or flexible connection may comprise a weakened, cut-out and/or a reduced width portion of the collet finger. At least part of at least one or each of the collet fingers may abut at least one or two adjacent collet fingers. The collet fingers may be bendable or movable radially inwardly, e.g. at the bendable connection. The collet fingers may be distributed circumferentially around the collet member. 
     The end member may comprise a cooperating member. The cooperating member may be configured to selectively engage the collet fingers so as to move the collet fingers radially inwardly and/or into a gripping configuration. 
     One or more or each collet finger may comprise a first surface or protrusion, which may be provided on an end of the one or more or each collet finger that is distal from the collet member body and/or bendable or flexible connection. The first surface or protrusion may be shaped so as to engage with a corresponding surface on the cooperating member to bend or move the collet finger, e.g. radially inwardly or into the bore or through passage and/or into a gripping configuration. The gripping configuration may be a configuration in which the collet finger grips the pipeline or other elongate structure, in use. 
     The first surface or protrusion may slope radially outwardly, e.g. in a direction from the distal end of the collet finger toward the collet member body and/or bendable or flexible connection. 
     The collet member may comprise or define a locating profile, such as a recess or protrusion, and/or a shoulder, which may be or comprise an annular or circumferential locating profile or shoulder. The shoulder may be configured to abut or engage with an end of the cooperating member in at least one relative position of the collet member and the cooperating member. The locating profile may be configured to engage or interlock with a corresponding locator profile on the cooperating member in the at least one relative position of the collet member and the cooperating member. In this way, the collet member and the cooperating member may be held together in the at least one relative position, which may be a relative position corresponding with the gripping configuration of the collet fingers. 
     The threaded members, e.g. the set screws and/or grub screws, may be provided or providable in the end member body. 
     The cooperating member may be or comprise an annular or cylindrical body. The cooperating member may define a through bore or passage, which may be defined by a bore or passage wall. At least part of the collet end member, which may comprise at least the collet fingers and optionally at least a part of the collet member body, may be received or receivable in the bore or passage of the cooperating member. The pipeline or other elongate structure may be receivable in the bore or passage of the cooperating member. 
     The at least part of the collet member may be receivable through a first end of the bore or passage of the cooperating member. A second end of the bore or passage, which may be opposite the first end, may have a smaller diameter than the first end of the bore or passage. 
     The bore or passage wall of the cooperating member may define the corresponding surface, which may engage with the first surface of the collet fingers. The corresponding surface may be or comprise a sloping surface. The bore or passage of the cooperating member may decrease in diameter from a side of the corresponding surface that is toward the first end of the bore or passage (e.g. the end into which the collet member is inserted) to a side of the corresponding surface that is toward the second end of the bore or passage. The corresponding surface may extend circumferentially around the bore or passage of the cooperating member. 
     In this way, when the collet fingers are inserted into the bore or passage of the cooperating member, the collet fingers (specifically the first surface of the collet fingers) may engage the corresponding surface of the cooperating member. The corresponding surface of the cooperating member and the first surface of the collet fingers may be shaped so that the corresponding surface pushes the collet fingers inwardly, e.g. towards a central axis of the bore or passage. In this way, insertion of the collet member into the bore or passage (or moving the cooperating member onto the collet fingers) may act to push the collet fingers into gripping engagement with the pipeline or other elongate structure located in the bore or passage. The provision of a collet beneficially may add an additional fixing mechanism and beneficially may prevent extrusion of seals past the end member, through the bore or passage. 
     At least one of the seals, e.g. the inner seal, may be or comprise an annular seal and/or may comprise a Viton or other elastomeric seal. 
     A positioning protrusion may extend into the bore or passage of the cooperating member. The positioning protrusion may extend circumferentially around the bore or passage of the cooperating member. The positioning protrusion may be provided towards the second end of the bore or passage of the cooperating member. The positioning protrusion may be configured to engage with an end of a seal, such as the inner seal. 
     An end of the support member (e.g. the core or sleeve) may be receivable through the second end of the bore or passage of the cooperating member. The end of the support member may abut a side of the positioning protrusion that is opposite a side of the positioning protrusion that engages the seal, e.g. the inner seal. In other words, the seal, e.g. the inner seal may abut against a side of the positioning protrusion that is towards the first end of the bore or passage and the support member may abut a side of the positioning protrusion that is towards the second end of the bore or passage. The support member may optionally be fixed or fixable to the cooperating member. 
     The distal ends of the collet fingers may be located or locatable adjacent, proximate or abutting the seal, e.g. the inner seal, e.g. in the at least one relative position of the collet member and the cooperating member. 
     The seal device, e.g. the or each end member, may comprise at least one, e.g. a plurality of, support elements. Each support element may be annular and or be or comprise a ring. The support member may be received or receivable through the annulus of the at least one or each support element, e.g. the support elements may be mounted or mountable on the support member. 
     The support elements may comprise opposed first and second faces. The first face of at least one of the support elements may abut and/or be bonded or fixed or fixable to an end of the cooperating member. The first face of the at least one support element may comprise a planar surface. 
     The first face of at least one of the support elements and/or a first face of the outer seal may comprise a protruding portion, such as an annular or circumferential protruding portion, that may extend around the first face. 
     The second face of at least one of the support elements may define a groove or recess, such as an annular or circumferential groove or recess, which may extend around the second face. The protruding portion of the first face of another of the support elements and/or of the outer seal may be located or receivable in the groove or recess of the at least one of the support elements. 
     The groove or recess may have a concave or generally C-shaped cross section. The groove or recess may be at least partially defined between a first extending part of the support element and/or a second extending part of the support element. The first extending part may be provided radially outwardly of the second extending part. The first and second extending parts may extend generally in parallel with a longitudinal, central or symmetry axis of the pipe, support element and/or bore or passage. At least one or each support element may be asymmetric, e.g. may comprise an asymmetric cross section, such as in the radial direction. The first (e.g. outer) extending part may be longer (e.g. in cross section) than the second (e.g. inner) extending part. The at least one support element may be formed from a deformable material, e.g. an elastomeric material. 
     In this way, when the outer seal swells or expands, the protruding section of the outer seal within the groove or recess of the support element may expand or swell, which may thereby force the first (e.g. outer) and second (e.g. inner) extending parts apart. In other words, swelling of the protruding portion of the outer seal may force the first extending part radially outwardly and/or force the second extending part radially inwardly. This may force the support element against a bore wall, conduit, liner or other structure in which the seal device is located and/or may force the support element against the support member. 
     In this way, the support element(s) may provide additional sealing of the wellbore, conduit, liner or other structure in which the seal device is located. In addition, the support element(s) may prevent extrusion of the outer seal past the support elements, thereby improving the sealing provided by the outer seal. 
     When a plurality of support elements are provided, the protruding portion of one of the support elements may be provided in the recess or groove of an other of the support elements. When the first and second extending parts of the support element are forced apart, the protruding portion of the support element also increases in size, which may thereby also force the first and second extending parts of the other support element apart. In this way, a plurality of support elements may be operable by swelling of the outer seal, which may provide additional or back-up sealing and further prevent extrusion of the outer seal. 
     Optionally, at least one of the fixers may comprise a lock device such as a lock ring. The lock device may comprise a gripping member, which may comprise a band, ring or a portion of a ring, such as a split ring. The gripping member may be elastomeric. The gripping member may be provided on an inner surface of the seal device, e.g. facing inwardly towards the passageway of the seal device so as to face the pipeline or other structure upon which the seal device is mountable. The gripping member may comprise a roughened surface, protrusions or other patterning, which may act to improve the grip on the pipeline. The lock device may comprise one or more operating devices such as screws, ratchets, or the like, that may be operable to act on the gripping member to selectively increase and/or decrease the grip of the gripping member on the pipeline or other structure, e.g. by selectively tightening/tensioning and/or loosening the gripping member. The operating device may be operable to selectively open and close the split ring, thereby adjusting the grip of the lock device. Preferably, the operating devices are operable from outside of the seal device. 
     The lock ring may apply grip over a whole surface area of the gripping member, which results in a larger gripping surface relative to a plurality of grub screws, which instead provide a series of discrete gripping points. Therefore, use of a lock ring may more securely secure the seal device in place on the pipeline or other structure. 
     Furthermore, a lock device, such as a lock ring, may require less operating devices such as set screws to achieve an acceptable grip on the pipeline or other structure, which may result in quicker and/or easier installation of the seal device. 
     At least one fixer (such as the lock ring or collet member) may be provided adjacent, in contact with or proximate a seal, e.g. an inner seal, on at least one and preferably each end member. One or more fixer may be provided on an endward or distal side of the seal, e.g. the inner seal, which may be a side of the seal opposite the support member and/or one or more fixer may be provided on an opposite or inner side of the seal. Each end member may comprise a fixer and the seal, e.g. the inner seal(s), may be provided between the fixers of opposing end members. 
     By providing one or more fixers such as the lock rings or collet members adjacent to one or more or each seal, e.g. inner seal, the fixers may provide additional support to the seal, e.g. the inner seal, such that extrusion or unwanted movement of the seals, e.g. the inner seals, under action of pressure differential in the bore may be minimised. In addition, since such fixers contribute both to fixing the seal device in place on the pipeline and inhibiting extrusion of the seals, e.g. the inner seals, the number of parts required to perform these functions may be reduced. 
     The seal device may comprise an eccentric seal device. In other words, the geometric centre of a transverse cross section of the seal device (and preferably the end ring(s) and/or outer seal member) is displaced relative to the geometric centre of the through passage (and preferably also the support member) in transverse cross section. The thickness of walls and/or the outer seal of the seal device may vary around its circumference, for example, such that the thickness of the walls and/or the outer seal of the seal device at one portion of its circumference is greater than that at another portion. Preferably the thickness of the walls and/or the outer seal of the seal device may continuously vary around its circumference. 
     In this way, the seal device may be suitably oriented on a pipeline or other structure but at the same time align with other components in the bore, which may be eccentric or unsymmetrical. 
     The seal device may comprise a longitudinally extending line passage, which may be configured to receive at least one line, such as an electrical, hydraulic, fibre optic and/or pneumatic line. The at least one line may comprise a control line. 
     The line passage may comprise a slit and/or conduit. The line passage may be provided in the outer seal and/or the end members. At least parts of the line passage may be open to an outer surface of the seal device, for example, via a slit or the like. The end members may be provided with at least one fixer or securing member, which may act to clamp or grip the line. The at least one fixer or securing member may be selectively fixable and/or removable, which may comprise use of fixing means such as bolts. 
     The above arrangement may provide a simple and/or quick method for securing the line. 
     The line passage may be provided at a thicker portion of the circumference of the seal device, such as the thickest portion, e.g. in an eccentric seal device. 
     According to a second aspect of the invention is an end member for a seal device, such as a downhole packer. 
     The seal device may comprise a seal device of the first aspect. 
     The end members may comprise or be formed as an end ring. The end members may comprise a cylindrical or annular member that defines a passageway or annulus therethrough, e.g. for receiving a pipeline or other elongate structure. The seal device may be mounted or mountable on the pipeline or other elongate structure. 
     The end member(s) may comprise an eccentric end member. The thickness of the walls of the end member may vary around its circumference, for example, such that the thickness of the walls of the end member at one portion of its circumference is greater than that at another portion. Preferably the thickness of the walls of the end member may continuously vary around its circumference. 
     The end member may be formed from a metallic material such as steel. 
     The end member may comprise at least one seal, e.g. inner seal. The seal, e.g. the inner seal, may comprise an annular seal. The seal, e.g. the inner seal, may be provided facing into the annulus or passageway of the end member. The seal, e.g. the inner seal, may comprise a swellable seal, which may be selectively or preferentially swellable in a desired fluid, which may comprise fluid found in the well bore or in use, such as oil or water. However, it will be appreciated that, for some applications, the seal, e.g. the inner seal, may comprise a non-swellable seal. For example, the seal, e.g. the inner seal, may comprise a Viton or other elastomeric seal. The inner seal may comprise a U-seal. The seal, e.g. the inner seal, may comprise a unidirectional seal. 
     The end member may be provided with at least one fixer. For example, the or each end member may comprise at least one first fixer and at least one second fixer, wherein the second fixers may be of a different type to the first fixers. 
     At least one of the fixers may comprise a collet. The end member may comprise a collet member and a cooperating member. The at least one inner seal may be provided between at least part of the collet member and at least part of the cooperating member. The collet member, cooperating member and/or the end inner seal may be annular. 
     The collet member may comprise at least one or a plurality of collet fingers. The cooperating member may define an annulus, bore or passage. The collet fingers may be located or locatable in the annulus, bore or passage of the cooperating member. The collet fingers may comprise a first outer surface, which may be configured to cooperate with a corresponding surface of a wall of the annulus, bore or passage of the cooperating member in order to force the collet fingers radially inwardly and/or into a gripping configuration. The first outer surface may be provided at a distal end of the collet fingers. The first outer surface may slope radially outwardly, e.g. in a direction from the distal end of the collet fingers towards a collet end member body. 
     The collet member may be operable to grip the pipeline or other elongate member, e.g. in the gripping configuration of the collet fingers. 
     The collet member and/or cooperating member may comprise at least one feature of the collet member and/or cooperating member and/or that at least one support element and/or inner seal described above in relation to the first aspect, but which are not repeated purely for the sake of conciseness. 
     At least one of the fixers may comprise a lock device such as a lock ring. The lock device may comprise a gripping member, which may be elastomeric. The gripping member may be in the form of a ring or a portion of a ring. The gripping member may be provided on an inner surface of the seal device, e.g. facing inwardly towards the passageway or annulus of the seal device. In this way, the gripping member may face the pipeline or other structure upon which the seal device is mountable in use. The lock device may comprise one or more operating devices such as screws, ratchets, or the like, that are operable to act on the gripping member to selectively increase and/or decrease the grip of the gripping member on the pipeline or other structure. 
     At least one of the fixers may comprise one or more threaded fixing members such as grub or set screws. 
     At least one or more of the fixers may be provided adjacent, proximate or abutting the inner seal. 
     According to a third aspect of the invention is a chassis for a seal device according to the first aspect, the chassis comprising a support member and first and second end members fixed to opposing ends of the support member. 
     According to a fourth aspect of the present invention is a method for producing a seal device according to the first aspect. 
     The method may comprise welding the support member to the at least one and preferably two end members. The weld may comprise a full circle weld. 
     The method may comprise integrally forming the support member and at least one and preferably two end members. 
     The method may comprise providing at least one inner seal facing an inner surface, passageway or annulus through the seal member. 
     The method may comprise providing at least one outer seal on an outer surface of the seal member. 
     The inner and/or outer seal member(s) may comprise swellable seal members. The inner and/or outer seal member(s) may comprise non-swellable members. The inner and/or outer seal member(s) may comprise a U-seal. The inner and/or outer seal may comprise a unidirectional seal. 
     According to a fifth aspect of the present invention is a method for fixing a seal device according to the first aspect to a pipeline or other structure. 
     The method may comprise mounting the seal device to the pipeline or other structure, such that at least a portion of the pipeline or other structure is received within the passageway or annulus of the seal device. The method may comprise providing fluid to the inner and/or outer seal(s) so as to swell the inner and/or outer seals. The inner seals may be swollen to seal against the pipeline or other structure. The outer seals may be swollen to seal against a bore wall or casing. 
     The method may comprise using the operating device(s) of the seal device in order to tighten or tension the gripping member of the lock device around or to the pipeline or other structure. 
     According to a sixth aspect of the present invention is a method for inserting a line though a seal device according to the first aspect. 
     The method may comprise providing a line, such as a control line, through a line passage in the seal device. The method may comprise securing the line using securing members of the end member(s). 
     It will be appreciated that features analogous to those described above in relation to any of the above aspects may be individually and separably or in combination applicable to any of the other aspects. 
     Apparatus features analogous to those described above in relation to a method and method features analogous to the use and construction of those described above in relation to an apparatus are also intended to fall within the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are now described, by way of non-limiting example, and are illustrated in the following figures, in which: 
         FIG. 1  shows a cross sectional view of part of a seal device according to an embodiment of the present invention; 
         FIG. 2  shows cross section view of a seal device, part of which is shown in  FIG. 1 ; 
         FIG. 3  shows a cross sectional view of a part of a seal device according to another embodiment of the present invention; 
         FIG. 4  shows a cross sectional view of a seal device, part of which is shown in  FIG. 3 , in situ on a pipeline; 
         FIG. 5  shows a cross sectional view of a detail of the seal device shown in  FIG. 4 ; 
         FIG. 6  shows a perspective view of the seal device of  FIG. 4  in situ on a pipeline; 
         FIG. 7  shows a side view of a seal device according to an embodiment of the present invention and a control line; 
         FIG. 8  shows a longitudinal cross section of the seal device of  FIG. 7 ; 
         FIG. 9  shows a transverse cross section through the seal device of  FIG. 7 ; 
         FIG. 10  shows a perspective view of the seal device of  FIG. 7 ; 
         FIG. 11  is a schematic side view of an alternative seal device having alternative end rings; 
         FIG. 12  is a perspective view of the seal device of  FIG. 11 ; 
         FIG. 13  is a schematic side view of a collet ring of the seal device of  FIGS. 11 and 12 ; 
         FIG. 14  is a perspective view of the collet ring of  FIG. 13 ; 
         FIG. 15  is a side cross sectional view of the collet ring of  FIGS. 13 and 14 ; 
         FIG. 16  is a cross sectional view of the collet ring taken through the section A-A in  FIG. 15 ; 
         FIG. 17  is an end view of a cooperating ring of the seal device of  FIGS. 11 and 12 ; 
         FIG. 18  is a side cross section view of the cooperating ring of  FIG. 17  taken through the section A-A in  FIG. 17 ; 
         FIG. 19  is a perspective view of the cooperating ring of  FIGS. 17 and 18 ; 
         FIG. 20  is a detail side cross sectional view of a part of the seal device of  FIGS. 11 and 12 ; 
         FIG. 21  is a perspective view of an inner seal for use with the collet end ring of  FIGS. 13 to 16  and the cooperating ring of  FIGS. 17 to 19 ; 
         FIG. 22  is en end view of the seal of  FIG. 21 ; 
         FIG. 23  is a cross section of the seal of  FIG. 22  taken through the section B-B in  FIG. 22 ; 
         FIG. 24  is detail side cross section view of a part of the seal as shown in area C in  FIG. 23 ; 
         FIG. 25  is a side cross section view of a back-up ring for use in the seal device of  FIGS. 11 and 12 ; 
         FIG. 26  is a detail view of a part of the back-up ring as shown in area C in  FIG. 25 ; 
         FIG. 27  is a perspective view of the back-up ring of  FIGS. 24 to 27 ; 
         FIG. 28  is a perspective view of a support ring for use in the seal device of  FIGS. 11 and 12 ; 
         FIG. 29  is a detail view of a part of the support ring of  FIG. 28 ; and 
         FIG. 30  is a detail view of a part of the support ring shown in area C in  FIG. 29 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a cross section through a chassis of a seal device in the form of a downhole packer  5  (shown in  FIG. 2 ) for mounting to a pipeline or other elongate structure. The packer  5  is operable to provide a seal between the pipeline or structure and a hole or bore wall (or bore casing if the bore is cased) or conduit in which the packer  5  is located.  FIG. 2  shows a cross section through the whole packer  5 . 
     The packer  5  comprises a support member in the form of a cylindrical core  10  disposed longitudinally between a pair of fixing members in the form of cylindrical end rings  15   a ,  15   b . Each of the end rings  15   a ,  15   b  and the core  10  are annular and define a longitudinally extending passage  20  therethrough to receive the pipeline. In this way, the packer  5  takes the form of a sleeve that can be fitted onto the pipeline. 
     Each of the end rings  15   a ,  15   b  is provided with an annular inner seal member  25   a ,  25   b  that faces the passage  20 . Each of the end rings  15   a ,  15   b  is also provided with a plurality of fixers in the form of set screws  30  for fixing the end rings  15   a ,  15   b  and thereby the packer  5  to the pipeline. For example, the set screws  30  could be tightened in threaded apertures in order to bear against and thereby grip the pipeline or other structure upon which the packer  5  is mounted. 
     The cylindrical core comprises an outer surface  65  that faces the bore wall or casing or conduit in use and an inner surface that faces the pipeline in use. The cylindrical core  10  is welded at longitudinal ends  35 ,  40  to the respective end rings  15   a ,  15   b  using a full circle weld. The end rings  15   a ,  15   b  each have an outer diameter  45  that is larger than the outer diameter  50  of the cylindrical core  10  so as to form shoulders  55   a ,  55   b  that protrude radially outwardly at each end of the cylindrical core  10 . 
     As can be seen from  FIG. 2 , a cylindrical outer seal member  60  is provided on the outer surface  65  of the cylindrical core  10 , between the shoulders  55   a ,  55   b  formed by the respective end rings  15   a ,  15   b . The outer seal member  60  is bonded to both the core  10  and the end rings  15   a ,  15   b.    
     Since the cylindrical core  10  is welded to the end rings  15   a ,  15   b  and the outer seal member  60  is bonded to the core  10  and end rings  15   a ,  15   b , the packer  5  is provided in the form of a one-piece or unitary structure. This results in a stronger and more robust packer  5  that is easily fitted and reduces the risk of failure, for example, when being run through tortuous well paths or under extreme operating conditions. 
     Advantageously, both the inner seal members  25   a ,  25   b  and the outer seal member  60  are formed using swellable material. The swellable material can comprise swellable rubber or other suitable swellable material known in the art. In particular, the swellable material is selectively swellable in specific fluids such as oil or water. In this way, swelling of the inner and outer seals can be inhibited until a required time, whereupon the seals can be selectively exposed to the appropriate swelling fluid. For example, the swelling fluid may be a fluid found downhole when the packer  5  is in use. In this way, the packer  5  may be easily mounted on the pipeline and the chance of forming a hydrostatic chamber between the two inner seals  25   a ,  25   b  due to premature swelling may be minimised, as the seals  25   a ,  25   b  do not form seals against the pipeline when the production pipeline is being assembled and will instead only swell to provide the seal when exposed to fluid in the bore or conduit, i.e. when in-situ. 
     Furthermore, since swellable inner  25   a ,  25   b  and outer  60  seal members are provided, the packer  5  can effectively seal against both the pipeline upon which it is mounted and the conduit, bore walls or casing within which the packer is provided. 
     Since the outer diameter  45  of the end rings  15   a ,  15   b  is greater than the outer diameter  50  of the cylindrical core  10 , the shoulders  55   a ,  55   b  formed by the end rings  15   a ,  15   b  act to inhibit extrusion or movement of the swollen outer seal under operational pressure differentials across the seal, particularly when working at depth. 
     In an initial (unswollen) configuration, embodiments of the packer can have an outer diameter of between 5 and 100 cms, and preferably between 10 and 30 cms, depending on the application. In this particular example, the packer in the initial (unswollen) configuration is approximately 20 cm in outside diameter. The packer can vary in length depending on the degree of sealing required. However, in embodiments, the packer may be between 10 and 150 cms long and preferably between 40 and 80 cms long. In this particular example, the packer is approximately 61 cms long. The passage or annulus in the initial (unswollen) configuration is sufficiently large to provide a gap between the packer and the pipeline or other structure to which it is to be mounted in order to allow the packer to be easily fitted over the pipeline or other structure, but not so large that the gap cannot be closed by the swelling of the inner seals. For example, the passage may have a diameter of between 5 cms and 100 cms and preferably between 10 and 20 cms. In this specific example, the diameter of the passage is approximately 14.5 cms. 
     Another embodiment of the present invention is illustrated with reference to  FIGS. 3 to 6 .  FIG. 3  shows a cross section of a chassis of a seal device in the form of a packer  5 ′, whilst the whole packer  5 ′ is shown in situ mounted on a pipeline  70  in  FIG. 4 . The packer  5 ′ of  FIGS. 3 to 6  is similar to the packer  5  shown in  FIGS. 1 and 2  and the same reference numerals are used to indicate like components. However, the packer  5 ′ of  FIGS. 3 to 6  comprises different fixers to the packer  5  of  FIGS. 1 and 2 . In particular, rather than using a plurality of set screws  30 , as in the packer of  FIGS. 1 and 2 , each end ring  15   a ′,  15   b ′ in the packer  5 ′ of  FIGS. 3 to 6  comprises a fixer in the form of a lock ring  80   
     Each lock ring  80  comprises an annular metal toothed band that is provided on an inner surface  85  of the respective end ring  15   a ′,  15   b ′ that forms the passage  20  that receives the pipeline  70 . A plurality of locking screws  90  are provided which are operable to exert a force on the metal toothed band so as to force the band into gripping engagement with the pipeline  70 , as shown in detail in  FIG. 5 . In an optional embodiment, the metal toothed band  80  is provided in the form of a split ring. 
     By providing a lock ring  80  rather than a plurality of set screws  30 , fewer screws may be required to achieve a satisfactory grip on the pipeline and the packer  5 ′ can be fixed in position on the pipeline much faster. Furthermore, since the lock ring  80  grips over the whole surface of the band, a much higher force may be required to move the end ring  5 ′ having the lock ring  80  relative to the embodiment that uses only set screws  30 , which instead grip at a plurality of discrete locations. 
     Advantageously, the lock ring  80  on each end ring  15   a ′,  15   b ′ is provided directly adjacent to the respective inner seal  25   a ,  25   b . In this embodiment, the lock ring  80  is provided on a longitudinally endward side of the inner seal  25   a ,  25   b , i.e. on a side away from the cylindrical core  10 . However, it will be appreciated that in other embodiments a lock ring could alternatively or additionally be provided on an opposite side of the inner seal  25   a ,  25   b , i.e. toward the centre of the seal device. 
     In this way, since the lock ring  80  is directly adjacent to the inner seal  25   a ,  25   b , when the inner seal  25   a ,  25   b  is swollen, it can butt against the lock ring  80  such that the lock ring  80  provides additional support to the inner seal  25   a ,  25   b  and reduces or substantially closes the gap between the pipeline  70  and the end ring  15   a ′,  15   b ′ on the endward side of each inner seal  25   a ,  25   b . In this way, extrusion or movement of the inner seals  25   a ,  25   b  under operational pressure differentials or fluid flow is inhibited. 
     As such, in this embodiment, the lock ring  25   a ,  25   b  serves a dual purpose of securing the packer  5 ′ on the pipeline  70  and minimising extrusion of the inner seal  25   a ,  25   b.    
     Another seal member in the form of a packer  5 ″ is shown in  FIGS. 7 to 10 . The packer  5 ″ of this embodiment is similar to the embodiment shown in  FIGS. 1 and 2  and like components are numbered similarly. However, whereas the packer shown in the embodiment of  FIGS. 1 and 2  is concentric, the packer  5 ″ of  FIGS. 7 to 10  is eccentric. In particular, although the passage  20  through the packer  5 ″ remains circular, the geometric centres of the end rings  15   a ″,  15   b ″ and the outer seal  60 ′ (and thereby the packer  5 ″ as a whole) in transverse cross section are displaced relative to the geometric centre of the passage  20  and the cylindrical core  10  in transverse cross section. The effect of this is that the thickness of the walls of the end rings  15   a ″,  15   b ″ and the outer seal  60 ′ continuously vary circumferentially, with a thinnest part of the end ring  15   a ″,  15   b ″ and outer seal  60 ′ being opposite the thickest part. 
     Furthermore, in the embodiment shown in  FIGS. 7 to 10 , a channel  100  is formed through the thickest part  105  of the end rings  15   a ″,  15   b ″ and the outer seal  60 ′. The channel  100  is configured to hold a line  110  such as a control line  110  (which may be, for example, an electric, fibre optic or pneumatic control line). A slit  115  extends between the channel  100  and the outer diameter  120  of the outer seal  60 ′ to allow insertion of the control line  110  into the channel  100 . The end rings  15   a ″,  15   b ″ each comprise a removable cap  125  attached by fixing bolts  130 , which forms part of the channel  100  that passes through the end caps  15   a ″,  15   b ″. In this way, the removable cap  125  can be selectively removed by unfastening the fixing bolts  130  to allow the control line  110  to be inserted or removed, and then bolted back into place such that the cap  125  securely clamps the control line  110  in place. 
     This allows the control line  110  to be simply inserted and securely held in place in order to enable the function of tools to operate beyond the isolation point formed by the packer  5 ″. 
     By providing an eccentric packer  5 ″, the packer  5 ″ can align with other eccentric completion components yet still seal off and create a positive seal against the inner diameter of an open or cased hole and the outer diameter of the pipeline to which the packer  5 ″ is mounted. 
     While various features have been described above in relation to three examples of a packer  5 ,  5 ′,  5 ″, it will be appreciated that features described in relation to one example could equally be provided in combination with one or more features described in relation to any of the other examples. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the invention. The accompanying claims and their equivalents are intended to cover such forms and modifications as would fall within the scope of the invention. 
     For example, whilst embodiments have been described above in which the core  10  is welded to the end rings  15   a ,  15   b , it will be appreciated that the core  10  may be integral with the end rings  15   a ,  15   b  or other suitable fixing or bonding mechanisms could be used. 
     Furthermore, whilst various of the examples of packer given above are secured to the pipeline by set screws  30  and/or lock rings  80 , it will be appreciated that other suitable clamping, gripping or fixing mechanisms could be used. 
     For example, in an embodiment shown in  FIGS. 11 to 30 , two different types of fixing mechanism are used to fix the end rings to the pipeline or other elongate structure. In this embodiment, a collet and grub screws are used as the two fixing mechanisms. However, it will be appreciated that other combinations of fixing mechanism could be used. 
       FIGS. 11 and 12  show a seal device in the form of a downhole packer  1005  for mounting to a pipeline or other elongate structure (not shown). The packer  1005  is operable to provide a seal between the pipeline or other elongate structure and a hole or bole wall or a casing, liner or conduit (not shown) in which the packer  1005  is located in use. In this example, the packer  1005  is a unitary packer comprising a support member in the form of a cylindrical core  1010  disposed longitudinally between, and fixed to, a pair of cylindrical end rings  1015   a ,  1015   b . However, it will be appreciated that the end rings  1015   a ,  1015   b  described herein may be used in other packer or seal device systems, which need not be unitary systems and need not be used with or fixed to the core  1010 . 
     As in the packers described above, each of the end rings  1015   a ,  1015   b  and the core  1010  are annular and define a longitudinally extending passage  1020  therethrough to receive the pipeline or other elongate structure. An outer seal member  1060  extends circumferentially around an outer surface  1065  of the core  1010 . The outer seal member  1060  is swellable in oil or other fluid. 
     Each of the end rings  1015   a ,  1015   b  comprises a collet ring  1105 , a cooperating ring  1110 , an inner seal  1115 , a back-up ring  1120  and a support ring  1125 , which are each annular and define a passage therethrough. In use, the pipeline or other elongate structure extends through the passage  1020 . In other words, each of the collet ring  1105 , the cooperating ring  1110 , the inner seal  1115 , the back-up ring  1120  and the support ring  1125  are effectively mounted around the pipeline or other elongate structure. However, it will be appreciated that at least the collet rings  1105 , (and optionally at least part of the inner seals  1115  and/or cooperating rings  1110 ) are directly mounted or mountable on the pipeline or elongate structure, whilst the back-up ring  1120  and the support ring  1125  are mounted on the core  1010 , which is in turn mounted or mountable on the pipeline or elongate structure. 
     As shown in  FIGS. 13 to 16 , the collet ring  1105  comprises an annular collet ring body  1130 . The collet ring body  1130  comprises a plurality of threaded through holes  1132  extending from an outer surface  1135  of the collet ring body  1130  to an inner surface  1140  that defines the part of the passage  1020 . The threaded holes  1132  are distributed circumferentially around the collet ring body  1130  and are configured to receive a grub or set screw  1145  for selectively gripping the pipeline or other elongate structure. 
     A plurality of collet fingers  1150  extend from an end of the collet ring body  1130  in a direction generally in parallel with a longitudinal axis  1155  of the passage  1020 . The collet fingers  1150  are distributed circumferentially around the collet ring body  1130  and together define a part of the passage  1020 . Each of the collet fingers  1150  are joined to the collet ring body  1130  by a bendable or flexible hinge  1160 , in this case formed by notches  1165  in the collet fingers that provide a reduced width portion  1170  of the respective collet finger  1150 . 
     In order to operate the collet ring  1105 , at least the collet fingers  1150  are inserted into a passage  1020   a  through the cooperating ring  1110  that forms part of the passage  1020 . Shaped outer surface portions  1175  of the collet fingers  1150  are configured to engage with correspondingly shaped cooperating portions  1180  of a passage wall  1185  of the cooperating ring  1110  when the collet fingers  1150  are inserted into the passage  1020   a  of the operating ring  1110  in order to force the collet fingers  1150  radially inwardly into the passage  1020 ,  1020   a , i.e. towards the pipeline or other elongate structure located in the passage  1020 ,  1020   a  and upon which the packer  1005  is mounted. 
     In particular, the shaped outer surface portions  1175  are located at a distal end  1190  of the respective collet finger  1150  (i.e. an end furthest from the collet ring body  1130  and/or the bendable or flexible hinge  1160 ), wherein the shaped outer surface portions  1175  slope radially outwardly from the distal end  1190  of the respective collet finger  1150 . 
     As shown in  FIGS. 17 to 19 , the cooperating portions  1080  of the cooperating ring  1110  protrude from, and extend circumferentially around, the passage wall  1185  of the cooperating ring  1110 . The cooperating ring  1110  is configured such that the collet ring  1105  is received into the passage  1020   a  through a first end  1195  of the passage  1020   a . The cooperating portion  1180  of the cooperating ring  1110  slopes such that an inner diameter of the passage  1020   a  through the cooperating ring  1110  decreases from a side of the cooperating portion  1180  closer to the first end  1195  of the passage  1020   a  to a side of the cooperating portion  1180  that is away from the first end  1195  of the passage  1020   a.    
     In this way, when the collet ring  1105  is inserted into the passage  1020   a  defined by the cooperating ring  1110 , then the shaped outer surface portion  1175  of each collet finger  1150  cams off the cooperating portion  1180  of the cooperating member  1110  in order to bend or force the collet fingers  1150  radially inwardly into the passage  1020 ,  1020   a , i.e. into pressing engagement with the pipeline or other elongate structure, in use. 
     The collet ring body  1130  is provided with a circumferential engagement groove  1200  having a radially projecting shoulder  1205  on a side of the engagement groove  1200  that is furthest from the collet fingers  1105 . The cooperating ring  1110  is provided with a corresponding engagement projection  1210  that projects from an end of the passage wall  1185  at the first end  1195  of the passage  1020   a . In this way, when the collet ring  1105  has been correctly inserted into the cooperating ring  1110 , then the engagement projection  1210  is received within the engagement groove  1200  of the collet ring body  1130  and an end of the cooperating ring  1110  abuts the shoulder  1205  of the collet ring body  1130 . 
     It will be appreciated that an engagement groove may instead be provided on the cooperating ring  1110  and an engagement projection may be provided on the collet ring  1105 . As such, it will be appreciated that the collet ring  1105  and the cooperating ring  1110  need only have interlocking or engaging structures that fix or limit the relative motion of the cooperating ring and the collet ring, without necessarily being limited in the form of the interlocking or engaging structures. 
     When the engagement projection  1210  is received within the engagement groove  1200  of the collet ring body  1130  and an end of the cooperating ring  1110  abuts the shoulder  1205  of the collet ring body  1130 , the collet ring  1105  is retained in the passage  1020   a  of the cooperating ring in a configuration in which the collet fingers  1150  securely grip the pipeline or other elongate structure. The grub or set screws  1145  can be tightened in order to provide additional gripping of the pipeline or other elongate structure and to retain the collet ring  1105  in place. 
     Since end rings  1015   a ,  1015   b  can be provided at both ends of the packer  1005 , it is possible to initially secure a collet ring  1105  of the first end ring  1015   a  in place using the grub screws  1145 , then the other components of the packer  1005 , such as the cooperating rings  1110 , core  1010  and outer seal member  1060 , can be mounted in place on the pipeline or other elongate member. The collet ring  1105  of the second end member  1015   b  can then be mounted in place on the pipeline or other elongate member and pressed into the corresponding cooperating ring  1110 . Since the collet ring  1105  of the first end ring  1015   a  is secured in position using the grub screws  1145 , the compressive force on the collet ring  1105  of the second end ring  1015   b  serves to fully engage both collet rings  1105 ,  1105  with the corresponding operating rings  1110 ,  1110 . This forces the respective sets of collet fingers  1150  radially inwardly into gripping engagement with the pipeline or other elongate member. The grub screws  1145  of the collet ring  1105  of the second end ring  1015   b  can then be tightened to secure the packer  1005  assembly in the gripping configuration on the pipeline or other elongate structure upon which the packer  1005  is mounted. 
     The inner seal  1115  is provided between part of the passage wall  1185  of the cooperating ring  1110  and the distal ends  1190  of the collet fingers  1150  in use. In particular, the passage wall  1185  of the cooperating ring  1110  is provided with a further protrusion  1215  that extends radially inwardly from the passage wall  1185  of the cooperating ring  1110  into the passage  1020   a . The further protrusion  1215  is provided toward a second end  1220  of the passage  1020   a  through the cooperating ring  1110  that is opposite to the first end  1195 . An end of the inner seal  1115  abuts a side of the further protrusion  1215  that faces towards the first end  1195  of the passage  1020   a . As shown in  FIGS. 21 to 24 , the inner seal  1115  optionally comprises an engaging profile  1225  (e.g. a C-shaped cross section profile) for engaging a corresponding profile of the cooperating ring  1110 , e.g. on the further protrusion  1215 , in order to secure the inner seal  1115  in place. The inner seal  1115  is compressible between the collet ring  1105  and the cooperating ring  1110  in use in order to seal between the collet ring  1105  and the cooperating ring  1110 . Since the collet fingers  1150  are forced into gripping engagement with the pipeline or other elongate structure, the collet fingers  1150  help prevent extrusion of the inner seal  1115  between the end rings  1015   a ,  1015   b  and the pipeline or other elongate structure in use. 
     Respective ends of the core  1010  extend into the respective second ends  1220  of the passages  1020   a  of respective cooperating rings  1110 ,  1110  such that the ends of the core  1010  abut a side of the respective further protrusion  1215  that faces towards the second end  1220  of the respective passage  1020   a . Optionally but not essentially, the core  1010  can be fixed, bonded to or integral with the respective cooperating rings  1110  in order to provide the unitary packer  1005 . 
     As shown in  FIG. 20 , the second end  1220  of the cooperating ring  1110  abuts or is fixed to a first side  1230  of the back-up ring  1120 . The first side  1230  of the back-up ring  1120  is shaped to match with the second end  1220  of the cooperating ring  1110 , e.g. both surfaces could optionally be planar or have cooperating profiles. The first side  1230  of the back-up ring  1120  is optionally but not essentially bonded or fixed to the second end  1220  of the cooperating ring. 
     A second side  1235  of the back-up ring  1120  that is opposite to the first side  1230  is formed with a circumferential groove  1240 , as shown in  FIGS. 25 to 27 . A part  1245  of the back-up ring  1120  on one side, e.g. a radially outer side, of the groove  1240  extends further from the first side  1230  in cross section, as shown in  FIGS. 25 and 26 , than a part  1250  of the back-up ring  1120  on the other side, e.g. the radially inner side, of the groove  1240 . The groove  1240  is configured to receive a corresponding protruding portion  1255  of the support ring  1125 . 
     In particular, the protruding portion  1255  is provided circumferentially around a first side  1260  of the annular support ring  1125 , as shown in  FIGS. 28 to 30 . A second side  1265  of the annular support ring  1125  that is opposite the first side  1260  defines a recess  1270  extending circumferentially around the second side  1265  of the support ring  1125 . Similarly to the second side  1235  of the back-up ring  1120 , a part  1275  of the support ring  1125  on one side, e.g. a radially outer side, of the recess  1270  extends further from the first side  1260  in cross section, as shown in  FIGS. 29 and 30 , than a part  1280  of the support ring  1125  on the other side, e.g. the radially inner side, of the recess  1270 . The recess  1270  is configured to receive a corresponding protruding portion  1285  of the outer seal member  1060 . 
     The support ring  1125  and the back-up ring  1120  are formed from a deformable material, e.g. an elastomeric material such as Viton. 
     In this way, when the outer seal member  1060  swells, the protruding portion  1285  of the outer seal member  1060  also swells, forcing the parts  1275 ,  1280  of the support ring  1125  apart. In this way, the parts  1275 ,  1280  of the support ring  1125  seal the areas above the support ring  1125 , i.e. sealing against the wellbore wall, liner or casing, and below the support ring  1125 , i.e. sealing against the core  1010 . The more the outer seal member  1060  expands, then the more the parts  1275 ,  1280  of the support ring  1125  are pushed against the wellbore wall, liner or conduit and the core  1060  respectively. This prevents extrusion of the outer seal member  1060  past the support ring  1125 . 
     A similar mechanism applies to the back-up ring  1120 . In this case, as the parts  1275 ,  1280  of the support ring  1125  are forced further apart, then this applies a force on the back-up ring  1120  in order to force the parts  1245 ,  1250  of the back-up ring  1120  apart, thereby respectively sealing against the wellbore wall, casing or liner and against the core. In this way, a back-up sealing mechanism to prevent extrusion of the outer seal member  1060  is provided. 
     It will be appreciated that other variations to the embodiments made above could be made by a person skilled in the art. 
     For example, whilst the above embodiment describes inserting the collet fingers  1150  into the passage  1020   a  in the cooperating ring  1110  in order to bend the collet fingers  1150  into the gripping configuration, it will be appreciated that the cooperating ring  1110  may equally be inserted onto the collet fingers  1150  in order to achieve the same effect. Indeed, it will be appreciated from the above that the packer  1005  is assembled by first fixing one of the collet rings  1105  onto the pipeline or other elongate structure, e.g. by using the grub screws  1145 , then pushing the cooperating ring  1110  onto the collet fingers  1150  to place the collet fingers  1150  into the gripping configuration. The packer  1105  is then then secured in position by pushing the other collet ring  1105  into the other cooperating ring  1110  and tightening the grub screws  1145  on the other collet ring  1105 . 
     In addition, whilst the lock ring  80  in one of the above embodiments is described as comprising a metal toothed band, by way of example, it will be appreciated that the seal device/downhole packer may comprise additional or alternative lock rings or other components, for example, comprising rubber bands, fine wicker threads and the like. 
     In addition, whilst various embodiments of the packer  5  comprise both inner and outer swellable seals  60 ,  25   a ,  25   b , it will be appreciated that other sealing technology or only the inner  60  or outer  25   a ,  25   b  seals could be provided. 
     In addition, an embodiment is described above in which each end ring  1015   a ,  1015   b  are provided with a plurality of fixing mechanisms in the form of grub screws  1145  and a collet  1105 / 1110 , it will be appreciated that the end rings could instead be provided with other combinations of fixing mechanisms, e.g. types of fixing mechanism, such as two or more of collet rings, grub or set screws and/or one or more lock rings. 
     Although two support rings or elements, i.e. a support ring and a back-up ring, are described above, it will be appreciated that one, three or more support rings may be used.