Patent Application
20150267497
This invention relates to a sealing apparatus and method for use in establishing a seal in an annulus between a mandrel and a bore wall. More particularly, but not exclusively, embodiments of the invention may take the form of a downhole packer for use in sealing a wellbore annulus.
Sealing apparatus and methods are used in many industries where it is desired to isolate, seal off or otherwise control movement of fluid in a given environment. In the oil and gas industry for example, sealing devices known as packers are commonly used to seal the annulus between a production conduit or the like, and a bore wall or a surrounding casing or other tubular.
In some instances, one or more packer may be used to prevent undesired movement of fluid up or down the annulus in order to seal off the wellbore. In other instances, a number of packers may be used to create an isolated annular region which, amongst other things, permits isolation of a problematic formation or permits controlled production from, or access into, a selected region of a formation.
Known packers may comprise an elastomeric annular sealing element mounted on a mandrel and which is capable of being extended radially outwardly to engage, for example, the wall of a bore in which the packer is located, thus providing a seal in the annulus defined between the mandrel and the bore wall. In some instances, the seal element may be axially compressed, for example by a setting tool, to effect radial expansion. In other instances, a swelling elastomer may be used which, in use, swells in response to the presence of an activation medium present in the annulus.
While such packers are effective and may be used reliably in a number of applications, the high temperature and pressure differences experienced in a downhole environment place particularly high demands on the seal elements of the packer to maintain the seal with the bore wall, the successful maintenance of the seal often being of critical importance to the safe, reliable and economic operation of the wellbore.
In view of the importance of maintaining the seal, packers are typically designed to apply large forces sufficient to overcome and resist the forces expected during deployment and in use. In some instances, however, the pressure difference acting across the seal element may be sufficient to cause extrusion of the seal element, thereby reducing seal performance or making activation more difficult or in more extreme cases risking failure of the seal. In other instances, the use of large applied activation forces may be prevented or restricted due to the possibility of damaging the surrounding bore wall or tubulars.
According to a first aspect of the present invention, there is provided a sealing apparatus for use in establishing a seal in an annulus between a mandrel and a bore wall, the apparatus comprising:
a mandrel; and
a seal element disposed on the mandrel, the seal element configured to define a first configuration and a second, expanded, configuration, the apparatus configured so that in the second configuration fluid from the annulus acts on the seal element to urge the seal element from the second configuration to a third configuration providing sealing or enhanced sealing engagement with the bore wall.
In use, the apparatus may be run into a bore with the seal element defining a first, retracted, configuration. The seal element may then be initially activated from the first configuration to the second, expanded, configuration. In the second configuration, pressurised fluid from the annulus between the apparatus and the bore wall (the annulus fluid) may be utilised to provide a second stage activation in which the seal element is urged into sealing or enhanced sealing engagement with the bore wall. In particular, but not exclusively, the annulus fluid used to urge the seal element from the second configuration to the third configuration may comprise fluid from upstream of the restriction created by the seal element defining the second configuration.
Beneficially, embodiments of the present invention provide for an initial activation of the seal element and a second activation which utilises the pressurised fluid in the annulus—which may otherwise cause extrusion of the seal element, reduce seal performance, make activation more difficult or risk failure of the seal—to maintain or enhance the seal with the bore wall. Moreover, by utilising the pressurised fluid present in the annulus the use of applied activation forces—which may otherwise damage the surrounding bore wall or tubulars and increase the size and weight of the apparatus—may be obviated or reduced.
The seal element may be of any suitable form or construction.
In particular embodiments, the seal element may comprise an annular seal element and the seal element may be disposed around the mandrel. However, other suitable forms may be used where appropriate. For example, the apparatus may comprise a plurality of seal elements extending around the mandrel, the plurality of seal elements forming the seal between the mandrel and the bore wall.
The seal element may be configured to expand in the presence of a selected activation medium. The activation medium may comprise a fluid. In particular embodiments, the fluid may comprise fluid from the annulus between the apparatus and the bore wall.
In particular embodiments, the seal element may comprise a material which swells in response to oil. For example, the seal element may comprise an oil-swellable material, such as an oil-swellable elastomer.
In other embodiments, the seal element may comprise a material which swells in response to water. For example, the seal element may comprise a water-swellable material, such as a water-swellable elastomer.
In use, the apparatus may be run into the bore, exposure of the seal element to the selected activation medium in the annulus fluid causing the seal element to expand from the first configuration to the second, expanded, configuration to provide the initial activation of the apparatus.
The apparatus may be configured so that the seal element is moveable relative to the mandrel. In particular embodiments, the apparatus may be configured so that, in the second configuration, the annulus fluid is directed between the seal element and the mandrel. For example, the apparatus may be configured so that the annulus fluid impinges on an inner circumferential surface of the seal element. Thus, the annulus fluid may be used to urge or push the seal element radially outwards into sealing or enhanced sealing engagement with the bore wall.
The apparatus may be configured to define a fluid-receiving chamber between the seal element and the mandrel. The fluid-receiving chamber may be present when the seal element is in the first, retracted, configuration. Alternatively, and in preferred embodiments, the fluid-receiving chamber may be formed when the seal element expands or moves from the first configuration to the second configuration. Beneficially, this allows the seal element to define a smaller diameter first configuration than would otherwise be possible where a fluid-receiving chamber is present during run-in. This may assist in preventing damage to the seal element during run-in, for example.
Any suitable means for permitting the pressurised annulus fluid to pass between the seal element and the mandrel may be provided. For example, the apparatus may comprise a fluid passage configured to permit the passage of the pressurised fluid between the seal element and the mandrel.
The fluid passage may comprise an axially-extending fluid passage. In particular embodiments, the apparatus may comprise a plurality of axially-extending passages.
The passage or passages may be of any suitable form. In particular embodiments, the passage or passages may of hemi-cylindrical form. Where a plurality of passages is provided, the passages may be arranged circumferentially
In use, the passage or passages may be arranged to provide at least some of the fluid communication to the fluid-receiving chamber, the pressurised annulus fluid passing through the passage or passages and impinging on the seal element forcing or assisting in urging the seal element into sealing or enhanced sealing engagement with the bore wall.
In some embodiments, the apparatus may be configured so that the seal element engages the bore wall in the second configuration. For example, and in preferred embodiments, the apparatus may be configured so that the seal element provides initial sealing engagement with the bore wall in the second configuration. In such embodiments, the seal element may be maintained in sealing engagement or urged into enhanced sealing engagement with the bore wall in the third configuration. Alternatively, the apparatus may be configured so that the seal element does not sealingly engage the bore wall in the second configuration. In such embodiments, the seal element may be urged into sealing engagement with the bore wall in the third configuration.
In other embodiments, the apparatus may be configured so that the seal element does not engage the bore wall in the second configuration. In such embodiments, the seal element may sealingly engage the bore wall in the third configuration.
The apparatus may comprise at least one further seal member and, in particular but not exclusively, the further seal member may be configured to define a cup seal.
The or each further seal member may be of any suitable form or construction.
The or each further seal member may comprise at least one of: an elastomeric seal member; a compression seal member; a packing member; an expandable member; a swellable member; an oil-swellable member; a water-swellable member; an inflatable member, or any suitable style of seal member.
The apparatus may comprise a single further seal member. In particular embodiments, the apparatus may comprise a plurality of further seal members.
Where the apparatus comprises a plurality of seal members, the seal members may be of the same or different construction.
The further seal members may be selected and/or arranged in order to provide selected properties to the apparatus. For example, one or more seal member may comprise a material of greater hardness than one or more other seal member.
Beneficially, the provision of a seal member having greater hardness may assist in preventing or at least mitigating extrusion of a seal member and/or the seal element.
In use, the seal element may be used to activate the further seal member. For example, the further seal member may be at least partially activated by expansion of the seal element from the first configuration to the second configuration. Alternatively, or additionally, the further seal member may be at least partially activated when the seal element is urged from the second configuration to the third configuration.
The apparatus may comprise one or more end ring, and in particular embodiments the apparatus comprises two end rings disposed at opposing ends of the apparatus. In particular embodiments, the fluid passage may be formed or otherwise provided in one of the end rings, for example around an inner circumferential surface of the end ring.
At least one end ring may comprise a radially-extending bore for receiving a retainer and, in particular embodiments, each end ring may comprise a plurality of radially-extending bores, each for receiving a retainer, such as a grub screw, bolt or the like. In use, the retainer or retainers may be used to secure the end ring to the mandrel.
The apparatus may be configured so that part of the annulus fluid also acts towards retaining the seal element and/or one or more seal member on the mandrel. For example, a component of the force generated by the annulus fluid may be directed radially inwards and so may assist in maintaining a seal element or seal member on the mandrel.
In use, embodiments of the present invention may utilise fluid pressure both to urge the sealing element into sealing or enhanced sealing engagement with the bore wall and also to retain the sealing element on the mandrel. The apparatus may be configured so that the fluid pressure impinges on selected areas, the selected areas configured to provide the required forces to urge the seal element radially outwards to provide sealing or enhanced sealing engagement with the bore wall and radially inwards to assist in maintaining the seal element on the mandrel.
The apparatus may comprise a back-up assembly for supporting the seal element in maintaining sealing engagement with the bore wall. The back-up assembly may comprise at least one of: a ring member; a support member arranged to extend over at least an end of the seal element; and a collar having a seal-engaging surface arranged to engage the end of the seal element, the collar interposed between the end of the seal element and the support member.
The apparatus may comprise a downhole packer.
The apparatus may comprise a uni-directional downhole packer. For example, the apparatus may be configured to be activated by the annulus fluid or differential fluid pressure acting in a selected direction.
The apparatus may comprise a uni-directional cup seal packer.
According to a further aspect of the present invention, there is provided a method comprising:
providing an apparatus comprising a mandrel and a seal element for establishing a seal in an annulus between the mandrel and a wall of a bore;
disposing the apparatus in the bore,
initially activating the seal element from a first configuration to a second, expanded, configuration; and
urging the seal element from the second configuration to a third configuration using fluid from the annulus between the mandrel and the wall of the bore, the seal element in the third configuration providing sealing or enhanced sealing engagement with the bore wall.
It should be understood that the features defined above in accordance with any aspect of the present invention or below in relation to any specific embodiment of the invention may be utilised, either alone or in combination, with any other defined feature, in any other aspect or embodiment of the invention.
These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
The figures show an end view and a longitudinal section view of a sealing apparatus 10 according to an embodiment of the present invention, the apparatus 10 in the illustrated embodiment comprises a downhole cup seal packer for use in sealing an open or uncased hole. In use, the apparatus 10 establishes a seal in an annulus 12 between the apparatus 10 and a wall (shown diagrammatically at 14) of a bore (shown diagrammatically at 16) which prevents passage of fluid along the annulus 12 in a selected direction, for example preventing passage of fluid in an uphole direction or in a downhole direction.
The apparatus 10 comprises a mandrel 18 which forms part of a tubing string such as production conduit or the like (not shown). An annular seal element 20 is disposed around the mandrel 18, the seal element 20 comprising a swellable seal element which swells in response to a selected activation fluid in the annulus 12. In the illustrated embodiment, the seal element 20 is constructed from an oil-swellable elastomer and, in use, the seal element 20 may be run into the bore 18 in a first, retracted, configuration before being initially activated from the first configuration to a second, expanded, configuration when exposed to oil in the annulus 12.
The seal element 20 is disposed around the mandrel and is free to move relative to the mandrel 18 such that, in use, when the seal element 20 moves to the second configuration a fluid-receiving chamber C is defined between the seal element 20 and the mandrel 18. The annulus fluid may be directed to the chamber C formed between the seal element 20 and the mandrel 18, the pressurised annulus fluid impinging on the inner circumferential surface of the seal element 20 being used to urge or push the seal element 20 radially outwards into sealing or enhanced sealing engagement with the bore wall 14 and so provide a secondary activation of the seal element 20.
As shown most clearly in
In use, the seal element 20 and the ring 22 are arranged to permit the passage of the annulus fluid into the fluid-receiving chamber C.
In the illustrated embodiment, the gauge ring 22 also comprises axial passages or grooves 32 and, in use, the grooves 32 permit additional fluid communication with the fluid-receiving chamber C.
In the illustrated embodiment, the gauge ring 22 comprises eight grooves 32. However, it will be recognised that one groove 32 or a plurality of grooves 32 may be provided, as appropriate. Following initial activation of the apparatus 10, annulus fluid may be directed through the grooves 32 and into the chamber C, thereby providing an additional activation force which urges the seal element 20 into sealing engagement (where the seal element 20 is not already in sealing engagement with the bore wall 14 in the second configuration) or enhanced sealing engagement (where the seal element is already in sealing engagement with the bore wall 14 in the second configuration). While the illustrated embodiment provides for passage of fluid between the ring 22 and the chamber C and through the grooves 32, it will be recognised that fluid may be directed to the chamber C by one or both of these.
Referring now to
In use, the seal element 20 is used to at least partially activate the further seal members 34, 36 by urging or pushing the seal members radially outwards to define the cup seal.
Beneficially, embodiments of the present invention provide for an initial activation of the seal element and a second activation which utilises the pressurised fluid in the annulus—which may otherwise cause extrusion of the seal element, reduce seal performance, make activation more difficult or risk failure of the seal—to maintain or enhance the seal with the bore wall. Moreover, by utilising the pressurised fluid present in the annulus the use of applied activation forces—which may otherwise damage the surrounding bore wall or tubulars and increase the size and weight of the apparatus—may be obviated or reduced.
It should be understood that the embodiment described herein is merely exemplary and that various modifications may be made thereto without departing from the scope of the invention.
For example, the apparatus may further comprise a back-up assembly 38 for supporting the seal members 34, 36 in maintaining sealing engagement with the bore wall 14.
While the illustrated embodiment describes apparatus for use in open hole, the apparatus may alternatively be used in a cased hole. While the seal element and seal members are described above at separate components, one or more of these may comprise a unitary component.
The apparatus may alternatively or additionally be configured so that the annulus fluid impinges on an end face of the seal element. In such embodiments, at least one of the seal element, the mandrel or other components of the apparatus may be formed or arranged to urge the seal element radially outwards in response to an axial force generated by the annulus fluid impinging on the end of the seal element. For example, at least one of the mandrel, seal element, first seal member may be tapered.
While in the illustrated embodiment, the initial activation may be taken up by expansion of the seal element, the apparatus may alternatively or additionally be configured to receive an initial applied activation force. The applied initial activation force may comprise an axial force, such as an axial compressive force. The apparatus may further comprise an activation arrangement for applying the initial activation force to the seal element. The activation arrangement may be of any suitable form or construction, and may comprise a setting tool or the like. The activation arrangement may form part of the apparatus. Alternatively, the activation arrangement may be provided separately from the apparatus.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1213278.3 | Jul 2012 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2013/052014 | 7/26/2013 | WO | 00 |
