U.S. patent application number 16/066046 was filed with the patent office on 2019-11-21 for expanding and collapsing apparatus and methods of use.
The applicant listed for this patent is PEAK WELL SYSTEMS LIMITED, PEAK WELL SYSTEMS PTY LTD. Invention is credited to Gareth Edward George BROWN.
Application Number | 20190352988 16/066046 |
Document ID | / |
Family ID | 57963362 |
Filed Date | 2019-11-21 |
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United States Patent
Application |
20190352988 |
Kind Code |
A1 |
BROWN; Gareth Edward
George |
November 21, 2019 |
EXPANDING AND COLLAPSING APPARATUS AND METHODS OF USE
Abstract
The invention provides an expanding and collapsing ring
apparatus (171) and method of use. The expanding and collapsing
ring comprises a plurality of elements (177) assembled together to
form a ring structure (172, 173a, 173b) oriented in a plane around
a longitudinal axis. The ring structure is operable to be moved
between a collapsed condition and a first expanded condition by
movement of the plurality of elements on actuation by an axial
force. The apparatus further comprises a secondary expanding and
collapsing mechanism operable to move the ring structure between
its collapsed condition or its first expanded conditions to a
second expanded condition on actuation by an axial force.
Applications of the invention include oilfield devices, including
anti-extrusion rings, plugs, packers, locks, patching tools,
connection systems, and variable diameter tools run in a
wellbore.
Inventors: |
BROWN; Gareth Edward George;
(Ellon, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PEAK WELL SYSTEMS PTY LTD
PEAK WELL SYSTEMS LIMITED |
Bayswater
Aberdeen |
|
AU
GB |
|
|
Family ID: |
57963362 |
Appl. No.: |
16/066046 |
Filed: |
December 23, 2016 |
PCT Filed: |
December 23, 2016 |
PCT NO: |
PCT/GB2016/054065 |
371 Date: |
June 25, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 47/08 20130101;
E21B 23/01 20130101; E21B 33/134 20130101; E21B 33/1216 20130101;
E21B 10/32 20130101; E21B 17/1014 20130101; E21B 33/04 20130101;
E21B 33/128 20130101 |
International
Class: |
E21B 23/01 20060101
E21B023/01; E21B 33/128 20060101 E21B033/128 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2015 |
GB |
1522725.9 |
Dec 23, 2015 |
GB |
1522741.6 |
Claims
1. An expanding and collapsing ring apparatus comprising: a
plurality of elements assembled together to form a ring structure
oriented in a plane around a longitudinal axis; wherein the ring
structure is operable to be moved between a collapsed condition and
a first expanded condition by movement of the plurality of elements
on actuation by an axial force; and wherein the apparatus further
comprises a secondary expanding and collapsing mechanism operable
to move the ring structure between its collapsed condition or its
first expanded condition to a second expanded condition on
actuation by an axial force.
2. The apparatus according to claim 1, wherein the plurality of
elements is operable to be moved relative to one another between
the expanded and collapsed conditions by sliding the elements with
respect to one another in the plane of the ring structure.
3. The apparatus according to claim 1, wherein the ring structure
comprises one or more ring surfaces configured to be presented to
an auxiliary surface when actuated to an expanded condition or a
collapsed condition.
4. The apparatus according to claim 3, wherein the one or more ring
surfaces comprises a substantially cylindrical surface arranged to
contact or otherwise interact with an inner surface of a tubular or
bore.
5. The apparatus according to claim 3, wherein the ring surface is
substantially smooth.
6. The apparatus according to claim 3, wherein the ring surface is
provided with one or more functional formations thereon, for
interacting with an auxiliary surface.
7. The apparatus according to claim 1, wherein the elements are
configured to move between their expanded and collapsed radial
positions in a path which is tangential to a circle described
around and concentric with the longitudinal axis.
8. The apparatus according to claim 1, wherein each element of the
ring structure comprises a first contact surface and second contact
surface respectively in abutment with first and second adjacent
elements, and wherein the elements are configured to slide relative
to one another along their respective contact surfaces.
9. The apparatus according to claim 8, wherein the first contact
surface and/or the second contact surface are oriented tangentially
to a circle described around and concentric with the longitudinal
axis.
10. The apparatus according to claim 8, wherein the first contact
surface and the second contact surface converge towards one another
in a direction towards an inner surface of the ring structure.
11. (canceled)
12. The apparatus according to claim 1, wherein the elements are
provided with interlocking profiles for interlocking with an
adjacent element.
13. The apparatus according to claim 1, comprising a biasing means
configured to bias the ring structure to one of its expanded or
collapsed conditions.
14-15. (canceled)
16. The apparatus according to claim 1, wherein the ring structure
is a first ring structure, and the secondary expanding and
collapsing mechanism comprises a second ring structure, wherein the
second ring structure is operable to move the first ring structure
from an intermediate expanded condition to a fully expanded
condition.
17. The apparatus according to claim 16, wherein the second ring
structure is one of a second pair of ring structures, operable to
move the first ring structure from an intermediate expanded
condition to a fully expanded condition.
18. The apparatus according to claim 17, wherein each of the second
pair of ring structures are disposed on opposing sides of the first
ring structure.
19. The apparatus according to claim 17, wherein each of the second
pair of ring structures comprises a plurality of second elements
assembled together to form the second ring structure oriented in a
plane around the longitudinal axis.
20. The apparatus according to claim 19, wherein the plurality of
second elements is operable to be moved relative to one another
between expanded and collapsed conditions of the respective second
ring structures by sliding the second elements with respect to one
another in the planes of the second ring structures.
21. The apparatus according to claim 16, wherein each of the second
ring structures defines a respective outer surface, which is
inclined with respect to a surface parallel to the longitudinal
axis.
22. The apparatus according to claim 21, wherein the respective
outer surfaces are conical wedge surfaces which face the first ring
structure.
23. The apparatus according to claim 19, wherein the plurality of
elements of the second ring structures are operable to be moved
between their expanded and collapsed conditions by sliding with
respect to one another in the plane of the second ring structure,
in a direction tangential to a circle concentric with the second
ring structure.
24. The apparatus according to claim 1, wherein the apparatus
comprises a plurality of additional ring structures arranged in
functional pairs, and operable to move the first ring structure
from an intermediate expanded condition to a subsequent
intermediate expanded condition, or a fully expanded condition.
25. The apparatus according to claim 24, wherein each additional
ring structure comprises a biasing means configured to bias the
first ring structure to one of its expanded or collapsed
conditions, and wherein biasing means of the first and second or
additional ring structures are selected to define a sequence of
expanding and collapsing of the apparatus.
26-29. (canceled)
30. The apparatus according claim 1, wherein each of a functional
pair of additional ring structures and/or the elements thereof are
configured to limit the travel of a corresponding additional ring
structures and/or the elements thereof.
31. An oilfield tool comprising the apparatus of claim 1.
32. The oilfield tool according to claim 31, configured as a
downhole tool selected from the group consisting of: a plug, a
packer, an anchor, a tubing hanger, or a downhole locking tool.
33-34. (canceled)
35. A variable diameter downhole tool comprising an apparatus
according to claim 1.
36. (canceled)
37. A connector system comprising a first connector and a second
connector, wherein one of the first and second connectors comprises
the apparatus of claim 1.
38. A patch apparatus for a fluid conduit or tubular, the patch
apparatus comprising the apparatus of claim 1.
39. A method of expanding an apparatus, the method comprising:
providing an apparatus comprising: a plurality of elements
assembled together to form a ring structure oriented in a plane
around a longitudinal axis; and a secondary expanding and
collapsing mechanism; imparting an axial force to the ring
structure to move the plurality of elements from a collapsed
condition to a first expanded condition; and imparting an axial
force to the secondary expanding and collapsing mechanism to move
the first ring structure from its first expanded condition to a
second expanded condition.
40. A method of collapsing an apparatus, the method comprising:
providing an apparatus comprising: a plurality of elements
assembled together to form a ring structure oriented in a plane
around a longitudinal axis; and a secondary expanding and
collapsing mechanism; releasing or reducing an axial force from the
secondary expanding and collapsing mechanism to move the ring
structure from a second expanded condition to a first expanded
condition; and releasing or reducing an axial force from the ring
structure to move the plurality of elements, thereby moving the
ring structure from the first expanded condition to a collapsed
condition.
Description
[0001] The present invention relates to an expanding and collapsing
apparatus and methods of use, and in particular aspects, to an
expanding apparatus in the form of a ring, operable to move between
a collapsed condition and an expanded condition. The invention also
relates to tools and devices incorporating the expansion apparatus
and methods of use. Preferred embodiments of the invention relate
to oilfield apparatus (including but not limited to downhole
apparatus and wellhead apparatus) incorporating the apparatus and
methods of use.
BACKGROUND TO THE INVENTION
[0002] In many fields of mechanical engineering, and in the field
of hydrocarbon exploration and production in particular, it is
known to provide expansion mechanisms for the physical interaction
of tubular components. Expansion mechanisms may expand outwardly to
engage an external surface, or may collapse inwardly to engage an
internal surface.
[0003] Applications are many and varied, but those in hydrocarbon
exploration and production include the actuation and setting of
flow barriers and seal elements such as plugs and packers,
anchoring and positioning tools such as wellbore anchors, casing
and liner hangers, and locking mechanisms for setting equipment
downhole. Other applications include providing mechanical support
or back up for elements such as elastomers or inflatable
bladders.
[0004] A typical anti-extrusion ring is positioned between a packer
or seal element and its actuating slip members, and is formed from
a split or segmented metallic ring. During deployment of the packer
or seal element, the segments move to a radially expanded
condition. During expansion and at the radially expanded condition,
spaces are formed between the segments, as they are required to
occupy a larger annular volume. These spaces create extrusion gaps,
which may result in failure of the packer or seal under working
conditions.
[0005] Various configurations have been proposed to minimise the
effect of spaces between anti-extrusion segments, including
providing multi-layered rings, such that extrusion gaps are blocked
by an offset arrangement of segments. For example, U.S. Pat. No.
6,598,672 describes an anti-extrusion rings for a packer assembly
which has first and second ring portions which are
circumferentially offset to create gaps in circumferentially offset
locations.
[0006] U.S. Pat. No. 2,701,615 discloses a well packer comprising
an arrangement of crowned spring metal elements which are expanded
by relative movement.
[0007] Other proposals, for example those disclosed in U.S. Pat.
Nos. 3,572,627, 7,921,921, US 2013/0319654, U.S. Pat. Nos.
7,290,603 and 8,167,033 include arrangements of circumferentially
lapped segments. U.S. Pat. No. 3,915,424 describes a similar
arrangement in a drilling BOP configuration, in which overlapping
anti-extrusion members are actuated by a radial force to move
radially and circumferentially to a collapsed position which
supports annular sealing elements. Such arrangements avoid
introducing extrusion gaps during expansion, but create a ring with
uneven or stepped faces or flanks. These configurations do not
provide an unbroken support wall for a sealing element, are
spatially inefficient, and may be difficult to reliably move back
to their collapsed configurations.
[0008] U.S. Pat. No. 8,083,001 proposes an alternative
configuration in which two sets of wedge shaped segments are
brought together by sliding axially with respect to one another to
create an expanded gauge ring.
[0009] In anchoring, positioning, setting, locking and connection
applications, radially expanding and collapsing structures are
typically circumferentially distributed at discrete locations when
at their increased outer diameter. This reduces the surface area
available to contact an auxiliary engagement surface, and therefore
limits the maximum force and pressure rating for a given size of
device.
SUMMARY OF THE INVENTION
[0010] It is amongst the claims and objects of the invention to
provide an expanding and collapsing apparatus and methods of use
which obviate or mitigate disadvantages of previously proposed
expanding and collapsing apparatus.
[0011] It is amongst the aims and objects of the invention to
provide an oilfield apparatus, including a downhole apparatus or a
wellhead apparatus, incorporating an expanding and collapsing
apparatus, which obviates or mitigates disadvantages of prior art
oilfield apparatus.
[0012] Further aims and objects of the invention will be apparent
from reading the following description.
[0013] According to a first aspect of the invention, there is
provided an expanding and collapsing ring apparatus comprising:
a plurality of elements assembled together to form a ring structure
oriented in a plane around a longitudinal axis; wherein the ring
structure is operable to be moved between a collapsed condition and
a first expanded condition by movement of the plurality of elements
on actuation by an axial force; and wherein the apparatus further
comprises a secondary expanding and collapsing mechanism operable
to move the first ring structure between its collapsed condition or
its first expanded condition to a second expanded condition on
actuation by an axial force.
[0014] The ring structure may be a first ring structure, and the
apparatus may comprise at least one additional ring structure,
wherein the additional ring structure is operable to move the first
ring structure from an intermediate expanded condition to a fully
expanded condition.
[0015] Preferably, the plurality of elements is operable to be
moved relative to one another between the expanded and collapsed
conditions, and more preferably, is operable to be moved by sliding
the elements with respect to one another in the plane of the ring
structure.
[0016] The plane of the ring structure may be perpendicular to the
longitudinal axis. The ring structure, and its plane of
orientation, may be operable to move on the apparatus during
expansion and/or collapsing. The movement of the plane may be an
axial sliding movement, during expanding and/or collapsing of the
ring structure.
[0017] The apparatus may be normally collapsed, and may be actuated
to be expanded. Alternatively, the apparatus may be normally
expanded, and may be actuated to be collapsed.
[0018] The ring structure may comprise one or more ring surfaces,
which may be presented to an auxiliary surface, for example the
surface of a tubular, when actuated to an expanded condition or a
collapsed condition. The one or more ring surfaces may include a
ring surface which is parallel to the longitudinal axis of the
apparatus. Alternatively, or in addition, the one or more ring
surfaces may include a surface which is perpendicular to the
longitudinal axis of the apparatus, and/or a surface which is
inclined to the longitudinal axis of the apparatus.
[0019] The ring surface may be an outer ring surface, and may be a
substantially cylindrical surface. The ring surface may be arranged
to contact or otherwise interact with an inner surface of a tubular
or bore.
[0020] The ring surface may be substantially smooth. Alternatively,
the ring surface may be profiled, and/or may provided with one or
more functional formations thereon, for interacting with an
auxiliary surface.
[0021] In the collapsed condition, the elements may be arranged
generally at collapsed radial positions, and may define a collapsed
outer diameter and inner diameter of the ring structure.
[0022] In the first expanded condition, the elements may be
arranged generally at expanded radial positions, and may define a
first expanded outer diameter and inner diameter of the ring
structure. The ring surface may be located at or on the expanded
outer diameter of the ring structure, or may be located at or on
the collapsed inner diameter of the ring structure.
[0023] The elements may be configured to move between their first
expanded and collapsed radial positions in a path which is
tangential to a circle described around and concentric with the
longitudinal axis.
[0024] Preferably, each element of the ring structure comprises a
first contact surface and second contact surface respectively in
abutment with first and second adjacent elements. The elements may
be configured to slide relative to one another along their
respective contact surfaces.
[0025] The first contact surface and/or the second contact surface
may be oriented tangentially to a circle described around and
concentric with the longitudinal axis. The first contact surface
and the second contact surface are preferably non-parallel. The
first contact surface and the second contact surface may converge
towards one another in a direction towards an inner surface of the
ring structure (and may therefore diverge away from one another in
a direction away from an inner surface of the ring structure).
[0026] At least some of the elements are preferably provided with
interlocking profiles for interlocking with an adjacent element.
Preferably the interlocking profiles are formed in the first and/or
second contact surfaces. Preferably, an element is configured to
interlock with a contact surface of an adjacent element. Such
interlocking may prevent or restrict separation of assembled
adjacent elements in a circumferential and/or radial direction of
the ring structure, while enabling relative sliding movement of
adjacent elements.
[0027] Preferably, at least some of, and more preferably all of,
the elements assembled to form a ring are identical to one another,
and each comprises an interlocking profile which is configured to
interlock with a corresponding interlocking profile on another
element. The interlocking profiles may comprise at least one recess
such as groove, and at least one protrusion, such as a tongue or a
pin, configured to be received in the groove. The interlocking
profiles may comprise at least one dovetail recess and dovetail
protrusion.
[0028] The first and second contact surfaces of an element may be
oriented on first and second planes, which may intersect an inner
surface of the ring at first and second intersection lines, such
that a sector of an imaginary cylinder is defined between the
longitudinal axis and the intersection lines. The central angle of
the sector may be 45 degrees or less. Such a configuration
corresponds to eight or more elements assembled together to form
the ring structure.
[0029] Preferably, the central angle of the sector is 30 degrees or
less, corresponding to twelve or more elements assembled together
to form the ring. More preferably, the central angle of the sector
is in the range of 10 degrees to 20 degrees, corresponding to
eighteen to thirty-six elements assembled together to form the
ring. In a particular preferred embodiment, the central angle of
the sector is 15 degrees, corresponding to twenty-four elements
assembled together to form the ring structure.
[0030] Preferably, an angle described between the first contact and
second contact surfaces corresponds to the central angle of the
sector. Preferably therefore, an angle described between the first
contact and second contact surfaces is in the range of 10 degrees
to 20 degrees, and in a particular preferred embodiment, the angle
described between the first contact and second contact surfaces is
15 degrees, corresponding to twenty-four elements assembled
together to form the ring structure.
[0031] In a preferred embodiment, the apparatus comprises a support
surface for the ring structure. The support surface may be the
outer surface of a mandrel or tubular. The support surface may
support the ring structure in a collapsed condition of the
apparatus.
[0032] In some embodiments, the apparatus is operated in its second
expanded condition, and in other embodiments, the apparatus is
operated in its collapsed condition. Preferably, elements forming
the ring structure are mutually supportive in an operating
condition of the apparatus. Where the operating condition of the
apparatus its expanded condition (i.e. when the apparatus is
operated in its expanded condition), the ring structure is
preferably a substantially solid ring structure in its second
expanded condition, and the elements may be fully mutually
supported.
[0033] The apparatus may comprise a formation configured to impart
a radial expanding or collapsing force component to the elements of
a ring structure and/or secondary expanding and collapsing
mechanism from an axial actuation force. The apparatus may comprise
a pair of formations configured to impart a radial expanding or
collapsing force component to the elements of a ring structure from
an axial actuation force. The formation (or formations) may
comprise a wedge or wedge profile, and may comprise a cone wedge or
wedge profile.
[0034] The apparatus may comprise a biasing means, which may be
configured to bias the first ring structure to one of its expanded
or collapsed conditions. The biasing means may comprise a
circumferential spring, a garter spring, or a spiral retaining
ring. The biasing means may be arranged around an outer surface of
a ring structure, to bias it towards a collapsed condition, or may
be arranged around an inner surface of a ring structure, to bias it
towards an expanded condition. One or more elements may comprise a
formation such as a groove for receiving the biasing means.
Preferably, grooves in the elements combine to form a
circumferential groove in the ring structure. Multiple biasing
means may be provided on the ring structure.
[0035] Preferably, the secondary expanding and collapsing mechanism
comprises a second ring structure, and more preferably comprises a
pair of second ring structures. The second ring structure(s) may be
operable to move the first ring structure from an intermediate
expanded condition to a fully expanded condition. The pair of
second ring structures may be disposed on opposing sides of the
first ring structure. The second ring structure(s) may comprise a
plurality of second elements assembled together to form the second
ring structure oriented in a plane around the longitudinal
axis.
[0036] The plurality of second elements may be operable to be moved
relative to one another between an expanded and collapsed
conditions of the respective second ring structure, and more
preferably, is operable to be moved by sliding the second elements
with respect to one another in the plane of the second ring
structure.
[0037] The second ring structures may define an outer surface,
which may be inclined with respect to a surface parallel to the
longitudinal axis. The outer surfaces may be conical wedge
surfaces, which may face the first ring structure.
[0038] The apparatus may comprise at least one pair of additional
ring structures, wherein the pair of additional ring structures are
operable to move the first ring structure from an intermediate
expanded condition to a fully expanded condition. The pair of
additional ring structures may be disposed (axially) on either side
of the first ring structure, and may act together to move the ring
structure from an intermediate expanded condition to a fully
expanded condition.
[0039] The plurality of elements of the additional ring structure
may be operable to be moved between the expanded and collapsed
conditions by sliding with respect to one another in the plane of
the additional ring structure, in a direction tangential to a
circle concentric with the additional ring structure. In other
respects, the additional ring structure and its elements may have
features in common with the ring structure described herein.
[0040] The additional ring structure, and/or its elements, may be
operable to transfer an axial actuation force to the elements of
the first ring structure. The additional ring structure, and/or its
elements may comprise one or more wedge profiles, which may be
conical wedge profiles. The one or more wedge profiles may be
defined by an outer surface of the elements of the additional ring
structure.
[0041] The apparatus may comprise a plurality of additional ring
structures, which may be arranged in functional pairs, and/or which
may be operable to move the first ring structure from an
intermediate expanded condition to a subsequent intermediate
expanded condition, or a fully expanded condition.
[0042] Preferably, each additional ring structure comprises a
biasing means, which may be configured to bias the first ring
structure to one of its expanded or collapsed conditions.
[0043] The biasing means may comprise a circumferential spring, a
garter spring, or a spiral retaining ring. Preferably, the biasing
means of the first and additional ring structures are selected to
define a sequence of expanding and collapsing of the apparatus.
Preferably, the biasing means of the first and additional ring
structures are selected to expand the centremost ring structure
before an adjacent pair of additional ring structures. The biasing
means additional ring structures may be selected to expand a first
pair of additional ring structures before an adjacent pair of
additional ring structures located axially outside of the first
pair or additional ring structures.
[0044] The biasing means may be disposed on an outer surface of a
ring structure, or may be disposed in a groove on the outer surface
of a ring structure.
[0045] Alternatively, or in addition, a biasing means may be
disposed in apertures in the elements. The biasing means may be
threaded through each element, and may then be joined to make a
continuous loop upon assembly. The biasing means may be disposed
in-board of the external surface of the elements. The biasing means
may be located directly over an interlocking feature such as a
dovetail, and/or may be located centrally on the ring
structure.
[0046] Preferably, a functional pair of additional ring structures
and/or the elements thereof is symmetrical about a centre ring
structure. Each of a functional pair of additional ring structures
and/or the elements thereof may be configured to move axially with
respect to one another on the apparatus, and may be configured to
move into abutment with one another. Preferably, each of a
functional pair of additional ring structures and/or the elements
thereof are configured to limit the travel of a corresponding
additional ring structures and/or the elements thereof.
[0047] External profiles of the elements may comprise chamfers,
which may at least partially define a surface of one or more flanks
of an assembled ring structure.
[0048] An assembled ring structure may comprise at least one flank
having an at least partially smoothed conical surface. In use, the
at least partially smoothed conical surface may facilitate
deployment of the apparatus, for example by improving the sliding
action of an adjacent ring on the flank during expansion. The flank
may be a flank of a supporting ring structure. The at least one
flank may be an inward facing flank, or a flank facing a central
ring structure or a ring structure disposed between the flank and a
central ring structure.
[0049] Alternatively, or in addition, the elements may be profiled
such that the ring structures define at least partially smooth
conical surfaces on their outward facing flanks when in their
expanded condition. The at least partially smooth conical surfaces
may combine in the assembled, expanded apparatus, to provide a
substantially or fully smooth surface of flank of the expanded
apparatus, which may be suitable for abutment with and/or support
of an adjacent element such as an elastomer.
[0050] The surfaces of the plurality of elements may be configured
to be presented directly against a surface with which it interacts,
such as a borehole wall. Alternatively, or in addition, the
apparatus may comprise an intermediate structure or material
disposed between the surfaces of the elements and a surface with
which it interacts.
[0051] In one embodiment, the elements of the ring structure are
configured to conform, deform or compress in a collapsed condition
to form a fluid barrier or seal with an object in the throughbore.
The elements may be formed, at least partially, from a compressible
and/or resilient material, such as an elastomer, rubber or
polymer.
[0052] Alternatively, or in addition, the elements may be formed,
at least partially, from a metal or metal alloy, and may be coated
or covered with a compressible and/or resilient material, such as
an elastomer, rubber or polymer.
[0053] According to a second aspect of the invention, there is
provided an expanding and collapsing ring apparatus comprising:
a plurality of elements assembled together to form a first ring
structure oriented in a plane around a longitudinal axis; wherein
the first ring structure is operable to be moved between a
collapsed condition and a first expanded condition by movement of
the plurality of elements on actuation by an axial force; and
wherein the apparatus further comprises at least one pair of
additional ring structures, wherein the pair of additional ring
structures are operable to move the first ring structure from an
intermediate expanded condition to a fully expanded condition.
[0054] The additional ring structure may comprise a plurality of
elements assembled together to form a ring structure, and may be
oriented in a plane around a longitudinal axis. The additional ring
structure may be operable to be moved between an expanded condition
and a collapsed condition by movement of the plurality of elements
on actuation by an axial force. The plurality of elements of the
additional ring structure may be operable to be moved between the
expanded and collapsed conditions by sliding with respect to one
another in the plane of the additional ring structure, in a
direction tangential to a circle concentric with the additional
ring structure. In other respects, the additional ring structure
and its elements may have features in common with the ring
structure described herein.
[0055] Embodiments of the second aspect of the invention may
include one or more features of the first aspect of the invention
or its embodiments, or vice versa.
[0056] According to a third aspect of the invention, there is
provided an oilfield tool comprising the apparatus of any of the
first or second aspects of the invention.
[0057] The oilfield tool may be a downhole tool. Alternatively, the
oilfield tool may comprise a wellhead tool.
[0058] The downhole tool may comprise a downhole tool selected from
the group consisting of a plug, a packer, an anchor, a tubing
hanger, or a downhole locking tool.
[0059] The plug may be a bridge plug, and may be a retrievable
bridge plug. Alternatively, the plug may be a permanent plug.
[0060] Embodiments of the third aspect of the invention may include
one or more features of the first or second aspects of the
invention or their embodiments, or vice versa.
[0061] According to a fourth aspect of the invention, there is
provided variable diameter downhole tool, the tool comprising an
apparatus according to a previous aspect of the invention.
[0062] The downhole tool may be selected from the group consisting
of a wellbore centraliser, a wellbore broach tool, and a wellbore
drift tool.
[0063] Embodiments of the fourth aspect of the invention may
include one or more features of the first or second aspects of the
invention or their embodiments, or vice versa.
[0064] According to a fifth of the invention, there is provided a
connector system comprising a first connector and a second
connector, wherein one of the first and second connectors comprises
the apparatus of any of the first or second aspects of the
invention.
[0065] Embodiments of the fifth aspect of the invention may include
one or more features of the first or second aspects of the
invention or their embodiments, or vice versa.
[0066] According to a sixth aspect of the invention, there is
provided patch apparatus for a fluid conduit or tubular, the patch
apparatus comprising the apparatus of any of the first or second
aspects of the invention.
[0067] Embodiments of the sixth aspect of the invention may include
one or more features of the first or second aspects of the
invention or their embodiments, or vice versa.
[0068] According to a seventh aspect of the invention, there is
provided a method of expanding an apparatus, the method
comprising:
providing an apparatus comprising: a plurality of elements
assembled together to form a ring structure oriented in a plane
around a longitudinal axis; and a secondary expanding and
collapsing mechanism; imparting an axial force to the ring
structure to move the plurality of elements from a collapsed
condition to a first expanded condition; and imparting an axial
force to the secondary expanding and collapsing mechanism to move
the first ring structure from its first expanded condition to a
second expanded condition.
[0069] Embodiments of the seventh aspect of the invention may
include one or more features of the first or second aspects of the
invention or their embodiments, or vice versa.
[0070] According to an eighth aspect of the invention, there is
provided a method of collapsing an apparatus, the method
comprising:
providing an apparatus comprising: a plurality of elements
assembled together to form a ring structure oriented in a plane
around a longitudinal axis; and a secondary expanding and
collapsing mechanism; imparting an axial force to the ring
structure to move the plurality of elements from a collapsed
condition to a first expanded condition; and releasing or reducing
an axial force from the secondary expanding and collapsing
mechanism to move the first ring structure from a second expanded
condition to a first expanded condition; and releasing or reducing
an axial force from the ring structure to move the plurality of
elements, thereby moving the ring structure from the first expanded
condition to a collapsed condition.
[0071] Embodiments of the eighth aspect of the invention may
include one or more features of the first or second aspects of the
invention or their embodiments, or vice versa.
[0072] According to a further aspect of the invention, there is
provided an expanding and collapsing ring apparatus comprising:
a plurality of elements assembled together to form a ring structure
oriented in a plane around a longitudinal axis; wherein the ring
structure is operable to be moved between a collapsed condition and
a first expanded condition by movement of the plurality of
elements; and wherein the apparatus further comprises a secondary
expanding and collapsing mechanism operable to move the first ring
structure between its collapsed condition or its first expanded
condition to a second expanded condition.
[0073] According to a further aspect of the invention, there is
provided an expanding and collapsing ring apparatus comprising:
a plurality of elements assembled together to form a first ring
structure oriented in a plane around a longitudinal axis; wherein
the first ring structure is operable to be moved between a
collapsed condition and a first expanded condition by movement of
the plurality of elements; and wherein the apparatus further
comprises at least one pair of additional ring structures, wherein
the pair of additional ring structures are operable to move the
first ring structure from an intermediate expanded condition to a
fully expanded condition.
[0074] According to a further aspect of the invention, there is
provided a method of expanding an apparatus, the method
comprising:
providing an apparatus comprising: a plurality of elements
assembled together to form a ring structure oriented in a plane
around a longitudinal axis; and a secondary expanding and
collapsing mechanism; imparting a force to the ring structure to
move the plurality of elements from a collapsed condition to a
first expanded condition; and imparting a force to the secondary
expanding and collapsing mechanism to move the first ring structure
from its first expanded condition to a second expanded
condition.
[0075] According to a further aspect of the invention, there is
provided a method of collapsing an apparatus, the method
comprising:
providing an apparatus comprising: a plurality of elements
assembled together to form a ring structure oriented in a plane
around a longitudinal axis; and a secondary expanding and
collapsing mechanism; imparting a force to the ring structure to
move the plurality of elements from a collapsed condition to a
first expanded condition; and releasing or reducing a force from
the secondary expanding and collapsing mechanism to move the first
ring structure from a second expanded condition to a first expanded
condition; and releasing or reducing a force from the ring
structure to move the plurality of elements, thereby moving the
ring structure from the first expanded condition to a collapsed
condition.
[0076] According to a further aspect of the invention, there is
provided fluid conduit tool comprising the apparatus according to
any previous aspect of the invention. The fluid conduit tool may be
configured for use in pipelines or other fluid conduits, which may
be surface fluid conduits or subsea fluid conduits, and may be
oilfield or non-oilfield fluid conduits.
[0077] Embodiments of the further aspects of the invention may
include one or more features of the first or second aspects of the
invention or their embodiments, or vice versa.
BRIEF DESCRIPTION OF THE DRAWINGS
[0078] There will now be described, by way of example only, various
embodiments of the invention with reference to the drawings, of
which:
[0079] FIG. 1A to FIG. 1D are respectively perspective, first end,
part sectional and second end views of an apparatus useful for
understanding the invention, shown in a collapsed condition;
[0080] FIGS. 2A to 2D are respectively perspective, first side,
part sectional and second side views of the apparatus of FIGS. 1A
to 1D, shown in an expanded condition;
[0081] FIGS. 3A and 3B are geometric representations of an element
of the apparatus of FIGS. 1A and 1D, shown from one side;
[0082] FIG. 4A to FIG. 4F are respectively first perspective,
second perspective, plan, first end, lower, and second end views of
an element of the apparatus of FIGS. 1A to 1D;
[0083] FIGS. 5A to 5C are respectively perspective, sectional and
end views of an apparatus according to an embodiment of the
invention, shown in a collapsed condition;
[0084] FIGS. 6A to 6C are respectively perspective, sectional and
end views of the apparatus of FIGS. 5A to 5C, shown in an expanded
condition;
[0085] FIG. 7 is a geometric representation of a centre element of
the apparatus of FIGS. 5A to 5C, shown from one side;
[0086] FIGS. 8A to 8F are respectively first perspective, second
perspective, plan, first end, lower, and second end views of a
centre element of the apparatus of FIGS. 5A to 5C;
[0087] FIG. 9 is a geometric representation of an outer element of
the apparatus of FIGS. 5A to 5C, shown from one side;
[0088] FIG. 10A to 10H are respectively first perspective, second
perspective, third perspective, fourth perspective, plan, first
end, lower, and second end views of an outer element of the
apparatus of FIGS. 5A to 5C;
[0089] FIGS. 11A to 11C are respectively perspective, sectional and
end views of an apparatus according to an alternative embodiment of
the invention, shown in a collapsed condition;
[0090] FIGS. 12A to 12C are respectively perspective, sectional and
end views of the apparatus of FIGS. 11A to 11C, shown in an
expanded condition;
[0091] FIGS. 13A and 13B are respectively perspective and sectional
views of an apparatus according to an alternative embodiment of the
invention, shown in a collapsed condition;
[0092] FIGS. 14A to 14D are respectively perspective, first
sectional, end, and second sectional views of the apparatus of
FIGS. 13A and 13B, shown in an expanded condition;
[0093] FIG. 15 is a geometric representation of a centre element of
the apparatus of FIGS. 13A and 13B, shown from one side;
[0094] FIGS. 16A to 16F are respectively first to fourth
perspective, first end, and second end views of a centre element of
the apparatus of FIGS. 13A and 13B;
[0095] FIGS. 17A and 17B are respectively perspective and sectional
views of a patch apparatus according to an embodiment of the
invention, shown in a collapsed condition;
[0096] FIGS. 18A and 18B are respectively perspective and sectional
views of the apparatus of FIGS. 17A and 17B, shown in an expanded
condition;
[0097] FIG. 19 is a side view of an apparatus according to an
alternative embodiment of the invention in a first, collapsed
condition;
[0098] FIG. 20 is a side view of the apparatus of FIG. 19 a second,
collapsed condition;
[0099] FIGS. 21A and 21B are respectively plan and isometric views
of an element of the apparatus of FIGS. 19 and 20; and
[0100] FIGS. 22A and 22B are respectively plan and isometric views
of a second element of the apparatus of FIGS. 19 and 20.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0101] Referring firstly to FIGS. 1A to 4F, the principles of the
invention will be described with reference to an expanding
apparatus which is useful for understanding the invention and its
embodiments. In the arrangement of FIGS. 1A to 4F, the expanding
apparatus, generally depicted at 10, comprises an expanding ring
structure configured to be expanded from a first collapsed or
unexpanded condition (shown in FIGS. 1A to 1D) and a second
expanded condition (shown in FIGS. 2A to 2D). The apparatus of this
and other embodiments may be referred to as "expanding apparatus"
for convenience, as they are operable to move to an expanded state
from a normal collapsed state. However, the apparatus may equally
be referred to as a collapsing apparatus, or an expanding or
collapsing apparatus, as they are capable of being expanded or
collapsed depending on operational state.
[0102] The expanding apparatus 10 comprises a plurality of elements
12 assembled together to form a ring structure 11. The elements 12
define an inner ring surface which is supported by the outer
surface of cylinder 14. Each element comprises an inner surface 20,
an outer surface 21 and first and second contact surfaces 22, 23.
The first and second contact surfaces are oriented in non-parallel
planes, which are tangential to a circle centred on the
longitudinal axis of the apparatus. The planes converge towards the
inner surface of the element. Therefore, each element is in the
general form of a wedge, and the wedges are assembled together in a
circumferentially overlapping fashion to form the ring structure
11. In use, the first and second contact surfaces of adjacent
elements are mutually supportive.
[0103] As most clearly shown in FIGS. 3A and 3B, when the ring
structure is expanded to its optimal outer diameter, the
orientation planes of the first and second contact surfaces
intersect an inner surface of the ring structure, and together with
the longitudinal axis of the apparatus, the lines of intersection
define a sector of a cylinder. In this case, the ring structure is
formed from twenty-four identical elements, and the central angle
.theta..sub.1 is 15 degrees. The angle described between the
orientation planes of the first and second contact surface is the
same as the central angle of the cylindrical sector, so that the
elements are arranged rotationally symmetrically in the
structure.
[0104] As shown in FIG. 3B, each element is based on a notional
wedge-shaped segment of a ring centred on an axis, with each
notional wedge-shaped segment being inclined with respect to the
radial direction of the ring. The nominal outer diameter of the
segment is at the optimum expansion condition of the ring (with
radius shown at r.sub.1).
[0105] The orientation planes of the first and second contact
surfaces of the element are tangential to a circle with radius
r.sub.3 concentric with the ring at points t.sub.1, t.sub.2. The
angle described between the tangent points is equal to the angle
.theta..sub.1 of the segment. The orientation planes of the first
and second contact surfaces of each notional wedge-shaped segment
intersect one another on a radial plane P which bisects radial
planes located at the tangent points (i.e. is at an angle of
.theta..sub.1/2 to both). This intersection plane P defines the
expanding and collapsing path of the segment.
[0106] In the configuration shown in FIGS. 1 and 2, notional
wedge-shaped segments are modified by removal of the tips 29 of the
wedges, to provide a curved or arced inner surface 20 with radius
r.sub.2 when the ring is in its expanded condition shown in FIGS.
2A and 2D. The modification of the wedge-shaped elements can be
thought of as an increase in diameter of an internal bore through
the ring structure by 2(r.sub.2-r.sub.3), or a truncation of the
inner diameter. This change in the inner diameter from the notional
inner diameter r.sub.3 to which the contact surfaces are tangential
to a truncated inner diameter r.sub.2, has the effect of changing
an angle between the contact surfaces and the radial plane from the
centre of the ring. Taking angle .theta..sub.2 to be the angle
described between the contact surface and a radial plane defined
between the centre point of the ring structure and the point at
which the orientation surface meets or intersects a circle at the
radial position of the inner surface, .theta..sub.2 is changed in
dependence on the amount by which the segment has its inner
diameter truncated. For the notional wedge shaped segment, the
orientation planes of the contact surfaces are tangential to a
circle at the inner diameter at r.sub.3 (i.e. angle .theta..sub.2
is 90 degrees). For the modified elements 12, the orientation
planes of the contact surfaces instead intersect a circle at the
(increased) inner diameter at r.sub.2 and are inclined at a reduced
angle .theta..sub.2.
[0107] The angle .theta..sub.2 at which the segment is inclined is
related to the amount of material removed from the notional
wedge-shaped segment, but is independent from the central angle
.theta..sub.1 of the wedge. Angle .theta..sub.2 is selected to
provide element dimensions suitable for manufacture, robustness,
and fit within the desired annular volume and inner and outer
diameters of the collapsed ring. As the angle .theta..sub.2
approaches 90 degrees, a shallower, finer wedge profile is created
by the element, which may enable optimisation of the collapsed
volume of the ring structure. Although a shallower, finer wedge
profile may have the effect of reducing the size of the gaps
created at the inner surface of the ring in the collapsed condition
and/or enabling a more compact collapsed condition, there are some
consequences. These include the introduction of flat sections at
the inner surfaces of the elements, which manifest as spaces at the
inner diameter of the ring when in an expanded or partially
expanded condition. When .theta..sub.2=90 degrees, all the segments
are purely tangential to inner diameter, the collapsed volume for a
given outer diameter and inner diameter is most efficient, but the
inner surface of the ring structure is polygonal with flat sections
created by each segment. In some configurations, these flat
sections may be undesirable. There may also be potential
difficulties with manufacture of the elements and robustness of the
elements and assembled ring structure. However, in many
applications, where the profile of the inner surface of the
expanded ring is not critical, for example when the inner diameter
of the ring structure is floating, and/or the true inner diameter
is defined by an actuation wedge profile rather than the inner
surface of the ring, this compromise may not be detrimental to the
operation of the apparatus, and the reduced collapse volume may
justify an inclination angle .theta..sub.2 of (or approaching) 90
degrees.
[0108] In the apparatus of FIGS. 1 to 4, the angle .theta..sub.2 is
75 degrees. Relaxing .theta..sub.2 to a reduced angle provides a
smooth outer diameter and inner diameter profile to the expanded
ring, as a portion of the inner circular arc is retained at the
expense of slightly increased collapsed volume. It should be noted
that the angle .theta..sub.2 is independent from the angle
.theta..sub.1. Where the ring structure is desired to have a
circular inner surface, preferred arrangements may have an angle
.theta..sub.2 which is in the range of (90 degrees-2.theta..sub.1)
to 90 degrees inclusive, and particularly preferred arrangements
have an angle .theta..sub.2 in the range of 70 degrees to 90
degrees (most preferably in the range of 73 degrees to 90 degrees).
In general, to provide sufficient truncation of the inner diameter
to retain a useful portion of an inner arc and provide a smooth
inner surface to the ring structure, a maximum useful value of
.theta..sub.2 is (90 degrees-.theta..sub.1/2). This would be 82.5
degrees in the described arrangements.
[0109] In other configurations, also in accordance with embodiments
of the invention (and as will be described below) the geometry of
the notional wedge-shaped segments forming the elements may be
unmodified (save for the provision of functional formations such as
for interlocking and/or retention of the elements), without the
removal of material from the tip of the notional wedge-shaped
segments. Such embodiments may be preferred when there is no
requirement for the ring structure to have a circular inner
surface.
[0110] As most clearly shown in FIGS. 4A to 4F, the first and
second contact surfaces of the element have corresponding
interlocking profiles 24 formed therein, such that adjacent
elements can interlock with one another. In this case, the
interlocking profiles comprise a dovetail groove 25 and a
corresponding dovetail tongue 26. The interlocking profiles resist
circumferential and/or radial separation of the elements in the
ring structure, but permit relative sliding motion between adjacent
elements. The interlocking profiles also facilitate smooth and
uniform expansion and contraction of the elements during use. It
will be appreciated that alternative forms of interlocking
profiles, for example comprising recesses and protrusions of other
shapes and forms, may be used within the scope of the
invention.
[0111] The elements are also provided with inclined side wall
portions 27, which facilitate deployment of the apparatus in use.
The side wall portions are formed in an inverted cone shape which
corresponds to the shape and curvature of the actuating cone wedges
profiles when the apparatus is in its maximum load condition
(typically at its optimum expansion condition).
[0112] Each element is also provided with a groove 28, and in the
assembled ring structure, the grooves are aligned to provide a
circular groove which extends around the ring. The groove
accommodates a biasing element (not shown), for example a spiral
retaining ring of the type marketed by Smalley Steel Ring Company
under the Spirolox brand, or a garter spring. In this case, the
biasing means is located around the outer surface of the elements,
to bias the apparatus towards the collapsed condition shown in
FIGS. 1A to 1D. Although one groove for accommodating a biasing
means is provided in this embodiment, in alternative embodiments of
the apparatus, multiple grooves and biasing means may be
provided.
[0113] The apparatus 10 comprises a wedge member 16, which in this
case is an annular ring having a conical surface 18 opposing one
side of the ring structure 11. The wedge angle corresponds with the
angle of the inclined conical side walls 27 of the elements. A
corresponding wedge shaped profile (not shown) is optionally
provided on the opposing side of the ring structure to facilitate
expansion of the ring elements. In alternative embodiments of the
invention this optional additional wedge may be substituted with an
abutment shoulder.
[0114] Operation of the expansion apparatus will now be described.
In the first, collapsed or unexpanded condition, shown most clearly
in FIG. 10, the elements are assembled in a ring structure 11 which
extends to a first outer diameter. In this embodiment, and as shown
in FIGS. 1B and 10, the wedge member 16 defines the maximum outer
diameter of the apparatus in the first condition. The elements are
biased towards the unexpanded condition by a spiral retaining ring
(not shown), and are supported on the inner surface by the outer
surface of the cylinder 14.
[0115] In use, an axial actuation force is imparted on the wedge
member 16. Any of a number of suitable means known in the art can
be used for application of the axial actuation force, for example,
the application of a force from an outer sleeve positioned around
the cylinder. The force causes the wedge member 16 to move axially
with respect to the cylinder, and transfer a component of the axial
force onto the recessed side wall of the elements. The angle of the
wedge transfers a radial force component to the elements 12, which
causes them to slide with respect to one another along their
respective contact surfaces.
[0116] The movement of the expanding elements is tangential to a
circle defined around the longitudinal axis of the apparatus. The
contact surfaces of the elements mutually support one another
before, during, and after expansion. The radial position of the
elements increases on continued application of the axial actuation
force until the elements are located at a desired outer radial
position. This radial position may be defined by a controlled and
limited axial displacement of the wedge member, or alternatively
can be determined by an inner surface of a bore or tubular in which
the apparatus is disposed.
[0117] FIGS. 2A to 2D show clearly the apparatus in its expanded
condition. At an optimal expansion condition, shown in FIGS. 2B and
2D, the outer surfaces of the individual elements combine to form a
complete circle with no gaps in between the individual elements.
The outer surface of the expansion apparatus can be optimised for a
specific diameter, to form a perfectly round expanded ring (within
manufacturing tolerances) with no extrusion gaps on the inner or
outer surfaces of the ring structure. The design of the expansion
apparatus also has the benefit that a degree of under expansion or
over expansion (for example, to a slightly different radial
position) does not introduce significantly large gaps.
[0118] It is a feature of the invention that the elements are
mutually supported before, throughout, and after the expansion, and
do not create gaps between the individual elements during expansion
or at the fully expanded position. In addition, the arrangement of
elements in a circumferential ring, and their movement in a plane
perpendicular to the longitudinal axis, facilitates the provision
of smooth side faces or flanks on the expanded ring structure. With
deployment of the elements in the plane of the ring structure, the
overall width of the ring structure does not change. This enables
use of the apparatus in close axial proximity to other functional
elements.
[0119] The apparatus has a range of applications, some of which are
illustrated in the following example embodiments. However,
additional applications of the apparatus are possible which exploit
its ability to effectively perform one or more of blocking or
sealing an annular path; contacting an auxiliary surface; gripping
or anchoring against an auxiliary surface; locating or engaging
with radially spaced profiles; and/or supporting a radially spaced
component.
[0120] The present invention extends the principles described above
to multi-stage or telescopic expansion apparatus, which have
applications to systems in which an increased expansion ratio is
desirable. The following embodiments of the invention describe
examples of such apparatus.
[0121] Referring now to FIGS. 5A to 6C, there is shown a two-stage
expansion apparatus in accordance with an embodiment of the
invention. FIGS. 5A to 5C are respectively perspective,
longitudinal sectional, and end views of the apparatus in a first,
collapsed condition. FIGS. 6A to 6C are equivalent views of the
apparatus in an expanded condition. The apparatus, generally
depicted at 170, comprises an expansion assembly 171 formed from
three ring structures 172, 173a, 173b, each of which is formed from
separate elements in the manner described with reference to FIGS. 1
to 4. The ring structures 172, 173a, 173b are disposed on a mandrel
174 between a wedge portion 175 which is fixed on a mandrel, and a
moveable cone wedge member 176. An inner ring structure 172 is
formed from a number of individual elements 177 assembled together.
The elements 177 are similar to the elements 12, and their form and
function will understood from FIGS. 1 to 4 and their accompanying
description.
[0122] FIG. 7 is a geometric representation of a centre element of
the apparatus of FIGS. 5A to 5C, shown from one side, and FIGS. 8A
to 8F are respectively first perspective, second perspective, plan,
first end, lower, and second end views of a centre element 177. The
Figures show the inner and outer surfaces, first and second contact
surfaces, interlocking profiles, and grooves for retaining
circumferential springs which are equivalent in form and function
to the features of the elements 12. Biasing means in the form of a
circumferential spring retains the centre ring structure in its
collapsed condition.
[0123] Disposed on either side of the centre ring structure are
first and second outer ring structures 173a, 173b in the form of
wedge ring structures. The wedge ring structures are also assembled
from an arrangement of elements which, again, are similar in form
and function to the elements 12. However, instead of providing an
outer surface which is substantially parallel to the longitudinal
axis of the apparatus, the outer surfaces of the outer elements are
inclined to provide respective wedge surfaces 178a, 178b which face
the centre ring structure 172.
[0124] FIG. 9 is a geometric representation of an outer element 182
of the apparatus of FIGS. 5A to 5C, shown from one side, and FIGS.
10A to 10H are respectively first perspective, second perspective,
third perspective, fourth perspective, plan, first end, lower, and
second end views of an outer element 182. The Figures show the
inner and outer surfaces 183, 184, first and second contact
surfaces 185, 186, interlocking profiles 187, 188, and grooves 189
for retaining circumferential springs which are equivalent in form
and function to the features of the elements 12. In the assembled
ring structure, the outer elements and the centre elements are
nested with one another, and the outer surfaces 184 of the outer
elements define respective wedge profiles for corresponding centre
elements 177 during a first expansion stage as will be described
below. Biasing means in the form of a circumferential spring
retains the outer rings structure in their collapsed conditions,
with the sequencing of the expanding and collapsing movement
controlled by the selection of the relative strengths of the
biasing means of the centre ring and the outer rings.
[0125] In a first, collapsed condition, the elements of the centre
ring structure and the elements of the first and second outer ring
structures, have a maximum outer diameter which is less than or
equal to the outer diameter of the wedge profile 175 and wedge
member 176.
[0126] Operation of this embodiment of the apparatus will be
described, with additional reference to FIGS. 6A to 6C.
[0127] In common with other embodiments, the apparatus is actuated
to be radially expanded to a second diameter by an axial actuation
force which moves the cone wedge member 176 on the mandrel and
relative to the ring structure. The axial actuation force acts
through the ring structures 173a, 173b to impart axial and radial
force components onto the elements. Radial expansion of the ring
structures 173a, 173b is resisted by their respective
circumferential springs arranged in grooves 179, and the forces are
transferred to the centre ring structure 172. The elements of the
centre ring experience an axial force from the wedge surfaces 178a,
178b of the elements of the outer ring structures, which is
translated to a radial expansion force on the elements of the
centre ring structure 172. The radial expansion force overcomes the
retaining force of a circumferential spring in the groove 181
(which is selected to be weaker than the retaining forces of the
circumferential springs in the outer rings), and the elements slide
with respect to one another to expand the centre ring structure as
the outer ring structures move together.
[0128] The pair of outer rings is brought together until the
elements of the centre ring structure are expanded on the wedge
profiles of the outer elements. In this condition, the first
expansion stage is complete, but the centre ring is not yet
expanded to its optimum outer diameter.
[0129] The elements of the wedge ring structure 173a, 173b are
symmetrical about a centre line of the ring structure, and are
configured to be brought into abutment with one another under a
central line under the centre segments. This design defines an end
point of the axial travel of an outer ring structure, and prevents
its elements from over-travelling. This abutment point changes the
mode of travel of an outer ring from axial displacement (during
which it expands an adjacent ring which is disposed towards the
centre of the apparatus by a wedging action) into a tangential
sliding movement of elements within the ring, to cause it to expand
radially on the apparatus.
[0130] The outer ring structures 173a and 173b have been brought
together into abutment, and further application of an axial
actuation force causes the elements of the respective outer ring
structures to experience a radial force component from the wedge
175 and the wedge profile 176. The radial force directs the
elements of the outer ring structures to slide with respect to one
another into radially expanded conditions. The radial movement of
the elements of the outer rings is the same as the movement of the
elements of the centre ring structure and the elements described
with reference to previous embodiments: the elements slide with
respect to one another in a tangential direction, while remaining
in mutually supportive planar contact. As the outer ring structures
expand, a radial force is imparted to the elements of the centre
ring, which continue to slide with respect to one another in a
tangential direction to their fully expanded condition.
[0131] The resulting expanded condition is shown in FIGS. 6A to 6C.
The apparatus forms an expanded ring structure which is solid, with
no gaps between its elements, and which has a smooth circular outer
surface at its full expanded condition. In addition, both of the
annular surfaces or flanks of the expanded ring are smooth. The
outer diameter of the expanded ring is significantly greater than
the outer diameter of the ring structures (and wedges) in their
collapsed state, with the increased expansion resulting from the
two stage mechanism.
[0132] Retaining the axial force on the wedges will retain the ring
structure in an expanded condition, and a reduction in the axial
force to separate the wedge profiles enables the inner and outer
ring structures to collapse under the retention forces of their
respective spring elements.
[0133] Collapsing of the apparatus to a collapsed condition is
achieved by releasing the axial actuation force. The sequence of
collapsing is the reverse of the expanding process: the outer ring
structures are collapsed first under the higher retaining forces of
their respective biasing springs. Collapse of the outer rings also
brings the centre ring structure from is fully expanded condition
to an intermediate condition. Further separation of the wedge
profiles collapses the centre ring structure under the retaining
force of its biasing spring, back to the collapsed position shown
in FIGS. 5A and 5B.
[0134] The principles of the two-stage expansion mechanism can be
extended to other multi-stage expanding and collapsing apparatus.
FIGS. 11A to 12C show such an apparatus, which has a four-stage
expansion system. FIGS. 11A to 11C are respectively perspective,
longitudinal sectional, and end views of the apparatus in a first,
collapsed condition. FIGS. 12A to 12C are equivalent views of the
apparatus in an expanded condition. The apparatus, generally shown
at 190, is similar to the apparatus 170, and its form and function
will be understood from FIGS. 5 to 10 and the accompanying
description. However, the apparatus 190 differs in that it
comprises a centre ring structure 191 formed from individual
elements, and three pairs of outer ring structures 192, 193, 194
(each consisting of upper and lower ring structures 192a, 192b,
193a, 193b, 194a, 194b) disposed on a mandrel 197 between wedge 195
and wedge profile 196.
[0135] In successive stages of actuation, the centre ring structure
191 is deployed to a first intermediate expanded state, and first,
second, and third pairs of outer ring structures are deployed to
their radially expanded states, from the inside of the apparatus
adjacent to the centre ring, to the outside. At each stage, the
centre ring structure is deployed to successive intermediate
expanded states, until it is fully expanded as shown in FIGS. 12A
to 12C. The outer diameter of the expanded ring is significantly
greater than the outer diameter of the ring structures (and wedges)
in their collapsed state, with the increased expansion resulting
from the four-stage mechanism. Sequencing of the expansion is
designed to be from the inside to the outside by selection of
biasing springs with successively higher retaining forces (moving
from the inside or centre of the apparatus to the outermost rings).
Collapsing of the apparatus to a collapsed condition is achieved by
releasing the axial actuation force, and the sequence of collapsing
is the reverse of the expanding process.
[0136] FIGS. 13A to 14D show a multi-stage expanding and collapsing
system in accordance with an alternative embodiment of the
invention. FIGS. 13A and 13B are respectively perspective and
longitudinal sectional views of the apparatus in a first, collapsed
condition. FIGS. 14A and 14B are equivalent views of the apparatus
in an expanded condition; FIG. 14C is an end view and FIG. 14D is a
section through line D-D of FIG. 14B. The apparatus, generally
shown at 280, is similar to the apparatus 170 and 190, and its form
and function will be understood from FIGS. 5 to 12 and the
accompanying description. However, the apparatus 280 differs in
that it comprises pars of ring structures 281, 282, 283 formed from
individual elements with geometry different from those of previous
embodiments.
[0137] FIG. 15 is a geometric representation of a centre element of
the apparatus of FIGS. 13A and 13B, shown from one side, and FIGS.
16A to 16F are respectively first perspective, second perspective,
plan, first end, lower, and second end views of a centre element
284. The Figures show the inner and outer surfaces, first and
second contact surfaces, interlocking profiles, and grooves for
retaining circumferential springs which are equivalent in form and
function to the features of the elements 12 and 177.
[0138] Each element is effectively a segment of a ring which has
its nominal outer diameter at the optimum expansion condition of
the ring, but which has been inclined at an angle .theta..sub.2
with respect to a radial direction. However, in this embodiment,
.theta..sub.2 is 90 degrees, and a shallower, finer wedge profile
is created by the element. The orientation planes of the contact
surfaces are tangential to the circle described by the inner
surface of the ring structure in its collapsed condition. This
enables optimisation of the collapsed volume of the ring structure,
by reducing the size of the gaps created at the inner surface of
the ring in the collapsed condition and enabling a more compact
collapsed condition. These include the introduction of flat
sections 285 at the inner surface of the elements (visible in FIG.
14D), which manifest as spaces at the inner diameter of the ring
when in an expanded or partially expanded condition. In the
construction shown, the profile of the inner surface of the
expanded ring is not critical, as the inner diameter of the ring
structure is floating, and the true inner diameter is defined by
the actuation wedge profiles 286, 287 rather than the inner surface
of the ring. The spaces are therefore not detrimental to the
operation of the apparatus, and the apparatus benefits from a
reduced collapse volume.
[0139] The elements 284 also differ from the elements of previous
embodiments of the invention in that the interlocking profiles
formed by grooves and tongues are inverted, such that the groove
288 is in the inner surface of the element, and the tongue 289 is
in the outer surface. This increases the engagement length between
adjacent elements.
[0140] The elements 290 of the ring structures 282 and 283 are
similarly formed, with angle .theta..sub.2 at 90 degrees, with the
orientation planes of their contact surfaces being tangential to
the circle described by the inner surface of the ring structure in
its collapsed condition.
[0141] It should be noted that in other embodiments, different
angles .theta..sub.2 may be adopted, including those which are in
the range of 80 degrees to 90 degrees (most preferably tending
towards 90 degrees).
[0142] Operation of the expanding and collapsing apparatus is the
same as that described with reference to FIGS. 11A to 12C, with the
centre ring structure 281 being deployed to a first intermediate
expanded state, and first and second pairs of outer ring structures
being deployed to their radially expanded states, in sequence from
the inside of the apparatus adjacent to the centre ring 281, to the
outside. Sequencing of the expansion is designed to be from the
inside to the outside by selection of biasing springs with
successively higher retaining forces (moving from the inside or
centre of the apparatus to the outermost rings). Collapsing of the
apparatus to a collapsed condition is achieved by releasing the
axial actuation force, and the sequence of collapsing is the
reverse of the expanding process.
[0143] The apparatus 280, by virtue of the compact collapsed inner
volumes achievable with the finer wedge profiles, is capable of
increased expansion ratios. In this example, the apparatus 280 is
configured to have the same expansion ratio as the apparatus 190,
with only two pairs of expanding ring structure compared with the
three pairs in the apparatus 190. This reduces the axial length of
the apparatus and greatly reduces the number of parts required.
[0144] The particularly high expansion ratios achieved with the
multi-stage expansion embodiments of the invention enable
application to a range of operations. For example, the apparatus
may form part of a mechanically actuated, high expansion,
production packer or high expansion annular flow barrier.
Particular applications include (but are not limited to) cement
stage packers or external casing packers for openhole
applications.
[0145] The expansion ratios achievable also enable use of the
apparatus in through-tubing applications, in which the apparatus is
required to pass through a tubing or restriction of a first inner
diameter, and be expanded into contact with a tubing of a larger
inner diameter at a greater depth in the wellbore. For example, the
apparatus may be used in a high expansion retrievable plug, which
is capable of passing through a production tubing to set the plug
in a larger diameter liner at the tailpipe.
[0146] An alternative application of the multi-stage expansion
apparatus of FIGS. 5 and 6 to a fluid conduit patch tool and
apparatus will now be described with reference to FIGS. 13A to 14B.
A typical patching application requires the placement and setting
of a tubular section over a damaged part of a fluid conduit (such
as a wellbore casing). A patch tool comprises a tubular and a pair
of setting mechanisms axially separated positions on the outside of
the conduit for securing the tubular to the inside of the fluid
conduit. It is desirable for the setting mechanisms to provide an
effective flow barrier, but existing patch systems are often
deficient in providing a fluid-tight seal with the inner surface of
the fluid conduit, and are limited in their expansion
capabilities.
[0147] FIGS. 13A and 13B show a high expansion patch tool,
generally depicted at 210, from perspective and longitudinal
sectional views shown in a collapsed, run position. FIGS. 14A and
14B are equivalent views of the apparatus in an expanded
condition.
[0148] The patch tool comprises a tubular section 211, and a pair
of expansion assemblies 212a, 212b (together 212) in axially
separated positions on the section. The distance between the
assemblies 212a, 212b is selected to span the damaged section of a
fluid conduit to be patched. Each of the assemblies 212 comprises a
pair of expansion apparatus 213a, 213b, disposed on either side of
an elastomeric seal element 214. The expansion apparatus 213 are
similar in form and function to the expansion apparatus 170, and
their operation will be described with reference to FIGS. 5 and 6.
Each comprises a centre ring structure and a pair of outer ring
structures. A pair of cone wedge members 215 is provided on either
side of the expansion apparatus 213.
[0149] The elastomeric seal elements 214 are profiled such that an
axially compressive force deforms the elastomeric material, and
brings first and second halves 214a, 214b of the seal element
together around a deformation recess 216.
[0150] The patch tool is, like other embodiments of the invention,
configured to be actuated by an axial force. The axial force acts
to radially expand the expansion apparatus 213 in the manner
described with reference to FIGS. 5 and 6, and into contact with
the fluid conduit to be patched. The elastomeric seals are deformed
by the axial force via the cone wedges 215, to change shape and
fill an enclosed annular space formed between a pair of expansion
apparatus 213a, 213b. The expanded condition is shown in FIGS. 14A
and 14B.
[0151] The expansion apparatus may provide sufficient frictional
force with the inner surface of the conduit being patched to secure
the patch tool in the conduit. This may be facilitated by providing
engaging profiles on the expansion apparatus. For example,
unidirectional or bidirectional arrangements of ridges and grooves
may be provided to engage a surrounding surface and resist movement
of the apparatus. Alternatively (or in addition), separate anchor
mechanisms may be provided.
[0152] The patch tool 210 provides a pair of effective seals which
are fully supported by the expansion apparatus, each of which forms
a solid anti-extrusion ring.
[0153] FIGS. 19 to 22B show a multi-stage expanding and collapsing
system in accordance with an alternative embodiment of the
invention. FIGS. 19 and 20 are respectively side views of the
apparatus in a first, collapsed condition and second expanded
condition. FIGS. 21A and 21B are respectively plan and isometric
views of the a first set of elements of the apparatus; FIGS. 22A
and 22B are respectively plan and isometric views of a second set
of elements of the apparatus. The apparatus, generally shown at
380, is similar to the apparatus 170, 190, and 280, with a central
ring structure 381 formed from an assembly of elements 384, and two
pairs of ring structures 382a, 382b (together 382), 383a and 383b
(together 383). The form and function of the apparatus will be
understood from FIGS. 5 to 18 and the accompanying description.
However, the apparatus 380 differs in that it comprises pairs of
ring structures 382, 383 formed from individual elements with
geometry different from those of previous embodiments.
[0154] FIGS. 21A and 21B are respectively plan and isometric views
of an element 385, from which the outer ring structures 383a, 383b
are assembled. FIGS. 22A and 22B are respectively plan and
isometric views of an element 386, from which the intermediate ring
structures 382a, 382b are assembled. The Figures show the outer
surfaces, first contact surfaces, and interlocking tongues. The
external profiles of the elements 385, 386 are modified by
provision of additional chamfers 387, 388. These chamfers modify
the external profile of the elements, so that when assembled into a
ring, the inward facing flank (i.e. the flank facing the centre
ring) has an at least partially smoothed conical surface. This
facilitates the deployment of the apparatus; the smoother conical
surface improves the sliding action of the elements the centre ring
381 on the conical profiles of the rings 382a, 382b as the elements
are brought together to expand the centre ring. Similarly, the
smoothed inward facing flank of the rings 383a, 383b facilitate the
sliding of the elements 382a of the rings 382a, 383b during their
expansion. The smoothed cones assist a supporting ring in punching
under the adjacent ring with a smooth action,
[0155] The outer surfaces 389, 390 of the elements 385, 386 are
profiled such that the ring structures 382, 383 define smooth
conical surfaces on their outward facing flanks when in their
expanded condition. These conical surfaces combine in the
assembled, expanded apparatus, to provide a substantially or fully
smooth surface which is suitable for abutment with and/or support
of an adjacent element such as an elastomer.
[0156] The elements 385, 386 also differ from the elements of
previous embodiments of the invention in that the biasing means in
the form of garter springs are not mounted in external grooves.
Instead, apertures 391, 392 are provided in the elements for
receiving the garter springs (or an alternative biasing means). The
garter spring may be threaded through each element and then joined
to make a continuous loop upon assembly. By providing the biasing
means in-board of the external surface, it may be better protected
from damage. In addition, the external profile of the elements is
simplified and is more supportive of adjacent elements as
supportive as possible. This configuration also facilitates
location of the biasing means directly over the dovetail feature,
so that the biasing force acts centrally to reduce the likelihood
of canting and jamming.
[0157] The invention may be used to provide an anti-extrusion ring
or back-up ring for a wide range of expanding, radially expanding
or swelling elements. For example, the apparatus may be used as an
anti-extrusion or back-up ring for compressible, inflatable and/or
swellable packer systems. Alternatively, or in addition, the
expansion apparatus may provide support or back-up for any suitable
flow barrier or seal element in the fluid conduit. This may
function to improve the integrity of the fluid barrier or seal,
and/or enable a reduction in the axial length of the seal element
or flow barrier without compromising its functionality. A
particular advantage is that equipment incorporating the expansion
apparatus of the present invention can be rated to a higher maximum
working pressure.
[0158] It will be appreciated that a "single stage" expansion
apparatus, for example as described with reference to FIGS. 1 to 4,
may be used in a patch tool and method of use. Indeed, in some
applications this may desirable, as the resulting patched tubular
can have an inner diameter close to the inner diameter of the fluid
conduit that has been patched, mitigating the reduction to bore
size. However, the patch tool 210 has the advantage of high
expansion for a slim outer diameter profile, which enables the tool
to be run through a restriction in the fluid conduit, to patch a
damaged part of the conduit which has a larger inner diameter than
the restriction. For example, the patching tool could be run
through a part of the fluid conduit that has already been patched,
either by conventional means or by a patching tool based on a
single-stage expansion apparatus. Higher expansion ratio patching
tools could be used, based on expansion apparatus having three or
more stage deployment.
[0159] In the foregoing embodiments, where the expanding and
collapsing apparatus is used to create a seal, the seal is
typically disposed between two expanding ring structures. In
alternative embodiments (not illustrated), an expanding ring
structure can be used to provide a seal, or at least a restrictive
flow barrier directly. To facilitate this, the elements which are
assembled together to create the ring structures may be formed from
metal or a metal alloy which is fully or partially coated or
covered with a polymeric, elastomeric or rubber material. An
example of such a material is a silicone polymer coating. All
surfaces of the elements may be coated, for example by a dipping or
spraying process, and the mutually supportive arrangement of the
elements keeps them in compression in their operating condition.
This enables the ring structures themselves to function as flow
barriers, and in some applications, a seal created is sufficient to
seal against differential pressures to create a seal.
[0160] Alternatively, or in addition, the elements themselves may
be formed from a compressible and/or resilient material, such as an
elastomer, rubber or polymer.
[0161] In a further alternative embodiment of the invention (not
illustrated) the characteristics of the expanding/collapsing
apparatus are exploited to provide a substrate which supports a
seal or other deformable element. As described herein, the expanded
ring structures of the invention provide a smooth circular
cylindrical surface at their optimum expanded conditions. This
facilitates their application as a functional endo-skeleton for a
surrounding sheath. In one example application, a deformable
elastomeric sheath is provided over an expanding ring structure 10,
as described with reference to FIGS. 5A to 6C. When in its
collapsed condition, the sheath is supported by the collapsed ring
structures. The ring structure are deployed in the manner described
with reference to FIGS. 1 and 2, against the retaining force of the
circumferential spring element and any additional retaining force
provided by the sheath, and the sheath is deformed to expand with
the ring structure into contact with the surrounding surface. The
sheath is sandwiched between the smooth outer surface of the ring
structure and the surrounding surface to create a seal.
[0162] It will be appreciated that a multistage expanding apparatus
(for example the apparatus 170) could be used as an endo-skeleton
to provide structural support for components other than deformable
sheaths, including tubulars, expanding sleeves, locking formations
and other components in fluid conduits or wellbores.
[0163] The multi-stage expansion apparatus of the invention may be
applied to a high expansion packer or plug, and in particular a
high expansion retrievable bridge plug. The ring structure may be
arranged to provide a high-expansion anti-extrusion ring for a seal
element of a plug. Alternatively, or in addition, elements of ring
structures of the apparatus may be provided with engaging means to
provide anchoring forces which resist movement in upward and/or
downward directions. The elements of the rings structure may
therefore function as slips, and may in some cases function as an
integrated slip and anti-extrusion ring. Advantages over previously
proposed plugs include the provision of a highly effective
anti-extrusion ring; providing an integrated slip and
anti-extrusion assembly, which reduces the axial length of the
tool; providing slips with engaging surfaces which extend around
the entire circumference of the tool to create an enlarged
anchoring surface, which enables a reduction in the axial length of
the slips for the same anchoring force; the ability of slips of a
ring structure of one particular size to function effectively over
a wider range of tubular inner diameters and tubing weights/wall
thicknesses.
[0164] Alternatively or in addition, the apparatus may be used to
anchor any of a wide range of tools in a wellbore, by providing the
surfaces of the element with engaging means to provide anchoring
forces which resist movement in upward and/or downward
directions.
[0165] The invention also has benefits in creating a seal and/or
filling an annular space, and an additional example application is
to downhole locking tools. A typical locking tool uses one or more
radially expanding components deployed on a running tool. The
radially expanding components engage with a pre-formed locking
profile at a known location in the wellbore completion. A typical
locking profile and locking mechanism includes a recess for
mechanical engagement by the radially expanding components of the
locking tool. A seal bore is typically provided in the profile, and
a seal on the locking tool is designed to seal against the seal
bore.
[0166] One advantage of the application of the invention to locking
mechanism is that the locking mechanism may be provided with an
integrated seal element between two expanding sring structures, and
does not require a seal assembly at an axially separated point.
This enables a reduction in the length of the tool. The integrated
seal is surrounded at its upper and lower edges by the surfaces of
the ring structures, which avoid extrusion of the seal. In
addition, each of the ring structures provides a smooth, unbroken
circumferential surface which may engage a locking recess,
providing upper and lower annular surfaces in a plane perpendicular
to the longitudinal axis of the bore. This annular surface may be
smooth and unbroken around the circumference of the ring
structures, and therefore the lock is in full abutment with upper
and lower shoulders defined in the locking profile. This is in
contrast with conventional locking mechanisms which may only have
contact with a locking profile at a number of discrete,
circumferentially-separated locations around the device. The
increased surface contact can support larger axial forces being
directed through the lock. Alternatively, an equivalent axial
support can be provided in a lock which has reduced size and/or
mass.
[0167] Another advantage of this embodiment of the invention is
that a seal bore (i.e. the part of the completion with which the
elastomer creates a seal) can be recessed in the locking profile.
The benefit of such configuration is that the seal bore is
protected from the passage of tools and equipment through the
locking profile. This avoids impact with the seal bore which would
tend to damage the seal bore, reducing the likelihood of reliably
creating a successful seal.
[0168] Similar benefits may be delivered in latching arrangements
used in connectors, such as so called "quick connect" mechanisms
used for latched connection of tubular components. A significant
advantage of the invention in connection system applications is
that the expansion apparatus forms a solid and smooth ring in an
expanded latched position. An arrangement of radially split
elements would, when expanded, form a ring with spaces between
elements around their sides. In contrast, the provision of a
continuous engagement surface on the expansion ring which provides
full annular contact with the recess results in a latch capable of
supporting larger axial forces. In addition, the by minimising or
eliminating gaps between elements, the device is less prone to
ingress of foreign matter which could impede the collapsing action
of the mechanism. These principles may also be applied to subsea
connectors such as tie-back connectors, with optional hydraulic
actuation of their release mechanism.
[0169] Additional applications of the principles of the invention
include variable diameter tools, examples of which include variable
diameter drift tools and variable diameter centralising tools. The
position a wedge member and a cooperating surface may be adjusted
continuously or to a number of discrete positions, to provide a
continuously variable diameter, or a number of discrete
diameters.
[0170] The invention provides an expanding and collapsing apparatus
and methods of use. The apparatus comprises a plurality of elements
assembled together to form a ring structure oriented in a plane
around a longitudinal axis. The ring structure is operable to be
moved between an expanded condition and a collapsed condition on
actuation by an axial force. The plurality of elements are operable
to be moved between the expanded and collapsed conditions by
sliding with respect to one another in the plane of the ring
structure.
[0171] The invention provides an expanding and collapsing ring
apparatus and method of use. The expanding and collapsing ring
comprises a plurality of elements assembled together to form a ring
structure oriented in a plane around a longitudinal axis. The ring
structure is operable to be moved between a collapsed condition and
a first expanded condition by movement of the plurality of elements
on actuation by an axial force. The apparatus further comprises a
secondary expanding and collapsing mechanism operable to move the
ring structure between its collapsed condition or its first
expanded conditions to a second expanded condition on actuation by
an axial force. Applications of the invention include oilfield
devices, including anti-extrusion rings, plugs, packers, locks,
patching tools, connection systems, and variable diameter tools run
in a wellbore.
[0172] The invention in its various forms benefits from the novel
structure and mechanism of the apparatus. The invention also
enables high expansion applications.
[0173] In addition, at an optimal expansion condition, shown in
FIGS. 2B and 2D, the outer surfaces of the individual elements
combine to form a complete circle with no gaps in between the
individual elements, and therefore the apparatus can be optimised
for a specific diameter, to form a perfectly round expanded ring
(within manufacturing tolerances) with no extrusion gaps on the
inner or outer surfaces of the ring structure. The design of the
expansion apparatus also has the benefit that a degree of under
expansion or over expansion (for example, to a slightly different
radial position) does not introduce significantly large gaps.
[0174] It is a feature of the invention that the elements are
mutually supported before, throughout, and after the expansion, and
do not create gaps between the individual elements during expansion
or at the fully expanded position. In addition, the arrangement of
elements in a circumferential ring, and their movement in a plane
perpendicular to the longitudinal axis, facilitates the provision
of smooth side faces or flanks on the expanded ring structure. With
deployment of the elements in the plane of the ring structure, the
width of the ring structure does not change. This enables use of
the apparatus in close axial proximity to other functional
elements.
[0175] In addition, each of the ring structures provides a smooth,
unbroken circumferential surface which may be used in engagement or
anchoring applications, including in plugs, locks, and connectors.
This may provide an increased anchoring force, or full abutment
with upper and lower shoulders defined in a locking or latching
profile, enabling tools or equipment be rated to a higher maximum
working pressure.
[0176] Various modifications to the above-described embodiments may
be made within the scope of the invention, and the invention
extends to combinations of features other than those expressly
claimed herein. In particular, the different embodiments described
herein may be used in combination, and the features of a particular
embodiment may be used in applications other than those
specifically described in relation to that embodiment.
* * * * *