Note: Descriptions are shown in the official language in which they were submitted.
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DOWN HOLE SEAL
FIELD OF THE INVENTION
The present invention relates to a downhole seal, and in particular to a
downhole seal suitable for use in various bore sizes.
BACKGROUND TO THE INVENTION
Seal assemblies or packers are frequently used in the oil and gas industry for
sealing an annulus in a wellbore, such as may exist between a bore wall and a
mandrel. Such sealing may be achieved by use of annular components which are
mounted on a mandrel and which extend between the mandrel and bore wall. Such
annular sealing components may include annular sealing bands, cup seals,
inflatable
bladders, swellable elements and the like.
Conventional downhole seal assemblies are typically provided to accommodate
quite specific bore diameters, and often a single seal assembly cannot be
effectively
used over a large bore diameter range. As such, it is typically necessary for
an
operator to run sealing assemblies which are quite precisely selected for the
particular
bore diameter at which the seal is required. This might require a large
inventory of
assemblies to be on-hand. In cases where an incorrect size of seal assembly is
selected, or where the bore diameter is larger than expected, such as due to
bore
wash-out and the like, an inadequate seal may result.
Although some known seal assemblies might permit a degree of variability in
terms of seal expansion, it is often the case that beyond the small design
limits seal
integrity is significantly compromised. For example, a seal which has been
expanded
beyond its design limits may provide very poor resistance to a pressure
differential, and
may be at serious risk of failure modes such as extrusion and the like.
SUMMARY OF THE INVENTION
An aspect of the present invention relates to a downhole seal assembly for
establishing a seal against a bore wall. The seal assembly may be configured
to
permit a seal to be established in multiple different bore sizes. That is, the
seal
assembly may permit a suitable seal to be established over a range of bore
sizes.
The seal assembly may comprise a seal element which is radially expandable
to be engaged with a bore wall. The seal element may be mounted on a mandrel,
such
as a tubular mandrel.
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The seal assembly may further comprise a setting element. The setting
element may be mounted on the mandrel.
The seal element may be radially expanded by being deflected radially
outwardly by the setting element when relative axial movement is established
between
the seal element and the setting element. In such an arrangement the seal
element
may be radially stacked on the setting element to become radially expanded.
The setting element may be radially expandable. Radial expansion of the
setting element may function to radially expand the seal element, for example
when the
seal element, or a portion thereof, is radially stacked on the setting
element.
Maximum radial expansion of the seal element may be achieved by a
combination of the seal element being radially deflected by the setting
element, and
radial expansion of the setting element.
In some embodiments the seal assembly may be sequentially actuated, firstly
by being radially deflected by the setting element, and secondly by the
setting element
being radially expanded.
Maximum radial expansion of the seal element may be achieved in response to
at least first and second sequential actuation events. During the first
actuation event
expansion of the seal element may be predominantly achieved by radial
deflection of
said seal element by the setting element. During the second actuation event
expansion of the seal element may be predominantly achieved by radial
expansion of
the setting element.
The seal element may be actuated to be radially expanded by application of an
axial force.
In some embodiments only partial actuation of the seal element may be
necessary to provide a seal against a bore wall. For example, full sealing
engagement
of the seal element with a bore wall may be achieved following only a first
actuation
event.
An aspect of the present invention relates to a downhole seal assembly for
establishing a seal against a bore wall, comprising:
a seal element;
a setting support member; and
a setting element mounted axially between the seal element and the setting
support member,
wherein the seal element is configured to be radially expanded by at least one
of radial deflection by the setting element and radial expansion of the
setting element.
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Relative axial movement between the seal element and the setting element
may cause the seal element to be deflected radially outwardly by the setting
element.
Further or subsequent relative axial movement between the seal element and the
setting element may cause radial expansion of the setting member to further
expand
the seal element.
An aspect of the present invention relates to a downhole seal assembly for
establishing a seal against a bore wall, comprising:
a mandrel;
a seal element mounted on the mandrel;
a setting support member mounted on the mandrel; and
at least one setting element mounted on the mandrel axially between the seal
element and the setting support member,
wherein relative axial movement between the seal element and the setting
support member over a first actuation distance causes the seal element to be
deflected
radially outwardly by an axially adjacent setting element, and relative axial
movement
of the seal element and the setting support member over a subsequent actuation
distance causes radial expansion of at least one setting element to further
expand the
seal element.
The axially adjacent setting element may be defined as the primary setting
element.
In use, the downhole seal assembly may be positioned within a bore, such as a
wellbore, pipe line or the like and axial movement established between the
seal
element and setting support member to cause the seal element to be radially
expanded
into engagement with a wall of the bore.
The downhole seal assembly may be configured for use within an open hole.
The seal assembly may be defined as an open hole seal assembly. Alternatively,
or
additionally, the downhole seal assembly may be configured for use within a
cased or
lined bore.
A maximum radial expansion of the seal element may be achieved by both
radial deflection of the seal element by the setting element and radial
expansion of the
setting element. Such maximum permitted radial expansion may be achieved by
relative axial movement of the seal element and the seal support member over a
maximum axial setting distance.
In some applications the maximum expansion of the seal element may be
required to establish a seal within a bore. However, in other applications
such
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maximum expansion may not be necessary to achieve a seal within a bore. For
example, full sealing engagement of the seal element with a bore wall may be
achieved
following relative axial movement between the seal element and the setting
support
member over a portion of the first actuation distance, the full first
actuation distance, or
the full first actuation distance plus a portion of the subsequent actuation
distance.
Accordingly, the seal assembly may be self-regulating to permit a seal to be
established in multiple different bore sizes. In this way, a single seal
assembly may
have application over a relatively wide range of bore dimensions. Such an
arrangement may provide an operator with improved assurance of an appropriate
seal
being established, for example by removing sensitivities of selecting an
incorrect size
of seal, the bore being smaller or larger than expected, and the like.
Further, such an
arrangement may minimise the required inventory of sealing assemblies when
multiple
bore sizes must be accommodated.
In use, relative axial movement between the seal element and the setting
support member may be performed until the seal element is sufficiently engaged
with a
bore wall. In some instances only a proportion of a maximum permitted range of
relative axial movement between the seal element and setting support member
(or only
a proportion of the maximum available radial expansion of the seal element)
may be
necessary or permitted to achieve sealing.
As defined above, relative axial movement between the seal element and the
setting support member over the first actuation distance causes the seal
element to be
deflected radially outwardly by the adjacent or primary setting element. As
such,
physical radial deflection of the seal element permits said seal element to be
initially
expanded.
Further, relative movement between the seal element and the setting support
member over the subsequent actuation distance may cause further expansion of
the
seal element by radial expansion of at least one setting element. That is,
radial
expansion of at least one setting element may act to further expand the seal
element.
In some embodiments relative movement of the seal element and the setting
support member over at least a portion of the subsequent actuation distance
may
cause axial compression of the seal element. Such axial compression of the
seal
element may cause radial expansion thereof, for example by radial buckling,
bulging or
the like. In some embodiments such axial compression may radially expand the
seal
element to close any gaps originally defined between the seal element and the
mandrel.
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In use, at least two mechanisms for expanding the seal element may be
established by a common actuation event, specifically the relative axial
movement of
the seal element and the setting support member. Requiring only a single
actuation
event to establish at least two expansion mechanisms may permit a simpler,
more
5 robust
seal assembly to be provided, minimising sensitivities to failure due to
complex
= and multiple seal actuators. Further, providing at least two expansion
mechanisms
may assist to provide a more robust seal, at least when a higher expansion
ratio is
required. That is, large expansion ratios may not rely exclusively on a single
expansion
mechanism.
10 Relative
axial movement between the seal element and the setting support
member over the first actuation distance causes the seal element to be
deflected
radially outwardly by the primary setting element, and relative movement over
the
subsequent actuation distance may cause further expansion of the seal element
by
radial expansion of the same primary setting element.
15 In some
embodiments at least one setting element may undergo a degree of
radial expansion during relative axial movement of the seal element and
setting support
member over the first actuation distance. However, in such embodiments radial
expansion of the seal element during relative axial movement of the seal
element and
setting support member over the first actuation distance may nevertheless be
20
predominantly achieved by the seal element being deflected radially outwardly
by at
least one setting element.
During relative axial movement of the seal element and setting support member
over the first actuation distance expansion of the seal element may be
predominantly
achieved by radial deflection of said seal element by the setting element.
During
25 relative
movement of the seal element and the setting support member over the
subsequent actuation distance expansion of the seal element may be
predominantly
achieved by radial expansion of the setting element.
The seal assembly may be configured such that the seal element preferentially
expands by being radially deflected by the primary setting element, prior to
radial
30 expansion,
or significant radial expansion, of at least one setting element. Such an
arrangement may facilitate sequential or staged expansion of the sealing
element,
initially by radial deflection, and subsequently by expansion of a setting
element.
Various arrangements may be provided to permit such preferential initial
expansion of
the seal element, examples of which will be specified in more detail below,
and may
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include variable material properties, such as stiffness, variable geometries,
such as
deflection ramp angles and the like.
The seal element may be configured to be deflected radially outwardly and over
an outer surface of the adjacent setting element. In such an arrangement the
seal
element and the adjacent setting element may be configured to become radially
stacked. Such radial stacking of the seal element and the adjacent setting
element
may permit subsequent radial expansion of the adjacent setting element to
cause
further radial expansion of the seal element.
In some embodiments the seal assembly may comprise a single setting
element.
In some embodiments the seal assembly may comprise a plurality of setting
elements. In such embodiments the setting element which is axially adjacent to
the
seal element may define the primary setting element. In such embodiments a
plurality
of setting elements may be configured to be radially stacked relative to each
other to
expand the seal element.
At least one setting element may be configured to provide support to the seal
element when said seal element is in a radially expanded position. This may
assist the
seal element to accommodate operational pressures and forces when extended and
in
sealing engagement with a bore wall. For example, such an arrangement may
provide
a degree of stability to the seal element when expanded, which may assist in
resistance to extrusion forces and the like. Such support from at least one
setting
element may also permit the seal assembly to be appropriately used to
accommodate
larger expansion ratios.
The entire seal element may be configured to be radially expanded. For
example, the entire seal element may be configured to be displaced outwardly
by the
primary setting element. In such an arrangement the entire seal element may be
configured to be deflected radially outwardly and over the outer surface of
the primary
setting element.
In some embodiments only a portion of the seal element may be configured to
be radially expanded. For example, only a portion of the seal element may be
configured to be displaced outwardly by the primary setting element. In such
an
arrangement only a portion of the seal element may be configured to be
deflected
radially outwardly and over the outer surface of the primary setting element.
In some cases the size of the bore in which the seal assembly is mounted may
determine the length of the seal element which is radially expanded.
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In some embodiments the seal element may comprise or define a fixed region
which is radially fixed, and thus prevented from radial expansion, and a free
end region
which is configured to be radially expanded by being deflected radially
outwardly by the
adjacent setting element. In such embodiments the free end region may be
configured
to be deflected radially outwardly and over the outer surface of the adjacent
setting
element.
The fixed region may be positioned intermediate opposing ends of the seal
element.
In one embodiment the fixed region may be positioned at one end region of the
seal element, opposite the free end region.
The seal element may be configured to define a cup or lip seal when in an
expanded configuration. Such an arrangement may be achieved by the provision
of a
fixed region and free end region of the seal element. In such an arrangement
an
additional sealing effect may be achieved by the action of fluid pressure
internally of
the seal element, thus contributing to the force pressing the seal element
against the
bore wall.
In some embodiments a fixed end region of the seal element may be sealingly
engaged with the mandrel. Such an arrangement may minimise leakage between the
seal element and the mandrel. Further, such an arrangement may permit pressure
to
be contained internally of the seal element, which may assist to press the
seal element
against the bore wall.
Also, the provision of a fixed region which is sealingly engaged with the
mandrel
may minimise any requirement to rely exclusively on the seal element
eventually
becoming sealing engaged with the mandrel during actuation of the seal
element, as
might be the case in convention compressible packers.
The seal element and the adjacent setting element may be generally arranged
axially relative to each other, for example in end-to-end relationship, when
the seal
element is in the retracted configuration.
The seal element and the adjacent setting element may define a seal deflection
interface therebetween configured to permit the seal element to be deflected
radially
outwardly by the adjacent setting element during relative axial movement
between the
seal element and the setting support member. The seal deflection interface may
comprise an interengaging ramp structure.
In one embodiment the seal element and the adjacent setting element may
each define a ramp surface to facilitate deflection of the seal element. The
ramp
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surfaces may be defined by tapered or bevelled regions. The ramp surface of
the seal
element may define an inwardly tapered region of the seal element. Where the
seal
element comprises or defines a free end, said ramp surface may be provided on
the
free end. Such a ramp surface provided on a free end may function to provide a
degree of relief between the seal element and the adjacent setting element
when the
seal element is expanded. Such an arrangement may assist to permit the seal
element
to function as a cup seal when expanded.
The ramp surface of the adjacent setting element may define an outwardly
tapered region of said setting element.
At least one setting element, for example the adjacent setting element, may be
radially expanded by being axially compressed during relative axial movement
between
the seal element and the setting support member over the subsequent actuation
distance. That is, axial compression may cause radial expansion, buckling
and/or
bulging of the setting element.
At least one setting element may be axially compressed against the setting
support member. At least one setting element may be directly compressed
against the
setting support member, for example by directly engaging the setting support
member.
At least one setting element may be indirectly compressed against the setting
support
member, for example via one or more further setting support members or other
intermediate component(s).
At least one setting element, for example the primary setting element, may be
radially expanded by being radially deflected outwardly during relative
movement
between the seal element and the setting support member over the subsequent
actuation distance.
The seal assembly may comprise a deflecting member for use in radially
deflecting at least one setting element. The deflecting member may be for use
in
radially deflecting the adjacent setting element.
The deflecting member may be defined by the setting support member. As
such, the setting support member may be configured to radially displace at
least one
setting member during relative axial movement of the seal element and the
setting
member, at least over the subsequent actuation distance.
In some embodiments the deflecting member may be defined by a further
setting element.
The deflecting member and at least one setting element may define a setting
deflection interface therebetween configured to permit the at least one
setting element,
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for example the adjacent setting element, to be deflected radially outwardly
by the
deflecting member. The setting deflection interface may comprise an
interengaging
ramp structure.
In one embodiment a setting element and the deflecting member may each
define a ramp surface to facilitate deflection of the setting element. The
ramp surfaces
may be defined by tapered or bevelled regions. The ramp surface of the setting
element may define an inwardly tapered region of the setting element. The ramp
surface of the deflecting member may define an outwardly tapered region of the
setting
deflecting member.
In one embodiment the seal element and the adjacent setting element may
define a seal deflection ramp interface therebetween, and the adjacent setting
element
and the deflecting member may define a setting deflection ramp interface
therebetween.
The seal deflection o dd
fletctioenroaumrapgine radial
fle
adnedtohteiosn of
tbngde seal
element
or
interface radial 15 each be fig
deflection of the adjacent setting element. Such an arrangement may facilitate
sequential or staged actuation of the seal element.
The seal deflection ramp interface and the setting deflection ramp interface
may
each define a ramp angle relative to a longitudinal axis of the mandrel. Each
ramp
angle may be substantially similar. However, in some embodiments the ramp
angles
may be different.
In one embodiment the seal deflection ramp interface may define a shallower
ramp angle than the setting deflection interface. Such an arrangement may
function to
encourage radial deflection of the seal element prior to radial deflection of
the adjacent
setting element
In one embodiment the adjacent setting element may be stiffer than the seal
element. Such an arrangement may function to encourage radial deflection of
the seal
element prior to radial expansion of the adjacent setting element. In such
an
embodiment differences in stiffness may be a function of differences in
geometry.
Alternatively, or additionally, differences in stiffness may be a function of
differences in
material properties, such as material type.
In some embodiments both of the setting support member and the seal element
may be axially moveable relative to the mandrel, such that movement of both
the
setting support member and the seal element establishes relative axial
movement
therebetween.
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In some embodiments one of the setting support member and the seal element
may be axially moveable relative to the mandrel, and the other of the setting
support
member and the seal element may be axially fixed relative to the mandrel.
In some embodiments the setting support member may be axially fixed relative
to the mandrel. Accordingly, the setting sport member may define an axially
fixed
reaction point within the seal assembly. In such embodiments the seal element
may be
axially moveable towards the setting support member to establish relative
axial
movement therebetween.
In some embodiments the seal element may be axially fixed relative to the
mandrel. For example, one axial end region of the seal element may be axially
fixed
relative to the mandrel. In such embodiments the setting support member may be
axially moveable towards the seal element to establish relative movement
therebetween.
At least one setting element may be axially moveable relative to the mandrel.
The seal assembly may comprise an actuator arrangement for establishing
relative axial movement between the seal element and the setting support
member.
The actuator arrangement may comprise a piston assembly, such as an annular
piston
assembly, ram or the like.
The seal element may be generally cylindrical when in the retracted
configuration. In such an arrangement the seal element may be arranged
substantially
coaxially with the mandrel.
The seal element may define an annular gap with the mandrel, at least when
the seal element is in its retracted configuration. Such an annular gap may
assist
interaction with a setting element, for example the adjacent setting element.
The seal assembly may comprise an actuation member, such as an actuation
ring mounted on the mandrel and axially adjacent the seal element. The
actuation ring
may be mounted on or adjacent one axial end region of the seal element, for
example
a radially fixed axial end of the seal element.
The actuation ring may axially support the seal element, for example to
facilitate
relative axial movement of the seal element and the setting support member.
In some embodiments the actuation ring may be axially fixed relative to the
mandrel. In such embodiments relative axial movement may be achieved by axial
movement of the setting support member towards the actuation ring.
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In some embodiments the actuation ring may be axially moveable relative to the
mandrel. In such embodiments relative axial movement may be achieved by axial
movement of the actuation ring towards the setting support member.
A seal arrangement may be provided between the mandrel and the actuation
ring. The seal arrangement may comprise one or more seal members, such as one
or
more o-rings or the like. The provision of a seal arrangement may effectively
permit
the seal element to be sealed relative to the mandrel. Such an arrangement may
minimise leakage between the seal element and the mandrel. Further, such an
arrangement may permit pressure to be contained internally of the seal
element, which
may assist to press the seal element against the bore wall.
The actuation ring may be secured to the seal element, for example by
integrally forming, fusing, adhesive bonding, interference fitting or the
like. This may
permit sealing to be achieved between the seal element and the actuation ring.
The actuation ring may be configured to radially fix one end region of the
seal
element.
The actuation ring may comprise an outer retaining structure, such as an outer
tubular structure extending along an outer surface of the seal element, for
example
along a portion of the outer surface at one end region of the seal element.
Such an
outer retaining structure may radially retain an end region of the seal
element.
The seal actuation ring may comprise an inner actuation structure, such as an
inner tubular structure extending along a portion of the inner surface of the
seal
element. The inner actuation structure may be arranged between the seal
element and
the mandrel.
When the seal element is in its retracted or non-expanded configuration the
actuation structure of the actuation ring may be axially separated from at
least one
setting element, such as the adjacent setting element. During relative axial
movement
between the seal element, specifically the actuation ring, and the setting
support
member the actuation structure of the actuation ring may eventually engage at
least
one setting element, such as the adjacent setting element. Such engagement may
define the full extent of the first actuation distance.
The actuation structure of the actuation ring may be configured to actuate a
setting element, such as the adjacent setting element, following engagement
therewith,
to cause said setting element to be radially expanded. The actuation structure
of the
actuation ring may be configured to actuate a setting element, such as the
adjacent
setting element, over the subsequent actuation distance.
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The actuation structure may be configured to axially compress a setting
element, such as the adjacent setting element. The actuation structure may be
configured to axially move the setting element, such as the adjacent setting
element.
Such axial movement may permit the setting element to be radially deflected,
for
example by a deflecting member. The actuation structure may be configured to
radially
deflect a setting element, such as the adjacent setting element.
The seal element may comprise or define a unitary component. In some
embodiments the seal element may comprise multiple components assembled or
arranged together to define the seal element.
The seal element may comprise regions of increased stiffness. Such regions
may provide stability and/or strength within the seal element, for example to
assist in
resisting operational forces, such as extrusion forces.
The seal element may comprise an elastic material. The seal element may
comprise an elastomeric material, such as a rubber.
The seal element may comprise a single or uniform material. In some
embodiments the seal element may comprise multiple materials.
The seal element may comprise an elastomeric compound, such as a rubber
compound. The seal element may comprise a single or uniform elastomeric
compound.
In some embodiments the seal element may comprise multiple different
elastomeric compounds. Such compounds may be intimately mixed, for example
during manufacture, such as during moulding, prior to vulcanisation, or the
like.
In some embodiments such compounds may be provided in separate layers. A
degree of intimate mixing at an interface region between different layers may
be
provided. Alternatively, or additionally, a bond may be provided between
different
layers.
At least two compounds may be provided to facilitate or accommodate different
operational conditions. For example, at least one compound may preferentially
resist
extrusion forces. At least one compound may preferentially accommodate
sealing. At
least one compound may preferentially resist erosion, such as during intimate
contact
with a bore wall, for example during deployment of the seal assembly.
The seal element may comprise a swellable material, such as a swelling
elastomer.
At least abtinstgeilliety and/or strength.
treasycnogmthp.rise regions of increased stiffness.
Such regions leons ay provide
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At least one setting element may comprise an elastic material. At least one
setting element may comprise an elastomeric material, such as a rubber.
At least one setting element may comprise a single or uniform material. In
some embodiments at least one setting element may comprise multiple materials.
In some embodiments at least one setting element may comprise multiple
different elastomeric compounds.
At least one setting element may comprise a swellable material, such as a
swelling elastomer.
At least one setting element may be configured to engage a bore wall. In some
embodiments at least one setting element may be configured to contribute to
providing
a seal against a bore wall.
At least one setting element may comprise an inner tubular structure, such as
a
metallic tubular structure, for example provided in the form of a spacing can.
In some
embodiments such an inner tubular structure may be configured to be engaged by
an
actuation structure of an actuation ring.
The setting support member may comprise a rigid material.
The setting support member may comprise a metal material.
The setting support member may comprise an elastic material.
The setting support member may comprise an elastomeric material.
The setting support member may comprise rubber. Beneficially, the provision of
an elastic material may facilitate setting in large bore sizes.
The seal assembly may comprise a back-up or seal support arrangement
configured to provide axial support to the seal element when said seal element
is in the
extended configuration. Such axial support may be provided to assist the seal
element
to resist operational axial forces, such as extrusion forces..
The seal support arrangement may extend over at least a portion of the outer
surface of the seal element.
The seal support arrangement may comprise an annular structure.
The seal support arrangement may comprise a petal structure.
The seal support arrangement may comprise a plurality of circumferentially
arranged petals or tabs, such as generally axially extending petals or tabs.
The seal support arrangement may be reconfigurable between a retracted
configuration and an extended configuration. The seal support arrangement may
be
configured in its extended configuration simultaneously with radial expansion
of the
seal element.
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The mandrel may comprise or define a tubular structure.
The mandrel may comprise or define a unitary structure, such that all
components of the seal assembly may be mounted on this unitary structure.
In some embodiments the mandrel may comprise multiple components.
Individual components of the seal assembly may be distributed over different
mandrel
components.
The seal assembly may comprise first and second sealing arrangements
mounted on the mandrel, wherein each sealing arrangement comprises:
a seal element mounted on the mandrel;
a setting support member mounted on the mandrel; and
at least one setting element mounted on the mandrel axially between the seal
element and the setting support member.
The features of each sealing arrangement may be provided as defined above.
The first and second sealing arrangements may be mounted adjacent each
other on the mandrel. The first and second sealing arrangements may be
configured to
be actuated by a common actuation event. For example, the first and second
sealing
arrangements may be configured to be moved axially relative to each other to
be
actuated to establish as seal within a bore.
In use, the first and second seal arrangements may provide mutual support to
each other, for example to assist in resisting operational forces, such as
extrusion
forces.
In some embodiments a single or common setting support member may be
provided, which forms part of each sealing arrangement.
The first and second sealing arrangements may be arranged in a front-to-front
orientation. In such an arrangement respective free end regions of the
individual seal
elements of each arrangement may face each other.
In an alternative embodiment the first and second sealing arrangements may be
arranged in a back-to-back orientation. In such an arrangement respective
radially
fixed end regions of the individual seal elements of each arrangement may face
each
other.
An aspect of the present invention relates to a method for establishing a seal
in
a bore using a seal assembly according to any other aspect.
An aspect of the present invention relates to a method for establishing a seal
against a wall of a bore, comprising:
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locating a seal assembly within the bore, wherein the seal assembly comprises
a seal element and a seal support element, wherein a maximum unconstrained
expansion of the seal element is achieved by a combination of radial
deflection of the
seal element by the setting element, and subsequent radial expansion of the
setting
5 element; and
expanding the seal element to sealingly engage a wall of the bore.
An aspect of the present invention relates to a method for establishing a seal
within a bore, comprising:
(a) running a mandrel into a bore, wherein the mandrel carries a seal
10 element, a
setting support member; and at least one setting element positioned axially
between the seal element and the setting support member;
(b) causing relative axial movement between the seal element and the
setting support member over a first actuation distance to cause the seal
element to be
deflected radially outwardly by a setting element; and
15 (c) causing
relative axial movement of the seal element and the setting
support member over a subsequent actuation distance to cause radial expansion
of at
least one setting element to further expand the seal element.
Step (c) may only be performed in the event that step (b) does not result in
sealing engagement of the seal element with a bore wall.
In some embodiments when step (c) is note required, the method may comprise
the further step of:
(d) axially
compressing the seal element, for example against a setting
element, to establish or improve sealing engagement with a bore wall.
The method may permit a seal to be provided in bores of different sizes using
a
common seal assembly.
An aspect of the present invention relates to a downhole seal assembly,
comprising:
a radially expandable seal element;
a radially expandable setting element; and
an actuator configured to radially stack at least portions of the seal element
and
the setting element, and to radially expand the setting element.
Features defined in relation to one aspect may be provided in combination with
any other aspect. It should be understood that the features defined above in
accordance with any aspect of the present invention or below in relation to
any specific
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embodiment of the invention may be utilised, either alone or in combination
with any
other defined feature, in any other aspect or embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the present invention will now be described, by way
of example only, with reference to the accompanying drawings, in which:
Figures 1A to 1C show sequential stages of actuation of a seal assembly within
a bore of a first diameter, according to an embodiment of the present
invention;
Figures 2A to 2C show sequential stages of actuation of the same seal
assembly within a bore of a second, smaller diameter;
Figures 3A to 3C show sequential stages of actuation of the same seal
assembly within a bore of a third, still smaller diameter;
Figures 4A to 4C show sequential stages of actuation of a seal assembly
according to an alternative embodiment of the present invention; and
Figures 5A to 5C show sequential stages of actuation of a seal assembly
according to a further alternative embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Figure 1A is a diagrammatic illustration of one side of a downhole seal
assembly, generally identified by reference numeral 10, shown in a retracted
configuration and run into an open hole wellbore 12a. As will be described in
further
detail below, the seal assembly 10 is configured for use in establishing a
seal against a
wall 13a of the wellbore 12a. Further, the seal assembly 10 may be suitable
for use in
providing a seal over a range of bore sizes.
The seal assembly 10 includes a mandrel 14, which may be tubular in form, and
may facilitate connection of the seal assembly 10 with a tubing string (not
shown), such
as a production string or the like. The seal assembly 10 further comprises a
seal
element 16, a setting support or deflecting member 18, and a setting element
20, all
mounted on the mandrel 14 and axially arranged relative to each other, with
the setting
element 20 being interposed between the seal element 16 and the setting
support
member 18.
The seal element 16 comprises a deformable material, such as an elastomeric
material, such as rubber. In the specific embodiment illustrated the setting
element 20
also comprises a deformable material, such as a rubber. However, in the
specific
embodiment shown the setting element 20 is stiffer than the seal element 16
(this could
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be achieved by being thicker, formed of a stiffer material or the like). In
the
embodiment shown the setting support member 18 comprises a rigid material,
such as
a metal material. However, it will be recognised that the setting support
member 18
may alternatively comprise an elastomeric material.
In the embodiment shown the setting support member is axially fixed relative
to
the mandrel 14, whereas both the seal element 16 and the setting element 20
are
axially moveable relative to the mandrel 14.
The seal assembly 10 further comprises an axially moveable metallic actuation
ring 22 mounted on the mandrel 14 and bonded to the upper end region 24 of the
seal
element. An o-ring seal 26 is provided between the actuation ring 22 and the
mandrel
14.
The provision of this bonding and the o-ring 26 facilitates or assures sealing
between the seal element 16 and the mandrel 14. This may remove any reliance
for
the seal element to become sealingly engaged with the mandrel during an
actuation
event, as might be the case in conventional seal arrangements, such as in
conventionalthus sealing axiallyon th e mandrel compressibleoan
packers.oe lowo e In h as ousc such resultingkno w n i n compressiblea seal
which
h i oh is packersoro initial
compression typically first moves the packer element outwardly into engagement
with
the bore wall (for example by buckling), with further compression expanding
the packer
radially inwardly to create a seal on the mandrel, with the result that
contact forces and
leakage.
Also, the provision of the bonding and the o-ring 26 may provide or assure
sealing against the mandrel such that the seal element 16 may be permitted to
function
in the manner of a cup or lip seal once expanded, as will be described in more
detail
below.
As will also be described in further detail below, the actuation ring 22 may
be
moved axially towards the setting support member 18 to cause radial expansion
of the
seal element 16 into sealing engagement with the bore wall 13a.
The actuation ring 22 includes an 'outer tubular wall structure 28 which
extends
along a portion of an outer surface of the seal element 16, thus radially
restraining the
upper end region 24.
The actuation ring 22 further includes an inner tubular structure 30 which
extends along a portion of an inner surface of the seal element 16, and within
an
annular region 32 defined between the seal element 16 and the mandrel 14. As
will be
described in detail below, the inner tubular structure 30 functions as an
actuator
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structure to actuate or cause radial expansion of the setting element 20.
However,
when the seal assembly 10 is in its relaxed configuration as shown in Figure
1A, the
inner tubular structure 30 is axially separated from the setting element 20.
The seal element 16 and the setting element 20 define a seal deflecting ramp
interface 34 therebetween. More specifically, the seal element 16 includes an
inwardly
facing ramp or tapered surface 36, and the setting element 20 includes a
complementary outwardly facing ramp or tapered surface 38. As will be
described in
further detail below, the seal deflecting ramp interface 34 permits the seal
element 16
to be deflected radially outwardly during relative axial movement of the seal
element 16
and the setting element 20.
In a similar manner the setting element 20 and the setting support member 18
define a setting deflecting ramp interface 40 therebetween. More specifically,
the
setting element 20 includes an inwardly facing ramp or tapered surface 42, and
the
setting support member 18 includes a complementary outwardly facing ramp or
tapered surface 44. As will be described in further detail below, the
deflecting ramp
interface 40 permits the setting element 20 to be deflected radially outwardly
during
relative axial movement of the setting element 20 and setting support member
18.
In the present embodiment the seal deflecting ramp interface 34 defines a
shallower ramp angle than the setting deflecting ramp interface 40. Such an
arrangement preferentially encourages the seal element 14 to be radially
deflected
before the setting element 20.
In the embodiment shown in Figure 1A the seal assembly 10 is positioned
within a bore 12a of relatively large diameter compared to the seal assembly
10.
Actuation of the seal assembly 10 may be achieved by axial movement of the
actuation ring 22 in the direction of arrow A, as illustrated in Figure 1B,
towards the
setting support member 18. Such axial movement of the actuation ring 22 may be
achieved by a setting arrangement (not shown), such as an annular piston
arrangement.
In Figure 1B the actuation ring 22 has axially moved the seal element 16 over
a
first actuation distance such that the seal element 16 has become radially
deflected
and thus expanded by the ramp interface 34, to extend over the outer surface
of the
setting element 20. At the end of the first actuation distance the inner
tubular structure
30 is brought into initial engagement with the setting element 20.
It should be noted that although some degree of radial deflection and
expansion
of the setting element 20 may also have occurred during movement of the
actuation
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ring 22 over this first actuation distance, this is minimal compared to the
extent of radial
deflection of the seal element 16.
As illustrated in Figure 1B, expansion of the seal element 16 by virtue only
of
the radial deflection by the setting element 20 is insufficient to permit the
seal element
16 to engage the bore wall 13a. As such, the actuation ring 22 may be moved
further
in the direction of arrow A by a subsequent actuation distance, as shown in
Figure 1C,
to cause the setting element 20 to become radially expanded, thus further
expanding
the seal element 16 into sealing engagement with the bore wall 13a. In such a
configuration a seal may be established within the annulus 50 defined between
the
mandrel 14 and the bore wall 13a.
During movement over this subsequent actuation distance the actuation ring 22
may apply an axial force against the setting element 20, directly via
engagement with
the tubular structure 30, and also indirectly via the upper region 24 of the
seal element
16. This axial force may cause the setting element 20 to be radially deflected
and
expanded by the ramp interface 40. Further, this axial force may axially
compress the
setting element 20, establishing expansion by a degree of radial bulging.
When in the fully set position, as shown in Figure 1C, the setting element 20
may provide a degree of stability to the seal assembly, assisting to resist
operational
conditions, such as axial extrusion forces and the like.
In the sealing configuration shown in Figure 1C, the seal element 16 may
define
or function as a cup or lip seal. In this respect pressure from below
(relative to the
orientation of the drawings) may be applied on the inner face of the seal
element 16,
thus assisting to increase the pressing force of the seal element 16 against
the bore
wall 13a. In this respect, the o-ring seal 26, in combination with the bonding
between
the actuation ring 22 and the seal element 16, permits this pressure to be
contained
internally of the seal element 16.
The particular arrangement of the seal assembly 10 permits expansion of the
seal element 16 to be achieved with a relatively low setting load, in
comparison to
convention packer arrangements, such as axially compressible packers.
Requiring a
lower setting force/load may have the advantages of simplifying the setting
mechanism
or improving the seal if the setting load is as high as would be required for
a standard
compression element. Such may be particularly advantageous in an irregular
borehole
as would often be the case with open hole.
As noted above, the seal assembly 10 may be suitable for use in establishing a
seal in bores of different diameters. For example, Figures 2A to 2C illustrate
sequential
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stages of setting the same seal assembly 10 against a bore wall 13b of a
smaller
diameter bore 12b. In the example illustrated in Figures 2A the bore 12b may
define
an extrusion gap with the assembly 10 which is around 60% of that in Figure
1A.
In Figure 2A the seal assembly 10 is initially provided in its retracted
5 configuration and located at the required position within the bore 12b.
The actuation
ring 22 is then moved in the direction of arrow A over the first actuation
distance, as
illustrated in Figure 2B, to cause the seal element 16 to be radially
deflected by the
setting element 20. In this example such initial expansion of the seal element
16 is
sufficient to permit the seal element 16 to engage the bore wall 13b. However,
the
10 contact pressure may be insufficient to provide the necessary pressure
resistance, and
as such further axial movement of the actuation ring 22 over a subsequent
actuation
distance in the direction of arrow A, as illustrated in Figure 2C, may cause a
degree of
radial expansion of the setting element 20, and thus further expansion of the
seal
element 16, increasing the contact pressure, and contact area, of the seal
element 16
15 with the bore wall 13b. As before, the seal element 16 may define or
operate also as a
= cup or lip seal when in the expanded configuration of Figure 2C.
Figures 3A to 3C illustrate sequential stages of setting the same seal
assembly
10 against the bore wall 13c of a yet smaller diameter bore 12c. In the
example
illustrated in Figures 3A the bore 12c may define an extrusion gap with the
assembly
20 10 which is around 15% of that in Figure 1A.
In Figure 3A the seal assembly 10 is initially provided in its retracted
configuration and located at the required position within the bore 12c. The
actuation
ring 22 is then initially moved in the direction of arrow A, as illustrated in
Figure 3B, to
cause the seal element 16 to be radially deflected by the setting element 20
and
25 engage the bore wall 13c. In the present example the actuation ring 22
is only required
to move a short distance to facilitate engagement with the bore wall 13c, and
is only
minimally deflected over the outer surface of the setting element 20. Further
axial
movement of the actuation ring 22 in the direction of arrow A, as illustrated
in Figure
30, causes a degree of radial deflection of the setting element 20, and also
causes
30 both the seal element 16 and the setting element 20 to be axially
compressed and thus
to be radially expanded to completely fill the annulus 50 between the bore
wall 13c and
the mandrel, and establish a robust seal.
As illustrated in Figure 3C, the setting element 20 is directly engaged with
the
bore wall 13c. This may contribute to the sealing effect of the seal assembly
10.
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Reference is now made to Figures 4A to 40 which illustrate the sequential
setting of a seal assembly 110, according to an alternative embodiment of the
present
invention, within the same bore 12a first illustrated in Figure 1A. Seal
assembly 110 is
similar to assembly 10 first shown in Figure 1A and as such like features
share like
reference numerals, incremented by 100.
Accordingly, seal assembly 110 includes a mandrel 114, a seal element 116, a
setting support member 118 and a setting element 120. An actuation ring 122
(which
is in the same form as ring 22 of seal assembly 10 and thus comprises outer
and inner
= tubular structures 128, 130) is bonded to an upper end region 124 of the
seal element
and is used to axially move the seal element 116 to initiate actuation of the
seal
assembly 110. A first ramp interface structure 134 is provided between the
seal
element 116 and setting element (with respective ramp surfaces 136, 138), and
a
second ramp interface structure 140 is provided between the setting element
120 and
setting support member 118 (with respective ramp surfaces 142, 144).
The seal assembly 110 further comprises a seal back-up arrangement in the
form of an annular support structure 60, which extends partially over the
outer surface
of the seal element 116 from its upper end region 124. As illustrated in
Figures 4B and
40, as the seal element 116 is radially expanded, so too is the support
structure 60.
The support structure 60 in the embodiment shown is formed of a metallic
material, and
provides axial support to the seal element 116 when expanded, to assist in
resisting
axial forces, such as extrusion forces. Although not shown in detail, the
support
structure 60 may be defined by a petal support structure.
In other, non-illustrated embodiments, the function of the support structure
60
may be achieved by a variation in the material properties of the seal element
116. For
example, the material of the sealing element may be of increased stiffness in
selected
locations.
Reference is now made to Figures 5A to 50 which illustrate the sequential
setting of a seal assembly 210, according to an alternative embodiment of the
present
invention, within a bore 212. Seal assembly 210 is similar to assembly 10
first shown
in Figure 1A and as such like features share like reference numerals,
incremented by
200.
Seal assembly 210 comprises first and second seal arrangements 62, 64
arranged on a mandrel 214 in a front-to-front orientation. Each seal
arrangement is
generally provided in the same form as the seal assembly 10 first shown in
Figure 1A.
The first seal arrangement 62 comprises a first seal element 216a, a first
setting
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element 220a and a first actuation ring 222a. Similarly, the second seal
arrangement
64 comprises a second seal element 216b, a second setting element 220b and a
second actuation ring 222b.
The seal assembly 210 further comprises a setting support member 218, which
is interposed between the first and second seal arrangements 62, 64.
The first seal arrangement 62 includes a first seal deflecting ramp interface
234a, and a first setting deflecting ramp interface 240a. Similarly, the
second seal
arrangement 64 includes a second seal deflecting ramp interface 234h and a
second
setting deflecting ramp interface 240b.
As illustrated in Figure 5B, initial actuation of the seal assembly 210 may be
achieved by establishing relative axial movement between the first and second
actuation rings, to cause the first and second seal elements 216a, 216b to be
initially
deflected radially outwardly by the respective first and second setting
elements 220a,
220b. Further relative axial movement of the first and second actuation rings
222a,
222b, as illustrated in Figure 5C, causes the setting elements 220a, 220b to
be radially
expanded, thus causing the respective seal elements 216a, 216b to be further
radially
expanded into engagement with the wall 213 of the bore 212.
When in this expanded and set position shown in Figure 5C, the first and
second seal arrangements 62, 64 may provide mutual support to each other,
assisting
to resist operational conditions and forces, such as extrusion forces.
It should be understood that the embodiments described herein are merely
exemplary and that various modifications may be made thereto without departing
from
the scope of the present invention. For example, in alternative embodiments
multiple
setting elements may be provided.
