Note: Descriptions are shown in the official language in which they were submitted.
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PACKER HAVING A SEAL AND A SUPPORT MEMBER FOR THE SEAL
BACKGROUND
[002] The invention generally relates to a packer.
[003] Hydrocarbon fluids, such as oil and natural gas, are obtained from a
subterranean geologic formation, referred to as a reservoir, by drilling a
well that
penetrates the hydrocarbon-bearing formation. Once a wellbore has been
drilled, the well
must be completed before hydrocarbons can be produced from the well. A
completion
involves the design, selection, and installation of equipment and materials in
or around
the wellbore for conveying, pumping, or controlling the production or
injection of fluids.
After the well has been completed, production of oil and gas can begin.
[004] In such well completion operations, packers are used to prevent fluid
flow
through an annulus formed by a tubing within the well and the wall of the
wellbore or a
casing. The packer is generally integrally connected to the tubing, using, for
example,
means such as a threaded connection, a ratch-latch assembly, or a J-latch, all
of which are
well known in the art. The tubing/packer connection generally establishes the
seal for the
inner radius of the annulus. The seal for the outer radius of the annulus is
generally
established by a deformable element such as rubber or an elastomer. A
compressive
force is generally applied to the deformable element, causing it to extrude
radially
outward. The element extends from the outer portion of the packer to the
wellbore wall
or casing and seals between those structures.
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SUMMARY
[005] In an embodiment of the invention, a packer that is
usable with a well includes a resilient seal element and a
support member. The resilient seal element is adapted to
radially expand in response to the longitudinal compression of
the element. The support member is at least partially
surrounded by the seal element and is adapted to radially
expand with the seal element to support the element. The
support sleeve is substantially harder than the seal element.
[006] In another embodiment of the invention, a technique
that is usable with a well includes compressing a resilient
seal element to cause the seal element to radially expand.
The technique includes in concert with the radial expansion of
the seal element, deforming a material that is substantially
harder than the seal element to support the seal element.
In another embodiment of the invention, there is
provided a packer usable with a well, comprising: at least
one gage; a resilient seal element adapted to radially expand
in response to a longitudinal compression of the seal element
by said at least one gage; and a support member at least
partially surrounded by the seal element and being harder and
radially thinner than the seal element, the support member
adapted to radially expand and deform with the seal element to
support the seal element.
In a further embodiment of the invention, there is
provided a method usable with a well, comprising: providing a
resilient seal element adapted to radially expand in response
to longitudinal compression of the seal element; and radially
inside the seal element, disposing a support member adapted to
radially expand and deform with the seal element to support
the seal element, the support member being radially thinner
and harder than the seal element.
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In a still further embodiment of the invention,
there is provided a method usable with a well, comprising:
compressing a resilient seal element to cause the seal element
to radially expand; and in concert with the radial expansion
of the seal element, deforming a material that is harder and
radially thinner than the seal element to support the seal
element.
In yet another embodiment of the invention, there is
provided a system usable with a well, comprising: a string;
and a packer connected to the string, the packer comprising:
a resilient seal element adapted to radially expand in
response to a longitudinal compression of the seal element by
said at least one gage; and a support member at least
partially surrounded by the seal element and being harder and
radially thinner than the seal element, the support member
adapted to radially expand and deform with the seal element to
support the seal element.
[007] Advantages and other features of the invention will
become apparent from the following drawing, description and
claims.
BRIEF DESCRIPTION OF THE DRAWING
[008] Fig. 1 is a schematic diagram of a well according to
an embodiment of the invention.
[009] Fig. 2 is a schematic diagram depicting a seal
assembly of the packer of Fig. 1 according to an embodiment of
the invention.
[0010] Fig. 3 depicts the seal assembly when the packer is
set according to an embodiment of the invention.
[0011] Figs. 4, 5, 6 and 7 depict seal assemblies according
to other embodiments of the invention.
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DETAILED DESCRIPTION
[0012] A packer is a device that is used in an oilfield well to form a seal
for
purposes of controlling production, injection or treatment. The packer is
lowered
downhole into the well in an unset state, and once in the appropriate position
downhole,
the packer is set, which means a seal of the packer radially expands to seal
off an annular
space. As an example, for a mechanically-set packer, a tubular string that
extends from
the surface to the packer may be moved pursuant to a predefined pattern to set
the packer.
For a hydraulically-set packer, fluid inside the tubular string may be
pressurized from the
surface, to create a tubing pressure differential to set the packer.
[0013] In its set state, the packer anchors itself to the casing wall of the
well (or to
the wellbore wall in an uncased or open well) and forms a seal in the annular
region
between the packer and the interior surface of the casing wall. This seal
subdivides the
annular region to form an upper annular region above the packer that is sealed
off from a
lower annular region below the packer. The packer also forms a seal for
conduits that are
inserted through the packer between the upper and lower annular regions. As
examples,
one of these conduits may communicate production fluid from a production zone
that is
located below the packer, one of the conduits may communicate control fluid
through the
packer, one of the conduits may house electrical wiring for a submersible
pump, allow
production or injection through two different reservoir zones, and so forth.
[0014] Fig. 1 depicts a well 10 (a subterranean or subsea well) that includes
a
packer 20 in accordance with an embodiment of the invention. The packer 20 may
be
connected to a tubular string 16 that extends downhole into the well. The
packer 20
forms an annulus seal with the interior surface of a wall of a casing string
12 that
circumscribes the packer 20 and lines a wellbore 11. The wellbore 11 may be
uncased in
some embodiments of the invention. Additionally, the wellbore 11 may be a
vertical or a
lateral wellbore, depending on the particular embodiment of the invention.
[0015] The packer 20 includes at least one seal assembly 24 to form the
annular
seal and at least one set of slips 22 to anchor the packer 20 to the casing
string 12. In this
manner, when run into the well, the seal assembly 24 and the slips 22 are
radially
retracted to allow passage of the packer 20 through the central passageway of
the casing
string 12. However, when the packer 20 is in the appropriate downhole
position, the
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packer 20 is set to place the packer 20 in a state in which the seal assembly
24 and slips
22 are radially expanded. When radially expanded, the slips 22 grip the
interior surface
of the wall of the casing string 12 to physically anchor the packer 20 in
position inside
the well. The radial expansion of the seal assembly 24, in turn, seals off the
annular
space between the string 16 and the casing string 12 to form a sealed annular
region
above the seal assembly 24 and a sealed annular region below the seal assembly
24.
[0016] In some embodiments of the invention, the packer 20 may be
hydraulically-actuated for purposes of controlling the packer 20 from the
surface of the
well to set the packer 20. This means that pressure may be communicated
through fluid
inside the string 16 to the packer 20. In response to this pressure reaching a
predefined
threshold level, pistons (not shown in Figure 1) move to radially expand the
slips 22 and
apply compressive forces on the seal assembly 24 to radially expand the
assembly 24. A
retention mechanism of the packer 20 serves to hold the packer 20 in the set
state when
the pressure that is used to set the packer 20 is released.
[0017] One or more mandrels 21, or tubular members, may extend through the
packer 20 for purposes of providing communicating paths through the packer 20.
Depending on the particular application of the packer 20, a particular mandrel
21 may
contain one or more communication paths, such as paths to communicate
production
fluid, electrical lines, or control fluid through the packer 20. For example,
in a particular
application, a single mandrel 21 may extend through the packer 20 for purposes
of
communicating production fluid from a tubular string 23 located below the
packer 20 to
the string 16 located above the packer 20. However, in other applications,
more than one
mandrel 21 may be extended through the packer 20. Thus, one mandre121 may be
used
for purposes of communicating electrical or hydraulic lines, for example, and
another
mandrel 21 may be used for purposes of communicating production fluid through
the
packer 20.
[0018] The packer 20 may be retrievable, and thus may include a release
mechanism that when engaged, releases the retention mechanism of the packer 20
to
radially retract the slips 22 and seal assembly 24 to permit retrieval of the
packer 20 to
the surface of the well.
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[0019] The packer 20 establishes two general seals: an interior seal between
the
interior of the packer 20 and the exterior of the one or more mandrels 21 that
are
extended through the packer 20 and an exterior seal between the exterior of
the packer 20
and the interior surface of the wall of the casing string 12 (or the wellbore
wall in
alternative embodiments). The seal assembly 24 includes a resilient seal
element (such as
one or more elastomer or rubber sleeves, or rings) for establishing the seal
between the
packer exterior and the casing 12 (or wellbore wall).
[0020] In general, as the requirements for packer designs tend towards larger
and
larger inner diameters through the packer, the annular seal element of the
packer is forced
to become thinner and thinner. Additionally, there may also desire to cover
multiple
casing weights with one size of packer, leading to larger gaps that must be
bridged off by
the annular seal element. Bridging off a large gap with a thin element may be
very
difficult, unless the rubber is supported. Embodiments of the invention that
are described
herein include a packer that has a resilient seal element, which has a support
that is
fabricated from a hardened material.
[0021] In the context of this application, a "hardened material" means a
material
that has a substantially greater resistance to deformation relative to the
seal element of the
packer. For example, in some embodiments of the invention, the hardened
material may
be a metal that has substantially more resistance to deformation than an
elastomer or
rubber material that forms the seal element. Alternatively, in accordance with
other
embodiments of the invention, the hardened material may be a composite or
plastic
material, which has substantially more resistance to deformation that an
elastomer or
rubber material that forms the seal element. Furthermore, in accordance with
other
embodiments of the invention, the hardened material may be a combination of
the above-
mentioned materials. Thus, many variations are contemplated and are within the
scope of
the appended claims.
[0022] As a more specific example, for some embodiments of the invention, the
hardened material is a soft metal, such as low carbon steel or copper, in
accordance with
some embodiments of the invention. However, in accordance with other
embodiments of
the invention, the hardened material may be a relatively resilient material.
For example,
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in accordance with some embodiments of the invention, the hardened material
may be a
metallic spring material. Thus, many variations are possible and are within
the scope of
the appended claims.
[0023] Fig. 2 depicts a more detailed section 50 (see Fig. 1) of the packer 20
in
accordance with some embodiments of the invention. As shown in Fig. 2, the
packer 20
includes sleeves, or gages 54 and 55 (also called "thimbles"), which are
designed to
longitudinally compress the seal assembly 24 (which is disposed in between) to
radially
expand the assembly 24 when the packer 20 is set. It is noted that Fig. 2
depicts the
packer 20 in its unset state.
[0024] In general, the seal assembly 24 includes a resilient seal element that
may
be formed from multiple seal sleeves, or rings, such as upper 56, middle 60
and lower 64
seal rings. The seal rings 56, 60 and 64 generally circumscribe the inner
mandrel 16 of
the packer 20 and may be formed from a rubber or an elastomer material (as
examples).
It is noted that the seal assembly 24 may include fewer or more seal rings,
depending on
the particular embodiment of the invention.
[0025] As also depicted in Fig. 2, the seal assembly 24 may include upper 88
and
lower 90 metallic shoes for purposes of minimizing the longitudinal extrusion
of the seal
element 24 when the packer 20 is set. In the packer's unset state, the upper
shoe 88
generally conforms to the upper edge of the seal ring 56 and is located
between the upper
edge of the seal ring 56 and the upper gage 54; and the lower shoe 90
generally conforms
to the lower edge of the lower seal ring 64 and is located between this lower
edge and the
lower gage 55.
[0026] In addition to the resilient seal element, the seal assembly 24
includes a
hardened (relative to the seal rings 56, 60 and 64) support sleeve 80 that is
located
between the resilient seal element and the mandrel 16. As a more specific
example, as
depicted in Fig. 2, in some embodiments of the invention, the support sleeve
80 may be
located (as an example) between the middle seal ring 60 and the outer surface
of the
mandrel 16. The support sleeve 80, which may have a substantially thinner
radial
thickness than the middle seal ring 60 (before the packer 20 is set), is
designed to be
radially expanded (and deformed) with the seal rings 56, 60 and 64 so that the
sleeve 80
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supports the seal rings 56, 60 and 64 in their radially-expanded states.
Although Fig. 2
depicts the support sleeve 80 as being located radially inside the middle seal
ring 60, in
accordance with other embodiments of the invention, the support sleeve 80 may
longitudinally extend inside all or part of the upper 56 and lower 64 seal
rings (as another
example). Therefore, many variations are possible and are within the scope of
the
appended claims.
[0027] The support sleeve 80 may or may not be bonded to the middle seal ring
60, depending on the particular embodiment of the invention. For embodiments
of the
invention in which the support sleeve 80 is bonded to the middle seal ring 60,
all or only
part of the outer surface of the support sleeve 80 may be bonded to the inner
surface of
the middle seal ring 60. It is noted that depending on the particular
embodiment of the
invention, the support sleeve 80 may be bonded to all, part or none of the
upper 56 and
lower 64 seal rings.
[0028] In some embodiments of the invention, the support sleeve 80 includes an
annular crimped section 82 at its longitudinal midpoint, which radially
extends away
from the outer surface of the mandrel 16. The crimped section 82 configures
the support
sleeve 80 to bend at the section 82 during the radial expansion of the seal
assembly 24, as
depicted in Fig. 3, which shows a section 95 of Fig. 2 when the packer 20 is
set.
Referring to Fig. 3, in the radially expanded state of the seal assembly 24,
the seal rings
56, 60 and 64 are radially expanded and deformed to at least partially contact
the inner
surface of the casing 12. As also shown in Fig. 3, the support sleeve 80 is
also radially
expanded and deformed to support the seal rings 56, 60 and 64. The shoes 88
and 90
minimize longitudinal extrusion of the seal element, in this state of the
packer 20.
[0029] Referring back to Fig. 2, in accordance with some embodiments of the
invention, the region between the inner surface of the crimped section 82 and
the outer
surface of the mandrel 16 may be a void space. However, in accordance with
other
embodiments of the invention, this space may be filled with a seal element
that partially
or totaling conforms to the boundaries of the spacc before the packer 20 is
set.
[0030] Fig. 4 depicts an exemplary section 100 of another packer in accordance
with another embodiment of the invention. The section 100 is to be compared to
the
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corresponding section 95 of the packer 20. In general, the packer has the same
overall
design as the packer 20, except the seal assembly of this packer includes a
single seal ring
124 (made from elastomer or rubber, for example) and an inner o-ring 110
behind a
support sleeve 112 (made from a hardened material relative to the seal ring
124). The
support sleeve 112 extends over the entire inner surface of the seal ring 124.
The support
ring 112 also includes a crimped section 114 that, in the unset state of the
packer 20,
radially extends away from the outer surface of the mandrel 16. The crimped
section 114
creates a void 116 that receives the o-ring seal 110. Other seals may be
located inside the
space 116, in accordance with other embodiments of the invention.
[0031] Referring to Fig. 5, in accordance with other embodiments of the
invention, another packer, which is illustrated by an exemplary section 150
(to be
compared to sections 95 and 100), includes expandable rings 160 and 178 that
are located
between the gages and a single seal ring 190. More specifically, an upper
expandable
ring 160 is located between an upper gage 154 and an upper edge of the seal
ring 190.
The upper gage 154 may include a sloped, or beveled, surface 156 for purposes
of
slidably engaging with the upper expandable seal ring 160. Likewise, a lower
expandable seal ring 178 may be located between a lower gage 164 and the lower
surface
of the seal ring 190. Similar to the upper gage 154, the lower gage 164
includes a sloped,
or beveled, surface 166 for purposes of slidably engaging the lower expandable
ring 178.
[0032] As also shown in Fig. 5, the packer includes a support sleeve 180 (made
from a hardened material) that extends over the entire surface of the seal
ring 190 for
purposes of providing support to the ring 190 for the set state of the packer.
The seal ring
180 includes a crimped section 182 that is predisposed to cause the support
ring 180 to
radially expand at the section 182 during the setting of the packer, similar
to the support
rings 80 and 112 that are described above.
[0033] As yet another variation, Fig. 6 depicts an exemplary section 200 of a
packer in accordance with another embodiment of the invention. As shown, the
packer
includes garter springs that are located between the gages and the seal
assembly. More
specifically, an upper garter spring 210 is located between an upper gage 202
and the
upper edge of a seal ring 230. A lower garter spring 212 is located between
the upper
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edge of a lower gage 220 and the lower edge of the seal element 230.
Additionally, the
packer includes a support sleeve 232 (made from a hardened material) that is
located over
the entire inner surface of the seal ring 230 between the seal ring 230 and
the outer
surface of the mandrel 16; and the sleeve 232 includes a crimped portion 234
to
predispose the sleeve 232 to radially expand at the section 234 during the
setting of the
packer.
[0034] As yet another example, Fig. 7 depicts an exemplary section 250 of a
packer in accordance with another embodiment of the invention. The section 250
is
similar to the section 50 (see Fig. 2) (with like reference numerals being
used), with the
following differences. In particular, the packer includes support rings 260
and 270 that
are located at the ends of the seal assembly 24 for purposes of minimizing
longitudinal
extrusion of the packer's seal element. The support ring 260 is located
between the upper
shoe 88 and the upper gage 54; and the lower ring 270 is located between the
lower gage
55 and the shoe 90.
[0035] Each of the rings 260 and 270 has a V-shaped cross-section and provides
support to minimize longitudinal extrusion of the seal element (seal rings 56,
60 and 64)
when the packer is set. More specifically, when the packer is set, the V-
shaped rings 260
and 270 each flatten to be substantially horizontal and rise above the gauge
diameter,
thereby minimizing the extrusion gap and supporting the seal element.
[0036] While the present invention has been described with respect to a
limited
number of embodiments, those skilled in the art, having the benefit of this
disclosure, will
appreciate numerous modifications and variations therefrom. It is intended
that the
appended claims cover all such modifications and variations as fall within the
true spirit
and scope of this present invention.
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