Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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HYDRAULIC PACKER WITH THERMAL ISOLATION MEMBER
BACKGROUND OF THE INVENTION
Field of the Invention
100011 In many well-related applications, packers are used to provide pressure
isolation in regions of a wellbore. Often, packers are designed to set or
anchor against
surrounding well casing. The setting of the packer both energizes a packer
sea] element
and engages packer slips with the surrounding casing. Energizing the packer
seal
element involves using an axial force to compress the seal element and to
cause the seal
element to extrude outwardly in a radial direction until it contacts the well
casing.
Similarly, engaging the packer slips with the casing also utilizes axial force
to push or
pull the slips into a cone which drives the slips outwardly in a radial
direction until the
slips contact and grip the casing. The axial force may be generated either
mechanically
or hydraulically.
Description of Related Art
10002] Mechanical methods of setting a packer rely on tubing manipulation
provided from the surface or from a setting tool attached to the packer.
Hydraulic
methods utilize pressurized fluid delivered down through the tubing string or
the
surrounding annulus. The pressurized fluid acts on a packer mechanism to
create the
desired axial force for setting the packer.
100031 In thermal wells having high temperatures, mechanical packers often
have
been preferred because hydraulic packers rely on elastomeric seals that can
degrade and
fail in the high temperature environment. For example, hydraulic packers may
utilize o-
ring seals to form the piston areas and fluid chambers used to convert
hydraulic pressure
into axial movement and force for setting the hydraulic packer. The standard
materials
from which such seals typically are manufactured do not have high service
temperature
ratings and can fail, causing release of the packer. However, many such well
applications
are better suited for hydraulic packers rather than mechanical packers.
Attempts have
been made to employ hydraulic packers in thermal wells by forming seals with
exotic
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elastomers and using high temperature backup rings to prevent seal extrusion.
However, such approaches are difficult and costly to implement, while
remaining
susceptible to seal deterioration from long-term high temperature exposure.
BRIEF SUMMARY OF THE INVENTION
[0004] In general, the present invention provides a system and methodology
for utilizing a hydraulically actuated packer in a high temperature, downhole
environment. The packer is actuated by directing pressurized fluid to the
packer and
routing the fluid to an actuation region of the packer to provide the force
for setting
the packer. A thermal isolation member is positioned in the packer along the
pressurized fluid flow path and activates upon exposure to heat. Once the
thermal
isolation member is fully activated, flow is blocked along the pressurized
fluid flow
path which prevents return flow of pressurized fluid.
An aspect of the invention relates to a system comprising: a packer
expandable by application of hydraulic pressure downhole, the packer
comprising: a
mandrel having an internal flow passage and a radial port extending through a
wall of
the mandrel to the internal flow passage; a cylinder positioned around the
mandrel to
create a cavity exposed to the radial port; a piston system slidably mounted
in the
cylinder and exposed to the cavity; an expandable member operatively engaged
with
the piston system; and a thermal isolation member positioned at the radial
port to
automatically block flow through the radial port when the thermal isolation
member is
exposed to sufficient heat.
Another aspect of the invention relates to a method, comprising:
constructing a hydraulically actuated packer with an actuation piston exposed
to an
actuating fluid via an inlet passage; and positioning a thermal isolation
member at the
inlet passage to automatically block flow through the inlet passage by
expanding
when exposed to sufficient heat.
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Still another aspect of the invention relates to a system for use in a well,
comprising a well completion comprising a packer, the packer having a fluid
passage
for receiving a fluid under pressure to actuate the packer, the packer further
comprising a thermal isolation member deployed along the fluid passage, the
thermal
isolation member reacting to heat in a manner that blocks return flow along
the fluid
passage.
A further aspect of the invention relates to a method, comprising:
moving a hydraulic packer downhole into a wellbore; setting the packer by
directing a
high pressure fluid into a packer actuation region; and blocking return flow
of fluid
from the packer actuation region with a thermally activated isolation member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Certain embodiments of the invention will hereafter be described with
reference to the accompanying drawings, wherein like reference numerals denote
like
elements, and:
[0006] Figure 1 is a view of a well system deployed in a wellbore with a
hydraulic packer, according to an embodiment of the present invention;
[0007] Figure 2 is an illustration of one example of the hydraulic packer
illustrated in Figure 1, according to an embodiment of the present invention;
[0008] Figure 3 is an enlarged view of a portion of the hydraulic packer
illustrated in Figure 2, according to an embodiment of the present invention;
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[0009] Figure 4 is a cross-sectional view of a thermal isolation device
positioned
in a packer flow passage, according to an embodiment of the present invention;
[0010] Figure 5 is a cross-sectional illustration similar to that of Figure 4
but
showing the thermal isolation device in an activated state, according to an
embodiment of
the present invention; and
[0011] Figure 6 is a cross-sectional illustration of another example of the
thermal
isolation device, according to an alternate embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] In the following description, numerous details are set forth to provide
an
understanding of the present invention. However, it will be understood by
those of
ordinary skill in the art that the present invention may be practiced without
these details
and that numerous variations or modifications from the described embodiments
may be
possible.
[0013] The present invention relates to a system and methodology for isolating
regions of a wellbore. For example, one or more packers may be deployed
downhole and
set to provide pressure isolation of specific wellbore regions with respect to
adjacent
wellbore regions. As described in greater detail below, the system and
methodology
facilitate the use of hydraulic packers, even when using standard elastomeric
seals, in
thermal wells that subject the hydraulic packer to high temperatures. The
hydraulic
packer may even be used in wells in which the temperatures at the packer are
above
450 F. Many standard elastomers used in the creation of seals reach a flow
phase at such
temperatures.
[0014] In the present system and methodology, a thermal isolation device is
located in the hydraulic packer to prevent formation of a leak path that would
allow
unsetting of the packer. The thermal isolation device blocks development of
such a leak
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path even if the hydraulic seals deteriorate in the high temperature well
environment. In
some embodiments, the thermal isolation device automatically reacts to heat in
a manner
that blocks return flow of actuation fluid in the packer. For example, the
thermal
isolation device may comprise a member or plug that expands or otherwise
changes form
in the presence of sufficient heat. The thermal isolation device can be used
in
cooperation with an actuation fluid passage to block flow through the passage
under high
heat conditions.
[0015] Referring generally to Figure 1, one example of a well system 20 is
illustrated according to an embodiment of the present invention. In the
embodiment
illustrated, well system 20 comprises well equipment 22 deployed downhole in a
well 24
defined by a wellbore 26. The wellbore 26 extends downwardly from a wellhead
28 at a
surface location 30, and the well equipment 22 may be deployed within a
surrounding
tubing 32, such as a well casing.
[0016] Well equipment 22 may comprise a well completion or other equipment
deployed downhole by a suitable conveyance 34, such as a flexible conveyance
or tubing,
e.g. coiled tubing. The well equipment 22 comprises a hydraulic packer 36 used
to
isolate regions of the wellbore 26. It should be noted, however, that well
equipment 22
may comprise a variety of components and include one or more hydraulic packers
36.
For purposes of description, the illustrated hydraulic packer 36 is
representative of the
one or more hydraulic packers that can be used to isolate regions of wellbore
26.
[0017] The hydraulic packer 36 may be constructed in a variety of shapes,
sizes
and forms that use various components and component configurations. By way of
example, hydraulic packer 36 comprises an actuation system 38 used to
selectively
expand one or more expandable members 40. Expandable members 40 may comprise
an
expandable packer seal element 42 that is selectively expanded against the
surrounding
tubing 32 to form a seal sufficient to isolate the wellbore region above
hydraulic packer
36 from the wellbore region below hydraulic packer 36. The expandable members
40
also may comprise retention mechanisms 44, e.g. slips, which may be
selectively
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expanded to engage the surrounding wall and secure the hydraulic packer 36 at
a desired
location along wellbore 26.
[0018] Referring generally to Figure 2, one embodiment of hydraulic packer 36
is
illustrated. In this embodiment, actuation system 38 comprises a piston system
46 having
one or more pistons 48 that may be moved by application of sufficient
hydraulic pressure.
As illustrated, the actuation system 38 further comprises a cylinder 50 and a
mandrel 52
disposed within the cylinder 50. An end structure 54 is connected between the
cylinder
50 and mandrel 52 to enable the cylinder 50 and the mandrel 52 to cooperate
and create
an actuation region 56 that receives actuating fluid under pressure to move
piston 48. In
this embodiment, piston(s) 48 ultimately is connected with packer seal element
42 and
retention mechanisms 44 via linkage 58 to provide the axial movement used to
actuate
packer seal element 42 and/or retention mechanisms 44.
[0019] Referring also to Figure 3, the actuating fluid is delivered to
actuation
region 56 which may comprise a cavity adjacent piston 48. The actuating fluid
is
delivered to actuation region 56 through a flow passage 60 that may include a
flow port
62. A thermal isolation device 64 is deployed along flow passage 60 and is
designed to
enable flow of actuating fluid along flow passage 60 during setting of
hydraulic packer
36. However, when exposed to sufficient heat due to, for example, the
temperature of the
environment in which hydraulic packer 36 is deployed, thermal isolation device
64
actuates to block flow along flow passage 60. The blockage prevents return
flow that
could otherwise allow an undesirable release/unsetting of hydraulic packer 36.
[0020] In the embodiment illustrated in Figures 2 and 3, piston 48 is designed
to
move axially relative to cylinder 50 and mandrel 52. The pressurized actuating
fluid acts
on piston 48 and is converted into axial movement and force. Cylinder 50 and
mandrel
52 function to contain the pressurized actuating fluid and piston 48. In some
embodiments, piston 48, cylinder 50, and mandrel 52 are three individual
components.
In other embodiments, the piston and cylinder may be combined into one
component
while the mandrel remains a separate component. Alternatively, the piston and
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mandrel may be combined into one component while the cylinder remains a
separate
component. Regardless of the specific configuration, the combination of
piston, cylinder,
and mandrel utilizes sealing elements to create a pressure integral seal
between the
relatively moving components. In many applications, the sealing elements are
constructed as o-rings, however other types of seals may be used.
[00211 Referring again to the embodiment of Figure 3, pressurized actuating
fluid
is delivered to the actuation region 56 to move piston 48, and any fluid on
the backside of
piston 48 can be discharged to the surrounding annulus via a discharge port
65. In the
embodiment illustrated, actuating fluid is delivered along a flow path through
an interior
66 of mandrel 52 and radially outwardly through flow port 62 formed through a
wall of
mandrel 52. The actuating fluid flows past thermal isolation device 64 to
actuation
region 56. In alternate embodiments, however, the actuating fluid can be
directed along a
surrounding annulus and to actuation region 56 by locating the inlet flow port
through a
wall of cylinder 50, as indicated by port 68. In other embodiments, the
actuating fluid
can be directed to actuation region 56 via a dedicated control line. In any of
these
embodiments, the thermal isolation device 64 is positioned at an appropriate
location
along the actuating fluid flow path.
[00221 Once the pressurized actuating fluid reaches actuation region 56, the
fluid
acts on piston 48 and causes it to move in an axial direction a sufficient
distance to set
hydraulic packer 36. The actuating pressure is maintained by a plurality of
seal elements,
such as seals 70 located between piston system 46 and cylinder 50. Seals 70 or
additional
seals 72 can also be used to form a pressure seal between the piston system 46
and
mandrel 52. Other seals 74 can be positioned at additional locations to again
form a
pressure seal between elements of piston system 46 and cylinder 50. In the
specific
embodiment illustrated, additional seals 76 may be used to form appropriate
pressure
seals between end structure 54 and the adjacent sections of cylinder 50 and
mandrel 52.
The number and type of seals may vary according to the design and
configuration of
hydraulic packer 36, but generally the seals containing the pressurized
actuating fluid
may be formed of elastomers that have a defined temperature range in which
such
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materials function properly. Once the ambient temperature exceeds this
temperature
range, the structural integrity of the seals can begin to deteriorate which
may lead to
leakage and failure of pressure integrity at high temperatures. Without
thermal isolation
device 64, such deterioration could create a leak path or return path along
flow passage
60 so as to release actuating fluid which could further result in
release/unsetting of
hydraulic packer 36.
[0023] Thermal isolation device 64 can be used to seal off flow passage 60 and
to
prevent unwanted release of actuating fluid. In some embodiments, thermal
isolation
device 64 is used to permanently block any communication through flow port 62
which
prevents unwanted release of hydraulic packer 36. For example, in many
downhole
applications, once hydraulic packer 36 is set, the function of the elastomeric
seals is no
longer necessary other than to prevent release of actuating fluid. However,
thermal
isolation device 64 removes the threat of seal deterioration in high
temperature
environments by automatically blocking the flow path that would otherwise
potentially
allow release of the actuating fluid. Accordingly, the presence of thermal
isolation
device 64 enables deterioration and failure of several seal elements without
affecting the
functionality of hydraulic packer 36 in these applications. Consequently, less
expensive
elastomers can be used to form various seal elements.
[0024] Referring generally to Figure 4, one example of thermal isolation
device
64 is illustrated. In this embodiment, thermal isolation device 64 comprises a
plug 78
deployed in flow port 62. Before being exposed to sufficient heat to fully
activate
thermal isolation device 64, a fluid gap 80 exists between plug 78 and the
wall of flow
port 62. The fluid gap 80 enables transfer of activating fluid to actuation
region 56
during setting of hydraulic packer 36. Plug 78 may be retained along the flow
passage,
e.g. retained in flow port 62, by a variety of mechanisms. For example, plug
78 may be
inserted into an expanded portion 82 of flow port 62 and held within the
expanded
portion 82 by a plug retainer 84 such as the illustrated snap ring 86.
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[0025] Once the temperature around hydraulic packer 36 within wellbore 26
reaches a high level and plug 78 is exposed to sufficient heat, plug 78
activates, which
eliminates the fluid gap 80 and blocks flow along flow port 62, as illustrated
in Figure 5.
By way of example, plug 78 may expand when exposed to sufficient heat and
create an
interference 88 with the surrounding port wall surface 90. If flow port 62 is
routed
through mandrel 52, the plug 78 creates interference 88 with the surrounding
material of
mandrel 52. Upon sealing off flow port 62, the potential leak path created by
seal
element failure is no longer a concern with respect to detrimentally affecting
the function
of hydraulic packer 36.
[0026] The materials, construction, configuration, and location of thermal
isolation device 64 may vary depending on the design of hydraulic packer 36
and the
environment in which it is employed. In the specific example illustrated, the
material,
form, and number of plugs 78 and plug retainers 84 can be adjusted. In Figure
6, for
example, another embodiment of plug retainer 84 is illustrated. In this
embodiment, plug
retainer 84 comprises a threaded member 92, such as an externally threaded
nut, having
an internal port 94 to accommodate the flow of actuating fluid when setting
hydraulic
packer 36.
[0027] The plug 78 or other member used for blocking flow along flow passage
60, e.g. through flow port 62, may be formed from a material 96 that reacts to
heat in a
desired manner. In many applications, the material 96 is selected based on its
thermal
expansion coefficient. In other words, the material is selected to expand more
than the
material 98 that surrounds the plug 78 or other actuation member. By way of
specific
example, the material 96 may be selected to expand and create interference 88
at a
temperature below the upper temperature limit of the elastomer seal elements.
[0028] The actual materials 96, 98 that are selected for a given hydraulic
packer
36 may vary depending on the specific application. In one example, the
surrounding
material 98 is an alloy steel having a thermal expansion coefficient range
from 8.6 x 10-6
inches/inch/ F to 6.3 x 10"6 inches/inch/ F. In this example, plug 78 may be
formed from
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a suitable material, such as aluminum, having a thermal expansion coefficient
ranging
from 13.7 x 10-6 inches/inch/ F to 11.7 x 10-6 inches/inch/ F. The aluminum
material
expands significantly more than the surrounding alloy steel material.
[0029] In other applications, material 96 may comprise a shape memory alloy.
The shape memory alloy can be used to construct plug 78 or other flow
isolation member
in a manner such that its outer diameter is greater than the diameter of the
flow port 62 at
a predetermined high temperature. The larger diameter created by material 96
causes the
desired interference 88 and seals off the flow port 62, thus preventing
unwanted
communication of activating fluid. In various applications, the use of shape
memory
alloy allows the thermal isolation plug 78 or other thermal isolation member
to retain its
expanded geometry even after the ambient temperature has decreased
significantly.
Additionally, shape memory alloys can be designed so that the thermal
expansion is more
reliable and predictable, which facilitates its use in a variety of thermal
isolation devices
employed in various components and at various locations along flow passage 60.
[0030] The design of hydraulic packer 36 with thermal isolation device 64
enables use of hydraulic packers in a wider variety of environments and
applications.
The size, type, and configuration of hydraulic packer 36 can vary according to
the
specific application and environment. For example, the type of piston system
or other
actuation system, the routing of activating fluid, the type and location of
the thermal
expansion device, and the type, arrangement and size of various other
components can be
adjusted to accommodate environmental conditions and operational parameters.
Additionally, the overall well system may utilize individual or multiple
hydraulic packers
to provide the desired pressure isolation zones. Furthermore, the size and
configuration
of the thermal isolation devices, as well as the materials used to construct
the thermal
isolation devices, can be selected and adjusted according to the specific well
applications.
[0031] . Accordingly, although only a few embodiments of the present invention
have been described in detail above, those of ordinary skill in the art will
readily
appreciate that many modifications are possible without materially departing
from the
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teachings of this invention. Such modifications are intended to be included
within the
scope of this invention as defined in the claims.
