Note: Descriptions are shown in the official language in which they were submitted.
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Description
EXPANDABLE SLEEVE
Technical field
[0001] This invention relates to an expandable sleeve of the type that are
generally used for lining oil or gas wells.
Background art
[0002] Expandable sleeves have been known for some time in the oil and gas
industry as a technique for lining and stabilising wells for the production of
fluids. In use, the sleeve is introduced into the well in a contracted form
and then expanded until it contacts the wall of the well bore. Expansion
can be achieved by a number of means, including inflation with
compressed fluid or cold working with a mandrel or rotating expansion
tool. The advantages of expandable sleeves (sometimes called
'expandable tubulars' or just 'expandables') are well known. In cased
wells, expandables can be used to shut off perforations or close other
holes in the casing. In open hole, expandables can be used to stabilise
the well. Expandables have also been used to shut off perforations in
steam injection wells as is discussed in US 2003015246 A. One
approach to sealing off perforations described in this document is the use
of a sealing sleeve comprising a cylindrical steel portion with rubber-like
gasket material bonded on the outer surface of the steel sleeve. Certain
problems are identified with such a construction. Another approach to
sealing such perforations that is stated as addressing these problems is
the use of a spirally would metal patch. Upon deployment, the patch
unwinds within the wellbore and seals the perforation in the casing wall.
Spring tension tends to keep the patch securely fixed over the perforation.
[0003] Where the expandable consists of a steel tube that is expanded, the
steel
undergoes plastic deformation in order to provide the increase in diameter
required. However, even though plastic deformation will have taken place,
the steel retains some elasticity and so may relax following removal of the
mandrel or expanding tool after expansion. This relaxation may be
sufficient to compromise the seal against the perforations or wellbore.
[0004] The present invention aims to mitigate the effect of such relaxation.
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Disclosure of the invention
[0005] A first aspect of the invention comprises an expandable sleeve for use
in a
well, comprising a tubular structure including: an external sealing layer
comprising a compliant material; an intermediate expandable tubular body
made from a plastically deformable material; and an internal spring
structure comprising a helically wound spring having a wound wire of
rectangular section, wherein the helically wound spring comprises an
outer diameter larger than an internal diameter of the intermediate
expandable tubular body; wherein the external sealing layer is disposed
on the outer surface of the tubular body, and the internal spring structure
is disposed inside the tubular body and acts so as to exert a radial force
on the body when in an expanded state.
[0006] Preferably, the internal spring structure comprises a helically wound
spring. In a particularly preferred construction, the spring comprises a
helically wound wire of rectangular section.
[0007] The spring can be provided with formations that resist compression, for
example, inter-engaging teeth formed on adjacent edges of the spring
windings.
[0008] The tubular body is typically formed from solid metal such as steel.
[0009] To assist in achieving good expansion ratios for the sleeve, the
tubular
body can have a corrugated structure prior to expansion.
[0010] The external sealing layer is preferably natural or synthetic rubber.
[0011] A second aspect of the invention comprises a method of installing an
expandable sleeve in a well, the method comprising: installing an internal
spring structure comprising a helically wound spring having a wound wire
of rectangular cross-section in an expandable sleeve comprising a tubular
body comprising expandable material, wherein installing the internal
spring structure comprises applying axial force to separate coils of the
spring and applying torque to reduce a diameter of the spring, such that
the internal spring structure exerts a radial force on the tubular body when
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in an expanded state; lowering the expandable sleeve in an unexpanded form
into a well; and expanding the expandable sleeve such that the external
sealing layer engages a wall of the well.
[0012] In one embodiment, the internal spring is installed in the tubular body
in a
compressed state prior to lowering the sleeve into the well.
[0013] Another embodiment comprises lowering the tubular body into the well
and lowering the spring into the tubular body after it has been lowered into
the well. In this case, the spring can be lowered into the tubular body after
the tubular body has been expanded.
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[0012] In one embodiment, the internal spring is installed in the tubular body
in a
compressed state prior to lowering the sleeve into the well.
[0013] Another embodiment comprises lowering the tubular body into the well
and lowering the spring into the tubular body after it has been lowered into
the well. In this case, the spring can be lowered into the tubular body after
the tubular body has been expanded.
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[0014] By providing the internal spring structure, the tendency of the tubular
body
to relax is resisted. Also, the spring can provide mechanical support
allowing potentially thinner material to be used.
[0015] The invention also comprises a method of completing a well, comprising
installing a completion string including at least one sleeve according to the
invention in the well.
[0016] Preferably, the completion string comprises an array of slotted liners
having sleeves dispersed at various locations along the array.
[0017] In one embodiment, the sleeves are expanded on installation of the
completion. In another embodiment, one or more of the sleeves is
expanded after installation to allow production management operations to
be performed in the region between the expanded sleeves.
[0018] At least one further sleeve can be installed between adjacent expanded
sleeves in the completion string to isolate that region.
[0019] Sleeves according to the invention can also be used during drilling
operations to stabilise the formation being drilled.
Brief description of the drawings
[0020] Figure 1 shows a horizontal section through a sleeve according to an
embodiment of the invention in a well;
Figure 2 shows a part vertical section of the sleeve of Figure 1;
Figure 3 shows a part exploded view of the sleeve of Figures 1 and 2;
Figure 4 shows a horizontal section through a corrugated sleeve according
to a further embodiment of the invention;
Figure 5 shows a sleeve with axial reinforcement;
Figure 6 shows a wireline conveyed expansion tool for use with sleeves
according to the invention;
Figure 7 shows a well completion using expandable sleeves according to
an embodiment of the invention;
Figure 8 shows the use of an expandable sleeve according to an
embodiment of the invention to isolate a water producing region of a
completion as shown in Figure 6; and
Figure 9 shows a well completion with length compensation sections.
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Mode(s) for carrying out the invention
[0021] Expandable sleeves in accordance with the invention are particularly
useful in wells such as oil and gas wells. They can be applied during the
well construction process to stabilise the formation through which the well
is drilled, or after completion to repair damage or to seal off perforations
that are producing unwanted fluids. Other uses will be apparent.
[0022] Referring to Figures 1-3, the embodiment of the invention shown
comprises a sleeve constructed in three layers: an outside layer 10, and
intermediate layer 12 and an internal layer 14. In Figures 1-3, the sleeve
is installed in a well that has been completed with a steel casing 16
secured in the well by cement 17 to provide zonal isolation and physical
support. Communication with the producing formation 19 is via
perforations 18 formed through the casing in the usual manner.
[0023] The outside layer 10 comprises a thin layer of a sealing compound such
as natural or synthetic rubber. The exact material will be selected
according to the physical and chemical environment to which the sleeve
will be selected. The principal function of this layer is to provide a seal
between the sleeve and the wall outside. The outside layer 10 is pressed
against the borehole wall (either open formation or previously installed
tubular such as a casing 16) by the other layers of the sleeve.
[0024] The intermediate layer 12 is a thin solid layer. It is typically could
be made
of metal such as steel of from 1 to 3 mm thickness (larger thicknesses
may be used according to requirements). The intermediate layer 12
ensures proper uniform compression of the outside rubber layer 10 against
the external wall of the well or casing 16. The thickness of the
intermediate layer 12 is a compromise between the need to for it to deform
easily during the expansion operation, while still being able to support the
internal well over-pressure, without being extruded into holes in the well
wall or tubular 16 such as perforation 18 or slots.
[0025] The internal layer 14 is a spring device 20 that provides elastic
expansion
of the sleeve against the well wall after the expanding tool (not shown) has
finished the expansion process. Furthermore, this structure resists
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potential collapse of the intermediate layer 12 when an external pressure
is being applied onto the sleeve system.
[0026] As is shown more clearly in Figure 2, the primary seal is provided by
the
rubber outside layer 10 which is pressed against the perforated tubular 16
by the expansion force of the thin intermediate metal layer 12 reinforced
by the radial force generated by the energizer spring 20.
[0027] The energizer spring 20 can be an helical spring made of an wound thick
wire of a rectangular section. The rectangular wire section allows a
smooth contact between the outer surface 22 of the spring 20 and the
intermediate thin metal layer 12.
[0028] This spring 20 is used to generate a radial expansion to push the
sleeve
against the well wall.
[0029] One method of constructing a spring for this application is to start
for a
tube of an elastic metal. This tube should be slightly too large to enter in
the well (especially if the thicknesses of the rubber outer layer 10 and thin
metal intermediate layer 12 are taken into account). The metal tube is
then cut following a spiral line to form the spring helix. To install the
spring, it is necessary to reduce its diameter: for this action, an axial
force
is applied to stretch the hellicoidal structure (to separate the coils) then a
torque is applied to reduce the helix diameter.
[0030] This spring 20 can have a number of functions when installed in the
well in
the sleeve. For example, the spring 20 can ensure that the intermediate
metal layer 12 is maintained in a cylindrical shape after its plastic
deformation in the expansion process. This can be particularly useful if
the sleeve was initially vertically corrugated prior to expansion as is shown
in Figure 4.
[0031] The spring 20 can also act to reinforce the sealing effect of the outer
rubber layer 10 against the well wall (either open-hole well-bore or the
perforated casing 16, or the slotted liner, or any other metal tubular). The
extra energization may be useful because the intermediate metal layer 12
has been plastically deformed against the well-wall: when the mechanical
force applied for this deformation (expansion) is removed, the intermediate
metal layer 12 will relax slightly due to the elastic property of the metal.
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[0032] The spring 20 will act to support the sleeve when external pressure
from
the formation is applied. On its own, the relatively thin intermediate layer
12 would have tendency to collapse, as it is thin and typically not fully
cylindrical after its plastic expansion against the well wall.
[0033] When installed in the well, the spring 20 can provide a reserve of
potential
energy, so that the sealing effect of the out rubber layer 10 can be
maintained and re-adjusted in case of slight movement either of the sleeve
or the wall. Such movement may occur due to thermal and pressure
variation, or due to some slight displacement of the structure relative to the
wall. Such movement can occur in open-hole situations, as the wall itself
may move due to change in fluid wetting or subsidence effects.
[0034] It is particularly preferred that the spring 20 is designed for a
locking effect
after installation. This effect can be achieved by friction between the
spring 20 and the inner wall of the intermediate layer 12, or by a ratchet
effect created by the structure of the edges of the coils of the spring20. For
example, the helicoidal cut used to make the spring can be in the form of
a toothed line so that the teeth on adjacent parts of the coils interact and
lock the spring in place. The locking effect is preferably directional, so
that
the spring can expand but retraction is resisted by the interlocking
formations.
[0035] The spring may be installed in the sleeve in a number of ways. In some
cases, the spring may be lowered into the well directly with the
intermediate and outer layers as a single unit, with the spring in its
compressed state. Such an approach can apply particularly when the
sleeve expansion ratio is limited. However, when large sleeve expansion
ratios are envisaged (particularly when a corrugated structure is used to
provide a greatly reduced starting diameter), it may be easier to install the
spring after the intermediate and outer layers have been installed and
expanded. In such a case, the expandable structure may be installed and
expanded in a first run of a setting tool and the spring installed after
expansion by a second run of a setting tool.
[0036] The basic sleeve according to one embodiment of the invention includes
a
intermediate thin layer 12. Typically, this is initially cylindrical. While
this
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layer is usually metal, other materials capable of easy plastic deformation
are also possible. This layer will be plastically deformed to the final
diameter, by a mechanical device which generates a radial expansion.
Starting with a cylindrical intermediate layer, the expansion is limited
typically to 20 % - 30%. Expansion is limited by the intrinsic properties of
the material of the intermediate layer. For larger expansion ratios, the
intermediate metal layer may need to be corrugated prior to installation as
is shown in Figure 4.
[0037] The intermediate layer can be optimised for minimizing the force
required
for expansion. One approach is to use a slightly corrugated sleeve with
corrugations of relatively small depth and relatively but short in
circumferential extent (small wavelength pattern) so that many
corrugations can be formed over the circumference. Such small but
numerous corrugations allows extension of the sleeve under a relatively
small force. However, the maximum extension may be limited. The use of
a corrugated sleeve allows the energizer spring to act more freely to apply
the sleeve against the wall. When the corrugations are axial, they may
also provide some support over perforations, so that internal pressure
does not extrude the thin intermediate layer into the perforations.
[0038] In case of open-hole application, the small numerous corrugation sleeve
may be replaced by a small numerous dimples sleeve. With this sleeve,
the wavy pattern is available for all direction, so that the sleeve can
comply to more type of deformation of the open-hole surface.
[0039] A sleeve according to the invention can be used in the role of an
external
casing packer (ECP) or a liner packer. In this role, the sleeve is installed
as a special tubular between either screen sections or slotted liners,
during the installation of the completion. The sleeve is handled and
installed as the other elements of the completion. Used in such an
application, the sleeve will typically have certain characteristics,
including:
¨ a sleeve diameter similar to that of the screens or slotted liners;
¨ connections provided at both ends of the sleeve, similar to the
screens
or liners.
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¨ axial load and torque strength similar to the screens or slotted
liners;
and
¨ a length adapted to the particular field needs (typically recommended
to be longer than 3 meters to ensure sufficient sealing after
expansion).
[0040] When compared to a conventional ECP, the expandable sleeve according
to the invention is more simple, as the control and setting mechanisms can
be contained in a wireline setting tool. Compared to an ECP, the
expandable sleeve has the advantage of not being susceptible to leaks in
the packer element (which, when they appear in an ECP prohibit proper
setting).
[0041] The expandable sleeve according to the invention contains its "reserve"
of
potential energy to adapt its seal when required due to small movement of
the formation or the device itself. Such adaptation is not possible with a
conventional ECP.
[0042] For an ECP-like application, the sleeve is preferably initially
cylindrical and
expanded to final diameter by plastic deformation (typically less than 20
%). In such a case, the intermediate layer preferably is able to support the
weight of the completion while running in the hole. However, if this layer
has insufficient strength to support this axial load, a slotted liner sleeve
may be added at the inside the intermediate layer and attached to both
end of the expandable sleeve as is shown schematically in Figure 5. The
cuts in the slotted sleeve 23 are parallel to the axis of the tubular so that
relatively high axial loads can be supported, while relatively little effort
is
required during radial expansion.
[0043] For this application, the spring may have to generate a relatively high
radial force to deform the intermediate layer (as it may be relatively thick).
Consequently, a thick helicoidal spring may have to be forced into place
with a high axial load. Extreme axial loads can be achieved by hammering
axially onto the spring in-situ.
[0044] In an ECP-like application, it is not necessary that the sleeve be
expanded
initially. Production may start without expansion. The expansion would be
performed only when fluid management is required. This situation may be
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particularly preferable if the length of the sleeve is large compared to the
total length of the completion; with the non-expanded situation, production
may be provided in front of the none-expanded sleeve.
[0045] Another application of sleeves according to the invention is in the
domain
of through-tubing fluid shut-off. The expansion of metal is typically less
than 30% in the plastic domain, but for some applications, larger
expansion may be required. In the case of perforation shut-off, the sleeve
may need to be lowered through the production tubing to enter the well,
and then expanded to the casing. In this application, the required
expansion may be up to three-fold. To achieve this large ratio, a
corrugated sleeve such as that shown in Figure 4 may be used. The
intermediate layer may need to be relatively thin as large bending
deformation is required. The rubber outer layer may also be of variable
thickness in the corrugated shape, so that it has a uniform thickness after
expansion into a cylindrical shape. Typically, it is thinner at the tip of the
corrugation, and thicker at the recess part of the corrugation.
[0046] This sleeve may have a retraction effect after setting, trying to move
elastically to its initial shape (usually only by a small percentage of the
deformation). To avoid this retraction, the inside layer provided, for
example, by the energizer spring is required. The length of the sleeve can
be selected depending of the length of entry port (perforation, slots) to be
sealed.
[0047] When installed over slotted liner or screens, the water shut-off sleeve
should extend across a perforated/slotted section and reach the adjacent
sections without perforations or slots. Furthermore, these adjacent
sections need to seal in the outside annulus.
[0048] For these and other applications, once the sleeve has been lowered to
the
proper depth in the well, it must be expanded. One way in which this
expansion can be performed is by use of a wireline expansion tool such as
is shown in Figure 6. It is common that installation of expandable sleeves
may have to take place in a well that is lined with a casing 16 and has
production tubing 24 secured therein by means of a packer 26.
Consequently, the expansion tool 28 will be dimensioned to pass through
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production tubing. The sleeve 30, preferably in corrugated form, is located
on the expansion tool 28 and the two are positioned together in the well
prior to expansion of the sleeve, after which the tool 28 is withdrawn.
[0049] The expansion tool ensures the cold forming of the sleeve to its final
diameter, pressing the sleeve against the well wall. Various expanding
processes can be used:
¨ Use of a set of rollers that rotates inside the sleeve with a slow
vertical
displacement.
¨ Use of a cone, which is forced axially inside the sleeve. This cone has
to expand the diameter of the sleeve in order for it to pass through.
The contact between the cone and the sleeve could be via rollers.
[0050] In some applications, it may be necessary to retrieve a sleeve that has
been installed within a completion for production management (or
treatment management). For this application, it may be necessary to
retrieve the energizing spring must first. Therefore, the spring design may
be adapted for this requirement:
¨ For example, both ends of the spring may be equipped with easy to
connect termination, so that the wireline tool can connect to it and
apply torque and tensile load to make the overall diameter of the
spring shrink to its original dimension. Then the spring is maintained in
the retracted shape and returned to surface. The termination could for
example be rolled towards the inside of the bore to approximately 180
deg (and in a small radius).
¨ Another connection technique is to equip both ends of the spring with
small holes to allow a finger on the recovery tool to connect and apply
the retraction load.
¨ Another alternative is to push the spring out of the sleeve and leave
it
in the well below (or above the sleeve).
[0051] Following this, there are several techniques for removal of the sleeve:
¨ Make a axial cut in the sleeve, so that it can rolled on itself and
removed out of the well.
¨ Use a sleeve with an axial weak line. Thanks to the weak-line, the
sleeve can be stripped away from the wall. After being stripped, the
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sleeve can be rolled as in the solution proposed above. The weak line
can be provided by the construction of the sleeve which can be formed
by rolling a sheet and welding it as a cylinder. The weld can be made
fragile (especially when the proper force is being applied). One way to
achieve the weak weld is to use a band which is "glued" or spot-
welded on to the extremities of the intermediate layer to form a joint to
create the tubular form. To break the sleeve, the lower end of the
band is grabbed by the recovery tool, for example by a hook; the
recovery tool can then pull the band away.
[0052] Another application of expandable sleeves according to the invention is
as
replacement for packer (ECP) as is shows schematically in Figure 7. The
expandable sleeves 30 are installed as completion tubulars between
screens or slotted liners 32, for example in a horizontal section of a well
34. Multiples sleeves 30 can be installed in one completion string
(possibly as many as 100 in a long horizontal well). The completion
(typically also comprising the slotted liners 32) is installed at the desired
depth. An expansion tool is lowered to the end of the completion, and
then pulled to the last sleeve (already in place with the completion) which
needs expansion. The expansion tool ensures all the expansion of all
sleeves in one single run in the hole. After the expansion of all of the
sleeves 32, the contact with the reservoir is compartmented.
[0053] Thanks to the compartmentalisation, it is possible to control water
production by isolating any sections producing water, for example section
36 in Figure 7, while leaving the remaining sections 38 open to produce
oil. This isolation can be performed by installing another expandable
sleeve for internal bore use as is shown schematically in Figure 8. This
sleeve 40 is sized to extend over the distance between two successive
completion sleeves 30 to ensure isolation of the water producing section
36.
[0054] Isolation of the water producing sections can be performed either at
the
beginning of the production phase (if the well passes through zones
producing water and oil) or when the problem starts (for example when the
oil water contact moves as the reservoir becomes depleted).
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[0055] In another version of this application, expansion of the sleeves 30 of
the
completion is not performed at the time the completion is installed. In this
case the sleeves 30 are expanded only when water entry occurs. A
further modification of this approach is to only expand the sleeves 30 at
both ends of the water-producing section 36. This can give more flexibility
for the operation, while ensuring maximum producing contact with the
reservoir.
[0056] Another application for the invention can be for length compensation
following expansion as is shown in Figure 9. The expanded sleeve has a
shorter length after expansion. As first approximation, the sleeve typically
shrinks in length at the same percentage as it has been expanded. For
example, a 5 meter sleeve expanded by 10% in diameter could shrink in
length by 0.5 meter.
[0057] When multiple sleeves are installed in the completion, problems may
occur
when the sleeves are not expanded in the successive order. For a
completion equipped with three or more expandable sleeves (see Figure
9), if sleeves 30' at the extremities are expanded first, the screens (or
tubulars) 30 between them are normally in a neutral state. When a sleeve
30 in the middle is expanded, shrinkage occurs in length, generating a
tensile load on the whole tubular completion. To avoid this situation, the
intermediate expandable sleeve 30 can be equipped with a "length-
compensation" tubular 42. When the intermediate sleeve shrinks its
length, this section of compensation tubular extends under low axial load.
[0058] The length compensation tubular section 42 can be made of
circumferentially corrugated pipe (bellows shape). It can also be made of
pipe with a spiral deformation (such as a thread). This shape allows axial
deformation under load. Such a structure may be limited in axial load
capability. For this purpose, the length compensation tubular may need
axial reinforcement to support the maximum weight of the completion. If
present, any axial load member providing such reinforcement needs to be
deactivated before starting the expansion of the neighbouring expandable
sleeve, so that length compensation can be performed by the
compensation sleeve. The deactivation of the axial reinforcement
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members of the length compensation sleeve can be obtained at the
beginning of the expansion process by cracking links radially, for example
by local radial deformation of the reinforcement members. This can be
achieved by the radial expansion device used to expand the sleeve.
Alternatively, a latch system can be disengaged radially to free this axial
reinforcement system.
[0059] During drilling operations, certain formations may be encountered that
can
give rise to problems if left untreated while drilling continues. In some
case, these formation may be mechanically fragile or unconsolidated, or
chemically reactive with the drilling fluid, or fractured so as to lead to
high
fluid loss. An insulating sleeve according to the invention can be installed
over the problematic zone and drilling may continue. To avoid loss of well
diameter after the sleeve installation, it may be desirable to under-ream
the well bore before the sleeve installation. The sleeve is then lowered
with the expansion tool. The sleeve is expanded over the under-reamed
section.
