Note: Descriptions are shown in the official language in which they were submitted.
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Description
APPARATUS AND METHOD FOR EXPANDING TUBULAR ELEMENTS
Technical field
[0001] This invention relates to methods and apparatus for expanding tubular
elements such as casing or other tubulars that are typically installed in
wells such as oil or gas wells, or tubulars of surface, subsea or subsurface
pipelines. Even further the invention relates to systems which employ
such methods and apparatus for expanding tubular elements.
Background art
[0002] Tubular elements such as casing and completion tubing, screens and
other such devices are well known in the field of oil and gas wells. In
order for them to be installed in the well, it is necessary that they have an
outer diameter that is less than the inner diameter of the borehole in which
they are to be installed. In fact, since the inner diameter of the borehole
can vary and the trajectory of the borehole is often not straight, the
maximum possible diameter can be significantly less than that of the
borehole at any point.
[0003] When a borehole is being drilled, it is usually necessary to stop
drilling
after a certain depth and stabilise the borehole by placing a steel tubular
casing in the well and filling the annulus between the outside of the casing
and the borehole wall with cement. This operation may need to be
repeated several times during the drilling of the well, each successive
casing being necessarily smaller than the inside diameter of the preceding
casing. This in turn leads to progressive reduction of the inner open
diameter of the well which in turn places limitations on the quantities of
fluids that can flow along the well and the depth to which the well can be
drilled.
[0004] To overcome this problem, it has been previously proposed to expand the
casing in the well to reduce the annular space. Also, expansion of
subsequent casings to match the diameter of the previous casing has also
been proposed to avoid the progressive diameter reduction found with
conventional casing techniques.
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[0005] Expansion is typically achieved using a cone shaped expansion tool
which
has a maximum diameter that is greater than the inside diameter of the
casing to be expanded. Forcing the expansion tool through the casing
causes it to expand. One difficulty in this operation is that because the
outer diameter of the expansion tool is greater than the inner diameter of
the casing, it is not possible to position the expansion tool in the casing;
it
must either start at the top or bottom and be moved either to the other end
or back to its starting place to be removed from the casing. To address
this, expansion tools have been proposed that are initially positioned in a
contracted state and then are reconfigured into their operational or
deployed configuration before being moved and forged through the casing.
However, since the deployed outer diameter is still greater than the inner
diameter of the casing, this must be done in an open section of the well or
in a section of wider diameter, since the forces used in deployment are
normally not large enough to expand the tubular.
[0006] It is an object of this invention to provide a method and apparatus by
which expansion can be initiated in a section of the casing or other tubular
in its unexpanded state and so can create either a complete expansion, or
a chamber in which a conventional expandable cone can be deployed.
This invention achieves this object by the use of a compressible member
on an expanding tool that can be squeezed to provide an expansion
surface on an expansion tool that can fit in the unexpanded tubular
element.
[0007] It is further an object of this invention to provide various
applications of the
expansion apparatus, some of which reduce the need for the use of
cementing in wells.
Disclosure of the invention
[0008] One aspect of this invention provides an apparatus for expanding
tubular
elements, comprising:
- a tool body;
- an axially compressible expansion body mounted on the tool body such
that the outer surface of the expansion body is substantially the same
outer diameter as that of the tool body; and
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- means for axially compressing the expansion body such that its outer
surface is expanded beyond the outer diameter of the tool body.
[0009] In one form of the invention the expansion body may comprise one or
more rings. In another form of the invention the expansion body may
comprise a cylinder. The expansion body can be mounted coaxially on a
longitudinal axis of the tool body. Typically the expansion body is made
from a flexible and elastic material such as polyurethane. In one form of
the invention the expansion body may be comprised of more than one
section.
[0010] The means for axially compressing the expansion member can comprise a
pair of surfaces on the tool body arranged such that the expansion body
can be squeezed therebetween. In one embodiment, the pair of surfaces
comprises a first surface that is fixed on the tool body and a second
surface that is moveable of the tool body. In one form of the invention the
first surface and the second surface may be substantially perpendicular to
the longitudinal axis of the tool body. In another form of the invention the
first surface and the second surface may be at different angles to the
longitudinal axis of the tool body.
[0011] The tool body can also comprise a cylinder in which a piston is
slidably
located, the second surface being formed on the piston. The cylinder is
preferably provided with a supply of pressurised fluid (either from surface
or via a downhole pump) for causing movement of the piston.
Alternatively, the cylinder may have a mechanical arrangement for causing
movement of the piston, such as a screw and thread type arrangement.
[0012] In one embodiment, the first surface is fixed to the body by means of
an
axial shaft around which the expansion body and piston are mounted.
[0013] The apparatus can further comprise means such as a cable for moving the
tool body through the tubular element. Alternatively, a "workstring",
comprising coiled tubing, drillpipe or other conduit can be used to move
the tool body through the tubular element.
[0014] Another aspect of the invention provides a method for expanding tubular
elements, comprising:
- positioning an apparatus as claimed in any preceding claim at a
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predetermined position in the tubular element; and
- compressing the expansion body such that its outer surface expands
against the inner wall of the tubular element and causes it to expand and
deform permanently.
[0015] It will be understood that permanent deformation is also known as
plastic
deformation in the art, wherein the deformation is beyond the elastic limit.
[0016] In a stationary mode (i.e. without movement of the apparatus in its
expanded form), this can be used to reduce compaction stresses in
casing. This can take place with or without a sleeve/sheet in between the
expansion body and the tubular element.
[0017] The method preferably comprises moving the apparatus with the
expansion body in its compressed configuration along the tubular element
to progressively expand and permanently deform a length of the tubular
element.
[0018] This dynamic mode may require a lubricant which can be a liquid or a
sheet or a coating to the inside of the tublar element to ease movement of
the apparatus in its expanded form.
[0019] Releasing the expansion body from compression such that it returns to
its
uncompressed shape allows movement of the tool body to another
location in the tubular element. Expansion of the tubular element at the
other location can then be repeated. This can be done at a number of
locations in the tubular element.
[0020] The method of the invention is preferably applied to the expansion of
tubular elements such as casing or completion or production tubulars
installed in wells such as oil or gas wells. It can be used for expansion of
the tubular against the borehole wall or against another casing or liner.
Alternatively, it can be used to create a bell or expanded region such as a
chamber in which another expansion tool can be deployed for further
expansion of the tubular. Another application can be to clad a relatively
thin steel tube (with or without seals on the outside) against the inside of a
deteriorated old tubing, casing, leaking connector, perforation, etc.
[0021] An application of the apparatus of the invention may be for a device to
produce one or more areas of isolation. The areas may be in the annulus
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of a well or the areas may be selected areas in a tubular of a well. The
method of producing these areas of isolation is attained by the expansion
of tubular elements in the areas of interest.
[0022] Another aspect of the invention provides for a liner hanger including
an
apparatus for expanding tubular elements as described above.
[0023] Another aspect of the invention provides for a fishing tool including
an
apparatus for expanding tubular elements as described above. The
fishing tool may further include a conduit. This conduit may allow for
circulation through the fishing tool. The conduit may further allow for
circulation through the article to be fished.
[0024] Another aspect of the invention provides for a wellhead including an
apparatus for expanding tubular elements as described above. The
apparatus may be used to expand more than one concentric tubular
element.
[0025] Another aspect of the invention provides for an abandonment plug
including an apparatus for expanding tubular elements as described
above. The apparatus may be used to expand a tubular element in a well
to be abandoned. This tubular element may be an additional tubular
element inside the casing or liner. The expansion body may be left in an
expanded state in the expanded tubular element to form the abandonment
plug. The additional tubular element may be expanded so as to close the
micro-annulus around the casing or liner.
[0026] Another aspect of the invention provides for an expandable sand screen
including an apparatus for expanding tubular elements as described
above.
[0027] Another aspect of the invention provides for a well pressure tester
including an apparatus for expanding tubular elements as described
above. The apparatus for expanding tubular elements in the well pressure
tester preferably uses expansion of a compressible expansion body
substantially to form a seal against the tubular element.
[0028] Another aspect of the invention provides for a pile expander including
an
apparatus for expanding tubular elements as described above.
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[0029] Another aspect of the invention provides for a bridge plug including an
apparatus for expanding tubular elements as described above. The bridge
plug may be permanent or it may be retrievable. This tubular element to
be expanded may be an additional tubular element inside the casing or
liner. The apparatus for expanding tubular elements in the well pressure
tester preferably uses expansion of a compressible expansion body
substantially to form a seal against the tubular element.
[0030] Another aspect of the invention provides for a packer including an
apparatus for expanding tubular elements as described above. This
tubular element to be expanded may be an additional tubular element
inside the casing or liner. The apparatus for expanding tubular elements
in the well pressure tester preferably uses expansion of a compressible
expansion body substantially to form a seal against the tubular element.
[0031] Another aspect of the invention provides for a pipe connector including
an
apparatus for expanding tubular elements as described above. Preferably
the pipe connector is a swage type pipe connector.
[0032] Another aspect of the invention provides for a selective chemical
placement tool including an apparatus for expanding tubular elements as
described above. The selective chemical placement tool may be slidably
displaceable.
[0033] Another aspect of the invention provides for an anchor device including
an
apparatus for expanding tubular elements as described above. The anchor
device may be used to anchor a tubular element or other equipment
against the formation or another tubular element.
[0034] Another aspect of the invention provides for a bellow expander
including
an apparatus for expanding tubular elements as described above. The
bellow expander may be used to relieve buckling or axial stresses in the
tubular element.
[0035] Another aspect of the invention provides for a downhole patching system
including an apparatus for expanding tubular elements as described
above. The downhole patching system may be used to repair casing or
liner damage, or leaking connectors. It may further include a sealing
element.
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[0036] Another aspect of the invention provides for a perforation shut off
patch
system including an apparatus for expanding tubular elements as
described above. The perforation shut off patch may further include a
sealing element.
[0037] Another aspect of the invention provides for a telescopic liner
expansion
system including an apparatus for expanding tubular elements as
described above.
[0038] Other uses will be apparent from the description below.
Brief description of the drawings
[0039] Figure 1 shows a schematic side view of an apparatus according to one
embodiment of the invention;
Figure 2 shows a schematic side view of detail of the head section of the
apparatus of Figure 1;
Figure 3 shows a schematic side view of detail of the head section of the
apparatus of Figure 1 in a different position;
Figure 4 shows a schematic side view of the apparatus of Figure 3 in situ;
Figure 5 shows a schematic side view of the apparatus of Figure 4 in an
expanded section of casing;
Figure 6 shows a schematic side view of a liner lap expansion application
of the apparatus of the invention;
Figure 7 shows a schematic side view of an application of the apparatus of
the invention used to pressure test a liner lap and then used to pressure
test the liner;
Figure 8 shows a schematic side view of a pressure tester application of
the apparatus of the invention; and
Figure 9 shows schematic side view of a liner bottom expansion
application of the apparatus of the invention.
Mode(s) for carrying out the invention
[0040] Figure 1 shows an apparatus or too110 according to one embodiment of
the invention suspended in a tubular 12 such as a well casing by means of
a wireline cable 14 providing power and data communication as well as
physical support. The apparatus of tool 10 comprises a tool body 16
which is provided with power and control electronics, a pump and
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hydraulic fluid supply and sensors (not shown). An operational head
section 18 is provided at the lower end of the tool body 16. Tool 10 may
also optionally in a central bore section to allow for circulation (not
shown).
[0041] It will be understood that tubular 12 may be one of a number of tubular
elements used in oil or gas wells such as, for example, a casing, a liner, a
pipeline, or the like. Tubular 12 may also be one of a number of types of
tubulars used in surface, subsea or subsurface pipelines. It will also be
understood that tubular 12 may be of a solid, slotted or perforated type.
[0042] Figure 2 shows detail of the head section 18 which comprises a main
head
part 20 which is connected to the tool body 16 and defines a cylinder 22
open at its lower end. An axial shaft 24 extends from the base of the
cylinder 22 and has an end plate 26 connected thereto. A piston 28 is
slidably mounted in the cylinder 22 around the shaft 24. The head 30 of
the piston 28 has a larger diameter than the part 32 received in the
cylinder bore 22, the outer diameter of the head 30 corresponding
approximately to the outer diameter of the tool body 16. A polyurethane
ring 34 is mounted around the shaft 24 between the piston head 30 and
the end plate 26. This too has an outer diameter corresponding
approximately to the outer diameter of the tool body 16. The working
space 36 in the cylinder 22 below the piston 28 is connected to a supply of
pressurised fluid (not shown) in the tool body 16.
[0043] It will be noted that in other embodiments of the invention instead of
having a ring 34 there may be a thick walled cylinder mounted around the
shaft 24 between the piston head 30 and the end plate 26, and this
cylinder may serve as an expansion body in tool 10. The material from
which the ring 34 or the cylinder is made may be other kinds of flexible
and elastic material such as, for example, rubber. Further, the ring 34 or
the cylinder may be comprised of more than one section, which may form
separate segments. These segments may be housed in compartments
specifically shaped therefore in the area around the shaft 24, between the
piston head 30 and the end plate 26.
[0044] In the position shown in Figures 1 and 2, pressurised fluid has not
been
admitted to the working space 36 and the ring 34 is uncompressed. Thus
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the tool 10 has a substantially constant outer diameter and can be run in
the casing 12 to any location of interest. In this example, the tool 10 is
used to make a`bell' or section of enlarged diameter know as a chamber
in the casing 12 such as might be used for deployment of a conventional
expanding tool.
[0045] When the tool 10 is positioned at the bottom of the section to be
expanded, pressurised fluid is admitted to the working space 36. This
forces the piston 28 out of the cylinder 22 so as to squeeze the ring 34
between the head 30 and end plate 26. This squeezing action causes the
ring 34 to bulge around its periphery 38 so as to project beyond the outer
diameter of the rest of the tool 10 (as is shown in Figure 3). The
peripheral bulge 38 of the ring 34 causes the casing 12 to be deformed
permanently 40 as is shown in Figure 4.
[0046] With the ring 34 held in its squeezed state, the tool 10 is then
advanced
through the casing 12 (in direction z in Figure 5), the squeezed ring forcing
the casing 12 to expand permanently 40 as the tool 10 is moved (see
Figure 5). Once the appropriate length L of casing 12 has been
expanded, pressure on the ring 34 is released by venting fluid from the
working space 36. The ring 34 then returns to its unexpanded position (as
shown in Figures 1 and 2), and the tool 10 can be moved to another
position in the unexpanded parts of the casing 12. In this dynamic mode,
the maximum thickness of tubular elements expandable by this technique
will depend on the maximum force that can be applied by the cable. The
presence of a lubricant and or sleeve will also have an impact.
[0047] In an alternative embodiment the tool can be moved downwards, for
example, by using a heavy drillstring in a near vertical well.
[0048] In the embodiment described above, the tool 10 is lowered to its start
depth on the cable 14, or by coiled tubing, pipe, as the case may be and
then raised to expand the length L of casing 12. It is also possible to start
the expansion at the top of the section of casing and force the tool down,
for example by pumping pressurised fluid into the casing above the tool
10.
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[0049] Various alternatives are also available to the piston and cylinder
arrangement described for squeezing the ring. For example, various types
of mechanical arrangements may be used such as a powered screw and
nut or rack and pinion arrangement can be used either to move a piston in
the manner described above or, alternatively, to hold the `piston' still and
draw the end plate towards it to obtain the same effect.
[0050] Various sensors can be provided in the tool to monitor its operation
and
provide feedback, typically via the cable, to allow accurate control of the
tool in use.
[0051] While the example given above is related to forming a chamber or bell
in
the casing 12, this invention can find uses in a number of applications.
For example, rather than just expanding a section of the casing to be used
for deployment of another expanding tool, it can be used as the primary
expansion method for the whole casing. Also, its ability to be released
and moved through the unexpanded casing means that it can be used for
providing a number of locally expanded sections of the casing separated
by unexpanded sections. The expansion provided can be used in the
manner of previously proposed expansions, for example, to avoid
cementing and progressive reduction in the flow diameter of the well,
connection of sections of casing, forming of expanded sections for
insertion of a succeeding casing section, expansion of a patch over open
borehole or existing casing, etc. Optionally a sealing element such as an
o-ring or coating may be placed over the expansion body to give a more
resilient seal.
[0052] In an alternative embodiment the expansion body being one or more rings
34 or one or more sleeves may be enclosed in a protective cover such as
a cage arrangement which is used to provide the expansion body with
more wear resistance and a longer lifespan. Instead of a complete cover
around the expansion body, there may be sections of the expansion body
covered by a protective layer of material to improve wear resistance.
[0053] The expansion effect may vary according to the dimensions of the tool,
in
particular the dimensions of the polyurethane ring. A thicker ring will allow
potentially greater expansion from the original diameter, as will a larger
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plunger or bore stroke. While polyurethane is the preferred material for
the ring due to its resilience, in particular its ability to return to its
original
dimensions after compression is released, as well as its greater wear
ability, impact resistance and greater operational temperature range,other
similar materials may be used. Polyurethane is also sufficiently smooth to
be able to slide over the casing surface as the tool is moved in its
expanded form. A lubricant/teflon-sheet or both can be provided to assist
in this, green soap being preferred.
[0054] The invention may also be used to form one or more localised
expansions,
such as is shown in Figure 4. A single expansion like this can be used to
anchor tubular members together (hangers). A series of these placed
relatively closely together can be used for stress relief or to prevent
buckling should the tubular be deformed following installation or later in
the lifetime of a well. This deformation may be for a variety of reasons
such as, for example, the depletion of a well leading to compaction. By
leaving the head section in place as is shown in Figure 4, the whole tool
can serve as an anchor to provide a reaction to allow movement of
another tool connected to it through the well. Reinforcement may be
required for effective use in dynamic expansion and for better grip, such
as in the required in a bridge plug or packer. Cutters, wear resistant pads,
etc can be mounted/cast within the ring. Also, multiple rings may be
expanded by one or more pistons. Other uses and variations of the
technique will be apparent.
[0055] Another application of the apparatus of the invention is for a downhole
anchor device. The anchor device may be used to anchor a tubular
element or other equipment against the formation or another tubular
element at selected locations in the wellbore.
[0056] The invention may be applied to expansion of tubular elements against
the
borehole wall or against another casing. In this way the invention can
extend to a telescopic liner expansion system which includes the
apparatus for expanding tubular elements as described above. Three
liners, for example, can be run down a hole at the same time, one inside
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the other. Each liner can then be extended and the apparatus for
expanding tubular elements used to expand each of them.
[0057] The invention may also be used to form a bell or expanded section,
known
as a chamber in the art, in which another expansion tool can be deployed
for further expansion of the tubular. The bell or expanded section, or
chamber, may be used for other purposes as well in drilling or completion
operations in oil or gas wells. Expanded section 40 shown in Figure 5 is
an example of such a chamber. The shape of the bell or expanded
section, or chamber that is formed may be symmetrical or asymmetrical.
Asymmetrical expansion may be accomplished by using a ring 34 which
has an asymmetrical shape such as an oval shape. In this case the piston
head 30 and the end plate 26 must first be centralised, so that the ring 34
does not move into a position to give symmetrical expansion during use.
One of the ways in which asymmetrical expansion is beneficial is when it is
used to create a weak point or a specific crack in the casing so that a side
passage can be put into the casing at that point.
[0058] The bell or expanded section could be used to locate anything that
would
otherwise cause a restriction downhole. The apparatus would have to be
centralised firmly when used in this way. It could thus, for example, be
used to house a sub-surface safety valve, pump, separator, etc.
[0059] Another application of the apparatus for expansion of tubular elements
can
be to clad a relatively thin steel tube (with or without seals on the outside)
against the inside of a deteriorated old tubing, casing, leaking connector,
perforation, etc. Substantially smaller sections or larger sections of tubular
can be clad by the apparatus. The cladding may, for example, be used to
store carbon dioxide gas in a depleted reservoir, enlarge production tubing
or repair leaks.
[0060] A further similar application of the apparatus is that it can be used
to
create a patch or pad downhole for holding sensors that are focused in
one direction close to a borehole wall. Similar applications of the
apparatus are for a downhole patching system and a perforation shut off
patch system. The downhole patching system may be used to repair
casing or liner damage, or leaking connectors. The patching system may
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further include a sealing element, such as an o-ring on the outer diameter
(OD).
[0061] The apparatus may also be used in the expansion of tubular elements to
produce areas of isolation. These areas may be in the annulus of a well or
these areas may be at selected zones of a well. These zonal areas of
isolation, for example, can be used to squeeze off selective sections for
shut off, acid injections, chemical sand consolidation, or the like.
[0062] Another application of the apparatus may be for a sand screen.
[0063] Yet a further application of the apparatus is for a pile expander. The
advantage of such a pile expander is that it can improve pile bearing
capacity and thus shorter piles may be used.
[0064] A further application of the apparatus of the invention is for a liner
hanger.
The liner hanger may be for use with liners, casing or tubing, as the case
may be. In this application the apparatus is preferably used with a sleeve
in combination with a sealing element such as an o-ring on the OD.
[0065] In Figure 6 a similar application for use in expanding an expandable
liner
lap 42 is illustrated.
[0066] Another application of the apparatus of the invention is for an
expandable
fishing tool. The expandable fishing tool may include a conduit through its
body. This allows for circulation through the fishing tool. The conduit also
allows for circulation through the article to be fished. In this case the
article
is preferable the tubular element and the conduit thus allows circulation
through the whole of the tubular element including its bottom end in the
wellbore. The expandable fishing tool has the advantage of including a
larger surface area, which may even create a recess, and thus there is a
better grip for the fish, or article to be fished.
[0067] Another application of the apparatus is for an expandable wellhead. The
apparatus may be used to expand more than one concentric tubular
element at the wellhead. Preferably there may be four or five concentric
elements at the wellhead which are expanded by the apparatus of the
invention. The advantage of this expandable wellhead is that it is then
more rigid or robust than conventionally formed wellheads, particularly
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those used offshore. A further advantage is that a wellhead with a smaller
OD can be made.
[0068] The apparatus of the invention may also be used in an abandonment plug.
The tubular element that is expanded in the abandonment plug may be an
additional tubular element inside the casing or liner. Such an
abandonment plug may comprise a tube with one open end and one
closed end with or without seals around its OD that is expanded against
the casing or liner to shut in the well and simultaneously close the micro-
annulus. The expansion used against the casing may be minor and is
used to close off the micro-annulus. The apparatus may be used to
expand the additional tubular element in a well to be abandoned and the
expansion body may be left in an expanded state in the expanded tubular
element. The abandonment plug may also include a steel sleeve which is
also expanded against the casing together with one or more rings 34. The
abandonment plug may be used with or without cement and may be
deployed by wireline, coiled tubing or other conduit.
[0069] Another application of the apparatus of the invention is for an
expandable
sand screen. Similarly the apparatus may also be used in perforated liner
and casing expansions.
[0070] As shown in Figures 7 and 8 a further application of the apparatus of
the
invention is for a well pressure tester. The well pressure tester can be
used to pressure test various parts of oil or gas wells such as, for example,
a liner lap, the drill pipe, or the formation cementation. The apparatus for
expanding tubular elements in the well pressure tester preferably uses
expansion of an expansion body substantially to form a seal against the
tubular element and not to expand the tubular element beyond its original
shape. The apparatus of the invention in this application may include a
plurality of rings 34 as shown in Figure 8. In this example of a pressure
tester 44 some of the rings 34 may be used for a packer application to
isolate the area of interest and others may be used to expand against the
area of interest so as to perform the actual pressure test. The pressure
tester 44 may be lowered downhole by wireline 14 having electrical
cabling, or by coiled tubing or workstring. A pump or pressure intensifier
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46 is also lowered downhole along with the pressure tester 44 to provide
the pressure used in the pressure test. The pressure may also be
supplied by an integrated pressure multiplier, or by other means of
supplying pressure.
[0071] A packer itself is yet another application of the apparatus of the
invention.
The packer may be a permanent installation in the wellbore or may be
retrievable and it is used to seal the wellbore either permanently or
temporarily. The tubular element to be expanded by the expansion
apparatus of the packer may be an additional tubular element inside the
casing or liner. The apparatus for expanding tubular elements in the well
pressure tester preferably uses expansion of a compressible expansion
body substantially to form a seal against the tubular element and not to
expand the tubular element beyond its original shape. The packer may be
used in production or for testing, and may be used in cased wellbores or in
open wellbores. Typically the packer is used in most completions to
isolate the annulus from the production conduit, enabling controlled
production, injection or treatment of the wellbore.
[0072] The well pressure tester 44 may also be used as a leakoff test device
to
test the strength or fracture pressure of the open formation. A section of
the wellbore can be sealed off using the apparatus and the pressure tester
44 can then be used along with fluid under pressure in the section to test
the maximum fluidic pressure which the well can withstand in that
particular section. The leakoff test device may also be used at the liner
bottom.
[0073] The apparatus of the invention may also be used to expand the liner
bottom 48 to seal the annulus, as illustrated in Figure 9.
[0074] Another application of the apparatus of the invention is for a bridge
plug
which is used to isolate the lower part of a wellbore. The bridge plug may
be permanent, enabling the lower part of the wellbore to be permanently
sealed off from production, or it may be retrievable enabling the lower part
of the wellbore to be temporarily isolate from the treatment conducted on
an upper zone of the wellbore. The tubular element expanded by the
bridge plug may be an additional tubular element inside the casing or liner.
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The apparatus for expanding tubular elements in the well pressure tester
preferably uses expansion of a compressible expansion body substantially
to form a seal against the tubular element and not to expand the tubular
element beyond its original size. The advantage of the bridge plug is that
it may be able to hold more pressure when it is expanded to a level just
below the yield of the tubular element. The result is that it will thus will
then have more holding force.
[0075] The apparatus may also be used in a pipe connector. Typically a pipe,
or
tubing or casing is expanded to fit substantially tightly against another
pipe, tubing or casing, as the case may be, which has been fitted over it
and it is then connected using known pipe connection methods. The pipe
connector may also be used to connect tubing to casing or to connect a
lateral pipe to a central pipe. Preferably the pipe connector is a swage
type pipe connector.
[0076] Another application of the apparatus of the invention is for a
selective
chemical placement tool. The selective chemical placement tool is
typically deployed downhole by coiled tubing, workstring or other conduit.
The selective chemical placement tool may be slidably displaceable. In
use the selective chemical placement tool is deployed to a particular area
of interest and then expansion takes place by the apparatus so that the
tool is anchored in the casing or liner across an area to be treated.
Chemical fluid is then injected into the body of the tool between its two
outer sections and this chemical fluid may then be able to enter areas
outside of the casing or liner, that is in the annulus, by squeezing to
perform various chemical treatments such as, for example, sand
consolidation and chemical shut-off. Once the chemical treatment has
been performed the selective chemical placement tool may then be
slidably displaced to another location and then be anchored at that
position so that another chemical treatment may be performed at this
location. In this way the selective chemical placement tool may be moved
sequentially down the wellbore to perform sequential chemical treatments
where required.
CA 02684913 2009-10-29
WO 2008/135538 PCT/EP2008/055442
17
[0077] The apparatus may also be used as part of a bellow expander. The
bellow expander may be used to relieve buckling or axial stresses in a
tubular element. It may further also be used to convert global buckling of a
pipe or casing to localised buckling.
