Note: Descriptions are shown in the official language in which they were submitted.
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Description
METHODS AND APPARATUS FOR EXPANDING TUBULAR MEMBERS
Technical field
[0001] This invention relates to methods and apparatus for use in the
expansion
of tubular members. The invention find particular application to such
operations conducted in underground well or boreholes such as are found
in the oil and gas industry.
Background art
[0002] The use of expandable tubular members to seal or isolate portions of
wells
has been widely proposed. In one version, a simple tubular member is
expanded against the borehole by stretching the wall of the tubular using
an expanding tool. In another, the tubular member is positioned in the
borehole in a vertically corrugated form and then expanded back to a
circular cross-section against the borehole.
[0003] Where expansion is achieved by simple stretching, the thickness of the
material forming the tubular decreases and there is typically a limit of 20-
30% expansion before plastic deformation of the material causes the
tubular to become weakened (and failure occurs). For practical purposes,
an upper limit of 10% expansion is used.
[0004] Where the tubular is vertically corrugated, much greater expansion
ratios
can be achieved. However, effective sealing against the borehole can be
an issue.
[0005] A number of techniques and tools have been proposed for expanding the
tubular. These include inflation with a pressurised fluid such that the
tubular 'balloons' against the borehole, forcing a tapered, oversize
mandrel through the tubular, either by using a cable or using fluid
pressure, or by use of a rotating system of rollers urged radially outwardly
against the tubular (see for example US 2002185274 A and WO
2005003511 A).
[0006] The expanding tools typically comprise a device for locating the tool
in the
tubular to be expanded and an expanding device that is moved axially
through the tubular to expand it to the desired diameter. The expanding
device can comprise a tapered, cone-like mandrel, or a radial array of
expanding elements that are urged against the tubular to expand it. The
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array may also rotate to expand the tubular and the array can be moved axially
through the tubular to increase the axial extent of the expanded portion.
[0007]
Disclosure of the invention
[0008] A first aspect of the invention comprises a tool for expanding a
tubular
member in a well, comprising:
- a locating device for locating the tool in the tubular member to be
expanded;
and
- an expanding device for expanding the tubular member beyond its starting
diameter, the expanding device comprising a radial array of expanding
elements,
each element, in use, acting on the tubular member to deform it radially
outwardly; and
- a control unit for controlling each element to be moveable in an axial
direction independently of the other elements in the array
[0009] Preferably each element is tapered inwardly at one end. Consequently,
the array
can comprise a sectored cone-like structure when all of the elements are
positioned at the same axial location in the member.
[0010] Each element can be moveable radially outwardly independent of the
other
elements in the array. The elements can also be rotatable about a longitudinal
axis. In such a case each element can be rotatable in use between a first
position
in which axial movement of the element causes no radial deformation of the
tubular, and a second position in which axial movement causes radial
deformation.
[0011] The array is preferably configurable such that the elements are axially
distributed so multiple elements of the array can be rotated into the first
position at the same time. The array can then be configured for expansion by
rotation of the elements into the respective second position.
[0012] In one embodiment of the invention, the elements comprise rollers.
[0013] In this embodiment, the tool preferably further comprises a mandrel
over which
the rollers move during expansion of the tubular. The rollers move axially
over
the surface of the mandrel from one end to the other as the mandrel is moved
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through the tubular, the rollers being returned to the one end through the
interior
of the mandrel. The mandrel preferably has a cone-like shape.
[0014] Power for operation of the tool can comprise electrical power provided
over a
wireline cable.
[0015] The tool can also comprise at least one sensor capable of making
measurements during the deformation operation.
[0016] In one preferred embodiment, the locating device comprises a cone-like
member
that is forced into the tubular member to counteract the force required to
move
the expanding elements axially while deforming the tubular member. Preferably,
the cone-like member deforms the tubular member radially outwardly.
[0017] The cone angle of the cone-like member can be different to the
corresponding
angle on the expanding elements. Also, more than one cone-like member can be
provided. When a single cone-like member is used, the cone angle may be
larger, when more than one is used, the angle may be smaller.
[0018] A second aspect of the invention comprises a method of expanding a
tubular
member in a well, comprising:
- positioning an expansion tool in the tubular member in the well, the
expansion tool comprising a radial array of expanding elements; and
- moving the elements in an axial direction to act on the tubular and
deform
it in a radial direction,
- controlling the elements with a control unit such that each at least one
element is moving in an axial direction independently of others in the array.
[0019] The method preferably further comprises positioning the tool in the
tubular
with the elements of the array positioned in a first position in which axial
movement causes no radial deformation of the tubular, the elements of the
array being moved to a second position such that axial movement causes
deformation once the tool is in position.
[0020] The movement between the first and second positions can be achieved by
rotation of each element about a longitudinal axis.
[0021] The method according to the second aspect of the invention is
preferably
performed using a tool according to the first aspect of the invention.
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[0022] The elements can be moved so as to deform the tubular member in a non-
axisymmetrical manner. It is particularly preferred that the geometry of the
well is measured and the expanding elements configured so as to provide
a corresponding geometry in the deformed tubular member.
[0023] A swelling material can be introduced between the tubular member and
the well wall so as to fill voids remaining after deformation of the tubular
member.
Brief description of the drawings
[0024] Figure 1 shows one embodiment of a tool according to the invention;
Figure 2 shows a corrugated sleeve prior to expansion;
Figure 3 shows a more detailed view of the tool of Figure 1;
Figure 4 shows the steps in a multi-stage operation;
Figure 5 shows a schematic side view of an expansion tool;
Figure 6 shows a schematic plan view of a tool according to an
embodiment of the invention;
Figure 7 shows a schematic side view of the tool of Figure 6;
Figure 8 shows a schematic side view of an embodiment of the tool of
Figure 7 with an actuator;
Figure 9 shows a schematic side view of another embodiment of the tool
of Figure 7;
Figure 10 shows the tool of Figure 9 when installed prior to expansion;
Figure 11 shows the use of a tool according to an embodiment of the
invention in an irregular borehole;
Figure 12 shows a tool according to another embodiment of the invention;
Figure 13 shows a plan view of the tool of Figure 12; and
Figure 14 shows details of an embodiment of a tool with a modified
anchoring unit.
Mode(s) for carrying out the invention
[0025] The fundamentals of expandable tubular in wells are well-known and will
not be described in detail here. One such application comprises the
expansion of a sleeve inside a casing to close off perforations that might
be producing water. The use of an embodiment of the invention in such
an application is shown schematically in Figure 1. In use, a tool 10
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according to one embodiment of the invention, is positioned in a well 12
through production tubing 16 located in the well 12 by means of a packer
14 and extending to the surface (not shown). The tool 10 is lowered
through the tubing 16 by means of a wireline cable 18 which provides
electric power and data to the tool 10. An expandable sleeve 20 is
positioned on the tool 10 with a mandrel 22 positioned below the sleeve 20
and connected to the tool 10 through the centre thereof. In this example,
the sleeve 20 is vertically corrugated as is shown in Figure 2 so as to
reduce its outer diameter and allow its installation through tubing. Other
forms of expandable tubular can also be used. To expand the sleeve 20,
the mandrel is drawn upwardly by the tool 10 through the sleeve where it
forces the sleeve outwardly.
[0026] Figure 3 shows more detail of the tool in use. In this preferred
embodiment, the tool 10 is suspended on the wireline cable 18 and
comprises a number of functional elements.
[0027] A control unit 24 is connected to the upper part of the tool and
providing
electrical and mechanical connection to the cable 18 and a proper
operational interface with the cable 18 for sending and receiving
commands and data. This unit provides for the management of the
electrical power transmitted by the cable 18 to the down-hole tool 10. In
particular, power supplies provide energy to control electronics (such as a
microprocessor (not shown)). This section includes also control systems
for high levels of electrical power which will be required to perform the
expansion of the tubular sleeve. This power control preferably allows
smooth starting of expansion functions.
[0028] The control unit 24 also performs monitoring of the expansion process
and
transmits this information to the surface, so that the operator may adapt
operational parameters for the optimum expansion process.
[0029] An anchorage mechanism 26 is provided that can be expanded into the
sleeve 20 to lock the tool 10 and sleeve 20 together. Typically this locking
is performed by hydraulic slips 27 which can be pushed radially against
the sleeve 20. This mechanism holds the tool in place while the expansion
is being performed. For the proper operation, this mechanism has to
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transmit the reaction forces of the expansion process. In some
application, this is only an axial force, but it can also be torque.
[0030] A retraction system 28 which operates to move the expansion system 29
(corresponding to the mandrel 22 described above) through the sleeve 20
over a predetermined length. The expansion/retraction section of the tool
generates the mechanical movement for the expansion process. This
section contains typically high power and high torque systems to generate
these expansion movement.
[0031] A retraction and expansion transmission system 30 for transmitting the
drive from the retraction system 28 to the expansion system 29.
[0032] The expansion system 29 is the device in direct contact with the sleeve
20
to cause it to expand. This device transmits the high contact force to the
sleeve 20 to deform it. It is driven by an expansion and retraction
transmission 30. The expansion system may include a cone-shaped
mandrel (as will be described in more detail below). In this case, the
mandrel is pulled towards the wireline tool 10 by the retraction
transmission 30.
[0033] The expansion of a sleeve 20 over lengths longer than the maximum stoke
of the retraction mechanism is feasible. However, expansion using the
tool of Figure 3 has to be performed in multiple steps of short expansion
as is shown in Figure 4. A short tubular section is expanded as previously
explained (Steps 1 and 2). Then the slips 27 are removed, the wireline
tool 24, 26, 28 is pulled upwards while the retraction mechanism 30 is
expanded (Step 3). After these operations, the wireline tool is in a new
upwards position inside the tubular 20 to be expanded, with its expansion
cone 29 still in contact with the upper part of tubular section already
expanded in the previous stroke. The slips 27 can then be reopened
(Step 4). The next section of tubular can be the expanded (Step 5).
[0034] The tool 10 may be provided with sensors to perform several
measurements relating to the expansion process, including:
= calliper information to track the shape of the expanded tubular;
= expanding force;
= thickness of tubular after expansion;
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= loss of diameter (relaxation) after unloading of tool following
expansion;
= contact quality with formation (and layer behind metal structure);
= presence of cracks and surface quality; and
= change of length of the tubular.
[0035] The expanding tooling 29 (such as a mandrel 22) can take a number of
forms. For smooth tubular at the end of the job, one option is to perform
the expansion by axial displacement of a cone. This process can be
considered as forcing a too-large cone 22 in the sleeve 20. Figure 5
shows schematically this process and is known in the art. An embodiment
of the present invention based on this process comprises the use of a
sectored cone as a mandrel. This is shown generally in Figures 6 and 7
which show the mandrel in the form of an eight sector hollow mandrel
(40a-40h). The sectored cone support high hoop stresses which press the
sectors (or parts) of the cone together. These high stresses are generated
by the contact force with the tubular during the expansion process.
[0036] The instantaneous axial force to displace the whole cone may be
important, depending on the sleeve thickness and diameter. To limit this
instantaneous axial force requirement, the sectored cone can be moved
one sector at a time. Figure 8 shows one embodiment of such a system.
Each conical sector 40 is dragged by a hook 42 pulled by the control unit
44. The tip of the hook 42 is a right angle turn which is applied against
only one sector 40 at a time. Before pulling a sector 40, the hook 42 is
rotated to apply its tip onto the proper sector.
[0037] In Figure 8, the hook 42 is represented as a small bar. The hook may
also
consist of a cylinder running inside the sector cone and equipped with a
solid (relatively high-strength) pin extending out of the cylinder. This pin
corresponds to the finger of the hook 42.
[0038] In some applications, each sector has its own dragging hook. In this
case,
the wireline control unit maintains a direct link to each sector and the hook
may be physically attached to the sector itself.
[0039] The sectored cone allows the expansion to start with the whole system
inside the none-expanded tubular. This is can be important when only a
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certain defined length of the tubular has to be expanded to a larger
diameter. For example, multiple short lengths of tubular inside a long
completion could be expanded: the expanded lengths acting as annular
seals (and replacing the ECP function).
[0040] To start inside the unexpanded tubular, the cone is initially assembled
with
missing sectors, so that the circumference of this initial assembly is
smaller than in complete assembly. Then, the missing sectors are axially
forced between sectors of the initial assembly cone. When these sectors
are added, the circumference of the assembled cone increases and grows
to its final size. During this growth, the tubular is also formed to a larger
diameter. When the cone is completely assembled to final shape, it can
then be dragged over some distance to perform the tubular expansion.
[0041] To ease the insertion of the missing sectors, these sectors may be
machined with major chamfer (corresponding to half of the width of the
sector). Other special cuts can also be considered.
[0042] With the design of the sector cone, sector can be added or removed so
that the overall cone diameter can either be increase or reduced. Above
an expanded zone in the well, the tubular may be left at its initial size.
[0043] Another major advantage offered by the use of sectored cone is to allow
the expanding tool to be passed through narrow section. For this purpose,
the cone sectors can be installed one below each other in a long string. In
this configuration, the global radial dimension of the system is small (in the
range of the sector lateral dimension). This can be important in order to
pass through production tubing. When reaching the proper location, the
control unit rebuilds the cone in one plane before starting the expansion
job. This reconstruction of the cone from the in-line setting of the sectors
can be achieved with limited manipulation. Figure 9 shows such a tool
with parts omitted for clarity. Each sector 40 is mounted on its own
connecting rod 46. In Figure 9, two sectors are shown, 40a which is in its
in-line position, and 40f which is in its operating position. The sectors
conserve their radial array position between their operating and in-line
positions. To pass from the in-line position to the operating position, the
sectors are first rotated radially towards the tubular, then they are moved
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to the same depth location. For the reverse transition, the sectors are first
spread in depth. Then they are rotated towards the centre of the borehole
to be positioned in-line. Figure 10 shows three sectors 40a, 40b, 40c each
in the in-line position at different depths. This function can be
implemented as already explained above: each sector 40 is attached to
the wireline control unit 44 with its own connecting rod 46 in a permanent
fashion. Each connecting rod 46 can be independently extended and
rotated by the control unit 44. When required by the control unit 44, the
connecting rod 46 can be extended each at a different length to stagger
the sectors 40 in depth so that each sector is held at a different depth.
Then each connecting rod and sector is rotated by 180 degrees, bringing
the sector to the centre of the system (as is shown in Figure 10). In this
configuration, all the sectors are in-line and centralized into a minimum-
sized overall dimension.
[0044] The reverse process is performed to prepare the tool for expansion.
[0045] If the sectored cone has a hollow centre (as shown) when assembled from
all of its sectors, the system can then provide a sleeve expansion of nearly
three fold (the hollow centre being one third of the final diameter, making
each sector width equal to one third of the final diameter).
[0046] The use of a cone mandrel is compatible with the expansion of a
corrugated sleeve. The cone is in contact with the internal part of the
corrugated sleeve at an earlier position than the part closer to the outside
diameter, making the opening of the corrugated surface quite smooth. The
cone can also have a shape matching the sleeve corrugated shape to help
smooth the process.
[0047] This proposed technique allows also the expansion of multiple sections
of
non-successive tubulars in a single run in the well-bore. In this case, only
critical zones of the completion can be expanded for a pre-defined
purpose. For example with long completion of slotted liner, slotted liner
elements can be separated by solid tubulars which can be expanded
against the formation to act as external sealing (and replace ECPs). The
present invention is well-suited to this application. The expansion cone (or
sectored cone) can be used over long length of tubular to expand without
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undue wear. The sectored cone allows expansion to be started from the
initial size of the tubular. The sectored cone can be easily moved to the
next section to be expanded by removal of some sectors to allow the
overall diameter to be reduced for this move. The expansion process can
be started even in front of a non-sealing tubular (such as screen, slotted
liner, or perforated structure).
[0048] The overall shape of the mandrel does not have to be circular but can
have a different shape than cylindrical over its large section. With such a
section, the tubular may have non-circular cross-section after expansion.
In particular, the tubular can be deformed to oval shape which can be
critical is some cases such as in the connection zone for multi-lateral well
with two legs.
[0049] In some applications, it is critical to perform the tubular expansion
so that
the expanded tubular is against the bore-hole (or the already installed
tubular). This is particularly true for the case of liner hanger expansions.
In this situation, the liner has to be in solid contact with the previous
casing
to be able to hang onto the casing. It can also be important for expansion
of completion for the largest internal bore for easy internal flow and for
sleeve for sealing against the well-bore.
[0050] In such situations, it is important that the tubular is expanded at
maximum
diameter allowed by the hole, and not a pre-defined diameter.
[0051] With the initial design of the sectored cone described above, and by
dragging the cone over the tubular length, the tubular is expanded to a
constant diameter. To achieved the new requirement of variable
expansion against the external structure (i.e. the formation or a pre-
installed casing), the system has be adapted. One solution is to use the
concept of using sectors with large entry chamfers and moving one sector
per unit of time. By moving each sector individually, the overall cone
diameter grows. During that growth, the overall diameter of the tubular
also grows as the sector chamfers engage and make the overall cone
diameter larger. The circumferential growth is sustained until a external
event stops it, for example:
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= The resistance to circumferential growth is too large, indicating that
the
tubular is expanded against the formation.
= The maximum engagement of all sectors is reached, ensuring the
maximum expansion size.
= The material of the tubular is at its limit for circumferential expansion
such that cracking may appear if more expansion is applied.
[0052] When this point has been reached, one (or more) sectors are backed-off
slightly from the assembled cone. The rest of the cone is moved slightly
forwards and then the missing sectors are reinserted to expand the next
zone of the tubular.
[0053] Only small displacement of the assembled cone is performed when the
sectors are missing to avoid creating an irregular (wavy) surface on the
tubular.
[0054] This latest technique can be slightly modified to ensure that the
tubular is
expanded against the well-bore, while ensuring proper contact over the full
perimeter. The tubular therefore has a variable diameter with depth and
but also its shape also conforms to the well. This may be important for
proper sealing at the outside face of the expanded tubular (which is vital
for sealing sleeves and tubular).
[0055] For this purpose, the sectored cone is modified as is shown in Figure
11,
so that the sectors 40 do not have flat faces for their contact area. In this
case, they are in contact only following a line. This can be achieved by the
use of axial small interface cylinders 47. Thanks to this local linear
contact, each sector can pivot slightly versus the neighbour sector.
Thanks to this pivoting, the overall shape is not exactly circular (as is
shown in Figure 6), but is an assembly of broken segments of a circle.
This irregular perimeter allows adequate adjustment to the shape of the
external surface 48 (bore-hole or already installed tubular). Alternatively,
the geometry of the hole can be measured prior to installation of the
tubular and the expanding elements configured to provide a corresponding
geometry in the expanded tubular. A swelling material can be introduced
between the tubular member and the borehole wall to fill any voids
remaining after expansion.
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[0056] In certain cases. the radius of the hole may vary from depth to depth.
In
such a case, it is desirable that the diameter of the expanded tubular
should vary correspondingly. This can be achieved by providing each
segment of the split cone with large chamfer. Thanks to these chamfers,
the global circumference of the assembled cone will grow by engaging
more the segments together. Tin order to maintain an overall cylindrical
shape, the segments are partially engaged, with all the "even" segments at
one axial position (or depth), while the "odd" segments are slightly shifted
in axial position (depth). The global circumference of the expansion
mandrel is depends directly on the axial shift of the chamfered split
segments.
[0057] The shape of the expansion mandrel can be modified from a cylindrical
shape to other shapes (such as oval, ellipse, egg shape, tri-angular
rounded...) by setting the proper axial shift for each segment. For example
for oval shape some segments (a quarter of the total number) are fully
engaged at the extremity of the small axis of the oval (this defines the arc
of large radius), and some segments (a quarter of the total number) are
partially engaged (high variation of axial shift from segment to segment) to
defined the arc of the small radius of the oval.
[0058] The control unit maintains the proper axial shift of the elements while
displacing the segment in sequential fashion. The shift is selected from the
target local expansion diameter. It can be also based on real-time
measurement outputs (such as required force for expansion or contact
detection with the formation).
[0059] The various expansion devices described above can be combined with a
wireline tool for effective control for all required functions. In particular
the
proper setting sequence for installation the sectors in the proper position
can be performed.
[0060] It should also be noted that the tubular to expand may be lowered in
the
well in advance of the expansion system. In some cases, the tubular to be
expanded may have been previously lowered with the completion (in case
of screens and slotted liner). In other applications, the tubular to be
expanded may be a sleeve of limited length (e.g. 10 meters). In these
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applications, the sleeve can be lowered by the wireline tool itself with a
consequent saving rig time.
[0061] A further embodiment of the present invention incorporating a cone
system
for expanding the sleeve involves the introduction of rollers between the
cone and the sleeve, for friction reduction. An example of this is shown in
Figures 12 and 13. The rollers 50 are injected at least in three rows, as the
circumference 52 at the point of injection is smaller, allowing that only a
limited number of rollers can be installed at once at a given circumference.
As soon as the rollers have moved, a second layer is injected with a small
angular offset (and so on for the third and further layers). Three layers can
achieve a expansion ratio of nearly three fold.
[0062] This technique allows expansion above the diameter of a pipe through
which the cone can pass, as the total internal diameter of the expanded
sleeve 54 is larger than (cone diameter + 2 x roller diameters) .
[0063] The rollers 50 are similar to the rollers of roller bearing. Their
curvature
can correspond to the final internal diameter of the expanded sleeve 54.
The cone 56 can also be made of sectors as is described above.
[0064] The rollers are re-circulated from the end of the stroke between the
cone
56 and the tubular 54. This re-circulation consists of catching the rollers
and returning them 58 to the upper end of the cone 56.
[0065] In the embodiments described above, the expansion is performed by a
wireline tool which is lowered in the well-bore. This tool pulls the
expanding elements upwards in the form of a cone which performs the
expansion of the tubular. The displacement of these elements may
require a relatively large force, depending on the shape and material of the
tubular to expand. In some cases, this force may be tens of tons.
Consequently, the tool needs to anchor itself in the tubular outside the
section that is to be expanded. In many cases, the tool creates a
displacement of the cone over a stroke in the range of less than a few
meters. When the cone is displaced over this stroke, the tool has to be
moved to the next position to allow the expansion of the next section. It is
therefore necessary that any anchoring can be easily released to allow
movement of the tool.
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[0066] In most case, the expansion process proceeds in a bottom to top
direction
(with respect to the well). In this situation, a tool that operates by pulling
must anchor itself in a tubular section which is not yet expanded.
[0067] The anchors have to be able to resist forces which generate the tubular
expansion. In a particularly preferred form of anchor, the anchoring effect
is obtained by plastic deformation of the tubular itself. The tool is
equipped with a similar set of slipped cone elements installed on top of the
tool. This cone works in the same way as the expansion cone, but it is
facing downwards. The tool installs this cone at the desired location and
deforms the tubular. After this installation, the tool locks itself in this
cone
and can then pull the expansion cone upwards. To ensure that the anchor
does not move downwards during the expansion, the anchor is set with a
higher plastic deformation force for it to move. To achieve this, the
anchoring cone is provided with a more aggressive cone angle so that the
axial force for its displacement is higher.
[0068] Another embodiment comprises two (or more) cones spaced axially by a
small distance, an example of which is shown in Figure 13. Each of these
cones 60 is installed by plastic deformation of the tubular 62 (as described
above). The total axial force to displace this anchor corresponds to the
sum of the anchoring force of each anchor. With this technique, each
anchor does not need to be expanded final diameter of the expanded
tubular, and the cone of each anchor 60 is smaller than the cone use for
the tubular expansion 29. While the maximum load supportable by each
anchor 60 is lower than the force to move the expansion cone 29, the sum
of the anchoring forces is higher. As the deformation 62 of the tubular by
the anchoring cone(s) 60 is smaller than the final expansion, the
expansion process will ensure a smooth surface even at the depth of
anchoring.
[0069] The load is shared between the anchoring cones 60, each cone supports
a certain axial load before starting tubular expansion while sliding. The
sliding of the anchors will stop when an even force distribution is achieved
due to the axial plastic deformation below each cone of the anchor.
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[0070] The anchoring cones can be constructed in a similar design as the
expansion cone. They can be made of splitted cones which can allow
each cone segment to be moved axially as well as rotated. This
construction allows to install the cone segment of the anchors in line to
insure small overall diameter: this small overall diameter allows to pass
through narrow well section (such as the production tubing).
[0071] The expansion of the final section of the limited length tubular may
need
particular attention, as the process described above requires that the tool
is anchored into the tubular to expand. In the final upper section of the
tubular, the expansion can be performed in the opposite direction
(downwards). For this to occur, an expansion cone is provided in the tool
system to be pulled downwards and an anchoring mechanism is
positioned at the bottom of the tool system. The previously described slip
mechanism based on split cone, allowing anchoring by plastic deformation
of the tubular can be modified to become the "upper" expansion cone.
This can work particularly well with the system equipped with the pair of
split cones for slips. In this case, one cone is left contracted so that it
plays no effect in the process, while the other cone is fully opened
imposing the full size deformation of the tubular. Furthermore, the lower
split cone which is the expanding tool for the normal expanding process
becomes the anchoring system for this downwards expansion. For this
operation, this lower split cone is opened at extremely high opening force.
This opening force is counter-balanced by the simultaneous strength of
the expanded tubular and the pre-existing structure (behind the expanded
tubular). Thanks to this combined resisting force, the anchor is capable of
supporting a larger force than the force for the downwards expansion.
[0072] Another tool configuration can have two sets of pairs of split cones
(one on
top and one at the bottom of the tool). With this symmetrical tool design,
the expansion process can be fully symmetrical (upwards or downwards).
When anchoring on one side, both cones of the relevant set are expanded
at limited forces, while the expansion process at the other extremity
requires the opening on only one cone.
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[0073] The expansion of the upper part of the tubular starts with the upper
cone
outside the tubular (just in contact with the tubular upper end).
[0074] When expanding downwards, slack can be provided in the wireline cable
so that the cable is not stretched by the downwards expanding process.
[0075] As will be appreciated from the above description, making the expanding
elements (cone sectors, rollers, etc,) moveable axially independently of
each other allows an expansion tool and method that addresses problems
associated with the previously proposed systems.
