U.S. patent application number 12/446673 was filed with the patent office on 2010-04-15 for radially expanding a tubular element.
Invention is credited to Fu Joseph Hou, Petrus Cornelis Kriesels, Pieter Van Nieuwkoop, Antonius Leonardus Maria Wubben.
Application Number | 20100089593 12/446673 |
Document ID | / |
Family ID | 37671998 |
Filed Date | 2010-04-15 |
United States Patent
Application |
20100089593 |
Kind Code |
A1 |
Hou; Fu Joseph ; et
al. |
April 15, 2010 |
RADIALLY EXPANDING A TUBULAR ELEMENT
Abstract
The invention relates to a method of radially expanding a
tubular element. The method comprises inducing the wall of the
tubular element to bend radially outward and in axially reverse
direction so as to form an expanded tubular section extending
around an unexpanded section of the tubular element, said wall
having a resistance to radially outward bending and a resistance to
stretching in circumferential direction. Said wall is provided with
at least one of primary means for increasing the resistance to
radially outward bending of the wall, and secondary means for
reducing the resistance to stretching in circumferential direction
of the wall.
Inventors: |
Hou; Fu Joseph; (Missouri
City, TX) ; Kriesels; Petrus Cornelis; (Rijswijk,
NL) ; Van Nieuwkoop; Pieter; (Rijswijk, NL) ;
Wubben; Antonius Leonardus Maria; (Rijswij, NL) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
37671998 |
Appl. No.: |
12/446673 |
Filed: |
October 23, 2007 |
PCT Filed: |
October 23, 2007 |
PCT NO: |
PCT/EP07/61324 |
371 Date: |
April 22, 2009 |
Current U.S.
Class: |
166/384 ;
166/207 |
Current CPC
Class: |
F16L 55/1651 20130101;
E21B 43/103 20130101 |
Class at
Publication: |
166/384 ;
166/207 |
International
Class: |
E21B 19/00 20060101
E21B019/00; E21B 23/02 20060101 E21B023/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 24, 2006 |
EP |
06122837.5 |
Claims
1. A method of radially expanding a tubular element, the method
comprising inducing the wall of the tubular element to bend
radially outward and in axially reverse direction so as to form an
expanded tubular section extending around an unexpanded section of
the tubular element, said wall having a bending stiffness and a
resistance to stretching in circumferential direction, wherein said
wall is provided with at least one of primary means for increasing
the bending stiffness of the wall, and secondary means for reducing
the resistance to stretching in circumferential direction of the
wall.
2. The method of claim 1, wherein said primary means comprises at
least one stiffening member extending in longitudinal direction
along said wall.
3. The method of claim 2, wherein the stiffening member is
connected to at least one of the outer surface and the inner
surface of said wall.
4. The method of claim 2, wherein the stiffening member and the
wall are integrally formed.
5. The method of any claim 2, wherein said primary means comprises
a plurality of said stiffening members regularly spaced along the
circumference of the tubular element.
6. The method of claim 1, wherein said secondary means comprises at
least one groove formed in said wall, each groove extending in
longitudinal direction of the tubular element.
7. The method of claim 6, wherein the groove is formed in at least
one of the outer surface and the inner surface of said wall.
8. The method of claim 6, wherein said secondary means comprises a
plurality of said grooves regularly spaced along the circumference
of the tubular element.
9. The method of claim 1, wherein said bending of the wall occurs
in a bending zone of the tubular element, and wherein the method
further comprises progressively increasing the length of said
expanded tubular section by inducing the bending zone to move in
axial direction along the tubular element.
10. The method of claim 1, wherein the wall is induced to bend by
moving the unexpanded tubular section in axial direction relative
to the expanded tubular section.
11. The method of claim 1, wherein the tubular element extends into
a wellbore formed in an earth formation.
12. The method of claim 11, wherein the expanded tubular section
extends between the wellbore wall and the unexpanded section of the
tubular element.
13. The method of claim 11, wherein said bending of the wall is
started at a lower end portion of the tubular element.
14. The method of claim 1, wherein the expanded tubular section is
kept substantially stationary in the wellbore and the unexpanded
tubular section is moved in downward direction of the wellbore to
induce said bending of the wall.
15. The method of claim 14, wherein a downward force is exerted to
the unexpanded tubular section to move the unexpanded tubular
section in downward direction of the wellbore.
16. The method of claim 1, wherein the wellbore is being drilled
with a drill string extending through the unexpanded tubular
section.
17. The method of claim 16, wherein the unexpanded tubular section
and the drill string are simultaneously lowered through the
wellbore during drilling with the drill string.
18. The method of claim 1, wherein the expanded tubular section is
compressed against the wellbore wall or against another tubular
element arranged in the wellbore as a result of the expansion
process.
19. A radially expanded tubular element obtained with the method of
claim 1.
20. (canceled)
21. (canceled)
Description
[0001] The present invention relates to a method of radially
expanding a tubular element.
[0002] Expansion of tubular elements finds application in various
fields of technology such as, for example, the production of
hydrocarbon fluid from a wellbore formed in an earth formation.
Wellbores are generally provided with one or more casings or liners
to provide stability to the wellbore wall, and/or to provide zonal
isolation between different earth formation layers. The terms
"casing" and "liner" normally refer to wellbore tubulars for
supporting and stabilising the wellbore wall, whereby it is
generally understood that a casing extends from a downhole location
to surface, whereas a liner does not fully extend to surface.
However, in this specification the terms "casing" and "liner" are
used interchangeably and without intended distinction.
[0003] In conventional wellbore construction, several casings are
set at different depth intervals in a nested arrangement whereby
each subsequent casing is lowered through the previous casing and
therefore must have a smaller diameter than the previous casing. As
a result, the cross-sectional wellbore size available for oil and
gas production decreases with depth. To alleviate this drawback, it
has been practiced to radially expand tubular elements in the
wellbore after lowering thereof to the required depth. Such
expanded tubular element forms, for example, an expanded casing
section or an expanded clad against a previously installed existing
casing. Also, it has been proposed to radially expand subsequent
casing sections to about the same diameter so that the available
diameter in the wellbore remains substantially constant along (a
portion of) its depth, as opposed to the conventional nested
arrangement whereby the available diameter decreases with depth.
EP-044706-A2 discloses a method of radially expanding a tubular
element by eversion of an inner tube to form an outer tube around a
portion of the inner tube, the tubes being interconnected at their
respective forward ends to present a rollover area capable of being
moved forwardly.
[0004] The rollover area is induced to move forward by pumping
driving fluid into the annular space between the inner and outer
tubes.
[0005] It is a drawback of the known system and method that there
is a risk that damage occurs to the tubular element as a result of
the eversion process in the rollover area where the inner tube
deforms into the outer tube, particularly for applications wherein
the inner and outer tubes have a relatively large wall
thickness.
[0006] Thus there is a need for an improved method of radially
expanding a tubular element, which overcomes the drawbacks of the
prior art.
[0007] In accordance with the invention there is provided a method
of radially expanding a tubular element, the method comprising
inducing the wall of the tubular element to bend radially outward
and in axially reverse direction so as to form an expanded tubular
section extending around an unexpanded section of the tubular
element, said wall having a bending stiffness and a resistance to
stretching in circumferential direction, wherein said wall is
provided with at least one of primary means for increasing the
bending stiffness of the wall, and secondary means for reducing the
resistance to stretching in circumferential direction of the
wall.
[0008] It is to be understood that the expression "bending the wall
radially outward and in axially reverse direction" refers to
eversion of the tubular element whereby a U-shaped wall portion is
formed of which one leg forms the unexpanded section and the other
leg forms the expanded section.
[0009] The resulting bending radius of the wall, and thus the
degree of radially outward movement of the wall, depends on the
bending stiffness of the wall and the resistance to stretching in
circumferential direction of the wall. More specifically, the
bending radius tends to increase with increasing bending stiffness
and to decrease with increased resistance to stretching in
circumferential direction. Therefore the actual bending radius
follows from a balance between the effect of the bending stiffness
tending to increase the bending radius, and the effect of the
resistance to stretching in circumferential direction tending to
decrease the bending radius. By providing the wall with means for
increasing the bending stiffness and/or means for reducing the
resistance to stretching in circumferential direction, it is
achieved that the balance is shifted in favour of a larger bending
radius. By virtue of such larger bending radius, the (equivalent)
strains in the wall become less severe and consequently the risk of
damage to the wall is reduced.
[0010] Suitably said primary means comprises at least one
stiffening member connected to said wall, each stiffening member
extending in longitudinal direction of the tubular element. The
stiffening member can be connected, for example, to the outer
surface and/or the inner surface of the wall by suitable connecting
means, or it can be integrally formed with the wall. Furthermore,
the stiffening member can be arranged parallel to the central
longitudinal axis of the tubular element, or at an angle relative
to the central longitudinal axis. In the latter case, the
stiffening member suitably extends in a spiral-shape along the
tubular element.
[0011] In a preferred embodiment, the primary means comprises a
plurality of said stiffening members regularly spaced along the
circumference of the tubular element.
[0012] Said secondary means suitable comprises at least one groove
formed in said wall, each groove extending in longitudinal
direction of the tubular element. The groove can be formed, for
example, in at least one of the outer surface and the inner surface
of said wall.
[0013] Preferably the secondary means comprises a plurality of said
grooves regularly spaced along the circumference of the tubular
element.
[0014] To progressively form the expanded tubular section, said
bending of the wall occurs in a bending zone of the tubular
element, and the method further comprises progressively increasing
the length of said expanded tubular section by inducing the bending
zone to move in axial direction along the tubular element.
[0015] The bending zone defines the location where the
instantaneous bending process takes place. By inducing the bending
zone to move in axial direction along the tubular element it is
achieved that the tubular element is progressively expanded without
the need for an expander that has to be pushed, pulled or pumped
through the tubular element. Moreover, if the tubular element
extends in vertical direction, for example into a wellbore, the
weight of the unexpanded tubular section can be utilised to
contribute to the force needed to induce downward movement of the
bending zone.
[0016] Suitably said wall is induced to bend by moving the
unexpanded tubular section in axial direction relative to the
expanded tubular section. For example, the expanded tubular section
can be held stationary while the unexpanded tubular section is
moved in axial direction through the expanded section.
[0017] In a preferred embodiment the tubular element extends into a
wellbore formed in an earth formation whereby, for example, the
expanded tubular section extends between the wellbore wall and the
unexpanded section of the tubular element. The expansion process is
carried out in an effective manner if the expanded tubular section
is kept substantially stationary in the wellbore and the unexpanded
tubular section is moved in downward direction of the wellbore to
induce said bending of the wall.
[0018] Further, the expansion process suitably can be initiated by
bending the wall of the tubular element at a lower end portion
thereof.
[0019] If the weight of the unexpanded tubular section is
insufficient to induce movement of the bending zone, suitably a
downward force is exerted to the unexpanded tubular section to move
the unexpanded tubular section in downward direction of the
wellbore.
[0020] Advantageously the wellbore is being drilled with a drill
string extending through the unexpanded tubular section. In such
application the unexpanded tubular section and the drill string
preferably are lowered simultaneously through the wellbore during
drilling with the drill string.
[0021] Optionally the bending zone can be heated to promote bending
of the tubular wall.
[0022] To reduce any buckling tendency of the unexpanded section
during the expansion process, the unexpanded section advantageously
is centralised in the expanded section using any suitable
centralising means.
[0023] Bending of the tubular wall can be promoted by providing
longitudinal grooves at the outer surface of the tubular element
before expansion.
[0024] The invention will be described hereinafter in more detail
and by way of example, with reference to the accompanying drawings
in which:
[0025] FIG. 1 schematically shows an example of a tubular element
during expansion thereof, not in accordance with the invention;
[0026] FIG. 2 schematically shows an embodiment of a tubular
element during expansion in accordance with the invention;
[0027] FIG. 3 schematically shows cross-section 3-3 of FIG. 2;
[0028] FIG. 4 schematically shows a cross-section of an alternative
embodiment of a tubular element during expansion in accordance with
the invention;
[0029] FIGS. 5a-5f schematically show various examples of
stiffening members for use in the embodiments of FIGS. 2-4;
[0030] FIG. 6 schematically shows the tubular element of FIG. 2
during expansion in a wellbore; and
[0031] FIG. 7 schematically shows the tubular element of FIG. 2
during expansion in a wellbore while the wellbore is being
drilled.
[0032] In the Figures and the description like reference numerals
relate to like components.
[0033] Referring to FIG. 1 there is shown a radially expandable
tubular element 1 comprising an unexpanded section 2 and a radially
expanded section 4 extending around the unexpanded section 2. The
unexpanded and expanded sections 2, 4 are interconnected at their
respective lower ends by a U-shaped wall portion 6 having a bending
radius R1. The expanded section 4 is formed by bending the lower
end of the wall of the tubular element 1 radially outward and in
axially reverse direction. Subsequently the unexpanded section 2 is
moved downward relative to the expanded section 4 so that, as a
result, the unexpanded section 2 gradually becomes everted to form
the expanded section 4. The resulting bending radius R.sub.1 at the
U-shaped wall portion 6 results from an equilibrium between the
tendency of the wall to assume a relatively large bending radius
due to the inherent bending stiffness of the wall, and the tendency
of the wall to assume a relatively small bending radius due to the
inherent resistance to stretching of the wall.
[0034] Referring to FIG. 2 there is shown a radially expandable
tubular element 10 comprising an unexpanded section 12 and a
radially expanded section 14 extending around the unexpanded
section 12, the unexpanded and expanded tubular sections 12, 14
being interconnected at their lower ends by a U-shaped wall portion
16 having a bending radius R.sub.2. The tubular element 10 is
substantially similar to the tubular element 1 of FIG. 1 with
regard to material properties, wall thickness and unexpanded
diameter. However the tubular element 10 is additionally provided
with a plurality of longitudinal stiffening members 20 extending
along the outer surface of the unexpanded section 12 and the inner
surface of the expanded section 14. The expanded section 14 is
formed by bending the wall of the tubular element 10, at the lower
end thereof, radially outward and in axially reverse direction, and
subsequently moving the unexpanded section 12 downward relative to
the expanded section 14 so that, as a result, the unexpanded
section 12 is gradually everted to form the expanded section 14.
The resulting bending radius R2 at the U-shaped wall portion 16
results from an equilibrium between the tendency of the wall to
assume a relatively large bending radius due to the inherent
bending stiffness of the wall, and the tendency of the wall to
assume a relatively small bending radius due to the inherent
resistance to stretching of the wall. By virtue of the stiffening
members 20, the bending stiffness of the tubular element 10 is
larger than the bending stiffness of the tubular element 1 of FIG.
1 so that, as a result, the equilibrium between said tendency of
the wall to assume a relatively large bending radius and said
tendency of the wall to assume a relatively small bending radius
shifts towards a larger bending radius for the tubular element 10.
In other words: R.sub.2>R.sub.1.
[0035] In FIG. 3 is shown a cross-sectional view of the unexpanded
section 12 of tubular element 10 whereby a layer 22 of metal, or
other suitable material, is arranged around the outer surface of
the tubular element 10. The layer 22 is provided with a plurality
of longitudinal grooves 24 regularly spaced in circumferential
direction of the tubular element 10. Each stiffening member 20 is
defined in-between a respective pair of adjacent grooves 24. The
layer 22 can be connected to the outer surface of the tubular
element 10 in any suitable manner, or it can be integrally formed
with the tubular element 10. In the latter case, the tubular
element 10 and the layer 22 can be machined from one piece.
[0036] In FIG. 4 is shown a cross-sectional view of an alternative
embodiment of a tubular element 26 to be expanded with the method
of the invention. The tubular element 26 is at its inner surface
provided with a layer 28 provided with a plurality of longitudinal
grooves 30 regularly spaced in circumferential direction of the
tubular element 10. The grooves 30 define a plurality of
longitudinal stiffening members 32, whereby each stiffening member
32 is defined in between a respective pair of adjacent grooves 30.
The metal layer 28 can be connected to the inner surface of the
tubular element 26 in any suitable manner, or it can be integrally
formed with the tubular element 26.
[0037] FIGS. 5a-5f show various embodiments, in cross-sectional
view, of stiffening members for a tubular element to be expanded
with the method of the invention.
[0038] In each of FIGS. 5a-5f, reference sign 34 indicates the wall
of the tubular element, and the respective stiffening members are
indicated by reference signs 35, 36, 37, 38, 39, 40.
[0039] Similarly to the embodiments shown in FIGS. 3 and 4, the
stiffening members 35, 36, 37, 38, 39, 40 can be arranged at the
outer surface or the inner surface of the unexpanded tubular
element.
[0040] In FIG. 6 is shown the tubular element 10 of FIG. 2 in a
wellbore 42 formed in an earth formation 44.
[0041] During normal operation the lower end portion of the wall of
the (yet unexpanded) tubular element 10 is bent radially outward
and in axially reverse direction by any suitable means so as to
initially form the U-shaped lower section 16. Subsequently, a
downward force is applied to the unexpanded section 12 to move the
unexpanded section 12 gradually downward. The unexpanded section 12
thereby becomes progressively everted to form into the expanded
section 14. During the eversion process, the U-shaped lower section
16 moves downward at approximately half the speed of the unexpanded
section 12. By virtue of the enhanced bending stiffness of the wall
of the tubular element 10 due to the stiffening members 20, the
bending radius R2 of the U-shaped lower section is relatively large
so that the tubular element 10 is expanded to a relatively large
diameter. If desired, the tubular element 10 and/or the stiffening
members 20 can be selected such that the expanded tubular section
14 becomes firmly expanded against the wellbore wall so that a seal
is formed between the expanded tubular section 14 and the wellbore
wall.
[0042] Referring to FIG. 7 there is shown the tubular element 10 of
FIG. 2 in combination with a drill string 48 extending from surface
through the unexpanded section 12, and further to the bottom of the
wellbore 42. The drill string 48 is provided with a tubular guide
member 52 for guiding and supporting the U-shaped lower section 16
of the tubular element 10, the guide member 52 being supported by a
support ring 54 connected to the drill string 48. The support ring
54 is made radially retractable so as to allow it to pass in
retracted mode through the guide member 52 and the unexpanded
section 12.
[0043] Furthermore, the drill string 48 is provided with a drill
bit 56 that is driven in rotation either by a downhole motor (not
shown) or by rotation of the drill string 48 itself. The drill bit
56 comprises a pilot bit 58 and a collapsible reamer 60 for
drilling the wellbore 48 to its nominal diameter. The pilot bit 58
and the reamer 60, when in collapsed mode, have a maximum diameter
slightly smaller than the internal diameter of the guide member 52
so as to allow the pilot bit 58 and the reamer 60 to be retrieved
to surface through the guide member 52 and through the unexpanded
tubular section 12.
[0044] During normal operation the drill bit 56 is driven in
rotation to deepen the wellbore 42 whereby the drill string 48 and
the unexpanded tubular section 12 move simultaneously deeper into
the wellbore 42. The unexpanded tubular section 12 can be assembled
from individual pipe sections at surface, as is normal practice for
tubular strings such as drill strings, casings or liners.
Alternatively the unexpanded tubular section can be supplied as a
continuous tubular element, such as a coiled tubing.
[0045] The U-shaped lower portion 16 of the tubular element 10 is
supported and guided by the guide member 52. Initially a downward
force needs to be applied to the unexpanded section 12 to induce
lowering thereof simultaneously with the drill string 48. As the
length of the unexpanded section 12 in the wellbore 42 increases,
the weight of the unexpanded section 12 gradually replaces the
applied downward force. Eventually, after the weight of the
unexpanded section has fully replaced the applied downward force,
an upward force may need to be applied to the unexpanded section 12
to prevent overloading of the U-shaped lower portion 16.
[0046] The weight of the unexpanded tubular section 12 also can be
used to thrust the drill bit 56 forward during drilling of the
wellbore 42. In the embodiment of FIG. 7 such thrust force is
transmitted to the drill bit 56 via the guide member 52 and the
support ring 54. In an alternative embodiment, the guide member is
dispensed with and the thrust force is directly transmitted from
the unexpanded tubular section to the drill string, for example via
a suitable thrust bearing (not shown) between the unexpanded
section and the drill string.
[0047] Thus, by gradually lowering the unexpanded tubular section
12 into the wellbore 42, the U-shaped lower wall portion 16
progressively bends in radially outward and axially reverse
direction, thereby progressively forming the expanded tubular
section 14. During the expansion process, the U-shaped lower
portion 16 is supported and guided by the guide member 52 so as to
promote bending of the wall of the unexpanded section 12.
[0048] When it is required to retrieve the drill string 48 to
surface, for example when the drill bit is to be replaced or after
drilling has completed, the support ring 54 is radially retracted
and the reamer bit 60 collapsed. Thereafter the drill string 48 is
retrieved through the unexpanded tubular section 12 to surface. The
guide member 52 can remain downhole. Alternatively the guide member
can be made collapsible so as to allow it to be retrieved to
surface in collapsed mode through the unexpanded tubular
section.
[0049] With the method described above it is achieved that there is
only a very short open-hole section in the wellbore 42 during
drilling since the expanded tubular section 14 extends to near the
lower end of the drill string 48 at any time. The method therefore
finds many advantageous applications. For example, if the expanded
tubular section is a casing, longer intervals can be drilled
without the need to interrupt drilling to set new casing sections,
thereby leading to fewer casing sections of stepwise decreasing
diameter. Also, if the wellbore is drilled through a shale layer
the substantial absence of an open-hole section eliminates problems
due to shale heaving.
[0050] After drilling of the wellbore 42 has been finalised and the
drill string 48 has been removed from the wellbore, the length of
unexpanded tubular section 12 still present in the wellbore 42 can
be cut-off from the expanded section 14 and subsequently retrieved
to surface, or it can be left in the wellbore. In the latter case
there are several options for completion of the wellbore, including
for example:
i) A fluid, for example brine, is pumped into the annular space
between the unexpanded and expanded sections 12, 14 so as to
increase the collapse resistance of the expanded section 14.
Optionally, an opening can be made in the wall of the tubular
element 10, near its lower end, to allow the pumped fluid to be
circulated therethrough; ii) A heavy fluid is pumped into the
annular space between the unexpanded and expanded sections 12, 14
to support the expanded tubular section 14 and increase its
collapse resistance; iii) Cement is pumped into the annular space
between the unexpanded and expanded sections 12, 14 to create a
solid body in the annular space after hardening of the cement.
Suitably, the cement expands upon hardening; iv) The unexpanded
section 12 is radially expanded against the expanded section 14,
for example by pumping, pushing or pulling an expander (not shown)
through the unexpanded section 12.
[0051] Optionally a weighted fluid can be pumped into the annular
space between the unexpanded and expanded sections, or the annular
space can pressurized, during or after the expansion process, to
reduce the collapse loading on the expanded section 14 and/or to
reduce the burst loading on the unexpanded liner section 12.
[0052] Furthermore, electric wires or optical fibres can be
arranged in the annular space between the unexpanded and expanded
sections for downhole data communication or for downhole electric
power transmission. Such wires or fibres can be attached to the
outer surface of the tubular element 10 before expansion thereof.
Also, the unexpanded and expanded sections 12, 14 can be used as
electric conductors for transferring data and/or power
downhole.
[0053] Since the length of unexpanded tubular section that is left
in the wellbore does not need to be expanded, less stringent
requirements regarding material properties etc. may apply to it.
For example, said length may have a lower or higher yield strength,
or a smaller or larger wall thickness than the expanded tubular
section.
[0054] Instead of leaving a length of unexpanded tubular section in
the wellbore after the expansion process, the entire tubular
element can be expanded with the method of the invention so that no
unexpanded tubular section remains in the wellbore. In such case,
an elongate member, for example a pipe string, can be used to exert
the necessary downward force to the unexpanded tubular section
during the last phase of the expansion process.
[0055] Suitably a friction-reducing layer, such as a Teflon layer,
is applied between the unexpanded and expanded tubular sections
during the expansion process to reduce friction forces. For
example, a friction reducing coating can be applied to the outer
surface of the tubular element before expansion. Such layer of
friction reducing material has the additional advantage of reducing
the annular clearance between the unexpanded and expanded sections,
thus resulting in a reduced buckling tendency of the unexpanded
section. Instead of, or in addition to, a friction-reducing layer,
centralizing pads and/or rollers can be applied between the
unexpanded and expanded sections to reduce friction forces.
[0056] With the method of the invention, the expanded tubular
section can extend from surface into the wellbore, or it can extend
from a downhole location deeper into the wellbore.
[0057] Instead of expanding the tubular element against the
wellbore wall (as described above), the tubular element can be
expanded against the inner surface of a tubular element previously
installed in the wellbore. Furthermore, instead of expanding the
tubular element in downward direction in the wellbore, the tubular
element can be expanded in upward direction whereby the U-shaped
section is located at the upper end of the tubular element.
[0058] Although the examples described above refer to applications
of the invention in a wellbore, it is to be understood that the
method of the invention also can be applied at the earth surface.
For example, the expanded tubular section can be expanded against
the inner surface of a pipe, for example an existing flowline for
the transportation of oil or gas located at the earth surface or at
some depth below the surface. Thereby the flowline is provided with
a new lining, thus obviating the need to replace the entire
flowline in case of damage or corrosion of the flowline.
* * * * *