U.S. patent application number 16/691930 was filed with the patent office on 2020-05-28 for annular barrier.
The applicant listed for this patent is WELLTEC OILFIELD SOLUTIONS AG. Invention is credited to Bala PRASAD, Ricardo Reves VASQUES.
Application Number | 20200165892 16/691930 |
Document ID | / |
Family ID | 68621319 |
Filed Date | 2020-05-28 |
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United States Patent
Application |
20200165892 |
Kind Code |
A1 |
VASQUES; Ricardo Reves ; et
al. |
May 28, 2020 |
ANNULAR BARRIER
Abstract
The present invention relates to an annular barrier for
providing zonal isolation in an annulus downhole between a well
tubular metal structure and another well tubular metal structure or
a wall of a borehole, comprising a tubular metal part configured to
be mounted as part of the well tubular metal structure, an
expandable metal tubular surrounding the tubular metal part forming
an expandable space there between, the expandable metal tubular is
configured to be expanded in a well downhole from a first outer
diameter to a second outer diameter to abut against the well
tubular metal structure or the wall of the borehole, the expandable
metal tubular having a first end, a second end, an outer face and a
longitudinal extension and comprising a plurality of first
circumferential grooves provided in the outer face, a plurality of
sealing units, each sealing unit comprising a sealing element
arranged in the first circumferential grooves, so that each first
circumferential groove comprises one of the sealing units occupying
the first circumferential groove along the longitudinal extension,
a second circumferential groove provided between two
circumferential edges provided on the outer face and defining a
first grooved tubular part of the expandable metal tubular between
the circumferential edges, the second circumferential groove being
closer to the first end than the first circumferential grooves with
the sealing units, a split ring-shaped support element having a
plurality of windings, so that when the expandable metal tubular is
expanded from the first outer diameter to the second outer
diameter, the split ring-shaped support element partly unwinds, the
split ring-shaped support element is arranged in the second
circumferential groove for supporting the first grooved tubular
part of the expandable metal tubular during expansion. The
invention also relates to a downhole completion comprising a well
tubular metal structure and an annular barrier, where the tubular
metal part of the annular barriers is mounted as part of the well
tubular metal structure.
Inventors: |
VASQUES; Ricardo Reves;
(Zug, CH) ; PRASAD; Bala; (Zug, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WELLTEC OILFIELD SOLUTIONS AG |
Zug |
|
CH |
|
|
Family ID: |
68621319 |
Appl. No.: |
16/691930 |
Filed: |
November 22, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/1285 20130101;
E21B 43/103 20130101; E21B 33/128 20130101; E21B 33/1208
20130101 |
International
Class: |
E21B 33/12 20060101
E21B033/12; E21B 33/128 20060101 E21B033/128; E21B 43/10 20060101
E21B043/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 23, 2018 |
EP |
18208153.9 |
Dec 13, 2018 |
EP |
18212358.8 |
Claims
1. An annular barrier for providing zonal isolation in an annulus
downhole between a well tubular metal structure and another well
tubular metal structure or a wall of a borehole, comprising: a
tubular metal part configured to be mounted as part of the well
tubular metal structure, an expandable metal tubular surrounding
the tubular metal part forming an expandable space therebetween,
the expandable metal tubular is configured to be expanded in a well
downhole from a first outer diameter to a second outer diameter to
abut against the well tubular metal structure or the wall of the
borehole, the expandable metal tubular having a first end, a second
end, an outer face and a longitudinal extension, comprising: a
plurality of first circumferential grooves provided in the outer
face, a plurality of sealing units, each sealing unit comprising a
sealing element arranged in the first circumferential grooves, so
that each first circumferential groove comprises one of the sealing
units occupying the first circumferential groove along the
longitudinal extension, a second circumferential groove without a
sealing element and provided between two circumferential edges
provided on the outer face and defining a first grooved tubular
part of the expandable metal tubular between the circumferential
edges, the second circumferential groove being closer to the first
end than the first circumferential grooves with the sealing units,
a split ring-shaped support element having a plurality of windings,
so that when the expandable metal tubular is expanded from the
first outer diameter to the second outer diameter, the split
ring-shaped support element partly unwinds, the split ring-shaped
support element is arranged in the second circumferential groove
for supporting the first grooved tubular part of the expandable
metal tubular during expansion.
2. An annular barrier according to claim 1, wherein the second
circumferential groove comprises only one or more split ring-shaped
support element.
3. An annular barrier according to claim 1, wherein the second
circumferential groove comprises only one or more split ring-shaped
support element and an intermediate element arranged between the
split ring-shaped support element and the grooved tubular part.
4. An annular barrier according to claim 1, wherein a third
circumferential groove provided between two circumferential edges
provided on the outer face and defining a second grooved tubular
part of the expandable metal tubular between the circumferential
edges, the third circumferential groove being closer to the second
end than the first circumferential grooves with the sealing units,
the third circumferential groove comprises another split
ring-shaped support element having a plurality of windings, so that
when the expandable metal tubular is expanded from the first outer
diameter to the second outer diameter, the split ring-shaped
support element partly unwinds, the split ring-shaped support
element is arranged in the third circumferential groove for
supporting the second grooved tubular part of the expandable metal
tubular during expansion.
5. An annular barrier according to claim 1, wherein the split
ring-shaped support element is a helically wounded ring-shaped
element.
6. An annular barrier according to claim 1, wherein the split
ring-shaped support element has at least 6 windings, preferably at
least 10 windings.
7. An annular barrier according to claim 1, wherein the split
ring-shaped support element is made of a spring material.
8. An annular barrier according to claim 1, wherein the split
ring-shaped support element is preferably made of a material having
a yield strength of at least 70 MPa, preferably at least 100 MPa,
more preferably at least 200 MPa.
9. An annular barrier according to claim 1, wherein the ring-shaped
support element is one split ring.
10. An annular barrier according to claim 1, wherein the expandable
metal tubular at the first end comprises an end sleeve surrounding
the expandable metal tubular in order to increase a collapse rating
of the annular barrier.
11. An annular barrier according to claim 1, wherein the end sleeve
abuts the expandable metal tubular and the first end of the end
sleeve is welded onto the outer face of the tubular metal part.
12. An annular barrier according to claim 1, wherein each of the
plurality of sealing units comprises both the sealing element and a
split ring-shaped retaining element arranged in the first
circumferential grooves, the split ring-shaped retaining element
forms a back-up for the sealing element, and the split ring-shaped
retaining element has more than one winding so that when the
expandable metal tubular is expanded from the first outer diameter
to the second outer diameter, the split ring-shaped retaining
element partly unwinds.
13. An annular barrier according to claim 1, wherein the ends of
the expandable metal tubular have a thickness greater than the
grooved tubular part of the expandable metal tubular.
14. An annular barrier according to claim 1, wherein the split
ring-shaped support element has at least 6 windings, preferably at
least 10 windings.
15. An annular barrier according to any claim 1, wherein an
intermediate element is arranged between the split ring-shaped
support element and the grooved tubular part.
16. An annular barrier according to claim 1, further comprising a
tubular metal element connecting the expandable metal tubular with
the tubular metal part and having an extension in the longitudinal
extension and a first end part connected with the tubular metal
part and a second end part connected with the expandable metal
tubular, wherein the first end part is arranged closer to the
sealing units along the longitudinal extension of the tubular metal
part than the second end part.
17. A downhole completion comprising a well tubular metal structure
and an annular barrier according to claim 1, where the tubular
metal part of the annular barriers is mounted as part of the well
tubular metal structure.
Description
[0001] The present invention relates to an annular barrier to be
expanded in a well downhole to provide zonal isolation.
[0002] In wellbores, annular barriers, such as Swell Packer,
SWELLPACKER, STEELSEAL, and ZONESEAL, are used for providing a
zonal isolation of the annulus between the casing and the wall of
another casing or the wall of the borehole, or for providing a
liner hanger.
[0003] When expanding annular barriers having an expandable metal
sleeve, the sleeve is expanded from a first diameter to a second
larger diameter, and in order to do so the expandable metal sleeve
is thinning. By this thinning, the strength of the sleeve decreases
after expansion, and thus the sleeves ability of withstanding a
certain amount of pressure from the annulus is measured by
measuring how high differential pressure across the sleeve the
sleeve can withstand before the sleeve collapses. The differential
pressure, which the sleeve is able to withstand before collapsing
after the sleeve has been expanded, is referred to as the collapse
rating of the expandable metal sleeve.
[0004] When expanding the expandable metal sleeve of the annular
barrier, at least part of the well tubular metal structure is
pressurised to the pressure needed to expand the expandable metal
sleeve. However, other components forming part of the well tubular
metal structure can often not withstand a very high pressure as
they are not rated to such high pressure and the expandable metal
sleeve therefore has to be thin enough to be expanded with the
pressure at which the other components are rated. However, when
lowering the expansion pressure, the expandable metal sleeve needs
to be substantially thinner and then the collapse rating decreases
accordingly. Therefore, known metal annular barriers cannot fit all
wells where the pressure rating of the components of the well
tubular metal structure and the collapse rating of the annular
barrier do not match the condition of the well.
[0005] It is an object of the present invention to wholly or partly
overcome the above disadvantages and drawbacks of the prior art.
More specifically, it is an object to provide an annular barrier
enhancing the collapse rating without increasing the expansion
pressure and without decreasing the sealing properties of the
annular barrier.
[0006] The above objects, together with numerous other objects,
advantages and features, which will become evident from the below
description, are accomplished by a solution in accordance with the
present invention by an annular barrier for providing zonal
isolation in an annulus downhole between a well tubular metal
structure and another well tubular metal structure or a wall of a
borehole, comprising: [0007] a tubular metal part configured to be
mounted as part of the well tubular metal structure, [0008] an
expandable metal tubular surrounding the tubular metal part forming
an expandable space therebetween, the expandable metal tubular is
configured to be expanded in a well downhole from a first outer
diameter to a second outer diameter to abut against the well
tubular metal structure or the wall of the borehole, the expandable
metal tubular having a first end, a second end, an outer face and a
longitudinal extension, comprising: [0009] a plurality of first
circumferential grooves provided in the outer face, [0010] a
plurality of sealing units, each sealing unit comprising a sealing
element arranged in the first circumferential grooves, so that each
first circumferential groove comprises one of the sealing units
occupying the first circumferential groove along the longitudinal
extension, [0011] a second circumferential groove provided between
two circumferential edges provided on the outer face and defining a
first groove part of the expandable metal tubular between the
circumferential edges, the second circumferential groove being
closer to the first end than the first circumferential grooves with
the sealing units, [0012] a split ring-shaped support element
having a plurality of windings, so that when the expandable metal
tubular is expanded from the first outer diameter to the second
outer diameter, the split ring-shaped support element partly
unwinds, the split ring-shaped support element is arranged in the
second circumferential groove for supporting the first groove part
of the expandable metal tubular during expansion.
[0013] By having the split ring-shaped support element, it may be
obtained that the collapse rating is increased while keeping a
relatively low expansion pressure without having to increase the
thickness of the expandable metal tubular.
[0014] Furthermore, the groove part may be a grooved tubular part,
i.e. the groove part may form part of the expandable metal tubular
in which the groove is formed.
[0015] In addition, the second circumferential groove may comprise
only one or more split ring-shaped support element.
[0016] Also, the second circumferential groove may comprise only
one or more split ring-shaped support element and an intermediate
element arranged between the split ring-shaped support element and
the grooved tubular part.
[0017] Thus, the second circumferential groove does not comprise
any sealing elements or sealing unit. The differential pressure,
which the expandable metal tubular is able to withstand before
collapsing after the expandable metal tubular has been expanded, is
referred to as the collapse rating of the expandable metal
tubular.
[0018] Moreover, the split ring-shaped support element may occupy
the second circumferential groove along the longitudinal extension
in the unexpanded condition of the expandable metal tubular.
[0019] In addition, the split ring-shaped support element has a
length along the longitudinal extension in the unexpanded condition
corresponding to a length of the second circumferential groove.
[0020] Furthermore, the one or more split ring-shaped support
element has a common length along the longitudinal extension in the
unexpanded condition corresponding to a length of the second
circumferential groove.
[0021] Further, a third circumferential groove may be provided
between two circumferential edges provided on the outer face and
defining a second grooved tubular part of the expandable metal
tubular between the circumferential edges, the third
circumferential groove being closer to the second end than the
first circumferential grooves with the sealing units, the third
circumferential groove comprising another split ring-shaped support
element having a plurality of windings, so that when the expandable
metal tubular is expanded from the first outer diameter to the
second outer diameter, the split ring-shaped support element partly
unwinds, the split ring-shaped support element is arranged in the
third circumferential groove for supporting the second grooved
tubular part of the expandable metal tubular during expansion.
[0022] In addition, the split ring-shaped support element may be
made of a metallic material.
[0023] Moreover, the split ring-shaped support element may be a
helically wounded ring-shaped element.
[0024] Further, the split ring-shaped support element may have at
least 6 windings, preferably at least 10 windings.
[0025] Also, the split ring-shaped support element may be made of a
spring material.
[0026] Furthermore, the split ring-shaped support element may
preferably be made of a material having a yield strength of at
least 70 MPa, preferably at least 100 MPa, more preferably at least
200 MPa.
[0027] In addition, the split ring-shaped support element in one
groove may be comprised of several separate parts, where each part
has a plurality of windings.
[0028] Furthermore, the split ring-shaped support element in the
second circumferential groove or the third circumferential groove
may be comprised of several separate parts, where each part of the
split ring-shaped support element has at least two windings.
[0029] Additionally, the ring-shaped support element may be one
split ring.
[0030] Furthermore, the split ring-shaped support element may be a
monolithic split ring-shaped support element.
[0031] Also, the ring-shaped support element may be a monolithic
split ring having more than one winding.
[0032] Further, the ring-shaped support element may be one split
ring having more than one winding.
[0033] Moreover, the expandable metal tubular at the first end may
comprise an end sleeve surrounding the expandable metal tubular in
order to increase the collapse rating.
[0034] Also, the end sleeve may be made of a metal material having
a different yield strength than that of the expandable metal
tubular.
[0035] Further, the end sleeve may have a yield strength being
twice as high as the yield strength of the expandable metal
tubular.
[0036] Additionally, the end sleeve may be welded onto the outer
face of the expandable metal tubular.
[0037] Furthermore, the expandable metal tubular at the second end
may comprise another end sleeve surrounding the expandable metal
tubular in order to hinder free expansion of the second end.
[0038] In addition, the end sleeve may abut the expandable metal
tubular, the first end of the end sleeve being welded onto the
outer face of the tubular metal part.
[0039] Moreover, each of the plurality of sealing units may
comprise both the sealing element and a split ring-shaped retaining
element arranged in the first circumferential grooves, the split
ring-shaped retaining element forming a back-up for the sealing
element, and the split ring-shaped retaining element having more
than one winding, so that when the expandable metal tubular is
expanded from the first outer diameter to the second outer
diameter, the split ring-shaped retaining element partly
unwinds.
[0040] Further, the split ring-shaped retaining element may ensure
that the sealing element is maintained in the longitudinal
extension of the expandable metal tubular even when it is being
expanded, so that the sealing element retains its intended position
and the sealing properties of the expandable metal tubular are
enhanced.
[0041] The sealing element may withstand a higher pressure on the
side where the split ring-shaped retaining element is positioned,
since the split ring-shaped retaining element functions as a
back-up and support system for the sealing element.
[0042] Also, the ends of the expandable metal tubular may have a
thickness greater than the grooved tubular part of the expandable
metal tubular.
[0043] Furthermore, the split ring-shaped support element may have
at least 6 windings, preferably at least 10 windings.
[0044] Additionally, an intermediate element may be arranged
between the split ring-shaped support element and the grooved
tubular part.
[0045] Moreover, the intermediate element may be made of
polytetrafluoroethylene (PTFE) or polymer.
[0046] In addition, the annular barrier may further comprise a
tubular metal element connecting the expandable metal tubular with
the tubular metal part and having an extension in the longitudinal
extension and a first end part connected with the tubular metal
part and a second end part connected with the expandable metal
tubular, wherein the first end part is arranged closer to the
sealing units along the longitudinal extension of the tubular metal
part than the second end part.
[0047] Also, the tubular metal element may be connecting the
expandable metal tubular with the tubular metal part, where the
first end part of the tubular metal element is connected with the
tubular metal part, and the second end part is connected with the
expandable metal tubular, the expandable metal tubular can be
expanded without substantially thinning. This is due to the fact
that the tubular metal element is flexing, hence providing the
sleeve with an additional flexing ability. If the expandable metal
tubular was just bent at its ends, the bend would unbend, which
would generate an extremely high stress in the connection between
the expandable metal tubular and the tubular metal part, which
might result in a crack in the connection to the tubular metal part
and hence a leaking annular barrier. By having the tubular metal
element fastened so that the first end part is arranged closer to
the sealing units along the longitudinal extension of the tubular
metal part than the second end part, the tubular metal element
seeks to keep the angle between the tubular metal element and the
tubular metal part at a minimum during expansion of the annular
barrier.
[0048] Further, the tubular metal part may have an opening fluidly
connected with the expandable space for allowing fluid from within
the tubular metal part to the expandable space to expand the
expandable metal tubular.
[0049] Additionally, the tubular metal element may be made as a
separate element, the first end part subsequently being connected
to the tubular metal part and the second end part being connected
to the expandable metal tubular.
[0050] Moreover, the tubular metal element may be without bends in
an unexpanded condition of the annular barrier.
[0051] Furthermore, the first end part of the tubular metal element
may be welded to the tubular metal part and/or the second end part
of the tubular metal element may be welded to the expandable metal
tubular.
[0052] Also, the split ring-shaped retaining element may be
arranged in an abutting manner to the sealing element.
[0053] In addition, the split ring-shaped retaining element may
preferably be made of material having a yield strength of at least
70 MPa, preferably at least 100 MPa, more preferably at least 200
MPa.
[0054] Further, the split ring-shaped retaining element may unwind
by less than one winding when the expandable metal tubular is
expanded from the first outer diameter to the second outer
diameter.
[0055] Additionally, the split ring-shaped retaining element may
have more than one winding in the second outer diameter of the
expandable metal tubular.
[0056] Moreover, the split ring-shaped retaining element may have a
width in the longitudinal extension, the width being substantially
the same in the first outer diameter and the second outer diameter
of the expandable metal tubular.
[0057] Furthermore, the split ring-shaped retaining element may
have a plurality of windings.
[0058] Also, the expandable metal tubular may have a first
thickness in the first circumferential groove between a first and a
second circumferential edge and a second thickness in the adjacent
areas, the first thickness being smaller than the second
thickness.
[0059] In addition, the expansion of the expandable metal tubular
may be facilitated between the first and second circumferential
edges, so that the expandable metal tubular may expand more in this
area than in the adjacent areas, whereby the sealing element may be
further forced against the inner face of a casing or borehole.
[0060] Furthermore, the split ring-shaped retaining element and the
sealing element may substantially fill a gap provided between the
first and second circumferential edges.
[0061] Moreover, the split ring-shaped retaining element may be
made of a metallic material.
[0062] Further, the split ring-shaped retaining element may be made
of a spring material.
[0063] Additionally, the split ring-shaped retaining element may be
arranged on a first side of the sealing element, with a second
split ring-shaped retaining element being arranged on another side
of the sealing element opposite the first side.
[0064] Also, the split ring-shaped retaining element may retain the
sealing element in a position along the longitudinal extension of
the expandable metal tubular while expanding the split ring-shaped
retaining element and the sealing element.
[0065] Furthermore, the ring-shaped retaining element may be a
split ring.
[0066] Moreover, the first and second circumferential edges may be
extending in a radial extension in relation to the expandable metal
tubular, said radial extension being perpendicular to the
longitudinal extension of the expandable metal tubular.
[0067] In addition, an intermediate element may be arranged between
the split ring-shaped retaining element and the sealing
element.
[0068] Further, the split ring-shaped retaining element and the
intermediate element may be arranged in an abutting manner to the
sealing element, so that at least one of the split ring-shaped
retaining elements and the intermediate element abut the sealing
element.
[0069] Also, the intermediate element may be made of
polytetrafluoroethylene (PTFE) or polymer.
[0070] Furthermore, the sealing element may be made of an
elastomer, rubber, polytetrafluoroethylene (PTFE) or another
polymer.
[0071] Additionally, the present invention relates to a downhole
completion comprising a well tubular metal structure and an annular
barrier, where the tubular metal part of the annular barrier is
mounted as part of the well tubular metal structure.
[0072] Moreover, the windings of the split ring-shaped retaining
element or the windings of the split ring-shaped support element
may be helically wound around the expandable metal tubular.
[0073] Further, the split ring-shaped support element may fill a
gap provided between the two circumferential edges.
[0074] Also, the split ring-shaped retaining element may have an
inner diameter, the inner diameter being substantially equal to an
outer diameter of the expandable metal tubular between the first
and second circumferential edges.
[0075] In one embodiment, the windings of the split ring-shaped
retaining element or the windings of the split ring-shaped support
element may have a square cross-section.
[0076] In another embodiment, the windings of the split ring-shaped
retaining element or the windings of the split ring-shaped support
element may have a circular cross-section.
[0077] Moreover, the sealing element may be partially
cone-shaped.
[0078] A plurality of sealing elements may be arranged between the
first and second circumferential edges.
[0079] The expandable metal tubular according to the present
invention may comprise at least two projections providing the
circumferential edges.
[0080] Moreover, the circumferential edges may be extending in a
radial extension in relation to the expandable metal tubular, said
radial extension being perpendicular to the longitudinal extension
of the expandable metal tubular.
[0081] Said split ring-shaped retaining element may partly overlap
the intermediate element.
[0082] Additionally, the sealing element may be made of an
elastomer, rubber, polytetrafluoroethylene (PTFE) or another
polymer.
[0083] Also, the intermediate element may be made of a flexible
material. The flexible material may be polytetrafluoroethylene
(PTFE) as a base material with for instance brass, carbon and/or
stainless steel contained therein.
[0084] Furthermore, the expandable metal tubular may be made from
one tubular metal blank.
[0085] The blank may be made by centrifugal casting or spin
casting.
[0086] In an embodiment, the first and second circumferential edges
may be provided by machining the blank.
[0087] The expandable metal tubular according to the present
invention may be machined from the blank by means of grinding,
milling, cutting or lathering or by means of a similar method.
[0088] Moreover, the expandable metal tubular may comprise a
plurality of circumferential edges, projections and/or grooves
along the longitudinal extension of the expandable metal
tubular.
[0089] Further, the expandable metal tubular may be a patch to be
expanded within a casing or well tubular structure in a well, a
liner hanger to be at least partly expanded within a casing or well
tubular structure in a well, or a casing to be at least partly
expanded within another casing.
[0090] Also, the expandable metal tubular may be provided with at
least one circumferential projection.
[0091] Additionally, a sleeve may be arranged in between the
expandable metal tubular and the tubular metal part in the annular
barrier, the sleeve being connected with the tubular metal part and
the expandable metal tubular, thus dividing the space into a first
space section and a second space section.
[0092] Finally, the projection may be a ring-shaped projection of
an increased thickness in relation to other parts of the expandable
metal tubular, the ring-shaped projection providing an enforcement
of the annular barrier when the annular barrier is expanded.
[0093] The invention and its many advantages will be described in
more detail below with reference to the accompanying schematic
drawings, which for the purpose of illustration show some
non-limiting embodiments and in which:
[0094] FIG. 1 shows a cross-sectional view of an unexpanded annular
barrier having a split ring-shaped support element,
[0095] FIG. 2 shows a cross-sectional view of another unexpanded
annular barrier,
[0096] FIG. 3 shows a cross-sectional view of the annular barrier
of FIG. 2 in an expanded condition,
[0097] FIG. 4 shows a partly cross-sectional view of the annular
barrier having a split ring-shaped support element with 11
windings,
[0098] FIG. 5 shows a cross-sectional view of yet another
unexpanded annular barrier,
[0099] FIG. 6 shows a cross-sectional view of yet another
unexpanded annular barrier,
[0100] FIG. 7 shows a cross-sectional view of yet another
unexpanded annular barrier,
[0101] FIG. 8 shows the annular barrier of FIG. 7 in its expanded
condition,
[0102] FIG. 9 shows a partly cross-sectional view of the annular
barrier having a sealing unit with two split ring-shaped retaining
elements abutting the sealing element,
[0103] FIG. 10 shows a partly cross-sectional view of another
sealing unit,
[0104] FIG. 11 shows a cross-sectional view of a downhole
completion system having several expanded annular barriers,
[0105] FIG. 12 shows in perspective part of another annular barrier
having a shear pin assembly and an anti-collapsing unit,
[0106] FIGS. 13A and 13B show a cross-sectional view of part of
another annular barrier having a shear pin assembly, the shear pin
assembly is shown in a first position in FIG. 13A and in its second
closed position in FIG. 13B, and
[0107] FIG. 14 shows a cross-sectional view of an anti-collapse
unit.
[0108] All the figures are highly schematic and not necessarily to
scale, and they show only those parts which are necessary in order
to elucidate the invention, other parts being omitted or merely
suggested.
[0109] FIG. 1 shows a cross-sectional view of an annular barrier 1
for providing zonal isolation in an annulus 2 downhole between a
well tubular metal structure 3 and a wall 5 of a borehole 4 or
another well tubular metal structure 3b, as shown in FIG. 2. The
annular barrier comprises a tubular metal part 7 configured to be
mounted as part of the well tubular metal structure 3 and an
expandable metal tubular 8 surrounding the tubular metal part
forming an expandable space 9 therebetween. After the well tubular
metal structure has been run in hole, the expandable metal tubular
is configured to be expanded in the well downhole from a first
outer diameter D.sub.1 to a second outer diameter D.sub.2 (shown in
FIG. 3) to abut against the other well tubular metal structure or
the wall of the borehole. The expandable metal tubular 8 has a
first end 11, a second end 12, an outer face 10 and a longitudinal
extension L and comprises a plurality of first circumferential
grooves 15 provided in the outer face. A plurality of sealing units
16, each sealing unit comprising a sealing element 17, are arranged
in the first circumferential grooves, so that each first
circumferential groove comprises one of the sealing units occupying
the first circumferential groove along the longitudinal extension.
The annular barrier further comprises a second circumferential
groove 18 provided between two circumferential edges 19 provided on
the outer face and defining a first grooved tubular part 20 of the
expandable metal tubular between the circumferential edges 19. The
second circumferential groove 18 is arranged closer to the first
end of the expandable metal tubular than the first circumferential
grooves 15 with the sealing units 16. The annular barrier further
comprises a split ring-shaped support element 21, which is arranged
in the second circumferential groove for supporting the first
grooved tubular part of the expandable metal tubular during
expansion. The split ring-shaped support element 21 has a plurality
of windings 22, so that when the expandable metal tubular is
expanded from the first outer diameter D.sub.1 to the second outer
diameter D.sub.2, the split ring-shaped support element 21 partly
unwinds and still supports the first grooved tubular part so as to
minimise plastic strain in the first grooved tubular part during
expansion. As can be seen, the second circumferential groove 18
does not contain a sealing unit nor any sealing elements. Thus, the
split ring-shaped support element opposite the first grooved
tubular part in the second circumferential groove is not sealing
but merely supporting the first grooved part of the expandable
metal tubular.
[0110] Thus, by having the split ring-shaped support element
opposite the first grooved tubular part plastic strain therein is
minimised, and the collapse rating of the annular barrier is
thereby increased while keeping a relatively low expansion pressure
without having to increase the thickness of the expandable metal
tubular. In order to maintain a low expansion pressure, the ends of
the expandable metal tubular cannot extend all the way to the
beginning of the sealing units since in order to make the thick
ends bend, a higher expansion pressure would be needed. Thus, the
transition between the sealing units and the thick ends need to be
relatively thin in order to bend and bridge between the thicker
ends and the thinner areas opposite the sealing units. Furthermore,
if there were no split ring-shaped support element supporting the
first groove tubular part, the thin first grooved tubular part
would just bend radially outwards between the projections 33, thus
weakening the first groove tubular part significantly so that the
expandable metal tubular could not withstand as high a differential
pressure. However, making the first grooved tubular part thicker
would increase the expansion pressure. The split ring-shaped
support element thus makes it possible to expand the expandable
metal tubular with a relatively low expansion pressure around 400
bar and maintain a high collapse rating i.e. withstanding 700 bar
differential pressure across the expandable metal tubular.
[0111] As can be seen in FIG. 1, the split ring-shaped support
element occupies the second circumferential groove 18 along the
longitudinal extension L in the unexpanded condition of the
expandable metal tubular 8. Thus, the split ring-shaped support
element has a length Ls along the longitudinal extension L in the
unexpanded condition corresponding to a length Lg of the second
circumferential groove. The split ring-shaped support element is a
monolithic split ring-shaped support element. The windings 22 of
the split ring-shaped support element abut the circumferential
edges 19 of the groove 18, as shown in FIG. 4, and each winding 22
of the split ring-shaped support element 8 abuts each other. After
expansion, as shown in FIG. 3, the groove 18 in the expandable
metal tubular 8 has increased in length and the split ring-shaped
support element 21 has partly unwinded and does no longer fill the
groove. During expansion, the split ring-shaped support element
supports the first grooved tubular part of the expandable metal
tubular, and part of the split ring-shaped support element may
after expansion be squeezed in between the other well tubular metal
structure 3b and the first grooved tubular part of the expandable
metal tubular 8. When the expandable metal tubular is later exposed
to a high pressure in the annulus, i.e. a high differential
pressure across the expandable metal tubular, the first grooved
tubular part has its largest possible strength in the expanded
condition and therefore is able to withstand the high pressure
without collapsing, i.e. the collapse rating. If the split
ring-shaped support element did not have substantially the same
length as that of the second circumferential groove, the split
ring-shaped support element cannot support the thinner grooved
tubular part of the expandable metal tubular during expansion as
efficient as when the split ring-shaped support element has
substantially the same length. The same applies if the second
circumferential groove comprises a sealing element occupying part
of the groove along the length, then the split ring-shaped support
element cannot support the thinner grooved tubular part of the
expandable metal tubular during expansion as efficient as when the
split ring-shaped support element has substantially the same
length.
[0112] Thus, the split ring-shaped support element may be a
monolithic split ring-shaped support element, such as a monolithic
split ring/one split ring having more than one winding.
[0113] The annular barrier 1 further comprises a third
circumferential groove 18B near the second end. The third
circumferential groove 18B is in the same way as the second
circumferential groove 18 provided between two circumferential
edges 19 provided on the outer face and defining a second grooved
tubular part 20B of the expandable metal tubular between the
circumferential edges. The third circumferential groove 18B is
closer to the second end than the first circumferential grooves
with the sealing units, and the third circumferential groove
comprises another split ring-shaped support element 21 having a
plurality of windings 22, so that when the expandable metal tubular
is expanded from the first outer diameter D.sub.1 to the second
outer diameter D.sub.2, the split ring-shaped support element 21
partly unwinds. The split ring-shaped support element is arranged
in the third circumferential groove for supporting the second
grooved tubular part of the expandable metal tubular during
expansion, so as to minimise plastic strain in the second grooved
tubular part during expansion in the same way as for the first
grooved tubular part.
[0114] In order to unwind during expansion, the split ring-shaped
support element may be made of a metallic material, such as spring
material, and like a helically coiled spring flex along the
circumference. The split ring-shaped support element is preferably
made of a material having a yield strength of at least 70 MPa,
preferably at least 100 MPa, more preferably at least 200 MPa. The
ring-shaped support element is preferably one monolithic split ring
but may also be divided into two matching helically wounded
rings.
[0115] The annular barrier 1 may have just one split ring-shaped
support element arranged at the first end of the expandable metal
tubular in the event that the annular barrier is only exposed to
the high differential pressure from the first zone 101 and not the
second zone 102 after expansion of the annular barrier. Thus, the
annular barrier 1 does not need to have a split ring-shaped support
element in the second circumferential groove 18 as shown in FIG.
6.
[0116] In FIGS. 1-3 and 5-6, the annular barrier further comprises
an end sleeve 23 at the first end of the expandable metal tubular.
The end sleeve 23 surrounds the expandable metal tubular in order
to increase the collapse rating and is welded onto the outer face
of the expandable metal tubular 8. The end sleeve 23 is made of a
metal material having a higher yield strength than that of the
expandable metal tubular. In a preferred embodiment, the end sleeve
has a yield strength being twice as high as the yield strength of
the expandable metal tubular. In another embodiment, the expandable
metal tubular may at the second end further comprise another end
sleeve surrounding the expandable metal tubular in order to hinder
free expansion of the second end and thus minimise the stress
strain of the metal. As can be seen in FIG. 3, the first end having
the end sleeve 23 has a straighter curve than the second end, not
comprising such end sleeve 23. The first end of the expandable
metal tubular is thus prevented from free expansion and the end
sleeve 23 having the higher yield strength forces the first end to
straighten out, thereby decreasing the stress strain in the first
end of the expandable metal tubular. The annular barrier may only
have one end sleeve 23 at the first end in the event that the
annular barrier is only exposed to the high differential pressure
from the first zone 101 and not from the second zone 102 after
expansion of the annular barrier.
[0117] In FIG. 1, the first end and the second end of the
expandable metal tubular are welded onto the outer face of the
tubular metal part 7. The annular barrier has three sealing
elements but may have several more. The sealing element 17 is made
of elastomer, rubber or similar. In FIG. 2, each of the plurality
of sealing units comprises both the sealing element 17 and a split
ring-shaped retaining element 31 arranged in the first
circumferential grooves 15, and the split ring-shaped retaining
element forms a back-up for the sealing element. The split
ring-shaped retaining element has more than one winding so that
when the expandable metal tubular is expanded from the first outer
diameter D.sub.1 to the second outer diameter D.sub.2, the split
ring-shaped retaining element partly unwinds but still abuts the
sealing element 17. Hereby, it is obtained that the split
ring-shaped retaining element ensures that the sealing element is
maintained in the longitudinal extension of the expandable metal
tubular even when it is being expanded, so that the sealing element
retains its intended position and the sealing properties of the
expandable metal tubular are enhanced. The sealing element may
withstand a higher pressure on the side where the split ring-shaped
retaining element is positioned, since the split ring-shaped
retaining element functions as a back-up and support system for the
sealing element.
[0118] As can be seen in FIG. 3, the ends of the expandable metal
tubular have a thickness t.sub.e greater than the thickness t.sub.g
(shown in FIG. 1) of the first and/or second grooved tubular part
of the expandable metal tubular. By having the split ring-shaped
support element opposite the first and/or second grooved tubular
part, the grooved tubular part is able to bridge between the ends
of the expandable metal tubular having the larger thickness and
smaller outer diameter and the part of the expandable metal tubular
having the largest outer diameter in the expanded condition.
Furthermore, the grooved tubular part partly conforms to the other
well tubular metal structure and thus provides that the sealing
units are arranged on a substantially straight part of the
expandable metal tubular which forms the best basis for a perfect
seal. The split ring-shaped support element may have at least 6
windings, preferably at least 10 windings as shown in FIG. 3. In
FIG. 2, an intermediate element 31 is arranged between the split
ring-shaped support element and the grooved tubular part. The
intermediate element is made of polytetrafluoroethylene (PTFE) or
polymer.
[0119] In FIGS. 5 and 7, the annular barrier further comprises a
tubular metal element 24 connecting the expandable metal tubular 8
with the tubular metal part 7. The tubular metal part is mounted as
part of the well tubular metal structure by means of threaded
connections 40. The tubular metal element 24 has an extension L in
the longitudinal extension and a first end part 25 connected with
the tubular metal part 7 and a second end part 26 connected with
the expandable metal tubular 8. The first end part is arranged
closer to the sealing units 16 along the longitudinal extension of
the tubular metal part 7 than the second end part 26. By having a
tubular metal element 24 connecting the expandable metal tubular
with the tubular metal part 7, where the first end part 25 of the
tubular metal element 24 is connected with the tubular metal part
and the second end part 26 is connected with the expandable metal
tubular, the expandable metal tubular can be expanded without
substantially thinning, as shown in FIG. 8. This is due to the fact
that the tubular metal element 24 is flexing, hence providing the
sleeve with an additional flexing ability. If the expandable metal
tubular 8 was only bent at its ends, the bend would unbend which
would generate an extremely high stress in the connection between
the expandable metal tubular and the tubular metal part which may
result in a crack in the connection to the tubular metal part and
hence a leaking annular barrier. By having the tubular metal
element 24 fastened so that the first end part is arranged closer
to the sealing units along the longitudinal extension of the
tubular metal part than the second end part, the tubular metal
element seeks to keep the angle between the tubular metal element
and the tubular metal part at a minimum during expansion of the
annular barrier. The tubular metal element is made as a separate
element, and subsequently the first end part is connected to the
tubular metal part and the second end part is connected to the
expandable metal tubular. The tubular metal element is without
bends in an unexpanded condition of the annular barrier and bends
during expansion. The first end part 25 of the tubular metal
element 24 is welded forming a welded connection 42 to the tubular
metal part and the second end part 25 of the tubular metal element
is welded to the expandable metal tubular 7.
[0120] The tubular metal part has an opening 28 fluidly connected
with the expandable space for letting fluid from within the tubular
metal part to the expandable space to expand the expandable metal
tubular. The opening may be arranged opposite the space 9, as shown
in FIGS. 7 and 8, or be arranged near one of the ends of the
expandable metal tubular 8 and connected with the expandable space
via a valve system. The valve system comprises a valve for shifting
between fluid communication between the space and the opening and
fluid communication between the space and the annulus for
equalising the pressure there between after expansion.
[0121] The split ring-shaped retaining element 34 is preferably
made of metal material having a yield strength of at least 70 MPa,
preferably at least 100 MPa, more preferably at least 200 MPa. The
split ring-shaped retaining element 34 is made of a spring material
and unwinds by less than one winding when the expandable metal
tubular 8 is expanded from the first outer diameter D.sub.1 to the
second outer diameter D.sub.2. As shown in FIG. 9, the split
ring-shaped retaining element 34 has a width w in the longitudinal
extension, the width being substantially the same in the first
outer diameter D.sub.1 and the second outer diameter D.sub.2 of the
expandable metal tubular. The sealing unit 16 has two split
ring-shaped retaining elements 34 which together with the sealing
element 17 fill the first circumferential groove 15 from edge 19B
to edge 19B at the projections 33. The split ring-shaped retaining
element 34 has a plurality of windings and in FIG. 9, the split
ring-shaped retaining element 34 has three windings. The expandable
metal tubular 8 has a first thickness T.sub.1 in the first
circumferential groove between a first and a second circumferential
edges 19B at the projections 33 and a second thickness T.sub.2 in
the adjacent areas, where the first thickness T.sub.1 being smaller
than the second thickness T.sub.2. Hereby, it is obtained that
expansion of the expandable metal tubular is facilitated in the
first circumferential groove so that the expandable metal tubular
may expand more in this area than in the adjacent areas, whereby
the sealing element may be further forced against the inner face of
the other well tubular metal structure or borehole.
[0122] The circumferential edges 19, 19B are extending in a radial
extension in relation to the expandable metal tubular, where radial
extension being perpendicular to the longitudinal extension L of
the expandable metal tubular. The grooves are thus provided between
projections 33 of the expandable metal tubular.
[0123] In FIG. 10, an intermediate element 35 is arranged between
the split ring-shaped retaining element 34 and the sealing element
17. The intermediate element is made of polytetrafluoroethylene
(PTFE) or polymer. The split ring-shaped retaining element 34 and
the intermediate element 35 are arranged in an abutting manner to
the sealing element, so that at least one of the split ring-shaped
retaining element and the intermediate element abut the sealing
element. The sealing element is made of an elastomer, rubber,
polytetrafluoroethylene (PTFE) or another polymer. The intermediate
element 35 may be made of a flexible material and is adapted to
maintain the split ring-shaped retaining element 34 in position and
functions as protection and support of the sealing element 17. The
split ring-shaped retaining element 34, the intermediate element 32
and the sealing element 17 are placed in the groove 15 between the
first and second circumferential edges 19B. In this embodiment, the
windings of the split ring-shaped retaining elements 34 have a
round cross-section and partly overlap the intermediate elements
35.
[0124] Thus, when the expandable metal tubular is expanded by 30%,
the split ring-shaped retaining element 7 is unwound by
approximately 30% of the circumference of the split ring-shaped
retaining element 7, and thus the split ring-shaped retaining
element 7 decreases its number of windings so that it is still
capable of closing the gaps in the longitudinal extension, whereby
the sealing element, the split ring-shaped retaining elements and
the intermediate elements (if present) fill out the gap between the
first and second circumferential edges 3, 4.
[0125] Even though not shown, the split ring-shaped support element
21 may have a round cross-section. In addition, the split
ring-shaped support element in one groove may be comprised of
several separate parts, where each part has a plurality of
windings. By being comprised of several parts, the split
ring-shaped support element can more easily and quickly unwind
without limiting the support effect and without increasing the
plastic strain of the expandable metal tubular.
[0126] In FIG. 11, the downhole completion 100 comprises the well
tubular metal structure 3 and the annular barrier 1, where the
tubular metal part of the annular barriers is mounted as part of
the well tubular metal structure.
[0127] In FIG. 12, the annular barrier 1 further comprises a shear
pin assembly 37 fluidly connecting the opening 28 in the tubular
metal part 7 and the expandable space 9 in order to allow expansion
fluid within the well tubular metal structure 3 to expand the
expandable metal tubular 8. The shear pin assembly 37 has a first
position (shown in FIG. 13A) in which expansion fluid is allowed to
flow into the space 9 and a second position (shown in FIG. 13B) in
which the opening 28 is blocked, preventing expansion fluid from
entering the space 9. As shown in FIG. 12, the annular barrier 1
further comprises an anti-collapsing unit 111 comprising an element
201 (as shown in FIG. 14) movable at least between a first position
and a second position. The anti-collapsing unit has a first inlet
25B which is in fluid communication with the first zone, and a
second inlet 26B which is in fluid communication with the second
zone, and the anti-collapsing unit having an outlet 27 which is in
fluid communication with the space 9. In the first position, the
first inlet is in fluid communication with the outlet, equalising
the first pressure of the first zone 101 with the space pressure in
the space 9, and in the second position, the second inlet is in
fluid communication with the outlet, equalising the second pressure
of the second zone with the space pressure.
[0128] As shown in FIG. 12, the shear pin assembly 37 has a port A
receiving fluid from an inside of the well tubular structure 3
through the screen 44. The port A is fluidly connected with a port
D during expansion, causing the expansion fluid within the well
tubular metal structure 3 to expand the expandable metal tubular 8.
When the expandable metal tubular 8 is expanded to abut the wall of
the tubular metal structure, the pressure builds up and a shear pin
24B (arranged in opening 45 in FIG. 13A) or disc (in the fluid
channel 125) within the shear pin assembly shears closing the fluid
connection from port A and the opening 28 (as shown in FIG. 13B)
and opening the fluid connection between a port B (in fluid
communication with the outlet 27) and a port C (in fluid
communication with the space 9), so that fluid from the second
inlet 26B can be let into the space 9 through the shear pin
assembly i.e. between opening 137 and channel 27B. When the first
pressure increases in the first zone, fluid from a port E connected
with a port I, being the first inlet 25B, presses the element 201
(shown in FIG. 14) to move so that fluid communication is provided
between port I and a port H, being the outlet, and thus further
through ports B and C and into the space 9 through port D. When the
second pressure increases in the second zone, the element is forced
in the opposite direction, and fluid communication between port G
(in fluid communication with the second zone through port F) and
port H is provided, i.e. fluid communication between the second
inlet 26B and the outlet 27 of the anti-collapsing unit 111, and
thus fluid is let into the annular space through ports B, C and
D.
[0129] The shear pin assembly shown in FIGS. 13A and 13B comprises
a first bore part 198 having a first inner diameter and a second
bore part 120B having an inner diameter which is larger than that
of the first bore part. The opening 28 and a second opening 17B are
arranged in the first bore part 19B and are displaced along the
bore extension. The annular barrier 1 further comprises a piston
121 arranged in the bore 18B, the piston comprising a first piston
part 22B having an outer diameter substantially corresponding to
the inner diameter of the first bore part 19B, and comprising a
second piston part 23B having an outer diameter substantially
corresponding to the inner diameter of the second bore part 120B.
The annular barrier 1 further comprises a rupture element 24B
preventing movement of the piston 121 until a predetermined
pressure in the bore 18B is reached. The strength of the rupture
element is set based on a predetermined pressure acting on the
areas of the ends of the piston, and thus, the difference in outer
diameters results in a movement of the piston when the pressure
exceeds the predetermined pressure. The piston 121 comprises a
fluid channel 125 being a through bore providing fluid
communication between the first and second bore parts 19B,
120B.
[0130] In FIGS. 13A and 13B, the rupture element 24B is a shear pin
but may also be a disc. In FIG. 13A, the shear pin 24B is intact
and extends through the piston and the inserts 43, and in FIG. 13B,
the shear pin is sheared and the piston is allowed to move, and the
inserts 43 have moved towards the centre of the bore 18B. Depending
on the isolation solution required to provide isolation downhole,
the rupture element 24B is selected based on the expansion pressure
so as to break at a pressure higher than the expansion pressure but
lower than the pressure rupturing the expandable metal tubular or
jeopardising the function of other completion components downhole.
The bore 18B and the piston 121 may be arranged in a connection
part connecting the first ends to the tubular metal part.
[0131] In FIG. 13A, the annular barrier 1 comprises a locking
element 38 which is arranged around the second piston part 23B. The
bore further comprises a third opening 137 in the second bore part
120B, which the third opening is in fluid communication with the
space 9 and the annulus/borehole 2. The third opening 137 may be
arranged in fluid communication with a shuttle valve, as shown in
FIG. 14, in such a way that the shuttle valve is arranged between
the third opening and the annulus, thus providing fluid
communication between the space 9 and the annulus. The shuttle
valve provides, in a first position, fluid communication between
the space 9 and the first zone 101 of the annulus, and in a second
position, the shuttle valve provides fluid communication between
the annular space and the second zone 102 of the annulus.
[0132] The expandable metal tubular may be made from one tubular
metal blank, wherein the blank may be made by centrifugal casting
or spin casting. Furthermore, the first and second circumferential
edges 19 may be provided by machining the blank.
[0133] FIG. 11 shows a cross-sectional view of annular barriers 1
which have been expanded in an annulus 2 between the well tubular
structure 3 and an inside face of the borehole 4. The annular
barrier 1 provides zone isolation between a first zone 101 and a
second zone 102 of the borehole. The annular barrier 1 has a
longitudinal extension which coincides with the longitudinal
extension of the casing/well tubular structure 3. The annular
barrier 1 comprises a tubular metal part 7 which may be a separate
tubular part or a casing part for mounting a part of the well
tubular structure 3. Furthermore, the annular barrier 1 comprises
the expandable metal tubular 1 which surrounds the tubular metal
part, and each end of the expandable metal tubular 1 may be
connected with the tubular metal part by means of connection parts.
The expandable metal tubular 1 and the tubular metal part 7 enclose
an annular barrier space 9, and an expansion opening 28 is provided
in the tubular metal part, through which fluid may enter the space
9 in order to expand the expandable metal tubular 1 as shown in
FIGS. 3 and 8. The expandable metal tubular 1 is expanded until the
sealing elements 16 or the projections 33 abut the inner face of
the borehole 4, so that fluid is prevented from flowing freely from
the first zone 101 to the second zone 102.
[0134] As shown in FIG. 11, two annular barriers 1 are often used
to isolate a production zone 400. A fracturing valve or inflow
valve section 120, also called the frac port or inflow/production
valve, is arranged in between the annular barriers 1, so that when
the annular barriers 1 have been expanded, the frac port or valve
120 is opened and fluid is let into the formation for creating
fractures in the formation to ease the flow of
hydrocarbon-containing fluid, such as oil, into the well tubular
structure 3. The fracturing valve or inflow section 120 may also
comprise an inlet section which may be the same as the frac port. A
screen may be arranged so that the fluid is filtered before flowing
into the casing.
[0135] The annular barrier further comprises an intermediate sleeve
(not shown) arranged in between the expandable metal tubular 1 and
the tubular metal part 7. The intermediate sleeve is connected with
the tubular metal part 7 and the expandable metal tubular 1, thus
dividing the space 9 into a first space section and a second space
section. The intermediate sleeve is squeezed in between the tubular
metal part and the expandable metal tubular. The intermediate
sleeve may also be connected with the tubular metal part in another
manner, such as crimped onto the tubular part. In order to equalise
the pressure, the expandable metal tubular has an aperture
providing fluid communication between the first or the second zone
and one of the space sections, thus equalising the pressure between
the space and the zone. When e.g. performing hydralic fracturing or
another well treatment, the pressure in one of the zones in which
hydraulic fracturing is performed is increasing, and in order to
prevent the expandable metal tubular from collapsing, the fluid is
let in through the aperture and into the first space section. When
exposed to the increased pressure, the intermediate sleeve moves
towards the tubular metal part, thus yielding to the increased
pressure in the first space section, and the first space section
increases until the pressure equalises or the intermediate sleeve
abuts the tubular metal part.
[0136] The expandable metal tubular part may also be crimped onto
the tubular part, or, if the annular barrier comprises a sleeve,
crimped onto the sleeve at its ends. The sleeve is flexible and
made of metal or a polymer, such as elastomer.
[0137] The tubular blank may be made of any kind of metal, such as
iron, steel or stainless steel, or more ductile materials, such as
copper, aluminium, lead, tin, nickel, or a combination thereof.
[0138] By fluid or well fluid is meant any kind of fluid that may
be present in oil or gas wells downhole, such as natural gas, oil,
oil mud, crude oil, water, etc. By gas is meant any kind of gas
composition present in a well, completion, or open hole, and by oil
is meant any kind of oil composition, such as crude oil, an
oil-containing fluid, etc. Gas, oil, and water fluids may thus all
comprise other elements or substances than gas, oil, and/or water,
respectively.
[0139] By a casing or well tubular metal structure is meant any
kind of pipe, tubing, tubular, liner, string etc. used downhole in
relation to oil or natural gas production.
[0140] Although the invention has been described in the above in
connection with preferred embodiments of the invention, it will be
evident for a person skilled in the art that several modifications
are conceivable without departing from the invention as defined by
the following claims.
* * * * *