Field of the invention
[0001] The present invention relates to an annular barrier to be expanded in a well downhole
to provide zonal isolation.
Background art
[0002] In wellbores, annular barriers 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
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 been 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.
Summary of the invention
[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:
- 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, which occupies 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 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,
- 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.
[0007] By having the slip 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.
[0008] 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.
[0009] Further, a third circumferential groove may be provided between two circumferential
edges provided on the outer face and defining a second groove 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 groove part
of the expandable metal tubular during expansion.
[0010] In addition, the split ring-shaped support element may be made of a metallic material.
[0011] Moreover, the split ring-shaped support element may be a helically wounded ring-shaped
element.
[0012] Further, the split ring-shaped support element may have at least 6 windings, preferably
at least 10 windings.
[0013] Also, the split ring-shaped support element may be made of a spring material.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] Additionally, the ring-shaped support element may be one split ring.
[0018] 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.
[0019] Also, the end sleeve may be made of a metal material having a different yield strength
than that of the expandable metal tubular.
[0020] Further, the end sleeve may have a yield strength being twice as high as the yield
strength of the expandable metal tubular.
[0021] Additionally, the end sleeve may be welded onto the outer face of the expandable
metal tubular.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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. 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.
[0026] Also, the ends of the expandable metal tubular may have a thickness greater than
the groove part of the expandable metal tubular.
[0027] Furthermore, the split ring-shaped support element may have at least 6 windings,
preferably at least 10 windings.
[0028] Additionally, an intermediate element may be arranged between the split ring-shaped
support element and the groove part.
[0029] Moreover, the intermediate element may be made of polytetrafluoroethylene (PTFE)
or polymer.
[0030] 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.
[0031] 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 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 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 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.
[0032] 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.
[0033] 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.
[0034] Moreover, the tubular metal element may be without bends in an unexpanded condition
of the annular barrier.
[0035] 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.
[0036] Also, the split ring-shaped retaining element may be arranged in an abutting manner
to the sealing element.
[0037] 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.
[0038] 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.
[0039] Additionally, the split ring-shaped retaining element may have more than one winding
in the second outer diameter of the expandable metal tubular. 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.
[0040] Furthermore, the split ring-shaped retaining element may have a plurality of windings.
[0041] 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
adjacent areas, the first thickness being smaller than the second thickness.
[0042] 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.
[0043] Furthermore, the split ring-shaped retaining element and the sealing element may
substantially fill a gap provided between the first and second circumferential edges.
[0044] Moreover, the split ring-shaped retaining element may be made of a metallic material.
[0045] Further, the split ring-shaped retaining element may be made of a spring material.
[0046] 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.
[0047] 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.
[0048] Furthermore, the ring-shaped retaining element may be a split ring.
[0049] 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.
[0050] In addition, an intermediate element may be arranged between the split ring-shaped
retaining element and the sealing element.
[0051] 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 element and the intermediate element abuts the sealing
element.
[0052] Also, the intermediate element may be made of polytetrafluoroethylene (PTFE) or polymer.
[0053] Furthermore, the sealing element may be made of an elastomer, rubber, polytetrafluoroethylene
(PTFE) or another polymer.
[0054] 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 barriers is mounted as part of the well tubular metal structure.
[0055] 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.
[0056] Further, the split ring-shaped support element may fill a gap provided between the
two circumferential edges.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] Moreover, the sealing element may be partially cone-shaped.
[0061] A plurality of sealing elements may be arranged between the first and second circumferential
edges.
[0062] The expandable metal tubular according to the present invention may comprise at least
two projections providing the circumferential edges.
[0063] 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.
[0064] Said split ring-shaped retaining element may partly overlap the intermediate element.
[0065] Additionally, the sealing element may be made of an elastomer, rubber, polytetrafluoroethylene
(PTFE) or another polymer.
[0066] 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.
[0067] Furthermore, the expandable metal tubular may be made from one tubular metal blank.
[0068] The blank may be made by centrifugal casting or spin casting.
[0069] In an embodiment, the first and second circumferential edges may be provided by machining
the blank.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] Also, the expandable metal tubular may be provided with at least one circumferential
projection.
[0074] 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.
[0075] 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.
Brief description of the drawings
[0076] 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:
Fig. 1 shows a cross-sectional view of an unexpanded annular barrier having a slip
ring-shaped support element,
Fig. 2 shows a cross-sectional view of another unexpanded annular barrier,
Fig. 3 shows a cross-sectional view of the annular barrier of Fig. 2 in an expanded
condition,
Fig. 4 shows a partly cross-sectional view of the annular barrier having a slip ring-shaped
support element with 11 windings,
Fig. 5 shows a cross-sectional view of yet another unexpanded annular barrier,
Fig. 6 shows a cross-sectional view of yet another unexpanded annular barrier,
Fig. 7 shows a cross-sectional view of yet another unexpanded annular barrier,
Fig. 8 shows the annular barrier of Fig. 7 in its expanded condition,
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,
Fig. 10 shows a partly cross-sectional view of another sealing unit,
Fig. 11 shows a cross-sectional view of a downhole completion system having several
expanded annular barriers,
Fig. 12 shows in perspective part of another annular barrier having a shear pin assembly
and an anti-collapsing unit,
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
Fig. 14 shows a cross-sectional view of an anti-collapse unit.
[0077] 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.
Detailed description of the invention
[0078] 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 there between. After the well tubular metal
structure has been run inhole, the expandable metal tubular is configured to be expanded
in the well downhole from a first outer diameter D
1 to a second outer diameter D
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,
which occupy 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 groove
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 element,
which is arranged in the second circumferential groove for supporting the first groove
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
1 to the second outer diameter D
2, the split ring-shaped support element 21 partly unwinds and still supports the first
groove part so as to minimise plastic strain in the first groove part during expansion.
[0079] Thus, by having the slip ring-shaped support element opposite the first groove 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 grove part,
the thin first groove part would just bend radially outwards between the projections
33 thus weakening the first grove part significantly, so that the expandable metal
tubular could not withstand as high a differential pressure. However, making the first
groove 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.
[0080] 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. 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 groove 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 groove 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 groove
part has its largest possible strength in the expanded condition and therefore is
able to withstand the high pressure without collapsing.
[0081] The annular barrier 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 groove 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
1 to the second outer diameter D
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
groove part of the expandable metal tubular during expansion, so as to minimise plastic
strain in the second groove part during expansion in the same way as for the first
groove part.
[0082] 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 split ring, but may also be divided into two matching helically wounded rings.
[0083] 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.
[0084] 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 the metal. As can be seen in Fig. 3, the first end having the end
sleeve 23 has a more straight 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.
[0085] 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
1 to the second outer diameter D
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.
[0086] As can be seen in Fig. 3, the ends of the expandable metal tubular have a thickness
t
e greater than the thickness t
g (shown in Fig. 1) of the first and/or second groove part of the expandable metal
tubular. By having the split ring-shaped support element opposite the first and/or
second groove part, the groove 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 groove 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 32 is
arranged between the split ring-shaped support element and the groove part. The intermediate
element is made of polytetrafluoroethylene (PTFE) or polymer.
[0087] 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 Lt 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 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
bending 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
25 part of the tubular metal element is welded to the expandable metal tubular 7.
[0088] 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.
[0089] The split ring-shaped retaining element 31 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 31 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
1 to the second outer diameter D
2. As shown in Fig. 9, the split ring-shaped retaining element 31 has a width w in
the longitudinal extension, and the width being substantially the same in the first
outer diameter D
1 and the second outer diameter D
2 of the expandable metal tubular. The sealing unit 16 has two split ring-shaped retaining
elements 31 which together with the sealing element 17 fill the first circumferential
groove 15 from edge 19 to edge 33. The split ring-shaped retaining element 31 has
a plurality of windings and in Figs. 8 and 9, the split ring-shaped retaining element
31 has three windings. The expandable metal tubular 8 has a first thickness T
1 in the first circumferential groove between a first and a second circumferential
edges 19 and a second thickness T
2 in adjacent areas, where the first thickness T
1 being smaller than the second thickness T
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.
[0090] The circumferential edges 19 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.
[0091] In Fig. 10, an intermediate element 32 is arranged between the split ring-shaped
retaining element 31 and the sealing element 17. The intermediate element is made
of polytetrafluoroethylene (PTFE) or polymer. The split ring-shaped retaining element
31 and the intermediate element 32 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 abuts the sealing element. The sealing element is made of an elastomer, rubber,
polytetrafluoroethylene (PTFE) or another polymer. The intermediate element 32 may
be made of a flexible material and is adapted to maintain the split ring-shaped retaining
element 31 in position and function as protection and support of the sealing element
17. The split ring-shaped retaining element 31, the intermediate element 31 and the
sealing element 17 are placed in the groove 15 between the first and second circumferential
edges 19. In this embodiment, the windings of the split ring-shaped retaining elements
31 have a round cross-section and partly overlap the intermediate elements 32.
[0092] 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.
[0093] Even though not shown, the split ring-shaped support elements 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.
[0094] 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.
[0095] 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.
[0096] 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 or disc within the shear pin assembly shears closing the
fluid connection from port A and opening 28 (as shown in Fig. 13B) and opens 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. 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.
[0097] The shear pin assembly shown in Fig. 13A and 13B comprises a first bore part 19B
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.
[0098] 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 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.
[0099] 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 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.
[0100] 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.
[0101] 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.
[0102] 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.
[0103] The annular barrier further comprises a 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 that 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.
[0104] 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.
[0105] 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.
[0106] 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.
[0107] 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.
[0108] 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.
1. An annular barrier (1) for providing zonal isolation in an annulus (2) downhole between
a well tubular metal structure (3) and another well tubular metal structure (3b) or
a wall (5) of a borehole (4), comprising:
- a tubular metal part (7) configured to be mounted as part of the well tubular metal
structure,
- an expandable metal tubular (8) surrounding the tubular metal part forming an expandable
space (9) there between, the expandable metal tubular is configured to be expanded
in a well downhole from a first outer diameter (D1) to a second outer diameter (D2) to abut against the well tubular metal structure or the wall of the borehole, the
expandable metal tubular (8) having a first end (11), a second end (12), an outer
face (10) and a longitudinal extension (L) and comprising:
- 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) arranged in the first circumferential grooves, so that each first circumferential
groove comprises one of the sealing units, which occupies the first circumferential
groove along the longitudinal extension,
- a second circumferential groove (18) provided between two circumferential edges
(19) provided on the outer face and defining a first groove part (20) 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 (21) having a plurality of windings (22), so
that when the expandable metal tubular is expanded from the first outer diameter (D1) to the second outer diameter (D2), the split ring-shaped support element (21) 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.
2. An annular barrier according to claim 1, wherein a third circumferential groove (18B)
provided between two circumferential edges (19) provided on the outer face and defining
a second groove part (20B) 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 (21) having a plurality of windings (22),
so that when the expandable metal tubular is expanded from the first outer diameter
(D1) to the second outer diameter (D2), 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
groove part of the expandable metal tubular during expansion.
3. An annular barrier according to any of the proceeding claims, wherein the split ring-shaped
support element is a helically wounded ring-shaped element.
4. An annular barrier according to claim 1 or 2, wherein the split ring-shaped support
element has at least 6 windings, preferably at least 10 windings.
5. An annular barrier according to any of the proceeding claims, wherein the split ring-shaped
support element is made of a spring material.
6. An annular barrier according to any of the proceeding claims, 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.
7. An annular barrier according to any of the proceeding claims, wherein the ring-shaped
support element is one split ring.
8. An annular barrier according to any of the proceeding claims, wherein the expandable
metal tubular at the first end comprises an end sleeve (23) surrounding the expandable
metal tubular in order to increase the collapse rating.
9. An annular barrier according to any of the proceeding claims, 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.
10. An annular barrier according to any of the proceeding claims, 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 (D1) to the second outer diameter (D2), the split ring-shaped retaining element partly unwinds.
11. An annular barrier according to any of the proceeding claims, wherein the ends of
the expandable metal tubular have a thickness (te) greater than the groove part of the expandable metal tubular.
12. An annular barrier according to any of the proceeding claims, wherein the split ring-shaped
support element has at least 6 windings, preferably at least 10 windings.
13. An annular barrier according to any of the proceeding claims, wherein an intermediate
element (31) is arranged between the split ring-shaped support element and the groove
part.
14. An annular barrier according to any of the proceeding claims, further comprising a
tubular metal element (24) connecting the expandable metal tubular with the tubular
metal part and having an extension (Lt) in the longitudinal extension and a first
end part (25) connected with the tubular metal part and a second end part (26) 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.
15. A downhole completion comprising a well tubular metal structure and an annular barrier
according to any of claims, where the tubular metal part of the annular barriers is
mounted as part of the well tubular metal structure.