Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM, METHOD, AND SLEEVE, FOR CLADDING AN UNDERGROUND
WELLBORE PASSAGE
FIELD OF THE INVENTION
The invention relates to a method and system for
cladding an inner surface of an underground wellbore
passage. The invention further relates to a sleeve for
cladding an inner surface of an underground wellbore
passage.
BACKGROUND
US 2011/0297400 discloses an inflatable packer for
use in wellbores to isolate specific wellbore regions.
The inflatable packer has an expandable bladder which
is expanded, e.g. inflated, into sealing engagement
with a surrounding surface inside the wellbore (such as
the wellbore wall surface). The expandable bladder is
pre-manufactured with a radially enlarged section
relative to the axial ends of the expandable bladder
when the bladder is in relaxed state. The radially
enlarged section offers a reduction in required
expansion ratio that is required to transition the
packer into sealing engagement with the surrounding
surface by inflating. Inflating can be accomplished by
excersising an axial force along the packer.
The packer of US 2011/0297400 is not suitable for
some applications, as it requires continuous energizing
to maintain the packer into sealing engagement with the
surrounding surface.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention
there is provided a method for cladding an inner
surface of an underground wellbore passage, the method
comprising:
- providing an elastic sleeve comprising a stretching
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device within the sleeve which stretching device is
connected to opposite ends of the sleeve;
- inducing the stretching device to stretch the sleeve
in a longitudinal direction, thereby reducing its
largest outer width such that it is less than the
smallest width of the inner surface;
- lowering the stretching device and the stretched
sleeve into the wellbore passage;
- releasing the sleeve from the stretching device
thereby enlarging the outer width of the sleeve and
cladding the sleeve against the inner surface.
In accordance with another aspect of the invention
there is furthermore provided an elastic sleeve for
cladding a inner surface of an underground wellbore
passage, the sleeve having a larger outer width than
the width of the inner surface and being:
- connectable to a stretching device within the sleeve
and to be longitudinally stretched by the stretching
device thereby reducing its outer width such that it is
less than the width of the inner surface; and
- releasable from the stretching device after lowering
with the stretching device in stretched condition into
the wellbore passage, thereby enlarging its outer width
and cladding the sleeve against the inner surface.
The underground wellbore passage may be formed by
the wellbore itself, or by a wellbore tubular arranged
within the wellbore.
In accordance with still another aspect of the
invention, there is provided a system for cladding an
inner surface of an underground wellbore passage,
comprising an elastic sleeve as defined above and a
stretching device arranged within the sleeve, which
stretching device is releasably connected to opposite
ends of the sleeve.
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These and other features, embodiments and
advantages of the method and system according to the
invention are described in the accompanying claims,
abstract and the following detailed description of non-
limiting embodiments depicted in the accompanying
drawings, in which description reference numerals are
used which refer to corresponding reference numerals
that are depicted in the drawings.
Objects and other features depicted in the figures
and/or described in this specification, abstract and/or
claims may be combined in different ways by a person
skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 schematically shows a longitudinal section
A-A through a system for cladding an underground
wellbore passage;
Fig. 2 schematically shows a top view of the system
of Fig. 1 in the longitudinal direction;
Fig. 3 schematically shows a perspective view of
the system of Fig. 1;
Fig. 4 schematically shows a longigudinal section
of a wellbore after cladding with the system of Fig. 1;
and
Fig. 5 schematically shows the same view on the
wellbore after inserting a cement slurry.
DETAILED DESCRIPTION OF THE DEPICTED EMBODIMENTS
An inner surface of an underground wellbore passage
(which can be the wellbore itself or a wellbore
tubular) is cladded by an elastic sleeve, which is
placed by:
- lowering the elastic sleeve into the wellbore which
sleeve is releasably connected to a stretching device
arranged within the sleeve and stretched by the
stretching device in longitudinal direction thereby
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reducing its largest outer width such that it is less
than the smallest width of the inner surface
surrounding the elastic sleeve; and
- releasing the sleeve from the stretching device
thereby enlarging the outer width of the sleeve and
cladding the sleeve against the inner surface.
When detached from the stretching device, the
elastic sleeve has an outer width that exceeds the
inner width of the inner surface of the wellbore
passage in a location where cladding is desired.
Figures 1, 2 and 3 show an elastic sleeve 1, as
example, which has end sections 1A, 1B in which
tensioning rods 2 are embedded at regular
circumferential intervals. The tensioning rods 2 are
configured to be coupled to a stretching device 4. The
sleeve 1 is stretchable by longitudinal expansion of
the stretching device.
In the shown embodiment, the stretching device 4
comprises two flanges 7,8 longigudinally spaced from
each other and between which the sleeve can be
configured. These flanges 7,8 are provided with
longitudinal slots 5 distributed around the
circumference and radially accessible. The tensioning
rods 2 are configured with heads 6 at their distal ends
relative to the sleeve 1. The tensioning rods 2 are
held in the longitudinal slots 5 with the heads 6
preventing slipping of the tensioning rods 2 through
the slots in longitudinal direction. The flanges 7,8
are longitudinally moved away from each other to
stretch the sleeve 1 by creating longitudinal tension.
It can also be seen that the outer diameter of the
flanges is smaller than the outer diameter of a middle
section of the sleeve. When the tension rods 2 are
inserted in the slots 5, the tension rods 2 are
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preferably pushed radially inward whereby elastically
deforming the sleeve beween the middle section of the
sleeve and the end sections 1A and 1B. This way, when
the stretching device 4 is released, for instance by
5 reducing the longitudinal spacing between the flanges 7
and 8, the elastic force which is directed radially
outward will cause the tensioning rods 2 to
automatically slide out of the slots 5 in radial
direction. This way, the stretching device 4 may
automatically detach from the sleeve 1 upon releasing
the longitudinal tension.
In stretched state the tension rods 2 may be kept
in place by virtue of friction between the heads 6 and
the flanges 7, 8. Suitably, some recesses may be
provided on the flanges 7, 8 for retaining the heads 6.
About halfway between each pair of tensioning rods
2, a V-shaped groove 3 may be present to mitigate
formation of ridges in between the rods 2 during
stretching of the sleeve 1. A V-shaped groove may be
arranged in each interval of each end section.
The sleeve may comprise an elastic elastomer and a
swelling agent that induces the elastomer to swell upon
contact with water and/or another wellbore fluid. The
swelling agent may be a water absorbing agent such as a
super absorbent polymer or a hygroscopic salt which is
dispersed in the elastic elastomer as an array of
finely divided solid particles. For example, the sleeve
1 may be made of a rubber or other elastomeric material
and comprise an additive that swells upon contact with
water or another well fluid as described in Patent
Application Publications US 2007/056735 Al and/or US
2016/0040038 Al (both incorporated herein by reference)
to generate a self-healing elastomer lining. An
objective of the use of a self-healing elastomer sleeve
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1 is to seal any micro-annuli and/or other leak paths
on a cement casing interface directly after placing a
cement plug inside the steel casing, liner or pipe. Any
leak paths that may subsequently occur during the life
of a well, e.g. induced by temperature or pressure
changes, will be restored by the self-healing
properties of the elastomer sleeve 1. The elastomer
sleeve 1 may swell in the presence of oil, water, brine
and/or water condensed from an wet natural gas phase.
Before running into a wellbore the elastomeric
sleeve 1 according to the invention is longitudinally
stretched by a mechanical stretching tool 4 that pulls
the opposite sets of rods 2 in longitudinal direction
away from each other. The increase in length of the
sleeve 1 causes a significant decrease in its Outer
Diameter (OD). The stretched elastomer sleeve 1 can be
Run Into Hole (RIH) to the desired downhole location
within the wellbore. At the required downhole location
the tension is released by longitudinal contraction of
the stretching tool 4, which reduces the distance
between the opposite sets of rods 2 thereby inducing
the elastomer sleeve 1 to radially re-expand and regain
its original length and Outer Diameter (OD), thereby
creating a clad on the inner surface of the surrounding
casing, liner, pipe or the formation.
As the tension is released the elastomer sleeve 1
detaches from the stretching device 4, after which the
stretching device 4 may be withdrawn from the elastomer
sleeve 1 and optionally retrieved from the wellbore 10
as shown in Fig. 4. The elastomer sleeve 1 stays behind
in the wellbore.
The sleeve may be cladded against the inner surface
of an uncased wellbore section or of a well casing,
liner or other well tubular. The sleeve may suitably be
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configured to swell upon contact with water and/or
another wellbore fluid.
The wellbore 10 may be a wellbore of an abandoned
oil and/or gas production well and after cladding the
sleeve 1 against the inner surface 8, a cement slurry
12 may be inserted into the sleeve 1 and allowed to
harden to plug the wellbore. This is schematically
illustrated in Fig. 5. The sleeve 1 may be induced to
swell and thereby seal any micro-annuli between the
cement plug and the inner surface.
The self-healing elastomer sleeve 1 allows the use
of ordinary (low cost) Portland class G cement slurries
to provide long-term zonal-isolation. Other types of
cement or well bore plugging materials, for example
bentonite, barite or resins, may also be used.
Application of the self-healing elastomer sleeve 1
mitigates use of complex and expensive cement slurries
comprising cement expansion additives to enhance zonal
isolation. Known complex expanding cement slurries
still don't give a 100% seal in all circumstances
neither do they have self-healing properties.
Experiments showed that the sealing performance of the
self-cladding sleeve 1 in combination with a simple and
cheap Portland class G is superior to known complex and
expansive cement systems as measured in the Wells R&D
Full scale Plugging and Abandonment (P&A) testing setup
described in the Example provided below.
Recent field data show that a number of wells after
placement of abandonment plugs have pressure build up
at surface. In general this problem is attributed to
the failure of cement due to either poor cement job
during the primary cement job or generation of micro
annuli during the curing or life time of a well. Micro
annuli can be formed during curing of the cement
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(shrinkage) or due temperature, pressure cycles in a
well. This may result in de-bonding of the cement from
the casing. The current invention provides a self-
healing sleeve 1 that adequately closes any micro
annuli between the cement and the casing.
EXAMPLE
An experiment has been performed by stretching a
tubular sleeve 1 with an initial Outer Diameter of 15
cm up to 60%, which generated a significant width
decrease that matched calculations. The stretched
sleeve 1 was then inserted into a full size Plugging &
Abandonment (P&A) testing pipe with an Internal
Diameter of 15 cm (6 inch). The stretching tool was
subsequently retracted such that the sleeve 1 was also
retracted and induced to regain its original diameter.
A zonal-isolation test was performed on the sample.
Sealing was proven after filling the interior of the
sleeve 1 with a conventional Portland class G cement up
to a pressure differential of 20 bar dP using nitrogen.
At 30 bar dP a leak was initiated, which leak was cured
due to the self-healing effect of the sleeve 1.
It will be understood that the method, system
and/or any products according to present invention are
well adapted to attain the ends and advantages
mentioned as well as those that are inherent therein.
The particular embodiments disclosed above are
illustrative only, as the present invention may be
modified, combined and/or practiced in different but
equivalent manners apparent to those skilled in the art
having the benefit of the teachings herein.
Furthermore, no limitations are intended to the
details of construction or design herein shown, other
than as described in the claims below.
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It is therefore evident that the particular
illustrative embodiments disclosed above may be
altered, combined and/or modified and all such
variations are considered within the scope of the
present invention as defined in the accompanying
claims.
While any methods, systems and/or products
embodying the invention are described in terms of
"comprising," "containing," or "including" various
described features and/or steps, they can also "consist
essentially of" or "consist of" the various described
features and steps.
All numbers and ranges disclosed above may vary by
some amount. Whenever a numerical range with a lower
limit and an upper limit is disclosed, any number and
any included range falling within the range is
specifically disclosed. In particular, every range of
values (of the form, "from about a to about b," or,
equivalently, "from approximately a to b," or,
equivalently, "from approximately a-b") disclosed
herein is to be understood to set forth every number
and range encompassed within the broader range of
values.
Also, the terms in the claims have their plain,
ordinary meaning unless otherwise explicitly and
clearly defined by the patentee.
Moreover, the indefinite articles "a" or "an", as
used in the claims, are defined herein to mean one or
more than one of the element that it introduces.
If there is any conflict in the usages of a word or
term in this specification and one or more patent or
other documents that may be cited herein by reference,
the definitions that are consistent with this
specification should be adopted.
