U.S. patent application number 12/675367 was filed with the patent office on 2010-12-02 for sealing assembly.
This patent application is currently assigned to SWELLFIX B.V.. Invention is credited to John Dewar, Graeme McRobb.
Application Number | 20100300689 12/675367 |
Document ID | / |
Family ID | 38599299 |
Filed Date | 2010-12-02 |
United States Patent
Application |
20100300689 |
Kind Code |
A1 |
McRobb; Graeme ; et
al. |
December 2, 2010 |
SEALING ASSEMBLY
Abstract
A downhole sealing assembly (10) includes a sleeve (12)
comprising a swellable medium (22). The sleeve (12) is mounted on a
base pipe (14) and defines a flow path (18) between the sleeve (12)
and the base pipe (14).
Inventors: |
McRobb; Graeme;
(Aberdeenshire, GB) ; Dewar; John; (Edinburgh,
GB) |
Correspondence
Address: |
FULWIDER PATTON LLP
HOWARD HUGHES CENTER, 6060 CENTER DRIVE, TENTH FLOOR
LOS ANGELES
CA
90045
US
|
Assignee: |
SWELLFIX B.V.
Rijswijk
NL
|
Family ID: |
38599299 |
Appl. No.: |
12/675367 |
Filed: |
August 26, 2008 |
PCT Filed: |
August 26, 2008 |
PCT NO: |
PCT/GB08/02887 |
371 Date: |
February 25, 2010 |
Current U.S.
Class: |
166/285 ;
166/133; 166/327; 166/387 |
Current CPC
Class: |
E21B 33/1208 20130101;
E21B 33/1277 20130101 |
Class at
Publication: |
166/285 ;
166/133; 166/387; 166/327 |
International
Class: |
E21B 33/00 20060101
E21B033/00; E21B 33/12 20060101 E21B033/12; E21B 34/00 20060101
E21B034/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2007 |
GB |
0716642.4 |
Claims
1. A downhole sealing assembly including a sleeve comprising a
swellable medium wherein the sleeve is adapted to be mounted on an
outer surface of a base pipe to define a flow path between the
sleeve and the base pipe.
2. The assembly of claim 1, wherein the swellable medium is adapted
to swell to provide a seal within an annulus formed between the
sleeve and a surrounding bore wall.
3. The assembly of claim 2, adapted to maintain the flow path
following formation of said seal.
4. The assembly of claim 1, wherein the swellable medium is adapted
to swell during deployment into a bore.
5. The assembly of claim 1, wherein the flow path is adapted to
permit resident or ambient wellbore fluids to be displaced
therethrough as the sealing assembly is run in-hole.
6. The assembly of claim 1, wherein the flow path is adapted to
permit cement to cure therein, such that the cement provides a seal
across the sealing assembly.
7. The assembly of claim 1, adapted to be utilised adjacent, in
combination with or part of a cement shoe.
8. The assembly of claim 1, comprising a base pipe.
9. The assembly of claim 8, wherein the base pipe comprises a
downhole tubular comprising at least one of: a casing tubular,
liner tubular, drilling tubular, drilling collar, cement shoe and
coiled tubing.
10. The assembly of claim 8, wherein the base pipe is adapted to
define or be coupled to and form part of a tubing string to be run
downhole into a bore.
11. The assembly of claim 1, wherein the swellable medium is
adapted to swell at least in part by volumetric expansion
thereof.
12. The assembly of claim 1, wherein the swellable medium is
adapted to swell upon exposure to an activator.
13. The assembly of claim 1, wherein the swellable medium comprises
an elastomer.
14. The assembly of claim 1, comprising a support assembly adapted
to mount the sleeve on the base pipe.
15. The assembly of claim 14, wherein the support assembly is
adapted for retrofitting the sleeve to an existing base pipe.
16. The assembly of claim 14, wherein the support assembly is
adapted for mounting the sleeve on the base pipe without
penetrating the base pipe.
17. The assembly of claim 14, wherein a support assembly is
provided at each axial end of the sleeve.
18. The assembly of claim 14, wherein a support assembly is
provided intermediate the axial ends of the sleeve.
19. The assembly of claim 1, wherein the sleeve is adapted to be
axially fixed relative to the base pipe.
20. The assembly of claim 1, wherein the sleeve is adapted to be
axially movable relative to the base pipe.
21. The assembly of claim 20, wherein the axial movement of the
sleeve relative to the base pipe is limited by at least one
stop.
22. The assembly of claim 1, wherein the sleeve is adapted to be
rotationally fixed relative to the base pipe.
23. The assembly of claim 1, wherein the sleeve is adapted to be
rotationally movable relative to the base pipe.
24. The assembly of claim 1, comprising a band of swellable medium
disposed on the sleeve.
25. The assembly of claim 24, comprising a plurality of bands of
swellable medium disposed axially along the sleeve.
26. The assembly of claim 25, wherein the bands are spaced
apart.
27. The assembly of claim 25, wherein the bands comprise the same
swellable material.
28. The assembly of claim 25, wherein the bands comprise different
swellable materials.
29. The assembly of claim 28, wherein at least one band comprises a
swellable material adapted to be activated by water, and at least
one band comprises a swellable material adapted to be activated by
hydrocarbons.
30. The assembly of claim 1, comprising a swellable medium disposed
outside the sleeve.
31. The assembly of claim 1, comprising a swellable medium disposed
inside the sleeve.
32. The assembly of claim 31, wherein the swellable medium disposed
inside the sleeve is adapted to establish a seal in the flow
path.
33. The assembly of claim 30, wherein swellable media disposed
outside and inside the sleeve have different swelling
characteristics.
34. The assembly of claim 33, wherein the swellable medium disposed
inside the sleeve is adapted to swell at a slower rate that the
swellable medium disposed outside the sleeve.
35. The assembly of claim 1, wherein the assembly is adapted to
provide downhole mechanical support for at least the base pipe.
36. The assembly of claim 35, wherein the assembly is adapted to
function as a tubing hanger.
37. (canceled)
38. A method of establishing a downhole seal, said method
comprising the steps of: providing a base pipe; mounting a sleeve
on an outer surface the base pipe to define a flow path
therebetween, wherein the sleeve comprises a swellable medium;
running the base pipe into a wellbore; and causing the swellable
medium to swell to establish a seal.
39. The method of claim 38, wherein the swellable medium establish
a seal against a wall of the wellbore.
40. The method of claim 38, wherein the swellable medium is caused
to swell by exposure to an activator.
41. The method of claim 38, further comprising flowing cement into
a wellbore and permitting the cement to flow through the flow path
defined between the sleeve and the base pipe.
42. The method of claim 41, comprising permitting the cement to
cure in and seal the flow path.
43. A method of completing a wellbore, said method comprising the
steps of: providing a tubing string; mounting at least one sleeve
on an outer surface of the tubing string to define a flow path
therebetween, wherein the sleeve comprises a swellable medium;
running the tubing string into a wellbore; causing the swellable
medium to swell; and flowing cement into the annulus formed between
the tubing string and a wall of the wellbore, wherein cement flows
through the flow path.
44. A cement shoe comprising: a tubular body adapted to be mounted
on a lower end of a tubing string; a sleeve including a swellable
medium mounted on an outer surface of the tubular body; and a flow
path defined between the tubular body and the sleeve.
45. A downhole support assembly including a sleeve comprising a
swellable medium and adapted to be mounted on an outer surface of a
base pipe and define a flow path therebetween.
46. A method of supporting a tubular body within a bore, said
method comprising the steps of: mounting a sleeve comprising a
swellable medium on an outer surface of the tubular body to define
a flow path between the sleeve and the body; running the tubular
body into a bore; and activating the swellable medium to engage a
wall of the bore.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a sealing assembly, and in
particular to a downhole sealing assembly incorporating a swellable
medium.
BACKGROUND TO THE INVENTION
[0002] In the oil and gas exploration and production industry there
are many occasions where seals of varying configurations must be
established downhole. For example, seals may be required within an
annulus defined between, for example, concentric tubulars, between
a tubular and a bore wall, or the like. Such seals may be achieved
by use of mechanical actuators which physically set, and in some
occasions release sealing members at the desired location. However,
there are inherent reliability concerns associated with any
downhole mechanical assembly in view of the significant
difficulties and costs associated with recovering a failed assembly
and implementing appropriate remedial measures.
[0003] It has been proposed in the art to establish seals in
downhole annular locations using materials which swell upon contact
with a particular activator, such as water, hydrocarbons or the
like. Generally, the swellable material, such as a swelling
elastomer, is positioned in an annular space and then subsequently
permitted to swell, for example upon contact with ambient fluids,
to fill the annular space and establish the necessary seal.
However, swellable materials which have been proposed for use in
downhole applications swell or expand very slowly and generally
require a number of days, often weeks, to complete the swelling
process and fill the annular space to establish the required seal.
This slow activation period may delay subsequent procedures, which
is highly undesirable. Furthermore, a constant desire to carry out
downhole operations as quickly as possible may encourage certain
procedures to be performed before the seal has sufficiently been
established which may inadvertently affect the integrity of the
seal.
[0004] Further concerns in the oil and gas industry relate to
wellbore cementing. In conventional wellbore completions, casing or
liner tubing strings are run into a drilled bore and cemented in
place to seal the annulus defined between the tubing strings and
the bore wall to therefore prevent migration of fluids along the
annulus. A conventional cementing process involves pumping an
appropriate volume of cement through the tubing string, through a
cement shoe mounted on the lower end of the string and ultimately
into the annulus. However, the condition of the wellbore may often
adversely affect the integrity of the cement seal. For example, mud
cake formed on the bore wall from the drilling operation may
prevent or at least minimise the adherence of the cement to the
bore wall. Additionally, after the cement has cured, micro annuli,
cracks or channels may form. For example, thermal expansion cycles
of the tubulars may cause cracking of the cement and even
separation of the cement from the tubulars and/or the bore wall.
Additionally, in-well operations may disturb the cured cement. For
example, in conventional cementing operations a proportion of the
cement will remain and set within the cement shoe, which must be
drilled through if the wellbore is to be advanced. Drilling through
the cement shoe in this manner may disturb the cement in the
adjacent annulus and therefore adversely affect annulus
sealing.
[0005] Remedial operations to remedy an ineffective prior cement
job include cement squeeze operations which involve pumping
additional cement through perforations in the tubing string and
into the ineffective cemented annulus to seek to fill the micro
annuli and other flow channels. However, cement squeeze operations
are time consuming and there is a risk that the subterranean
producing formation will be damaged.
SUMMARY OF THE INVENTION
[0006] According to a first aspect of the present invention, there
is provided a downhole sealing assembly including a sleeve
comprising a swellable medium and adapted to be mounted on a base
pipe and define a flow path between the sleeve and the base
pipe.
[0007] Advantageously, in use, the sleeve may be mounted on a base
pipe and subsequently run downhole into a bore, and the swellable
medium may be activated to swell to provide a seal within the
annulus formed between the sleeve and a bore wall. The bore wall
may comprise an inner surface of a downhole tubular. Alternatively,
or additionally, the bore wall may be defined by an inner wall
surface of an open drilled bore. In this arrangement the sealing
assembly may be adapted to prevent migration of fluids from the
surrounding earth into the wellbore, or alternatively, or
additionally the loss of fluids from the wellbore into the
surrounding earth.
[0008] Beneficially, the present invention permits a seal to be
established more rapidly than would be achievable if the swellable
medium were mounted directly on the base pipe. That is, the annulus
area between the sleeve and the bore wall will be less than the
annulus area between the base pipe and bore wall, and as such
requires a lower expansion ratio of the swellable medium to
establish the seal.
[0009] The swellable medium may be adapted to swell during
deployment into a bore. Accordingly, permitting the swellable
medium to begin the swelling process during deployment shortens the
final sealing time once the sealing assembly is located at the
required depth. Beneficially, the swellable medium may displace
ambient or other fluids present in the wellbore during swelling to
establish a seal between the bore wall and the sleeve.
[0010] The flow path may be defined between an inner surface of the
sleeve and an outer surface of the base pipe.
[0011] The flow path may be adapted to permit fluids, such as
cement, drilling mud, wellbore fluids or the like to flow
therethrough. Accordingly, when the swellable medium has
established a seal, as described above, the flow path may permit
fluids to bypass said seal.
[0012] Additionally, the flow path may be adapted to permit
resident or ambient wellbore fluids, such as drilling mud,
hydrocarbons, water and the like to be displaced therethrough while
the sealing assembly is run in-hole. The flow path may therefore
assist to prevent or substantially minimise the occurrence of
hydraulic locking, permitting easier running in of the sealing
assembly. This arrangement is particularly advantageous where the
swellable medium defines an outer diameter or dimension which
closely corresponds to the diameter or width of the wellbore,
especially where the swellable medium is permitted to swell during
running into the wellbore. Providing a sealing assembly of an outer
dimension or diameter close to the bore diameter also assists in
centralising the base pipe in the bore.
[0013] The sealing assembly may be adapted for use in combination
with a downhole cementing process. For example, the swellable
medium may be activated to establish a seal between the sleeve and
a bore wall at a desired location, while the flow path permits
cement to bypass said seal to provide conventional annulus cement
sealing on either side of the established seal. Accordingly,
annulus sealing at the desired location is not dependent on cement
making a sufficient bond with the bore wall. Additionally, the
sealing assembly may provide additional assurance that sealing
integrity will be maintained at the desired location, even when
flow channels, micro annuli or the like form within the cement or
at the cement/bore wall interface. Furthermore, any movement of the
sealing assembly relative to the bore wall after a seal is
initially established will be accommodated by further swelling of
the swellable medium to thus continually maintain a seal.
[0014] The flow path may be adapted to permit cement to cure
therein, such that the cement provides a seal across the sealing
assembly. Advantageously, the flow channel may provide a relatively
clean surface permitting good adherence of the cement. Furthermore,
any thermal expansion effects will be experienced by both the base
pipe and sleeve, which may be formed of the same material, thus
minimising any separation of cement from the surface of the flow
path.
[0015] In embodiments of the invention the sealing assembly may be
adapted to be located at a pre-selected location within a wellbore.
For example, the sealing assembly may be adapted to be positioned
at a location within a wellbore which extends through geological
zones or regions containing fluids, such as water, which are
preferably to be prevented from being produced to surface.
Accordingly, the sealing assembly may be utilised to provide
downhole zonal or regional isolation to assist in preventing
migration of fluids between regions. For example, the sealing
assembly may be utilised to seek to prevent migration of water from
one zone towards an oil or gas-producing zone to minimise the
volume of water produced to surface.
[0016] The sealing assembly may be adapted to be positioned at a
region within a wellbore which exhibits undesirable geological
properties. For example, particularly porous regions may absorb a
significant volume of fluids from the wellbore. Such porous
regions, conventionally termed thief regions, may absorb, for
example, uncured cement from the wellbore, resulting in incomplete
annulus cement sealing. The sealing assembly of the present
invention may therefore be utilised to isolate such regions from
the wellbore while allowing fluid bypass.
[0017] Furthermore, the sealing assembly may be adapted for use in
wellbores which extend through relatively weak rock structures, to
thus ensure that sufficient sealing and wellbore support may be
established.
[0018] The sealing assembly may be adapted for use in regions
within a wellbore where in-well operations are known to adversely
affect the annulus sealing integrity of conventional cement. For
example, the sealing assembly may be utilised adjacent, in
combination with or part of a cement shoe.
[0019] The pre-selected location may be determined by conventional
techniques, such as open hole logging or the like. For example,
properties of the wellbore may be determined by wireline logging,
for example, after the wellbore has been formed or alternatively
during drilling of the wellbore using logging while drilling
techniques.
[0020] The base pipe may comprise a downhole tubular such as a
casing tubular, liner tubular, drilling tubular, drilling collar,
cement shoe, coiled tubing or the like, or any suitable combination
thereof. The base pipe may be of a conventional size, such as a
full size 9.14 m (30 feet) pipe section, or a reduced size 4.57 m
(15 feet) pup-joint pipe section. The base pipe may be adapted to
define or be coupled to and form part of a tubing string to be run
downhole into a bore.
[0021] The swellable medium may be adapted to swell by volumetric
expansion thereof. Alternatively, or additionally, the swellable
medium may be adapted to swell by inflation thereof. In embodiments
of the invention the swellable medium may be adapted to swell upon
exposure to an activator. The swellable medium may be adapted to be
activated by a chemical activator, thermodynamic activator, fluid
dynamic activator, or the like, or any suitable combination
thereof. For example, the swellable medium may be adapted to be
activated by a fluid, such as water, hydrocarbons, cement, drilling
mud, or the like, or any suitable combination thereof.
Alternatively, or additionally, the swellable medium may be adapted
to be activated by heat, pressure or the like.
[0022] The swellable medium may comprise an elastomer, such as
rubber or the like.
[0023] The sealing assembly may further define fluid ports adapted
to permit fluid to be communicated to and from the flow path. Fluid
ports may be disposed on either side of the swellable medium to
thus permit fluid communication past said swellable medium. At
least one fluid port may be defined by a bore extending through the
wall of the sleeve. Alternatively, or additionally, at least one
fluid port may be defined between the sleeve and base pipe. For
example, at least one port may be defined between an open end of
the sleeve and an outer surface of the base pipe. In this
arrangement the at least one port may be generally annular in form.
In a preferred embodiment, a first fluid port may be defined
between one end of the sleeve and the outer surface of the base
pipe, and a second fluid port may be defined between an opposite
end of the sleeve and the outer surface of the base pipe, wherein
the flow path extends between the first and second ports.
[0024] The sleeve may be concentrically mounted on the base pipe.
Alternatively, the sleeve may be eccentrically mounted on the base
pipe.
[0025] The sealing assembly may further comprise a support assembly
adapted to mount and support the sleeve on the base pipe. A single
support assembly may be provided, and may partially or completely
extend along the axial length of the sleeve. In embodiments of the
invention a plurality of support assemblies may be provided and may
be axially distributed along the length of the sleeve. In one
embodiment, a support assembly may be provided at axially opposing
ends of the sleeve. A further support assembly may be provided
intermediate the ends of the sleeve.
[0026] The support assembly may be freely disposed between the
sleeve and the base pipe to therefore define a spacer therebetween.
Alternatively, the support assembly may be secured to at least one
of the sleeve and base pipe. The support assembly may be releasably
secured to at least one of the sleeve and base pipe, and preferably
releasably secured to at least the base pipe. This arrangement may
advantageously permit the sleeve to be mounted on an existing base
pipe. The support assembly may be releasably secured by screwing,
bolting, interengagement, interference fitting, clamping or the
like. The use of securing or fixing arrangements which can be
operated without provision of specialised equipment or skilled
personnel offers the advantage that the sealing assembly may be
mounted on base pipe by operators on-site in response to locally
identified requirements.
[0027] Alternatively, the support assembly may be permanently
secured to at least one of the sleeve and base pipe, for example by
welding, integrally forming, clamping or the like.
[0028] The support assembly may comprise a support member, such as
a rib, extending between the sleeve and the base pipe. The support
member may extend through or across the flow path, or across at
least one fluid port providing fluid communication into the flow
path. The support assembly may comprise a plurality of support
members which may be circumferentially distributed between the
sleeve and base pipe. The support member may directly engage at
least one of the sleeve and base pipe. Alternatively, the support
assembly may comprise at least one mounting element, wherein the
support member engages at least one of the sleeve and base pipe via
a mounting element. The mounting element may comprise a ring
adapted to be mounted on one of the sleeve and base pipe.
[0029] In one embodiment the support assembly may comprise a first
mounting element adapted to be mounted on the sleeve and a second
mounting element adapted to be mounted on the base pipe, and at
least one support member extending between the first and second
mounting elements. The first and second mounting elements may be
adapted to be releasably secured to the sleeve and base pipe,
respectively. In a preferred arrangement the mounting elements may
be adapted to be releasably secured by a clamping arrangement, such
as by grub screws. This arrangement advantageously eliminates the
requirement to penetrate the sleeve and base pipe which may
establish a leak path.
[0030] The sleeve may be rigidly mounted relative to the base pipe
such that relative movement therebetween is not permitted.
[0031] Alternatively, the sleeve may be adapted to be non-rigidly
or releasably mounted relative to the base pipe such that relative
movement therebetween is permitted. This arrangement advantageously
permits the base pipe to be reciprocated relative to the sleeve to,
for example, jar the sleeve and assist to unstick or assist passage
of the sealing assembly from or through a tight spot within a well
bore as the sealing assembly is run into the bore. Additionally,
permitting the base pipe to be moveable relative to the sleeve will
enable the base pipe, and any associated tubing string, to be moved
after the sealing assembly has established a seal. This may
therefore allow manipulation of the base pipe and associated tubing
string during a cementing operation, for example, which may be
desirable to assist in the uniform flow of cement within the
annulus.
[0032] The sleeve may be adapted to be axially slidably mounted or
alternatively, or additionally, rotatably mounted relative to the
base pipe. The sleeve may be adapted to slide axially on the base
pipe between axial limits defined on the base pipe. At least one
axial limit may be defined by a connector disposed on an end of the
base pipe to permit the base pipe to be connected to a tubing
string. Alternatively, or additionally, at least one axial limit
may be defined by a collar mounted on the base pipe.
[0033] The sealing assembly may comprise a band of swellable medium
disposed on the sleeve. The band may continuously extend around the
outer surface of the sleeve or alternatively may extend
discontinuously. In one embodiment a plurality of bands of
swellable medium may be provided and disposed axially along the
sleeve. The bands may be directly adjacent or spaced apart at
regular or irregular intervals. The bands may comprise the same
swellable material, or alternatively different swellable material.
For example, at least one band may comprise a swellable material
adapted to be activated by water, and at least one band may
comprise a swellable material adapted to be activated by
hydrocarbons.
[0034] The sealing assembly may further comprise a swellable medium
disposed inside the sleeve. The swellable medium within the sleeve
may be adapted to establish a seal in the flow path. The swellable
medium disposed both outside and inside the sleeve may be of the
same material, or alternatively of different materials. The
swellable medium disposed both outside and inside the sleeve may be
adapted to swell at the same rate, or alternatively different
rates. In one embodiment the swellable medium inside the sleeve may
be adapted to swell at a slower rate that the swellable medium
disposed on the outer surface of the sleeve. In this arrangement
the outer swellable medium may be permitted to establish a seal
within a bore while allowing flow through the flow path, wherein
the flow path may be subsequently sealed by the inner swellable
medium.
[0035] The swellable medium may be disposed on an inner surface of
the sleeve, or alternatively, or additionally on an outer surface
of the base pipe.
[0036] The sleeve may be adapted to be mounted on a plurality of
base pipes.
[0037] A plurality of sleeves may be adapted to be mounted on a
single base pipe.
[0038] The base pipe upon which the sleeve is mounted may form part
of the sealing assembly of the present invention.
[0039] The sealing assembly may be adapted to provide downhole
mechanical support. For example, the sealing assembly may be
adapted to support the base pipe, and any associated tubing string,
for example, within a wellbore. In one embodiment the sealing
assembly may be adapted to function as a tubing hanger. In this
arrangement the sealing assembly may be adapted to be located
within a wellbore, such as within a lower end of an existing tubing
string, and the swellable medium permitted to swell to engage an
inner surface of the wellbore to thus provide a support or hanger
for the base pipe. The flow path may provide fluid communication
across the established support of hanger which may be beneficial in
permitting annulus fluid to be displaced during a subsequent
cementing operation.
[0040] According to a second aspect of the present invention, there
is provided a downhole sealing assembly comprising:
[0041] a base pipe; and
[0042] a sleeve mounted on the base pipe and comprising a swellable
medium, a flow path being defined between the base pipe and the
sleeve.
[0043] According to a third aspect of the present invention, there
is provided a method of establishing a downhole seal, said method
comprising the steps of:
[0044] providing a base pipe;
[0045] mounting a sleeve on the base pipe to define a flow path
therebetween, wherein the sleeve comprises a swellable medium;
[0046] running the base pipe into a wellbore; and
[0047] causing the swellable medium to swell to establish a
seal.
[0048] The swellable medium may establish a seal against a wall of
the wellbore.
[0049] The method may comprise the step of locating the sleeve at a
desired location in the wellbore. Furthermore, the method may
comprise the step of determining the desired location, for example
by performing wellbore logging, which logging may be performed
prior to or alternatively or additionally during the step of
running the base pipe into the wellbore.
[0050] The method may comprise the step of coupling the base pipe
to a tubing string and running the base pipe into the wellbore on
the tubing string.
[0051] The method may comprise the step of mounting a plurality of
sleeves on the base pipe.
[0052] The method may comprise the step of providing a plurality of
base pipes and mounting at least one sleeve on each base pipe, and
subsequently running the base pipes into the wellbore. The
plurality of base pipes may be coupled to each other, either
directly or indirectly via intermediate tubular members.
[0053] The swellable medium may be caused to swell by exposure to
an activator, such as water, hydrocarbons, heat pressure or the
like, or any suitable combination thereof. The swellable medium may
be caused to swell once the desired depth is achieved.
Alternatively, the swellable medium may be caused to swell during
deployment into the wellbore and prior to reaching the required
depth.
[0054] The method may further comprise the step of flowing cement
into a wellbore and permitting the cement to flow through the flow
path defined between the sleeve and the base pipe. Accordingly, a
combined seal may be established between the base pipe and the wall
of the wellbore, including the swellable medium and the cement. The
swellable medium may provide additional sealing assurance to
accommodate any possible failure or reduction in the sealing
integrity of the cement. The cement may be flowed into the wellbore
prior to the swellable medium fully establishing a seal.
Preferably, the swellable medium is adapted to fully establish the
seal before the cement cures. This arrangement therefore permits
the swellable medium to displace the cement in order to establish
the seal.
[0055] In one embodiment the base pipe may comprise a cement shoe,
or at least a portion of a cement shoe.
[0056] According to a fourth aspect of the present invention, there
is provided a method of completing a wellbore, said method
comprising the steps of:
[0057] providing a tubing string;
[0058] mounting at least one sleeve on an outer surface of the
tubing string to define a flow path therebetween, wherein the
sleeve comprises a swellable medium;
[0059] running the tubing string into a wellbore;
[0060] causing the swellable medium to swell; and
flowing cement into the annulus formed between the tubing string
and a wall of the wellbore, wherein cement flows through the flow
path.
[0061] The tubing string may comprise a casing tubing string, liner
tubing string or the like, or any suitable combination thereof.
[0062] According to a fifth aspect of the present invention, there
is provided a cement shoe comprising:
[0063] a tubular body adapted to be mounted on a lower end of a
tubing string;
[0064] a sleeve including a swellable medium mounted on the tubular
body; and
a flow path defined between the tubular body and the sleeve.
[0065] According to a sixth aspect of the present invention, there
is provided a downhole support assembly including a sleeve
comprising a swellable medium and adapted to be mounted on a base
pipe and define a flow path therebetween.
[0066] In use, the base pipe supporting the sleeve may be
positioned within a bore, and the swellable medium activated to
swell to engage an inner surface of the bore to thus secure and
support the base pipe within the bore.
[0067] The support assembly may be adapted to support the base pipe
and any associated tubing string. In one embodiment the support
assembly may be adapted to function as a tubing hanger.
[0068] The flow path may provide fluid communication across the
established support or hanger which may be beneficial in permitting
annulus fluid to be displaced during a subsequent cementing
operation.
[0069] According to a seventh aspect of the present invention,
there is provided a method of supporting a tubular body within a
bore, said method comprising the steps of:
[0070] mounting a sleeve comprising a swellable medium on the
tubular body to define a flow path between the sleeve and the
body;
[0071] running the tubular body into a bore; and
[0072] activating the swellable medium to engage a wall of the
bore.
[0073] The form and function of the components of the sealing
assembly defined above in connection with the first aspect may be
applied within or in combination with the invention defined by the
second to seventh aspects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0074] These and other aspect of the present invention will now be
described, by way of example only, with reference to the
accompanying drawings, in which:
[0075] FIG. 1 is a diagrammatic representation of a sealing
assembly in accordance with an embodiment of aspects of the
invention;
[0076] FIG. 2 is a longitudinal cross-sectional view of the sealing
assembly of FIG. 1;
[0077] FIG. 3 is an enlarged view of a support member portion of
the sealing assembly of FIG. 1;
[0078] FIG. 4 is a diagrammatic representation of the sealing
assembly of FIG. 1 shown in use at one location within a
wellbore;
[0079] FIG. 5 is a diagrammatic representation of the sealing
assembly of FIG. 1 shown in use at an alternative location within a
wellbore and forming part of a cement shoe;
[0080] FIG. 6 is a lateral cross-sectional view of a sealing
assembly according to an alternative embodiment of the present
invention;
[0081] FIG. 7 is a lateral cross-sectional view of a further
alternative embodiment of the present invention;
[0082] FIG. 8 is a lateral cross-sectional view of another
alternative embodiment of the present invention; and
[0083] FIG. 9 is a diagrammatic representation of the sealing
assembly of FIG. 1 functioning as a tubing hanger.
DETAILED DESCRIPTION OF THE DRAWINGS
[0084] Reference is first made to FIGS. 1 and 2 of the drawings in
which there is shown a sealing assembly, generally identified by
reference numeral 10, in accordance with an embodiment of the
present invention, wherein FIG. 2 is a longitudinal cross-sectional
view through the assembly 10. The sealing assembly 10 comprises a
sleeve 12 which is mounted on a base pipe 14, which in the
embodiment shown is a pup joint length of casing. The sleeve 12 is
concentrically mounted on the base pipe 14 via support assemblies
or caps 16 which are positioned at axially opposed ends of the
sleeve 12. The support caps 16 will be described in further detail
below.
[0085] An annular flow path 18 (FIG. 2) is defined between the
outer surface of the base pipe 14 and an inner surface of the
sleeve 12. Axially opposed annular ports 20 are defined between the
open ends of the sleeve 12 and the outer surface of the base pipe
14, wherein the ports 20 permit fluid communication to and from the
annular flow path 18. A plurality of circumferential bands of
swellable material 22 are distributed along the length of the outer
surface of the sleeve 12. The swellable material is adapted to
swell upon exposure to a particular activator, such as water,
hydrocarbons, drilling mud, cement of the like. Each band 22 may be
formed of the same material, or alternatively the bands 22 may be
formed of different materials, depending upon user requirements.
For example, adjacent bands 22 may contain swellable material which
is adapted to be activated by water and hydrocarbons
respectively.
[0086] In use, the base pipe 14 may be connected at either end
thereof to a tubing string (now shown) via end connectors 24 and
subsequently run into a wellbore (not shown) to position the sleeve
12 at a desired depth. When the swellable material within the bands
22 is exposed to a particular activator, the material will be
caused to swell and therefore radially expand to fill the annulus
between the sleeve 12 and the wall of the wellbore within which the
sealing assembly 10 is located. Accordingly, the sealing assembly
10 may be adapted to establish a seal against a particular section
within a wellbore. The flow path permits fluid communication past
the seal established by the bands 22. Additionally, the flow path
18 will permit fluids resident in the wellbore to be displaced
therethrough when the sealing assembly 10 is run into the wellbore.
This may therefore assist to prevent the occurrence of hydraulic
locking, particularly when the bands of swellable material describe
a diameter similar to the wellbore and provide little if any
external clearance. Use of the sealing assembly 10 will be
described in further detail below.
[0087] Reference is now additionally made to FIG. 3 of the drawings
in which there is shown an enlarged view of one of the support caps
16 of the sealing assembly 10. Each support cap 16 comprises a
first mounting element or ring 26 which is mounted on the outer
surface of the base pipe 14, and a second mounting element or ring
28 which is mounted on the outer surface of the sleeve 12 at an end
thereof. A plurality of support members or ribs 30 extend between
the first ring 26 and second ring 28 to concentrically mount the
sleeve 12 on the base pipe 14. The support ribs 30 are evenly
circumferentially distributed around the support assembly 16 and
the spaces defined between each adjacent rib 30 collectively define
the annular port 20 which allows or permits fluid communication to
and from the annular flow path 18.
[0088] The second ring 28 defines a plurality of circumferentially
distributed screw holes 32 which permit the second mounting ring 28
and thus the support cap 16 to be secured to the sleeve 12 via
suitable screws. In a preferred embodiment the screws are grub
screws and are adapted to clamp against the outer surface of the
sleeve 12.
[0089] The first ring 26 also comprises a plurality of
circumferentially distributed screw holes 34 which permit the ring
26 and thus support assembly 16 and sleeve 12 to be secured to the
base pipe 14 via suitable screws. In one embodiment the screws are
grub screws adapted to clamp against the outer surface of the base
pipe 14. This arrangement is particularly advantageous in that
penetration of the base pipe 14 is not required and as such a leak
path is not established, and that welding equipment and the like
need not be provided or used to secure the support assembly 16 to
the sleeve 12 and the support assembly 16 to the base pipe 14.
[0090] In embodiments of the invention, the sleeve 12 may be
secured on the base pipe 14 in the manner described above. However,
in alternative embodiments the sleeve 12 may remain unsecured to
the base pipe 14 such that the sleeve 12 may be permitted to slide
axially. In this arrangement the sleeve 12 may be limited to slide
on the base pipe 14 between the connectors 24 (FIGS. 1 and 2) which
will be engaged by the respective first rings 26 of each support
cap 16. This sliding arrangement advantageously permits the base
pipe 14 to be reciprocated relative to the sleeve 12 to, for
example, jar the sleeve 12 and assist to unstuck or assist passage
of the sealing assembly 10 from or through a tight spot within a
wellbore.
[0091] Reference is now made to FIG. 4 of the drawings in which the
sealing assembly 10 first shown in FIG. 1 is shown diagrammatically
in use within a subterranean wellbore 36. In the example shown the
wellbore 36 extends through a first earth formation 38 which
predominately contains hydrocarbons, such as oil, and a second
earth formation 40 which predominately contains water.
[0092] Conventionally, a tubing string such as a liner string would
be run into a wellbore, similar to wellbore 36, and subsequently
cemented in place to therefore prevent fluids from different earth
formations, such as formations 38, 40 from entering the annulus
between the liner tubing and the bore wall. Perforations may then
be formed within the liner string using explosive charges to open a
preferred formation, such as formation 38, to the string. However,
on many occasions the sealing integrity of the annulus cement is
inefficient or is reduced over time, for example, by the formation
of cracks, flow channels, micro-annuli and the like. Such flow
passages and the like may permit fluid from a closed formation,
such as formation 40 to migrate along the annulus towards the open
formation 38 and subsequently be produced to surface, which may be
undesirable. In one use of the present invention, as shown in FIG.
4, the sealing assembly 10 seeks to address this problem.
[0093] Specifically, the sealing assembly 10 incorporating the
sleeve 12 and base pipe 14 is coupled to a liner string 42 via the
connectors 24. The liner string 42 may then be run into the
wellbore 36 to locate the sealing assembly 10 adjacent formation
40. The location of the formation 40 may be determined by use of
conventional logging techniques such as open hole logging, logging
while drilling or the like.
[0094] The sealing assembly 10, and in particular the bands of
swellable material 22, may be of a diameter equal to the diameter
of the drill bit which was used to drill the wellbore section 36.
Thus, only a relatively limited degree of swelling, and a limited
time, is required to obtain a sealing contact between the swellable
material 22 and the wellbore wall. Disadvantages normally
associated with such tight sizing are avoided by various features
of the assembly. Fluid displaced by the descending tubing string
may pass through the flow path 18 between the sleeve 12 and the
base pipe 14, and does not have to negotiate the small gap between
the sealing assembly 10 and the wellbore wall. Also, the swellable
material 22 is elastomeric and has a degree of compliancy.
Furthermore, if the swellable material 22 is worn or damaged by
contact with the bore wall such wear and damage will tend to have
little if any effect on sealing performance as adjacent swellable
material will tend to swell into and occupy areas of damage or
wear. The thickness of swellable material provided in the assembly
will also be selected to provide an excess of swelling capacity
such that, for example, a loss of some material through wear, will
not compromise the assembly's sealing capability.
[0095] The bands 22 of swellable material may then be activated to
swell to engage the bore wall and thus seal the formation 40. The
swellable material may be adapted to swell when exposed to water
within the well bore 36, and the swelling process may begin while
the liner string 42 incorporating the sealing assembly 10 is being
run into the well bore 36. Accordingly, the bands of sealing
material 22 may be almost entirely swollen to the desired sealing
diameter when total depth is achieved, thus further decreasing the
swelling and sealing time at the required depth.
The annulus 44 formed between the wall of the bore 36 and the outer
surface of the liner string 42 may be filled with cement 46 in a
conventional manner, wherein the flow path 18 defined between the
sleeve 12 and base pipe 14 permits the cement to bypass the seal
established by bands 22 and therefore fill the portion of the
annulus 44 located above the sealing assembly 10.
[0096] Accordingly, the sealing assembly 10 may be used in
combination with a conventional cementing operation to assure that
sufficient sealing integrity will be achieved, particularly at
locations, such as at the location of formation 40 where
conventional cement sealing is known to be ineffective or
inefficient. Additionally, annulus sealing at the desired location
utilising the sealing assembly 10 of the present invention is not
dependent upon the cement 46 making a sufficient bond with the
borewall. Furthermore, any movement of the sealing assembly 10
relative to the borewall after a seal is initially established will
be accommodated by further swelling of the bands 22 to thus
continually maintain a seal.
[0097] It should be noted that subsequent to the cementing process,
cement will be cured to seal the flow path 18. In this respect, the
inner surface of the sleeve 12 and outer surface of the base pipe
14 will provide a clean surface to ensure bonding of the cement
thereto. Additionally, thermal expansion of the base pipe 14 and
sleeve 12 should occur at substantially the same rate and as such
should not impart significant stresses into the cement which may
otherwise cause damage thereof and create cracks and flow paths to
therefore reduce the integrity of the cement seal.
[0098] Once the liner string 42 is adequately sealed within the
wellbore 36, perforations 48 may be formed through the wall of the
liner string 42 and through the annulus cement 44 at the location
of formation 38 to therefore permit production of hydrocarbons.
[0099] It should be noted that any number of sealing assemblies 10
may be positioned axially along the length of the tubing string 42
in order to provide sealing assurance at any desired location
within the wellbore 36.
[0100] Reference is now made to FIG. 5 of the drawings in which the
sealing assembly 10 is shown in use at an alternative location
within a wellbore 36a and forming part of a cement shoe 50. The
cement shoe 50 is mounted on a lower end of a tubing string 52,
such as a casing string, and as such is adapted to be located
within the bottom of the bore 36a. The cement shoe 50 comprises a
plurality of ports 54 which permit cement 46 to exit the tubing
string 52 and cement shoe 50 and flow into the annulus 44a.
[0101] The bands of swelling material 22 may be activated to swell
to engage the wall of the bore 36a and thus establish a seal, while
the flowpath 18 formed between the base pipe 14 and sleeve 12
permits cement 46 to bypass the established seal and thus fill the
annulus 44a positioned above the sealing assembly 10.
[0102] Conventionally, following a cementing operation at least a
portion of the cement shoe 50 remains filled with cement which will
subsequently cure. Accordingly, if the wellbore 36a is to be
advanced, the cured cement within the cement shoe 50 will need to
be drilled through using an appropriate drilling assembly.
Accordingly, the cement shoe 50 and surrounding annulus 44a, cement
46 and formation 54 will be exposed to vibration and other
mechanical loading as a result of the drilling process. However,
the presence of the sealing assembly 10 forming part of the cement
shoe 50 will assist to ensure that sealing integrity within the
annulus 44a will be maintained.
[0103] A lateral cross-sectional view of a sealing assembly,
generally identified by a reference numeral 60, in accordance with
an alternative embodiment of the present invention is shown in FIG.
6, reference to which is now made. The sealing assembly 60 is
similar to sealing assembly 10 first shown in FIG. 1 and as such
comprises a base pipe 62 upon which is mounted a sleeve 64 to
define a flow path 66 therebetween. A swellable material 68, which
may be provided in a band arrangement as shown in the embodiment of
FIG. 1, is mounted on the outer surface of the sleeve 64.
[0104] The sleeve 64 is supported on the base pipe 62 via a
plurality of ribs 70 which extend between the outer surface of the
base pipe 62 and an inner surface of the sleeve 64. The ribs 70 may
be secured, either releasably or permanently, to either one of the
base pipe 62 and sleeve 64. Additionally, the ribs 70 may extend at
least partially along the length of the sleeve 64.
[0105] A further alternative embodiment of a sealing assembly
according to the present invention is shown in FIG. 7, reference to
which is now made. The sealing assembly, generally identified by
reference numeral 80, is similar to the assembly 60 shown in FIG.
6, and as such comprises a base pipe 82 which supports a sleeve 84
via ribs 90, wherein a flow path 86 is established between the base
pipe 82 and sleeve 84. A swellable material 88 is disposed on the
outer surface of the sleeve 84. Additionally, a further swellable
material 92 is disposed on the inner surface of the sleeve 84.
Accordingly, the swellable material 92 may be activated to swell to
seal the flow path 86. In embodiments of the invention, the
swellable material 92 on the inner surface of the sleeve 84 may be
adapted to swell at a different rate than the outer swellable
material 88. For example, the inner swellable material 92 may be
adapted to swell at a slower rate than the outer material 88. In
this arrangement, material 88 may swell to establish a necessary
seal against a bore wall, while the flow path 86 remains open to
allow fluid to bypass the established seal. The inner material 92
may subsequently fill the flow path 86 and therefore prevent
further fluid communication thereacross.
[0106] It should be noted that while the sleeve 84 is shown mounted
on the base pipe 82 via ribs 90, the sleeve 84 may alternatively be
mounted via a support cap 16 first shown in FIG. 1.
[0107] Reference is now made to FIG. 8 of the drawings in which
there is shown a lateral cross-sectional view of a sealing
assembly, generally identified by reference numeral 100, in
accordance with a further alternative embodiment of the present
invention. The sealing assembly 100 comprises a base pipe 102 which
supports an outer sleeve 104 via ribs 110, wherein the base pipe
102 and outer sleeve 104 collectively define a flow path 106. A
swelling material 108 is mounted on the outer surface of the sleeve
104. Additionally, a swellable material 112 is mounted on an outer
surface of the base pipe 102. The swellable material 112 may
therefore swell to seal the flow path 106.
[0108] It should be noted that a support cap arrangement 16 as
shown in FIG. 1 may alternatively be used to support the sleeve 104
on the base pipe 102 of the sealing assembly 100.
[0109] Reference is now made to FIG. 9 of the drawings in which a
sealing assembly according to an embodiment of the present
invention is shown in use as a tubing hanger. The sealing
assembly/tubing hanger, generally identified by reference numeral
120, is generally similar to any of the previously described
sealing assemblies 10, 60, 80, 100 described above, and as such
comprises a sleeve 122 which is mounted externally of a base pipe
124 to define a flow path 126 therebetween. Bands of swellable
material 128 are mounted on an outer surface of the sleeve 122. In
the embodiment shown the base pipe 124 forms part of a lower tubing
string 130.
[0110] In use, the sealing assembly/tubing hanger 120 is adapted to
secure the lower tubing string 130 to a lower end portion of an
upper tubing string 132. In use, the upper tubing string 132 may be
mounted within a first wellbore section 134 and subsequently
cemented in place. A second wellbore section 136 may then be
drilled and the lower tubing string 130 may be run into the second
wellbore section 136 such that the upper end of the lower tubing
string 130 overlaps with the lower end of the upper tubing string
132. The bands of swellable material 128 may be activated to swell
to engage the inner surface of the upper tubing string 132 to
therefore secure the lower tubing string 130 relative to the upper
tubing string 132. The lower tubing string 130 may subsequently, or
simultaneously, be cemented in place within the second wellbore
section 136. Advantageously, the flow path 126 may permit fluids to
be displaced from the second wellbore section 136 during the
cementing operation.
[0111] Although not shown in FIG. 9, the flow path 126 may
incorporate a further swellable material which may be adapted to
swell to subsequently seal the flow path 126, for example after the
lower tubing string 130 has been cemented in place.
[0112] It should be understood that the embodiments described above
are merely exemplary and that various modifications may be made
thereto without departing from the scope of the present invention.
For example, the swellable material disposed on the outer surface
of the sleeve may be provided as a continuous band. Additionally,
the sleeve may be supported on the base pipe by any suitable
support means which permit a flow path to be maintained.
Furthermore, the sleeve is shown in the various embodiments being
concentrically mounted on the base pipe. However, in alternative
embodiments the sleeve may be eccentrically mounted. One or more
collars may be mounted on the base pipe which may be used to limit
axial sliding of the sleeve thereon.
[0113] The sealing assembly may be utilised at any location within
a wellbore where a seal is required to be established against a
bore wall. Additionally, although the embodiments described above
demonstrate the sealing assembly being used in combination with a
cementing process, it should be understood that the sealing
assembly is not adapted exclusively for use as such.
[0114] Furthermore, the base pipe may comprise any downhole
tubular, such as a casing tubular, production tubular, drilling
tubular, liner tubular or the like.
* * * * *