Note: Descriptions are shown in the official language in which they were submitted.
CA 02564290 2006-10-30
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DOWNHOLE SEALING FOR PRODUCTION TUBING
This is a divisional application of Canadian Patent
Application Serial No. 2,356,131 filed on December 22, 1999.
This invention relates to downhole sealing, and to an
apparatus and method for use in forming an arrangement to
allow creation of a downhole seal. In particular, but not
exclusively, the invention relates to the provision of a seal
or packer between concentric downhole tubing, such as bore
lining casing and production casing.
It should be understood that the expression "the
invention" and the like encompasses the subject-matter of
both the parent and the divisional applications.
In tha oil and gas exploration and production
industry, bores are drilled to access hydrocarbon-bearing
rock formations. The drilled bores are lined with steel
tubing, known as casing, which is cemented in the bore.
Oil and gas are carried from the hydrocarbon-bearing or
production formation to the surface through smaller
diameter production tubing which is run into the fully-
cased bore. Typical production tubing incorporates a .
number of valves and other devices which are employed, for
example, to allow the pressure integrity of the tubing to
be tested as it is made up, and to control the flow of
fluid through the tubing. Further, to prevent fluid from
passing up the annulus between the inner wall of the casing
and the outer wall of the production tubing, at least one
seal, known as a packer, may be provided between the tubing
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and the casing. The tubing will normally be axially
movable relative to the packer, to accommodate expansion of
the tubing due to heating and the like. The packer may be
run in separately of the tubing, or in some cases may be
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2
run in with the tubing. In any event, the packer is run
into the bore in a retracted or non-energised position, and
at an appropriate point is energised or "set" to fix the
packer in position and to form a seal with the casing. A
typical packer will include slips which grip the casing
wall and an elastomeric sealing element which is radially
deformable to provide a sealing contact with the casing
wall and which energises the slips. Accordingly, a ~ , ''
conventional .packer has a significant thickness, thus . '
reducing the available bore area to accommodate the
production tubing. Thus, to accommodate production tubing
of a predetermined diameter, it is necessary to provide
relatively large diameter casing, and thus a relatively
large bore, with the associated increase in costs and
.,:
drilling time. Further, the presence of an elastomeric
element in conventional packers limits their usefulness in
high temperature applications.
It is among the objectives of embodiments of the
present invention to provide a means of sealing production
tubing relative to casing which obviates the requirement to
i
provide a conventional packer, by providing a relatively
compact or "slimline" sealing arrangement which does not
require the provision of slips and elastomeric elements to
lock the arrangement in the casing.
According to one aspect of the present invention there
is provided a method of providing a downhole seal in' a
drilled bore between inner tubing and outer tubing, the
method comprising: providing an intermediate tubing section
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defining means for sealingly engaging with the inner
tubing; and plastically deforming the intermediate tubing
section downhole to form an annular extension, said
extension creating a sealing contact with the outer tubing.
The invention also relates to a downhole seal as
formed by this method.
The invention thus permits the formation of a seal
between inner and outer tubing without requiring the
provision of a conventional packex or the like externally
of the inner tubing. In the preferred embodiment, the
intermediate tubing section ie of metal and the invention
may thus be utilised to create a metal-to-metal seal
between the intermediate tubing section and the outer
tubing. The sealing means between the intermediate tubing
section and the inner tubing may be of any appropriate
form, including providing the intermediate tubing section
with a polished bore portion and providing the inner tubing
with a corresponding outer wall portion defining
appropriate sealing bands of elastomer, which permits a
degree of relative axial movement therebetween. In other
embodiments, the sealing means may be in the form of a
fixed location seal. In other aspects of the invention the
intermediate tubing may be omitted, that is the inner
tubing itself may be deformed to engage the outer tubing.
The outer tubing may be elastically deformed and thus
grip the extension, most preferably the deformation
resulting from contact with the extension as it is Formed.
In certain embodiments, the outer tubing may also be
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subject to plastic deformation. Accordingly, the outer
tubing need not be provided with a profile or other
arrangement for engagement with the intermediate tubing
portion prior to the formation of the coupling.
Preferably, the inner tubing is production tubing, or
eome other tubing which is run into a drilled bore
subsequent to the outer tubing being run into the bore.
Preferably also, the outer tubing is bore-lining casing.
Accordingly, this embodiment of the invention may be
utilised to obviate the need to provide a conventional
production packer, as the intermediate tubing section forms
a seal with the outer tubing and sealingly receives the
inner tubing. This offers numerous advantages, one being
that the inner tubing may be of relatively large diameter,
there being no requirement to accommodate a conventional
packer between the inner and outer tubing; in the preferred
embodiments, the intermediate tubing section requires only
a thickness of metal at the sealing location with the outer
tubing, and does not require the provision of anchoring
elipe or a mechanism far allowing slips or a resilient
element to be energised and maintained in an energised
condition. Alternatively; the outer tubing may be of
relatively small diameter to accommodate a given diameter
of inner tubing, reducing the costs involved in drilling
the bore to accommodate the outer tubing.
Preferably, said deformation of the intermediate
tubing section is at least partially by compressive yield,
most preferably by rolling expansion, that is an expander
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member is rotated within the tubing section with a face in
rolling contact with an internal face of said section to
roll the tubing section between the expander member arid the
tubing section. Such rolling expansion causes compressive
5 plastic deformation of the tubing section and a localised
reduction in wall thickness resulting in a subsequent
increase in diameter. The expander membex may describe the
desired inner diameter of the extension, and is preferably
' urged radially outwardly into contact with the section
inner diameter; the expander member may move radially
outwardly as the deformation process progresses,
progressively reducing the wall thickness of the
intermediate tubing section.
Preferably, at the extension, the intermediate tubing
section is deformed such that an inner thickness of the
tubing section wall is in compression, and an outer
thickness of the wall is in tension. This provides a more
rigid and robust structure.
At least a degree of deformation of the intermediate.
section, most preferably a degree of initial deformation,
may be achieved by other mechanisms, for example by
circumferential yield obtained by pushing or pulling a cone
.or the like through the intermediate section, or by a
combination of compressive and circumferential yield
obtained by pushing or pulling a cone provided with
inclined rollers or rolling elements.
Preferably, the intermediate tubing section is
plastically deformed at a plurality of axially spaced
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locations to form a plurality of annular extensions.
..
Preferably, relatively ductile material, typically a
ductile metal, is provided between the intermediate tubing
section and the outer tubing, and conveniently the material
is carried on the outer surface of the intermediate tubing
section, Thus, on deformation of the intermediate tubing
section the ductile material will tend to flow or deform
away from the points of contact .between the lees ductile --
material of the intermediate tubing and the outer tubing,
creating a relatively large contact area; this will improve
the quality of the seal between the sections of tubing.
Most preferably, the material is provided in the form of a '
plurality of axially spaced bands, between areas of the
intermediate tubing section which are intended to be
subject to greatest deformation. The intermediate tubing
section and the outer tubing will typically be foi-reed of
steel, while the relatively ductile material may be copper,
a lead/tin alloy or another relatively soft metal, or may
even be an elastomer.
f
Preferably, relatively hard material may be provided
between the intermediate tubing section and the outer
tubing, such that on deformation of the intermediate tubing
section the softer material of one or both of the
intermediate tubing section and the outer tubing deforms to
accommodate the harder material and thus facilitates in
securing the coupling against relative axial or rotational
movement. Most preferably, the relatively hard material is
provided in the form of relatively small individual
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elements, such as sharps, grit or balls of carbide or some
other relatively hard material, although the material may
be provided in the form of continuous bands or the like.
Most preferably, the relatively hard material is carried in
a matrix of relatively ductile material.
Preferably, the method comprises the step of running
an expander device into the bore within the intei~tnediate
tubing section and energising the expander device to
radially deform at least the intermediate tubing section.
The expander device is preferably fluid actuated, but may
alternatively be mechanically activated. The device may be
run into the bore together with the intermediate tubing
section or may be run into the bore after the tubing
section. Preferably, the device defines a plurality of
circumferentially spaced tubing engaging portions, at least
one of which is radially extendable, and is rotated to
create the annular extension in the tubing section. Most
preferably, an initial radial extension of said at least
one tubing engaging portion, prior to rotation of the
device, creates an initial contact between the intermediate
tubing section and the casing which is sufficient to hold
the tubing section against rotation.
As noted above, in other aspects of the invention the
intermediate tubing section may be omitted, or provided
integrally with the inner tubing. For example, the inner
tubing may be production tubing and may be deformed to
engage surrounding casing. Embodiments of this aspect of
the invention may include some or all of the various
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preferred features of the first-mentioned aspect of the ' w
invention, and may be installed using substantially similar
apparatus.
Other aspects of the invention relate to locating
tubing sections in existing tubing ~or use in other
applications, such as serving an a mounting or support for
a downhole device, such as a valve.
According to another aspect of the present invention
there is provided apparatus for use in forming a downhole
arrangement for permitting sealing between inner tubing and
outer tubing utilising an intermediate tubing section fixed
to and in sealing contact with the outer tubing and for
sealingly engaging the inner tubing, the apparatus for
location within the intermediate tubing section and
comprising a body carrying a plurality of circumferentially
spaced tubing engaging portions, at least one of the tubing
engaging portions being radially extendable to plastically
deform the intermediate tubing section, the body being
rotatable to form an annular extension in the intermediate
tubing section for sealing engagement with the outer
tubing.
The invention also relates to the use of ouch an
apparatus to form said downhole arrangement.
Preferably, the apparatus comprises at least three
tubing engaging portions.
Preferably, the tubing engaging portions define
rolling surfaces, such that following radial extension of
said at least one tubing engaging portions the body may be
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rotated, with the tubing engaging portions in contact with
the intermediate tubing section, to create the intermediate
tubing section extension, In other embodiments the
extension may be created in a step-wise fashion.
Most preferably, the tubing engaging portions are in
the form of radially movable rollers. The rollers may have
tapered ends for cooperating with inclined supports. At
least one of the supports may be axially movable, such
movement inducing radial movement of the rollers.
Preferably also, each roller defines a circumferential rib,
to provide a small area, high pressure contact surface.
Preferably, said at least one tubing engaging portion
is fluid actuated. Most preferably, the tubing engaging
portion is coupled to a piston; by providing a relatively
large piston area with .respect to the area of the portion
which comes into contact with the tubing it is possible to
produce high pressure forces on the tubing, allowing
deformation of relatively thick and less ductile materials,
such as the thicknesses and grades of steel conventionally
used in downhole tubing and casing. Most preferably, a
support for the tubing engaging portion is coupled to a
piston, preferably via a bearing or other means which
permits relative rotational movement therebetween.
The apparatus may be provided in conjunction with a
downhole motor, or the apparatus may be rotated from
surface .
The apparatus may further include other tubing
expansion arrangements, particularly for achieving initial
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deformation of the tubing, such as cones, which cones may
include inclined rollers.
The apparatus may be provided in combination with an
intermediate tubing section.
In other aspects of the invention, the apparatus may
be utilised to locate a tubing section for use in other
applications, for example as a mounting for a valve or
other device, in a bore.
According to an aspect of the invention there is
provided a method of providing a downhole seal in a drilled
bore between inner tubing and outer tubing, the method
comprising:
providing an intermediate tubing section defining means
for sealingly engaging with the inner tubing; and
plastically deforming the intermediate tubing section
downhole to form an annular extension, said extension
creating a sealing contact with the outer tubing;
wherein the deformation is accomplished with at least two
radially extendable members that are fluid actuated.
According to another aspect of the invention there is
provided a method of providing a downhole seal in a drilled
bore between inner tubing and outer tubing, the method
comprising:
providing an intermediate tubing section defining means
for sealingly engaging with the inner tubing; and
deforming a portion of the intermediate tubing section
downhole by compressive plastic deformation with a
localised reduction in wall thickness resulting in a
subsequent increase in diameter of the intermediate tubing
section to form an annular extension, said extension
forming a sealing contact with the outer tubing;
wherein the deformation is accomplished with at least two
radially extendable members that are fluid actuated.
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10a
According to a further aspect of the invention there
is provided an apparatus for use in forming a downhole
arrangement for permitting sealing between inner tubing and
outer tubing utilizing and intermediate tubing section
fixed and in sealing contact with the outer tubing and for
sealingly engaging the inner tubing, the apparatus
comprising an intermediate tubing section and a body
carrying at least two circumferentially spaced tubing
engaging portions for location within the tubing section,
the at least two tubing engaging portions being fluid
actuated and radially extendable to plastically deform a
portion of the intermediate tubing section, the, body being
rotatable to form an annular extension in the intermediate
tubing section for sealing engagement with the outer
tubing.
According to a further aspect of the invention there
is provided a packer for providing a downhole seal in a
drilled bore between inner tubing and outer tubing, the
packer comprising an intermediate tubing section defining
means for sealingly engaging with the inner tubing and a
radially plastically deformed annular extension for sealing
contact with the outer tubing, wherein the deformation is
accomplished with at least two radially extendable members
that are fluid actuated.
According to a further aspect of the invention there
is provided a method of providing a downhole seal in a
drilled bore between inner tubing and outer tubing, the
method comprising: plastically deforming at least a portion
of the inner tubing downhole to form an annular extension,
said extension creating a sealing contact with the outer
tubing, wherein the deformation is accomplished with at
least two radially extendable members that are fluid
actuated.
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According to a further aspect of the invention there
is provided a packer arrangement comprising outer and inner
tubing for location downhole, the inner tubing having a
radially plastically deformed annular extension for sealing
contact with the outer tubing, wherein the deformation is
accomplished with at least two radially extendable members
that are fluid actuated.
According to a further aspect of the invention there
is provided an apparatus for providing a sealing connection
with outer tubing in a drilled bore to permit an item
operatively associated with the apparatus to be sealingly
located in the bore, the apparatus comprising a tubing
section having a radially plastically deformed annular
extension for sealing contact with the outer tubing and a
non-deformed section for cooperating with the item to be
located in the bore, wherein the deformation is
accomplished with at least two radially extendable members
that are fluid actuated.
According to a further aspect of the invention there
is provided an apparatus for use in forming a seal between
an inner tubing and an outer tubing, using an intermediate
tubing section in sealing contact with the outer tubing for
creating a sealed engagement between the inner and outer
tubings, the apparatus comprising:
an intermediate tubing section; and
a body with at least two circumferentially spaced tubing
engaging portions for location within the tubing section,
the tubing engaging portions being fluid actuated and
radially extendable to plastically deform a portion of the
intermediate tubing section to form an annular extension in
the intermediate tubing section for sealing engagement with
the outer tubing.
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According to a further aspect of the invention there
is provided a method of sealing an annular area in a
wellbore comprising:
providing a tubular member;
deforming the tubular member in a manner whereby an outer
surface of the tubular assumes a shape of a non uniform
inner surface of an outer tubular therearound and forms a
seal therebetween, wherein the deformation is accomplished
with at least two radially extendable members that are
fluid actuated.
According to a further aspect of the invention there
is provided an apparatus for forming a seal between and
inner tubular and an outer tubular, the apparatus
comprising:
a body disposable within the inner tubular, the body
having at least two radially extendable, fluid actuated
members to expand an outer surface of the inner tubular
into sealing contact with the outer tubular.
According to a further aspect of the invention there
is provided a method of providing a downhole seal in a
wellbore, the wellbore having a lined portion, the method
comprising:
running a first tubular into the wellbore, the first
tubular having a polished bore portion and an expandable
portion;
suspending the first tubular at a selected depth within
the wellbore, wherein at least the expandable portion of
the first tubular is in an overlapping relationship with
the lined portion of the wellbore;
expanding the expandable portion of the first tubular,
wherein the expandable portion of the first tubular is
sealingly engaged to the lined portion of the wellbore,
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lOd
wherein the deformation is accomplished with at least two
radially extendable members that are fluid actuated;
running a second tubular into the wellbore; and
mating a lower portion of the second tubular with the
polished bore portion of the first tubular, wherein the
lower portion of the second tubular is configured to
sealingly land into the polished bore portion of the first
tubular.
According to a further aspect of the invention there
is provided a method of providing a downhole seal in a
wellbore, the wellbore having a lined portion, the method
comprising:
running a first tubular into the wellbore, the first
tubular having a polished bore portion and an expandable
portion, wherein the polished bore portion is disposed
below the expandable portion;
suspending the first tubular at a selected depth within
the wellbore wherein at least the expandable portion of the
first tubular is in an overlapping relationship with the
lined portion of the wellbore;
expanding the expandable portion of the first tubular,
wherein the expandable portion of the first tubular is
sealingly engaged to the lined portion of the wellbore,
wherein the deformation is accomplished with at least two
radially extendable members that are fluid actuated;
running a second tubular into the wellbore; and
mating a lower portion of the second tubular with the
polished bore portion of the first tubular, wherein the
lower portion of the second tubular is configured to
sealingly land into the polished bore portion of the first
tubular.
According to a further aspect of the invention there
is provided a tubular for use with a downhole seal assembly
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10e
in a wellbore, the wellbore having a lined portion, the
tubular comprising:
an expandable portion, the expandable portion being
sealingly expandable against the lined portion of the
wellbore by a radial outward force applied on an inner wall
thereof, wherein the deformation is accomplished with at
least two radially extendable members that are fluid
actuated; and
a polished bore portion, the polished bore portion
configured to sealingly receive a second tubular.
According to a further aspect of the invention there
is provided an apparatus for use in forming a downhole seal
assembly in a wellbore, the wellbore having a lined
portion, the apparatus comprising:
at least two radially extendable members that are fluid
actuated; and
an axially movable means, wherein the axially movable
means can be selectively operated to mechanically direct
the at least two radially extendable members radially
outwards or inwards relative to the longitudinal axis of
the apparatus, thereby allowing the radially extendable
members to contact the inner surface of an expandable
portion of a tubular to sealingly engage the tubular with
the lined portion of the wellbore.
According to a further aspect of the invention there
is provided a method of sealing an annular area in a
wellbore, the method comprising:
providing a tubular member; and
deforming the tubular member in a manner whereby an outer
surface of the tubular member assumes a shape of a non-
uniform surrounding surface and forms a seal therebetween,
wherein the deformation is accomplished with at least two
radially extendable members that are fluid actuated.
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1 Of
According to a further aspect of the invention there
is provided a method of forming a profile in a section of
tubing within a wellbore, the method comprising:
providing an expander device having at least two radially
extendable expander members that are fluid actuated;
positioning the expander device in the wellbore at a
predetermined location in the section of tubing; and
extending the members to deform the tubing at said
location to create the profile in the internal face of the
tubing.
These and other aspects of the present invention will
now be described, by way of example, with reference to the
accompanying drawings, in which:
Figures 1 to 5 are schematic sectional views of
apparatus for use in forming a downhole arrangement for
permitting sealing between inner tubing and outer tubing
utilising an intermediate tubing section, and showing
stages in the formation of the downhole arrangement, in
accordance with a preferred embodiment of the present
invention;
Figure 6 is an enlarged perspective view of the
apparatus of Figure 1;
Figure 7 is an exploded view corresponding to Figure
6;
Figure 8 is a sectional view of the apparatus of
Figure 6; and
Figures 9 and 10 are schematic sectional views of
apparatus for use in forming a downhole sealing arrangement
in accordance with further embodiments of the present
invention.
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11
Reference is first made to Figures 1 of the drawings,
which illustrated apparatus in the form of an expander
device l0 for use in forming a downhole arrangement 12
(Figure 51 for permitting provision of a seal between inner
tubing, in the form of production tubing 11 (Figure 5), and
outer tubing, in the form of bore-lining casing 16,
utilising an intermediate tubing section 18. In Figure 1
the device 10 is illustrated located within the tubing
section 18 and is intended to-be run into a casing-lined
bore, with the section 18, on an appropriate running string
20. A running mandrel 22 extends from the lower end of the
device 10, and extends from the lower end of the tubing
section 18.
The general configuration and opez-ation of the device
10, and the "setting" of the tubing section 18, will be
described initially with reference to Figures 1 to 5 of the
drawings, followed by a more detailed description of the
device 10.
The device 10 comprises an elongate body 24 which
carries three radially movable rollers 26. The rollers 26
may be urged outwards by application of fluid pressure to
the body interior, via the running string 20. Each roller
26 defines a circumferential rib 28 which, as will be
described, provides a high pressure contact area. The
device l0 is rotatable in the bore, being driven either
from surface via the string 20, or by an appropriate
downhole motor.
The tubing section 18 comprises an upper relatively
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12
thin-walled hanger seal portion 30 and, welded thereto, a
thicker walled portion 32 defining a polished bore 34.
Once the tubing section 18 has been set in the casing 16,
the polished bore 34 allows an appropriate section of the
production tubing 11, typically carrying sealing bands, to
be located within the bore 34 and form a fluid-tight seal
therewith.
The seal portion 30 carries three axially-spaced seal
rings or bands 36 of ductile metal. Further, between the ' ;
bands 36, the seal. portion 30 is provided with grip banding
37 in the form of carbide grit 38 held in an appropriate
matrix.
To set the tubing section 18 in the casing 16, the
device 10 and tubing section 18 are run into the casing-
lined bore and located in a pre-selected portion of the
casing 16, as shown in Figure 1. At this point the tubing
section 18 may be coupled to the device 10, running mandrel-
22 or running string 20, by an appropriate releasable
connection, such as a shear ring. The outer diameter of
the tubing section 18 and the inner diameter of the casing
16 where the section 18 is to be located are closely
matched to provide limited clearance therebetween.
Fluid pressure is then applied to the interior of the
device body 24, causing the three rollers 26 to extend
radially outwardly into contact with the inner surface of
the adjacent area of the seal portion 30. The rollers 26
deform the wall of the seal portion 30 (to a generally
triangular form) such that the outer surface of the tubing
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section 18 comes into contact with the inner surface of the
casing 16 at three areas corresponding to the roller
locations. Further, the pressure forces created by the
rollers 26 may be sufficient to deform the casing 16, thus
creating corresponding profiles to accommodate the radial
extension of the intermediate tubing section 18. The
carbide grit 38 carried by the sealing section 30 is
pressed into the softer material of the opposing tubing
surfaces, keying the surfaces together.
This initial deformation of the intermediate tubing
section 18 is sufficient to hold the tubing section 18
against rotation relative to the casing 16.
The device l0 is then rotated relative to the tubing
section 18 with the rollers 26 in rolling contact with the
inner surface of the sealing portion 30, to create an
annular extension ~40a in the sealing portion 30 and a
corresponding profile 42a in the casing 16, as shown in
Figure 2. The deformation of the sealing portion 30 is by
rolling expansion, that is the rollers 26 are rotated
within the sealing portion 30 with the ribs 28 in rolling
contact with an internal face of the portion 30, with the
sealing portion 30 being restrained by the relatively
inflexible casing 16. Such rolling expansion causes
compressive plastic deformation of the portion 30 and a
localised reduction in wall thickness resulting in a
subsequent increase in diameter. In the illustrated
embodiment this increase in diameter of the sealing portion
also defozms the adjacent casing 16, to form the profile
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42a, by compression.
The device 10 is initially located in the intermediate
tubing section 18 such that the roller ribs 28 are located
adjacent one of the grip bands 37, such that on extension'
S of the rollers 26 and rotation of the device 10, the area
of greatest deformation at the extension 40a corresponds to
the grip band location. Following the creation of the
first extension 40a, the fluid pressure in communication
with the device l0 is bled off, allowing the rollers 26 to
retract. The device 10 is then moved axially by a
predetermined distance relative to the tubing section 18
before being energised and rotated once more to create a
second extension 40b and casing profile 42b, as shown in
Figure 3. If desired, this process may be repeated to
create subsequent extensions. The deformation at the two '
tubing section extensions 40a, 40b continues into the seal
bands 36; such that the bands 36 are brought into sealing
contact with the casing inner surface, between the areas of
greatest deformation of the tubing section 18, and flow or
deform as the bands 36 and the casing surface are
"squeezed" together; this creates fluid tight seal areas ~ , t
at least between the tubing section 18 and the casing 16.
Following creation of the second extension 40b, the
device 10 is retrieved from the bore, as illustrated in
Figure 4, leaving the deformed tubing section 18 fixed in
the casing 16.
The production tubing 11 is then run into the bore, as
shown in Figure S, a lower section of the tubing being of
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corresponding dimensions to the polished bore 34 of the
tubing section 18 and provided with appropriate seal bands
to provide a seal between the production tubing and the
intermediate tubing section 18.
5 The "set" intermediate tubing section 18 may thus be
seen to act in effect as a permanent packer, although the
configuration and "setting" procedure for the tubing
section 18 is quite different from a conventional packer.
It is apparent that the set tubing section 18 may only
l0 be removed by milling or the like, however the absence of
large parts of relatively hard materials, such as is used
in forming the slips of conventional packers, facilitates
removal of the tubing section 18.
Reference is now made to Figures 6, 7 and a of the
15 drawings, which illustrate the device 10 in greater detail.
The device body 24 is elongate and generally cylindrical,
and as noted above provides mounting for the three rollers
26. The rollers 26 include central portions each defining
a rib 28, and taper from the central portion to circular
bearing sections 50 which are located in zadially extending
slots 52 defined in body extensions 54 provided above and
below the respective roller-containing apertures~56 in the
body 24.
The radial movement of the rollers 26 is controlled by
conical roller supports 58, 59 located within the body 24,
the supports 58, 59 being movable towards and away from one
another to move the rollers radially outwardly and
inwardly. The roller supports 58, 59 are of similar
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16
construction, and therefore only one support 58 will be
described in detail as exemplary of both, with particular
reference to Figure 7 of the drawings. , The support 58
features a loading cone 60 having a conical surface 62 '
which corresponds to the respective conical surface of the
roller 26. The cone 60 is mounted on a four point axial
load bearing 64 which is accommodated within a bearing
housing 66. A piston 68 is coupled to the other end of the
bearing housing 66, and has a stepped profile to
accommodate a chevron seal 70. The piston 68 is located in
the upper end of the body, below a connection between the
body 24 and a crossover sub 72.
Accordingly, increasing the fluid pressure in the
running string 20 produces an increasing pressure force on
the piston 68, which tends to push the loading cone 60 in
the direction A, towards and beneath the roller 26.
Similarly, a fluid line leads from the upper end of the
body 24 to the area beyond the other roller support 59,
such that an increase in fluid pressure tends to urge the
other loading cone 61 in the opposite direction.
Accordingly, this forces the rollers 26 radially outwardly,
and into contact with the inner surface of the intermediate
tubing section 18.
This arrangement allows creation of very high pressure
forces and, combined with the rolling contact between the
roller ribs 28 and the intermediate tubing section 18, and
the resulting deformation mechanism, allows deformation of
relatively heavy materials, in this case providing
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a . _ 17
deformation , of both the tubing section 18 and the
surrounding casing 16. Further, the nature of the
deformation is such that the deformed wall of the
intermediate tubing section 18 features an inner thickness
of metal which is in compression, and an outer thickness of
metal which is in tension. This creates a rigid and stable
structure.
Reference is now made to Figures 9 and 10 of the
drawings which illustrate an alternative expander device
11D for use in forming downhole arrangements 112, 113 for
permitting provision of a seal between inner tubing, in the
form of production tubing (not shown), and outer tubing, in
the form of bore-lining casing 116, utilising an
intermediate tubing section 118. The form of the tubing
section 118 is substantially the same as the section 18
described above and in the interest of brevity will not be
described in detail again. However, these embodiments of
the present invention utilise a different form of expander
device 110, as described below.
The device 110 comprises an elongate hollow body 124
which carries three radially movable rollers 126. The
rollers 126 may be urged outwards by application of fluid
pressure, via the running string 120, to the body interior.
The device 110 is rotatable in the bore, being driven
- either from surface via the string 120, or by an
appropriate downhole motor. The rollers 126 are rotatably
mounted on relatively large area pistons such that, on
application of elevated fluid pressures to the body
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interior, the 126 rollers are urged radially outwardly into
contact with the tubing section 118.
The deformation of the section 118a as illustrated in
Figure 9 is carried out in substantially the same manner as
the deformation of the section 18 described above, that is
by deforming or crimping the tubing section 118 at two
locations 140a, 140b. However, the deformation of the.
section 118b as illustrated in Figure 10 ie achieved by
deforming or crimping the section 118 along an extended
axial. portion 140c. This may be achieved in a step-wise
fashion, or alternatively by locating the device 110 in the
upper end of the section 118, activating the device 110,
and then rotating the device 110 and simultaneously
applying weight to the device 110 to move the device 110
downwards through the section 118.
It will be clear to those of skill in the art that the
above-described embodiments of the invention provide a
simple but effective means of allowing the annulus between w
production tubing and casing to be sealed, using a metal- .
to-metal seal, the intermediate tubing section acting as a
"Blimline" replacement for a conventional packer, without
requiring the provision of slips and elaetomeric eeale.
It will also be apparent to those of skill in the art
that the above-described embodiments are merely exemplary
of the present invention, and that various modifications
and improvements may be made thereto without departing from
the scope of the invention. For example, the above-
deacribed embodiment features an arrangement in which the
casing is subject to plastic deformation. In other
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19
embodiments, the casing may only be subject to only minor,
if any, elastic deformation, sufficient to form a secure
coupling between the intermediate tubing section and the
casing; where heavy gauge casing is securely in a bore
cemented it may not be desirable or even possible to
deform the casing to any significant extent. In other
aspects of the invention, an intermediate tubing section
may be provided for purposes other than creating a seal
between inner and outer tubing; the tubing aectian may
provide a sealed mounting for a valve or other device in
the outer tubing. -w
