U.S. patent application number 11/150836 was filed with the patent office on 2006-02-23 for expandable device for use in a well bore.
This patent application is currently assigned to Schlumberger Technology Corporation. Invention is credited to Barrie Hart, Craig D. Johnson, L. McD. Schetky.
Application Number | 20060037745 11/150836 |
Document ID | / |
Family ID | 27367758 |
Filed Date | 2006-02-23 |
United States Patent
Application |
20060037745 |
Kind Code |
A1 |
Hart; Barrie ; et
al. |
February 23, 2006 |
Expandable device for use in a well bore
Abstract
An expandable device comprising a plurality of expandable cells.
The cells may be bistable cells or other types of cells that are
expanded from a contracted position towards an expanded position.
Additionally, the cells may be combined with locking mechanisms to
hold the structure in an expanded position.
Inventors: |
Hart; Barrie; (Ipswich,
GB) ; Johnson; Craig D.; (Montgomery, TX) ;
Schetky; L. McD.; (Camden, ME) |
Correspondence
Address: |
SCHLUMBERGER RESERVOIR COMPLETIONS
14910 AIRLINE ROAD
ROSHARON
TX
77583
US
|
Assignee: |
Schlumberger Technology
Corporation
Sugar Land
TX
|
Family ID: |
27367758 |
Appl. No.: |
11/150836 |
Filed: |
June 10, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10050468 |
Jan 16, 2002 |
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11150836 |
Jun 10, 2005 |
|
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60296875 |
Jun 8, 2001 |
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60261749 |
Jan 16, 2001 |
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Current U.S.
Class: |
166/242.1 |
Current CPC
Class: |
E21B 33/1277 20130101;
E21B 43/105 20130101; E21B 23/06 20130101; E21B 43/103 20130101;
E21B 43/086 20130101; E21B 43/106 20130101; E21B 33/1208 20130101;
E21B 41/02 20130101; E21B 33/124 20130101; A61F 2/91 20130101; E21B
43/108 20130101; E21B 43/164 20130101 |
Class at
Publication: |
166/242.1 |
International
Class: |
E21B 17/00 20060101
E21B017/00 |
Claims
1. An expandable device for use in a well comprising: a well device
comprising an expansion member having a plurality of cells that are
expandable from a closed position to an open position, each cell
having a thin strut pivotably coupled to a thick strut, wherein the
expansion member is readily moved along a well bore when the
plurality of cells are in the closed position, further wherein the
expansion member is expandable by transitioning the plurality of
cells to the open position at a desired location in the well
bore.
2. The expandable device as recited in claim 1, wherein the
expansion member comprises a tubular member that undergoes radial
expansion during expansion of the plurality of cells.
3. The expandable device as recited in claim 1, wherein the
expansion member comprises an expandable tubular member sized to
exert an external radial force on a well bore surface.
4. The expandable device as recited in claim 1, wherein the
expansion member comprises an expandable tubular member sized to
support an open hole formation in the well.
5. The expandable device as recited in claim 1, wherein the
expansion member comprises a well bore liner.
6. The expandable device as recited in claim 1, wherein the
expansion member comprises an expandable sand screen.
7. An expandable device for use in a well comprising: a well device
comprising a tubular member having a plurality of cells that are
expandable from a closed position to an open position when the
tubular member is radially expanded, each cell having a thin strut
coupled to a thick strut for pivotal motion relative to the thick
strut, wherein the thickness ratio of the thick strut to the thin
strut determines the force required to transition the plurality of
cells to the open position.
8. The expandable device as recited in claim 7, wherein the tubular
member is an expandable sand screen
9. The expandable device as recited in claim 7, wherein the
thickness ratio is at least 2 to 1.
10. The expandable device as recited in claim 7, wherein the
thickness ratio is at least 3 to 1.
11. The expandable device as recited in claim 7, wherein the
tubular member is sized to support an open hole formation in the
well.
12. An expandable device for use in supporting or stabilizing a
desired region of the wall within a well bore hole comprising: a
downhole well device comprising a substantially tubular expansion
member having a plurality of cells that are expandable from a
closed position to an open position, each cell having a thin strut
coupled to a thick strut, wherein the tubular expansion member is
in a contracted state when the cells are in the closed position and
the tubular expansion member is in an expanded state when the cells
are in the open position; wherein the tubular expansion member when
in the contracted state is readily moved along the well bore; and
wherein the tubular expansion member when in the expanded state can
engage the wall of the well bore to provide support or
stabilization of the desired region of the wall of the well bore.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of and claims the benefit
of priority to U.S. application Ser. No. 10/050,468, filed Jan. 16,
2002, which application is incorporated herein by reference; the
present application also claims the benefit of priority to U.S.
Provisional Application No. 60/261,749, filed Jan. 16, 2001, and
U.S. Provisional Application No. 60/296,875, filed Jun. 8, 2001,
which applications are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to expandable devices, and
particularly to devices formed from one or more expandable cells
that facilitate transition of the device from a contracted state to
an expanded state.
BACKGROUND OF THE INVENTION
[0003] In a variety of applications and environments, it would be
beneficial to have a device able to transition from a contracted
state to an expanded state. Such devices can comprise planar
members, tubular members, rectangular members and a variety of
other configurations. Exemplary applications include medical
applications in which expandable devices, such as stents, are
deployed at a desired location and then expanded. Another exemplary
application comprises the use of expandables in the retrieval of
various fluids, e.g. oil, from subterranean locations.
[0004] For example, fluids such as oil, natural gas and water are
obtained from subterranean geologic formations (a "reservoir") by
drilling a well that penetrates the fluid-bearing formation. Once a
wellbore has been drilled to a certain depth, the borehole wall
typically is supported to prevent collapse. During the drilling and
use of a wellbore, various tubular members, such as liners,
casings, sandscreens, etc. are deployed within the wellbore.
[0005] Various methods have been developed for radially expanding
tubulars by, for instance, pulling an expansion mandrel through the
tubular to plastically deform the tubular in a radially outward
direction. Such an approach, however, requires a large amount of
force to achieve the desired expansion.
[0006] The medical industry, oil industry and a variety of other
industries utilize certain types of expandables or would benefit
from the use of expandables in numerous applications. However,
there are very few existing devices that are readily expandable at
a desired location. Of the devices that do exist, substantial
forces are required to create the expansion. Also, substantial
plastic deformation often occurs which can limit the selection of
available materials for a given expandable device. The present
invention is directed to overcoming, or at least reducing, the
effects of one or more of the problems set forth above.
SUMMARY OF THE INVENTION
[0007] The present invention relates generally to expandable
devices that may be used, for example, in subterranean
environments. In one embodiment of the invention, the expandable
device comprises one or more expandable cells that facilitate
expansion of the device. By way of example, a tubular may be formed
with a plurality of expandable cells that facilitate radial
expansion of the device from a collapsed or contracted state to an
expanded state. A variety of cell types and cell designs may be
utilized depending on the application and desired parameters of the
expandable device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention will hereafter be described with reference to
the accompanying drawings, wherein like reference numerals denote
like elements, and:
[0009] FIGS. 1A and 1B are illustrations of the forces imposed to
make a bistable structure;
[0010] FIGS. 2A and 2B show force-deflection curves of two bistable
structures;
[0011] FIGS. 3A-3F illustrate expanded and collapsed states of
three bistable cells with various thickness ratios;
[0012] FIGS. 4A and 4B illustrate a bistable expandable tubular in
its expanded and collapsed states;
[0013] FIGS. 4C and 4D illustrate a bistable expandable tubular in
collapsed and expanded states within a wellbore;
[0014] FIGS. 5A and 5B illustrate an expandable packer type of
deployment device;
[0015] FIGS. 6A and 6B illustrate a mechanical packer type of
deployment device;
[0016] FIGS. 7A-7D illustrate an expandable swage type of
deployment device;
[0017] FIGS. 8A-8D illustrate a piston type of deployment
device;
[0018] FIGS. 9A and 9B illustrate a plug type of deployment
device;
[0019] FIGS. 10A and 10B illustrate a ball type of deployment
device;
[0020] FIG. 11 is a schematic of a wellbore utilizing an expandable
bistable tubular;
[0021] FIG. 12 illustrates a motor driven radial roller deployment
device;
[0022] FIG. 13 illustrates a hydraulically driven radial roller
deployment device;
[0023] FIG. 14 is a cross sectional view of one embodiment of the
packer of the present invention;
[0024] FIG. 15 is a cross sectional view of another embodiment of
the packer of the present invention;
[0025] FIG. 16 is a side elevation view of an embodiment of the
present invention in a contracted state;
[0026] FIG. 17 is a side elevation view of an embodiment of the
present invention in an expanded state;
[0027] FIGS. 18A-C are schematic views of an alternative embodiment
of the present invention;
[0028] FIG. 19 is a perspective view of an alternative embodiment
of the present invention;
[0029] FIG. 20 is a schematic view of an alternative embodiment of
the present invention;
[0030] FIG. 21 is a schematic view of an alternative embodiment of
the present invention;
[0031] FIGS. 22A-B are partial side elevational view of an
embodiment of the present invention in the contracted and expanded
positions respectively;
[0032] FIGS. 23A-B are partial side elevational views of an
embodiment of the present invention in the contracted and expanded
positions respectively;
[0033] FIGS. 24A-B are side elevational views of an alternate
embodiment of an expandable cell in its contracted and expanded
positions, respectively;
[0034] FIGS. 25A-B are side elevational views of a cell similar to
that illustrated in FIGS. 24A-B deployed in its contracted and
expanded positions, respectively;
[0035] FIGS. 26A-B illustrate another embodiment of expandable
cells displayed in their contracted and expanded positions,
respectively;
[0036] FIGS. 27A-B illustrate another embodiment of expandable
cells displayed in their contracted and expanded positions,
respectively;
[0037] FIGS. 28A-B illustrate another embodiment of expandable
cells displayed in their contracted and expanded positions,
respectively;
[0038] FIGS. 29A-B illustrate another embodiment of expandable
cells displayed in their contracted and expanded positions,
respectively;
[0039] FIGS. 30A-B illustrate another embodiment of an expandable
cell displayed in its contracted and expanded position,
respectively;
[0040] FIGS. 31A-C illustrate a cell with energy storage members
moving from a contracted state to an expanded state;
[0041] FIGS. 32A-32B illustrate another embodiment of the cell
illustrated in FIGS. 31A-C in a contracted position and expanded
position, respectively;
[0042] FIG. 33 illustrates another exemplary expandable cell
design;
[0043] FIG. 34 illustrates another exemplary expandable cell
design;
[0044] FIGS. 35A-D illustrate an exemplary locking mechanism moving
through various stages from a closed position to an open, locked
position;
[0045] FIGS. 36A-D illustrate another embodiment of the locking
mechanism of FIG. 35;
[0046] FIG. 37 illustrates a locking mechanism combined with an
expandable cell;
[0047] FIG. 38A-B illustrate an expandable cell combined with a
locking mechanism in a collapsed and expanded position,
respectively;
[0048] FIG. 39 illustrates an expandable cell with another
embodiment of a locking mechanism;
[0049] FIGS. 40A-B illustrate an individual expandable cell and a
plurality of expandable cells, respectively, combined with
corresponding locking mechanisms;
[0050] FIGS. 41A-B illustrate another embodiment of combined
expandable cells and locking mechanisms in collapsed and expanded
positions, respectively; and
[0051] FIG. 42 is a schematic representation of the combination of
expandable cells having differing sizes and configurations in a
single expandable device.
[0052] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that the description
herein of specific embodiments is not intended to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0053] The following describes a variety of expandable devices that
utilize expandable cells to facilitate expansion of the device from
a contracted state to an expanded state. Various expansion
techniques, expandable cell designs, and locking mechanisms are
described, and typically the description is related to one or more
exemplary applications. For example, the cells are described for
use in tubular components, such as tubulars used in the oil
production industry. However, this application is only an exemplary
application to demonstrate the applicability of the various cells
and locking mechanisms described herein. The description should not
be construed as limiting the application of such expandable devices
to the particular environments or applications described herein.
Rather the techniques for formulating expandable devices can have a
wide range of applications in other environments and
industries.
[0054] As described below, exemplary expandable devices may or may
not comprise bistable cells. Whether bistable or not, the
expandable cells facilitate expansion of a given device between a
contracted state and an expanded state for a variety of operations
or procedures. The selection of a particular type of expandable
cell depends on a variety of factors including environment, degree
of expansion, materials available, etc.
[0055] Bistable devices used in the present invention can take
advantage of a principle illustrated in FIGS. 1A and 1B. FIG. 1A
shows a rod 10 fixed at each end to rigid supports 12. If the rod
10 is subjected to an axial force it begins to deform as shown in
FIG. 1B. As the axial force is increased rod 10 ultimately reaches
its Euler buckling limit and deflects to one of the two stable
positions shown as 14 and 15. If the buckled rod is now clamped in
the buckled position, a force at right angles to the long axis can
cause the rod to move to either of the stable positions but to no
other position. When the rod is subjected to a lateral force it
must move through an angle .beta. before deflecting to its new
stable position.
[0056] Bistable systems are characterized by a force deflection
curve such as those shown in FIGS. 2A and 2B. The externally
applied force 16 causes the rod 10 of FIG. 1B to move in the
direction X and reaches a maximum 18 at the onset of shifting from
one stable configuration to the other. Further deflection requires
less force because the system now has a negative spring rate and
when the force becomes zero the deflection to the second stable
position is spontaneous.
[0057] The force deflection curve for this example is symmetrical
and is illustrated in FIG. 2A. By introducing either a precurvature
to the rod or an asymmetric cross section the force deflection
curve can be made asymmetric as shown in FIG. 2B. In this system
the force 19 required to cause the rod to assume one stable
position is greater than the force 20 required to cause the reverse
deflection. The force 20 must be greater than zero for the system
to have bistable characteristics.
[0058] Bistable structures, sometimes referred to as toggle
devices, have been used in industry for such devices as flexible
discs, over center clamps, hold-down devices and quick release
systems for tension cables (such as in sailboat rigging
backstays).
[0059] Instead of using the rigid supports as shown in FIGS. 1A and
1B, a cell can be constructed where the restraint is provided by
curved struts connected at each end as shown in FIGS. 3A-3F. If
both struts 21 and 22 have the same thickness as shown in FIGS. 3A
and 3B, the force deflection curve is linear and the cell lengthens
when compressed from its open position FIG. 3B to its closed
position FIG. 3A. If the cell struts have different thicknesses, as
shown in FIGS. 3C-3F, the cell has the force deflection
characteristics shown in FIG. 2B, and does not change in length
when it moves between its two stable positions. An expandable
bistable tubular can thus be designed so that as the radial
dimension expands, the axial length remains constant. In one
example, if the thickness ratio is over approximately 2:1, the
heavier strut resists longitudinal changes. By changing the ratio
of thick-to-thin strut dimensions, the opening and closing forces
can be changed. For example, FIGS. 3C and 3D illustrated a
thickness ratio of approximately 3:1, and FIGS. 3E and 3F
illustrate a thickness ratio of approximately 6:1.
[0060] An expandable bore bistable tubular, such as casing, a tube,
a patch, or pipe, can be constructed with a series of
circumferential bistable connected cells 23 as shown in FIGS. 4A
and 4B, where each thin strut 21 is connected to a thick strut 22.
The longitudinal flexibility of such a tubular can be modified by
changing the length of the cells and by connecting each row of
cells with a compliant link. Further, the force deflection
characteristics and the longitudinal flexibility can also be
altered by the design of the cell shape. FIG. 4A illustrates an
expandable bistable tubular 24 in its expanded configuration while
FIG. 4B illustrates the expandable bistable tubular 24 in its
contracted or collapsed configuration. Within this application the
term "collapsed" is used to identify the configuration of the
bistable element or device in the stable state with the smallest
diameter, it is not meant to imply that the element or device is
damaged in any way. In the collapsed state, bistable tubular 24 is
readily introduced into a wellbore 29, as illustrated in FIG. 4C.
Upon placement of the bistable tubular 24 at a desired wellbore
location, it is expanded, as illustrated in FIG. 4D.
[0061] The geometry of the bistable cells is such that the tubular
cross-section can be expanded in the radial direction to increase
the overall diameter of the tubular. As the tubular expands
radially, the bistable cells deform elastically until a specific
geometry is reached. At this point the bistable cells move, e.g.
snap, to a final expanded geometry. With some materials and/or
bistable cell designs, enough energy can be released in the elastic
deformation of the cell (as each bistable cell snaps past the
specific geometry) that the expanding cells are able to initiate
the expansion of adjoining bistable cells past the critical
bistable cell geometry. Depending on the deflection curves, a
portion or even an entire length of bistable expandable tubular can
be expanded from a single point.
[0062] In like manner if radial compressive forces are exerted on
an expanded bistable tubular, it contracts radially and the
bistable cells deform elastically until a critical geometry is
reached. At this point the bistable cells snap to a final collapsed
structure. In this way the expansion of the bistable tubular is
reversible and repeatable. Therefore the bistable tubular can be a
reusable tool that is selectively changed between the expanded
state as shown in FIG. 4A and the collapsed state as shown in FIG.
4B.
[0063] In the collapsed state, as in FIG. 4B, the bistable
expandable tubular is easily inserted into the wellbore and placed
into position. A deployment device is then used to change the
configuration from the collapsed state to the expanded state.
[0064] In the expanded state, as in FIG. 4A, design control of the
elastic material properties of each bistable cell can be such that
a constant radial force can be applied by the tubular wall to the
constraining wellbore surface. The material properties and the
geometric shape of the bistable cells can be designed to give
certain desired results.
[0065] One example of designing for certain desired results is an
expandable bistable tubular string with more than one diameter
throughout the length of the string. This can be useful in
boreholes with varying diameters, whether designed that way or as a
result of unplanned occurrences such as formation washouts or
keyseats within the borehole. This also can be beneficial when it
is desired to have a portion of the bistable expandable device
located inside a cased section of the well while another portion is
located in an uncased section of the well. FIG. 11 illustrates one
example of this condition. A wellbore 40 is drilled from the
surface 42 and comprises a cased section 44 and an openhole section
46. An expandable bistable device 48 having segments 50, 52 with
various diameters is placed in the well. The segment with a larger
diameter 50 is used to stabilize the openhole section 46 of the
well, while the segment having a reduced diameter 52 is located
inside the cased section 44 of the well.
[0066] Bistable collars or connectors 24A (see FIG. 4C) can be
designed to allow sections of the bistable expandable tubular to be
joined together into a string of useful lengths using the same
principle as illustrated in FIGS. 4A and 4B. This bistable
connector 24A also incorporates a bistable cell design that allows
it to expand radially using the same mechanism as for the bistable
expandable tubular component. Exemplary bistable connectors have a
diameter slightly larger than the expandable tubular sections that
are being joined. The bistable connector is then placed over the
ends of the two sections and mechanically attached to the
expandable tubular sections. Mechanical fasteners such as screws,
rivets or bands can be used to connect the connector to the tubular
sections. The bistable connector typically is designed to have an
expansion rate that is compatible with the expandable tubular
sections, so that it continues to connect the two sections after
the expansion of the two segments and the connector.
[0067] Alternatively, the bistable connector can have a diameter
smaller than the two expandable tubular sections joined. Then, the
connector is inserted inside of the ends of the tubulars and
mechanically fastened as discussed above. Another embodiment would
involve the machining of the ends of the tubular sections on either
their inner or outer surfaces to form an annular recess in which
the connector is located. A connector designed to fit into the
recess is placed in the recess. The connector would then be
mechanically attached to the ends as described above. In this way
the connector forms a relatively flush-type connection with the
tubular sections.
[0068] A conveyance device 31 transports the bistable expandable
tubular lengths and bistable connectors into the wellbore and to
the correct position. (See FIGS. 4C and 4D). The conveyance device
may utilize one or more mechanisms such as wireline cable, coiled
tubing, coiled tubing with wireline conductor, drill pipe, tubing
or casing.
[0069] A deployment device 33 can be incorporated into the overall
assembly to expand the bistable expandable tubular and connectors.
(See FIGS. 4C and 4D). Deployment devices can be of numerous types
such as an inflatable packer element, a mechanical packer element,
an expandable swage, a piston apparatus, a mechanical actuator, an
electrical solenoid, a plug type apparatus, e.g. a conically shaped
device pulled or pushed through the tubing, a ball type apparatus
or a rotary type expander as further discussed below.
[0070] An inflatable packer element is shown in FIGS. 5A and 5B and
is a device with an inflatable bladder, element, or bellows
incorporated into the bistable expandable tubular system bottom
hole assembly. In the illustration of FIG. 5A, the inflatable
packer element 25 is located inside the entire length, or a
portion, of the initial collapsed state bistable tubular 24 and any
bistable expandable connectors (not shown). Once the bistable
expandable tubular system is at the correct deployment depth, the
inflatable packer element 25 is expanded radially by pumping fluid
into the device as shown in FIG. 5B. The inflation fluid can be
pumped from the surface through tubing or drill pipe, a mechanical
pump, or via a downhole electrical pump which is powered via
wireline cable. As the inflatable packer element 25 expands, it
forces the bistable expandable tubular 24 to also expand radially.
At a certain expansion diameter, the inflatable packer element
causes the bistable cells in the tubular to reach a critical
geometry where the bistable "snap" effect is initiated, and the
bistable expandable tubular system expands to its final diameter.
Finally the inflatable packer element 25 is deflated and removed
from the deployed bistable expandable tubular 24.
[0071] A mechanical packer element is shown in FIGS. 6A and 6B and
is a device with a deformable plastic element 26 that expands
radially when compressed in the axial direction. The force to
compress the element can be provided through a compression
mechanism 27, such as a screw mechanism, cam, or a hydraulic
piston. The mechanical packer element deploys the bistable
expandable tubulars and connectors in the same way as the
inflatable packer element. The deformable plastic element 26
applies an outward radial force to the inner circumference of the
bistable expandable tubulars and connectors, allowing them in turn
to expand from a contracted position (see FIG. 6A) to a final
deployment diameter (see FIG. 6B).
[0072] An expandable swage is shown in FIGS. 7A-7D and comprises a
series of fingers 28 that are arranged radially around a conical
mandrel 30. FIGS. 7A and 7C show side and top views respectively.
When the mandrel 30 is pushed or pulled through the fingers 28 they
expand radially outwards, as illustrated in FIGS. 7B and 7D. An
expandable swage is used in the same manner as a mechanical packer
element to deploy a bistable expandable tubular and connector.
[0073] A piston type apparatus is shown in FIGS. 8A-8D and
comprises a series of pistons 32 facing radially outwardly and used
as a mechanism to expand the bistable expandable tubulars and
connectors. When energized, the pistons 32 apply a radially
directed force to deploy the bistable expandable tubular assembly
as per the inflatable packer element. FIGS. 8A and 8C illustrate
the pistons retracted while FIGS. 8B and 8D show the pistons
extended. The piston type apparatus can be actuated hydraulically,
mechanically or electrically.
[0074] A plug type actuator is illustrated in FIGS. 9A and 9B and
comprises a plug 34 that is pushed or pulled through the bistable
expandable tubulars 24 or connectors as shown in FIG. 9A. The plug
is sized to expand the bistable cells past their critical point
where they will snap to a final expanded diameter as shown in FIG.
9B.
[0075] A ball type actuator is shown in FIGS. 10A and 10B and
operates when an oversized ball 36 is pumped through the middle of
the bistable expandable tubulars 24 and connectors. To prevent
fluid losses through the cell slots, an expandable elastomer based
liner 38 is run inside the bistable expandable tubular system. The
liner 38 acts as a seal and allows the ball 36 to be hydraulically
pumped through the bistable tubular 24 and connectors. The effect
of pumping the ball 36 through the bistable expandable tubulars 24
and connectors is to expand the cell geometry beyond the critical
bistable point, allowing full expansion to take place as shown in
FIG. 10B. Once the bistable expandable tubulars and connectors are
expanded, the elastomer sleeve 38 and ball 36 are withdrawn.
[0076] Radial roller type actuators also can be used to expand the
bistable tubular sections. FIG. 12 illustrates a motor driven
expandable radial roller tool. The tool comprises one or more sets
of arms 58 that are expanded to a set diameter by means of a
mechanism and pivot. On the end of each set of arms is a roller 60.
Centralizers 62 can be attached to the tool to locate it correctly
inside the wellbore and the bistable tubular 24. A motor 64
provides the force to rotate the whole assembly, thus turning the
roller(s) circumferentially inside the wellbore. The axis of the
roller(s) is such as to allow the roller(s) to rotate freely when
brought into contact with the inner surface of the tubular. Each
roller can be conically-shaped in section to increase the contact
area of roller surface to the inner wall of the tubular. The
rollers are initially retracted and the tool is run inside the
collapsed bistable tubular. The tool is then rotated by the motor
64, and rollers 60 are moved outwardly to contact the inner surface
of the bistable tubular. Once in contact with the tubular, the
rollers are pivoted outwardly a greater distance to apply an
outwardly radial force to the bistable tubular. The outward
movement of the rollers can be accomplished via centrifugal force
or an appropriate actuator mechanism coupled between the motor 64
and the rollers 60.
[0077] The final pivot position is adjusted to a point where the
bistable tubular can be expanded to the final diameter. The tool is
then longitudinally moved through the collapsed bistable tubular,
while the motor continues to rotate the pivot arms and rollers. The
rollers follow a shallow helical path 66 inside the bistable
tubular, expanding the bistable cells in their path. Once the
bistable tubular is deployed, the tool rotation is stopped and the
roller retracted. The tool is then withdrawn from the bistable
tubular by a conveyance device 68 that also can be used to insert
the tool.
[0078] FIG. 13 illustrates a hydraulically driven radial roller
deployment device. The tool comprises one or more rollers 60 that
are brought into contact with the inner surface of the bistable
tubular by means of a hydraulic piston 70. The outward radial force
applied by the rollers can be increased to a point where the
bistable tubular expands to its final diameter. Centralizers 62 can
be attached to the tool to locate it correctly inside the wellbore
and bistable tubular 24. The rollers 60 are initially retracted and
the tool is run into the collapsed bistable tubular 24. The rollers
60 are then deployed and push against the inside wall of the
bistable tubular 24 to expand a portion of the tubular to its final
diameter. The entire tool is then pushed or pulled longitudinally
through the bistable tubular 24 expanding the entire length of
bistable cells 23. Once the bistable tubular 24 is deployed in its
expanded state, the rollers 60 are retracted and the tool is
withdrawn from the wellbore by the conveyance device 68 used to
insert it. By altering the axis of the rollers 60, the tool can be
rotated via a motor as it travels longitudinally through the
bistable tubular 24.
[0079] Power to operate the deployment device can be drawn from one
or a combination of sources such as: electrical power supplied
either from the surface or stored in a battery arrangement along
with the deployment device, hydraulic power provided by surface or
downhole pumps, turbines or a fluid accumulator, and mechanical
power supplied through an appropriate linkage actuated by movement
applied at the surface or stored downhole such as in a spring
mechanism.
[0080] The bistable expandable tubular system is designed so the
internal diameter of the deployed tubular is expanded to maintain a
maximum cross-sectional area along the expandable tubular. This
feature enables mono-bore wells to be constructed and facilitates
elimination of problems associated with traditional wellbore casing
systems where the casing outside diameter must be stepped down many
times, restricting access, in long wellbores.
[0081] The bistable expandable tubular system can be applied in
numerous applications such as an expandable open hole liner where
the bistable expandable tubular 24 is used to support an open hole
formation by exerting an external radial force on the wellbore
surface. As bistable tubular 24 is radially expanded, the tubular
moves into contact with the surface forming wellbore 29. These
radial forces help stabilize the formations and allow the drilling
of wells with fewer conventional casing strings. The open hole
liner also can comprise a material, e.g. a wrapping, that reduces
the rate of fluid loss from the wellbore into the formations. The
wrapping can be made from a variety of materials including
expandable metallic and/or elastomeric materials. By reducing fluid
loss into the formations, the expense of drilling fluids can be
reduced and the risk of losing circulation and/or borehole collapse
can be minimized.
[0082] Liners also can be used within wellbore tubulars for
purposes such as corrosion protection. One example of a corrosive
environment is the environment that results when carbon dioxide is
used to enhance oil recovery from a producing formation. Carbon
dioxide (CO.sub.2) readily reacts with any water (H.sub.2O) that is
present to form carbonic acid (H.sub.2CO.sub.3). Other acids can
also be generated, especially if sulfur compounds are present.
Tubulars used to inject the carbon dioxide as well as those used in
producing wells are subject to greatly elevated corrosion rates.
The present invention can be used to place protective liners, e.g.
a bistable tubular 24, within an existing tubular to minimize the
corrosive effects and to extend the useful life of the wellbore
tubulars.
[0083] Another exemplary application involves use of the bistable
tubular 24 as an expandable perforated liner. The open bistable
cells in the bistable expandable tubular allow unrestricted flow
from the formation while providing a structure to stabilize the
borehole.
[0084] Still another application of the bistable tubular 24 is as
an expandable sand screen where the bistable cells are sized to act
as a sand control screen. Also, a filter material can be combined
with the bistable tubular as explained below. For example, an
expandable screen element can be affixed to the bistable expandable
tubular. The expandable screen element can be formed as a wrapping
around bistable tubular 24. It has been found that the imposition
of hoop stress forces onto the wall of a borehole will in itself
help stabilize the formation and reduce or eliminate the influx of
sand from the producing zones, even if no additional screen element
is used.
[0085] The above described bistable expandable tubulars can be made
in a variety of manners such as: cutting appropriately shaped paths
through the wall of a tubular pipe thereby creating an expandable
bistable device in its collapsed state; cutting patterns into a
tubular pipe thereby creating an expandable bistable device in its
expanded state and then compressing the device into its collapsed
state; cutting appropriate paths through a sheet of material,
rolling the material into a tubular shape and joining the ends to
form an expandable bistable device in its collapsed state; or
cutting patterns into a sheet of material, rolling the material
into a tubular shape, joining the adjoining ends to form an
expandable bistable device in its expanded state and then
compressing the device into its collapsed state.
[0086] The materials of construction for the bistable expandable
tubulars can include those typically used within the oil and gas
industry such as carbon steel. They can also be made of specialty
alloys (such as a monel, inconel, hastelloy or tungsten-based
alloys) if the application requires.
[0087] The configurations shown for the bistable tubular 24 are
illustrative of the operation of a basic bistable cell. Other
configurations may be suitable, but the concept presented is also
valid for these other geometries.
[0088] In FIGS. 14 and 15, a packer 80 formed of bistable cells is
illustrated. The packer 80 has a tubular 82 formed of bistable
cells 83, such as those previously discussed. In addition, the
packer 80 has at least one seal 84 along at least a portion of its
length. An exemplary seal 84 may include one or more layers
positioned internally, externally, or both with respect to tubular
82. Additionally, the layer(s) may be intermixed with the openings
formed in the cells.
[0089] FIG. 14 illustrates an embodiment having an internal and an
external seal 84. FIG. 15 illustrates a packer 80 having only an
internal seal 84. The seal 84 may be formed of an elastomer or
other material. Further, the properties of the seal 84 allow it to
at least match the expansion ratio of the tubular 82. Folds or
other design characteristics of the seal 84 may be used to
facilitate the expansion.
[0090] Also, a resin or catalyst 85 may be used to allow the seal
84 to harden after setting. In one alternative embodiment a resin
or other flowable material is placed between the layers of seals 84
(as in FIG. 14). Once the packer 80 is placed in the well and
expanded, the flowable material may be hardened or otherwise
altered to improve the sealing characteristics of the packer 80. In
some applications, hardening of the resin or other material
requires heating of the material by a service tool. The packer 80
can be expanded as described herein, and may comprise a variety of
bistable cells. In one embodiment of use, the packer 80 is deployed
on a run-in tool that includes an expanding tool. The packer 80 is
positioned at the desired location and expanded to seal against the
walls of the casing or other tubular. Typically, the packer 80 is
connected to a tubing or other conduit that extends downhole below
the packer 80. The packer 80 provides a seal in the annulus to
prevent or restrict fluid flow longitudinally in the well (the
typical use for packers). The present invention also may act as a
well anchor which includes or excludes the seal 84.
[0091] In FIG. 16, an alternative embodiment is illustrated in
which the packer 80 forms a portion of a conduit. In the embodiment
shown, a well conduit 90 (such as a tubing) has a portion (marked
as the packer 80) that is cut to form the bistable cells. The
packer portion 80 has a seal 84 thereon as previously described. In
FIG. 16, a portion of the seal material 84 is illustrated as
removed to reveal the bistable cells 83 in the underlying tubular
82. In FIG. 17, the packer portion 80 is illustrated in its
expanded state. It should be noted that in typical applications the
well conduit 90 which does not have bistable cells formed therein,
does not expand. Thus, one embodiment for attaching the well
conduit to the packer 80 is to form the packer 80 as an integral
part of the well conduit 90 (note that a welded connection
resembles this embodiment and is an alternative method of forming
the present invention). Other methods include conventional methods
of non-integral connection.
[0092] In alternative embodiments, the well conduit has a plurality
of bistable cell packers 80 formed thereon. In yet another
alternative embodiment, a portion or portions 91 of the well
conduit in addition to the packer portions 80 are formed of
bistable cells so that these other portions also undergo expansion
(see FIG. 17). The other portions may or may not have a material
applied thereto. For example, the other portion may have a screen
or filter material applied thereto to provide a well sand
screen.
[0093] Referring to FIGS. 18A-C, an alternative design of the
present invention is illustrated in a schematic, partial
cross-sectional view. The expandable packer is shown in the
retracted and expanded states, respectively, and in partial side
elevational view (FIG. 18C). The packer shown includes a base
tubular 82 formed of thin struts 21 and thick struts 22 forming
bistable cells 23/83 as previously described. Slats 92 are attached
to the tubing 82 at one edge and extend generally longitudinally in
the embodiment shown (see FIG. 18C). Specifically, each slat 92 is
attached to the tubing 82 at the thick struts 22, and the width of
the slats is such that they overlap at least the adjacent slat when
the tubing 82 is in the expanded state. Although illustrated as
having a slat attached to each of the thick struts, the packer may
have a slat attached to alternate thick struts 22 or in other
configurations. Furthermore, the slats may extend in a direction
other than the longitudinal direction. The slats 92 slide over one
another during expansion so that the outside of the tubing 82 is
covered by the overlapping slats 92.
[0094] A seal 84 may be attached to the slats 92 to provide the
seal for the packer. Although shown in the figures as folded, the
seal 84, may have other characteristics that facilitate its ability
to expand with the slats 92 and tubular 82. Also, the seal 84 may
have other characteristics previously mentioned (e.g., resin,
internal seal, etc).
[0095] It should be noted that although described as a packer, the
present invention may be used to provide isolation over a long
length as opposed to a traditional packer or downhole tool which
generally seals only a relatively short longitudinal distance.
Thus, the present invention may be used in a manner similar to a
casing to provide isolation for an extended length.
[0096] In FIG. 19, a perspective view of packer 80 (or isolation
device) having a plurality of slats 92 attached thereto is
illustrated in an overlapping arrangement as previously described.
The tubing 82 includes end extensions 94 that extend longitudinally
from the endmost cells. The slats 92 may be attached to the end
extensions 94, to certain portions of the thick struts 22 and/or to
certain thick struts 22. In one embodiment, for example, the struts
92 are attached to the thick struts which are longitudinally
aligned with the end extensions 94. Although generally shown as
attached at an edge of the slats 92, the slats also may attach to
the tubing 82 at a position intermediate the edges.
[0097] In FIG. 20, an expandable tubing (or conduit) 90 is
illustrated positioned in a well 100. The conduit 90 includes a
plurality of spaced packers 80 or expandable sealing devices. The
expandable packers 80 engage the wellbore wall preventing annular
flow thereby. Therefore, any microannulus formed between the
expandable tubing 90 and the well 100 (which may include a casing)
is sealed in the longitudinal direction to restrict or prevent
unwanted flow thereby. The conduit 90 may include one or more such
packers 80, as desired, to control the flow. Further, the packers
80 may be spaced at regular intervals or at some other
predetermined spacing to control the flow in the annulus as
needed.
[0098] In one example, illustrated schematically in FIG. 21, the
individual joints of tubing 90 are interconnected by a packer 80 to
compartmentalize each joint of conduit from the adjacent joint(s).
The packer 80 can be a separate connector as shown in FIG. 21 or it
can be formed as part of the joint. Accordingly, the packer 80 can
be positioned at an end of the joint 90, in the middle of the joint
90, or at any other location along its length. In one embodiment
both conduit 90 and packers 80, of FIGS. 20 and 21, are formed of
bistable cells.
[0099] Referring generally to FIGS. 22A-B, an alternative
embodiment of the present invention is disclosed. The device shown
in these figures may be used as a packer, hanger, casing patch, or
other device requiring expansion and is generally referred to
herein in reference to these figures as an expandable tubular 120
for ease of description. The expandable tubular 120 comprises a
series of cells 122 formed therein, such as by laser cutting, jet
cutting, water jet cutting or other manufacturing methods. The
cells 122 are oriented such that a number of longitudinal struts 24
are formed on the expandable tubular 120. Thus, as shown in the
figures, the longitudinal struts 124 lie between longitudinal
lengths of cells 122 with the cells 122 having relatively thinner
struts 126 extending between adjacent longitudinal struts 124. As
shown in the figures, as the adjacent longitudinal struts 124 are
moved longitudinally relative to one another (e.g. in opposite
directions), the cells 122 open to expand the structure radially.
Not all of the longitudinal struts 124 must move; alternate
longitudinal struts 124 may be moved while the other struts remain
stationary. The relative movement of the longitudinal struts 124
provides the expansion of the cells 122 and the expandable tubular
120. This type of cell is an example of an expandable cell that is
not bistable.
[0100] A locking mechanism 128 may be used to maintain the expanded
position of the expandable tubular 120. As shown in FIGS. 22A-B,
the expandable tubular may comprise one or more locking mechanisms
128 spaced along the length of the expandable tubular 120 and
spaced radially about the expandable tubular 120. One embodiment of
the locking mechanism is shown in FIGS. 23A-B. In the embodiment
shown, the locking mechanism 128 comprises a detent (or finger) 130
extending from one longitudinal strut 124 and cooperating with a
set of ratchet teeth 132 provided on another longitudinal strut
124. The ratchet teeth 132 extend from a ramp area 134 of the
longitudinal strut 124 to accommodate for the relative movement of
the detent 130 to the longitudinal strut 124 having the ratchet
teeth 132. The ratchet teeth 132 generally allow movement of the
detent 130 thereon in a first direction associated with the
expansion of the expandable tubular 120, and prevent movement of
the detent 130 in the opposite direction. Once in the expanded
position, the detent 130 acts as a locked strut preventing
retraction of the expandable tubular 120. To increase the
structural integrity of the expanded tubular 120 and to resist
forces tending to move the expandable tubular 120 from an expanded
state or position to a reduced position. The expandable tubular 120
may include a plurality of locking mechanisms 128.
[0101] Although shown as a ratchet, as an alternative the locking
mechanism may have fewer discrete positions, such as one, in which
the detent locks in the fully expanded position only. In another
embodiment the detent may comprise a resilient finger biased toward
an extended position that snaps into a groove in an adjacent
longitudinal strut 124. Likewise, the adjacent struts 124 may each
have resilient detents that cooperate to lock the device in the
expanded position only upon the tubular 120 achieving the expanded
position. These are only a few examples of the many possible
alternatives for the locking mechanism 128.
[0102] Also, various other tubular expansion mechanisms and
expandable cells may be utilized such expandable tubulars and other
devices. For example, details of one type of expandable cell are
illustrated in FIGS. 24A, 24B, 25A and 25B. In this embodiment, as
in other embodiments, the cell is transitioned from a compressed
state to an expanded state.
[0103] During movement from the compressed state to the expanded
state and depending upon the environmental conditions as well as
the materials used, material thickness and other design parameters
of the cell and devices formed from the cell, some areas of the
cell and struts may experience plastic deformation. In FIGS. 24A,
24B, 25A and 25B alternative embodiments of a cell are illustrated
in compressed and expanded states. In these embodiments, one of the
struts 21 (shown as the thinner, upper strut) has thinned portions
140 that serve as flexible hinges or joints. The thinned portions
140 are preferably placed at areas where plastic deformation of the
strut is likely to occur as the strut moves from a compressed to an
expanded state. Thus, for example, the thinned portions 140 may be
placed near the intersection of the struts 21, 22 to provide an
area that is less susceptible to plastic deformation. Although the
figures show a plurality of thinned portions 140, the strut may
include a single thinned portion 140, for example, at an area of
increased plastic deformation. Also, the thinned portions 140 may
be placed in other positions along the struts 21, 22 for other
purposes. The thinned areas 140 define linkages 142 there between
that comprise portions which are generally thicker than the thinned
portions 140. Placing a plurality of thinned portions 140 along the
length of a strut 21, 22 produces a plurality of linkages 142.
[0104] Another factor in determining the positioning of the thinned
portions 140 is the number, placement, and design of the linkages.
Although shown in the figures as having a uniform thickness, the
linkages 142 may also have a variation in thickness to further
tailor the expansion, contraction, and other characteristics of the
cell as desired. Therefore, in one broad aspect of the inventions,
at least one of the struts 21, 22 has a thickness that varies.
Also, other factors may be considered in placement of the thinned
portions 140 and the thickness variations of the struts 21, 22.
Also, the thinned portions may occur at the intersection of the
struts 21, 22.
[0105] In FIGS. 24A and 24B a cell with three linkages 142 is
illustrated; and in FIGS. 25A and 25B a cell with two linkages is
illustrated. Although FIGS. 24A-25B disclose only a single cell,
the cells may be incorporated into a tool, such as a tube, having a
plurality of cells such as that shown in FIGS. 4A and 4B. The
figures illustrate a single cell to more clearly show the basic
concept and the cell design. The handles shown in the figures are
not a part of the cell structure, but are merely used on test cells
to facilitate testing of the cells.
[0106] Referring generally to FIGS. 26A and 26B, another embodiment
of expandable cells, labeled as expandable cells 150, is
illustrated. Each expandable cell 150 comprises a thick strut 152
and one or more thin struts 154, e.g. two thin struts 154. In the
embodiment illustrated, each expandable cell 150 comprises a pair
of thin struts, and each thin strut 154 has a pair of ends 156
pivotably coupled to adjacent thick struts, respectively. Ends 156
may comprise pins that are pivotably received in corresponding
sockets 158.
[0107] As the plurality of expandable cells 150 is moved from the
contracted state illustrated in FIG. 26A to the expanded state
illustrated in FIG. 26B, thin struts 154 deform sufficiently to
permit pivoting of pins 156 in their corresponding sockets 158. As
illustrated best in FIG. 26B, the pairs of thin struts 154 that
form each cell 150 have outlying ends 156 pivotably coupled to
upper attachment regions 160 of the lower thick strut 152. The
opposite ends of each pair of thin struts 154 are pivotably coupled
to a lower attachment region 162 of the next upwardly adjacent
thick strut 152. It should be noted that positional terms such as
upper and lower or merely used to facilitate explanation of the
location of various features relative to the figures provided and
should not be construed as limiting.
[0108] In another embodiment illustrated in FIGS. 27A and 27B, a
plurality of expandable cells, labeled with reference numeral 164,
each comprise a thick strut 166 and one or more thin struts 168.
Each thick strut 166 is generally arcuate and connected to a
corresponding thin strut 168 at a fixed connection region 170
disposed at a generally central location along the outer or convex
portion of the arcuate thick strut. The outer ends of each thin
strut 168 are pivotably coupled to the next adjacent thick strut
166 via a pivot connection 172 that may comprise a ball and
socket.
[0109] As the plurality of cells are moved from the contracted
state illustrated in FIG. 27A to the expanded state illustrated in
FIG. 27B, thin struts 168 flex or deform as their outer ends pivot
at each pivot connection 172. As with many of the other cells
described herein, when the thin struts 168 move past their point of
greatest flexure, the stored spring energy tends to force the cells
164 to their stable expanded state illustrated in FIG. 27B. Thus,
as with the bistable cells illustrated in FIGS. 26A and 26B, cells
164 move between a stable contracted state and a stable expanded
state.
[0110] Another expandable cell embodiment is illustrated in FIGS.
28A and 28B. In this embodiment, each expandable cell 174 is formed
of a thick strut 176 and a thin strut 178. Each thin strut 178 has
a pair of ends 180 that are pivotably coupled to a thick strut. For
example, a given thick strut may comprise a pair of sockets 182 to
pivotably receive pin or ball shaped ends 180. Additionally, thin
strut 178 is fixedly coupled to adjacent thick struts 176 in an
alternating pattern. For example, each cell in the illustrated
embodiment comprises three fixed couplings 184 that alternate
between adjacent thick struts 176. With this design, the expandable
cells 174 again are movable between a stable contracted state as
illustrated in FIG. 28A and a stable expanded state as illustrated
in FIG. 28B.
[0111] With reference to FIGS. 29A and 29B, another expandable cell
design is illustrated. In this embodiment, each of a plurality of
expandable cells 186 comprises a thick strut 188 and at least a
pair of stacked thin struts 190, 192, respectively. Thin struts
190, 192 are generally disposed in a stacked orientation and
connected by a linking member 194. Thin strut 192 comprises a pair
of ends 196 affixed to a corresponding thick strut 188. An
intermediate connection region 198 of thin strut 192 is affixed to
the next adjacent thick strut 188, as best illustrated in FIG. 29B.
Thin strut 190, on the other hand, has unattached ends 200. Ends
200 are captured in an abutting engagement with a notched region
202 formed in the same thick strut 188 to which ends 196 are
affixed. As the plurality of expandable cells 186 are moved from
the contracted state illustrated in FIG. 29A to the expanded state
illustrated in FIG. 29B, each pair of thin struts 190 and 192
deforms to a deflection point where stored energy in the thin
struts is maximized. As the thin struts are moved past this
deflection point, the stored energy is released to facilitate
expansion of the cells to their expanded state.
[0112] Of course, with any of these types of bistable cells, the
degree of expansion may be limited by an external barrier. For
example, if the bistable cells are used to form a tubular, the
tubular may be expanded against a wellbore wall that prevents the
cells from moving to their fully expanded condition. Typically, the
size of the tubular is selected to permit expansion of the cells at
least past the point of maximum deformation. Thus, depending on the
material used, the cells may actually cooperate to apply an
outwardly directed radial force against the wellbore wall.
[0113] Referring generally to FIGS. 30A and 30B, another expandable
cell design is illustrated. Each expandable cell 204 comprises a
pair of arcuate thin struts 206 pivotably coupled to a
corresponding thick strut 208 at a generally centralized extended
region 210 via pivot ends 212. Generally opposite pivot ends 212,
thin struts 206 comprise outer pivot ends 214 that are pivotably
coupled to the next adjacent thick strut 208. Pivot ends 212 and
214 can be formed in a variety of configurations, such as ball
joints, pin joints, etc. Removal of each thin strut 206 is
prevented by appropriate ligaments 216 and 218 disposed at pivot
ends 212 and 214, respectively. The ligaments 216 and 218 are
coupled between the thin strut 206 and the corresponding thick
struts 208.
[0114] In FIGS. 31A-31C, a different type of expandable cell 220 is
illustrated. In this embodiment, a thick strut 222 is coupled to
one or more thin struts 224 by one or more spring elements 226. In
the particular embodiment illustrated, two spring elements 226 are
formed generally in the shape of a horn, with the base of each horn
connected to thick strut 222 and the tip of each horn coupled to
the adjacent thin strut 224. In this embodiment, a thin strut 224
is connected to each spring element 226 by a flexible hinge 228.
The two thin struts 224 are coupled to each other through a center
beam 230 and a pair of flexible hinges 232.
[0115] As cells 220 are expanded from a contracted state,
illustrated in FIG. 31A, to an expanded state, illustrated in FIG.
31 C, spring elements 226 flex outwardly and store spring energy.
With this design, thin struts 224 typically do not undergo
substantial deformation during movement from the contracted state
to the expanded state. Rather, spring elements 226 are elastically
deformed as they are forced outwardly during movement of center
beam 230 from the contracted state to the expanded state. When
spring elements 226 are flexed outwardly, they store spring energy
at least to the point of maximum flexure illustrated in FIG. 31B
where thin struts 224 are generally parallel with thick strut 222.
Once center beam 230 moves past this point of maximum stored spring
energy, spring elements 226 tend to release the stored energy and
move inwardly, thereby forcing thin struts 224 and center beam 230
to the expanded position illustrated best in FIG. 31C. Deformation
of hinges 228 and 232 facilitates the pivoting of thin struts 224
from the contracted state to the expanded state.
[0116] A double horn cell design is illustrated in FIGS. 32A and
32B. In this design, a plurality of thick struts 236 are coupled
together via thin struts 238 and horn spring members 240.
Specifically, each thin strut 238 is coupled to two horn spring
members 240 to permit storage of a greater amount of energy. This
greater energy storage provides added positive energy for opening
cells 234 to their expanded positions as illustrated in FIG.
32B.
[0117] In the example illustrated, each double horn cell 234 has
two outer horn spring members 240, coupled to one thick strut 236,
and two inner horn spring members 240, coupled to the next adjacent
thick strut 236. One thin strut 238 is coupled to each cooperating
pair of inner and outer horn spring members via appropriate hinge
regions 242. Thus, as the double horn cells 234 are moved from the
contracted state illustrated in FIG. 32A to the expanded state
illustrated in FIG. 32B, cooperating pairs of inner and outer horn
spring members 240 are flexed outwardly to a point at which the
thin struts 238 are generally aligned. Subsequent to this point of
expansion, the horn spring members 240 begin to release the stored
spring energy and force thin struts 238 towards the fully expanded
state.
[0118] Other forms of spring elements also may be utilized in
facilitating expansion of a variety of cell types. For example, in
FIG. 33 an expandable cell 244 is illustrated in which adjacent
thick struts 246 are coupled to a thin strut 248 by a different
type of spring members 250. Spring members 250 may be coiled,
undulating or arranged along other paths that accommodate the
transitioning of thin strut 248 from the contracted state
illustrated in FIG. 33 to an expanded state.
[0119] Another type of spring system is illustrated in FIG. 34 as
an expandable cell 252. A pair of thick struts 254 are coupled by a
pair of undulating thin struts 256. The design of thin struts 256
incorporates a plurality of spring elements 258 that both
accommodate flexure of the thin struts 256 and expansion of the
cell 252 by storing and then releasing spring energy. The spring
energy is released as the thin struts transition past a point of
maximum flexure towards the fully expanded state.
[0120] To secure the overall device, e.g. tubular, in the expanded
position, a locking mechanism may be utilized to prevent the
individual cells from contracting. Exemplary locking mechanisms may
be associated with individual cells, or they may be located at one
or more positions along the expandable device. In FIGS. 35A-35D,
one type of locking mechanism 258 is illustrated. In this
embodiment, a post 260 is slidably received in a corresponding
recess 262. A ratchet finger 264 extends generally transversely
towards post 260. Specifically, ratchet finger 264 comprises an
engagement end 266 that resides in a recessed area 268 of post 260
when the overall device and locking mechanism 258 are in a
contracted state, as illustrated in FIG. 35A.
[0121] As the device, e.g. tubular, is expanded, ratchet finger 264
is flexed away from an adjacent support surface 270, as illustrated
best in FIG. 35D. The ratchet finger 264 continues to slide along
the side of post 260 as the device is expanded to a maximum degree
illustrated in FIG. 35C. When the expansion force is relaxed, any
substantial movement of post 260 towards the contracted position is
blocked by ratchet finger 264, as illustrated in FIG. 35D. As post
260 attempts to move towards its contracted state, engagement end
260 is pressed firmly into interfering engagement with the side of
post 260. Additionally, support surface 270 limits the movement of
ratchet finger 264 in the contracting direction. The side wall of
post 260 may comprise teeth or other interfering features that aid
in preventing movement of post 260 back towards the contracted
state.
[0122] Another exemplary locking mechanism 272 is illustrated in
FIGS. 36A-36D. In this embodiment, a fork ratchet 274 is formed in
the expandable device, such as in the wall of an expandable
tubular. Fork ratchet 274 comprises a pair of prongs 276 that each
have a divergent end 278. In the contracted state, prongs 276 are
received in an opening 280 having a generally hourglass shape
profile. In other words, divergent ends 278 reside in a divergent
or expanded portion 282 of opening 280 and must be pulled through a
narrow or constricted portion 284 when the device is expanded.
[0123] During expansion of the tubular or other device, divergent
portions 282 are drawn through constricted region 284 (see FIGS.
36B and 36C.) Once prongs 276 are drawn clear of opening 280, the
divergent portions 282 once again spring outwardly to their normal
position. In this position, divergent portions 282 are wider than
the entrance to opening 280, and fork ratchet 274 is prevented from
reentering opening 280. Thus, the overall device is held in its
expanded state.
[0124] Another exemplary locking mechanism 284 is illustrated in
FIG. 37. Locking mechanism 284 is designed for use with horn style
cells. In the specific example illustrated, a slot 286 is formed
between a pair of spring member horns 288 within a thick strut 290
of an expandable cell 292. A wedge 294 extends from an adjacent
thick strut 296 into slot 286. As cell 292 is expanded, wedge 294
is drawn outwardly through slot 286. The size of the wedge tip 298
and slot outlet 300 are selected to interfere when cell 292 is in
its expanded state. This prevents flexing of horns 288 towards slot
286 and thereby inhibits collapse of the expanded cell.
[0125] Referring generally to FIGS. 38A-41B, a variety of
expandable cell and locking mechanism combinations are illustrated.
With specific reference to FIGS. 38A and 38B, one embodiment of an
expandable cell 302 comprises thick struts 304 that are coupled
together by thin struts 306 via spring members 308. Each thick
strut 304 comprises one or more, e.g. two, ratchet fingers 310 that
slide along a corresponding ratchet surface 312 formed on expanded
regions of the thin struts 306 (see FIG. 38B).
[0126] Ratchet surface 312 may incorporate ratchet teeth to engage
the end of the corresponding ratchet finger 310. As the expandable
cell 302 is transitioned from its contracted state, as illustrated
in FIG. 38A, to an expanded state, as illustrated in FIG. 38B,
ratchet fingers 310 are flexed away from a support surface 314
while sliding along corresponding ratchet surfaces 312. The ends of
the ratchet fingers 310 do not allow sliding motion of
corresponding ratchet surfaces 312 back towards the contracted
state. Furthermore, support surfaces 314 may be relied on to limit
any flexing of fingers 310 back towards the contracted position.
Thus, when the expandable cell in its expanded state, each of the
ratchet fingers 310 acts against a corresponding ratchet surface
312 to support the cell against collapse.
[0127] Another embodiment of the system is illustrated in FIG. 39
and utilizes fingers in the form of ratchet pawls 316. In this
embodiment, each ratchet pawl is formed in an appropriate thick
strut 304 by creating an open area 318 configured to receive a
corresponding portion 320 of thin strut 306 when in the contracted
position. Each ratchet pawl 316 may comprise a plurality of teeth
322 positioned to engage corresponding teeth 324 extending from
portion 320. Additionally, a relief cut 326 may be formed along
ratchet pawl 316 generally opposite open area 318. Relief cut 326
allows ratchet pawl 316 to flex as teeth 322 are dragged past teeth
324 during transition of the cell from a contracted state to an
expanded state. Teeth 322 and 324 are designed to prevent closure
of the cell once expansion begins. Thus, the ratchet pawl 316
effectively ratchets along portion 320 holding the cell at each
additional degree of expansion. As an alternative to teeth, the
ratchet pawl 316 and cooperating portion 320 may utilize other
types of interfering features to prevent contraction of the
cell.
[0128] The locking mechanisms also may be used in cooperation with
expandable cells that are not necessarily bistable cells. For
example, in FIG. 40A an expandable cell 330 comprises a thin strut
332 disposed in an expandable "wishbone" type configuration between
the thick struts 334 to which it is connected. A locking mechanism
336 cooperates with one or more of the expandable thin struts 332
to hold the expandable cells 330, at an expanded position. As
illustrated in FIG. 40B, a locking mechanism 336 may be combined
with each expandable cell 330, or there may be multiple expandable
cells for each locking mechanism 336.
[0129] In this embodiment, locking mechanism 336 comprises a post
338 having external teeth 340. Post 338 is slidably received within
an opening 342 defined by one or more flexible fingers 344 having
engagement tips 346 that engage teeth 340. Fingers 344 flex
outwardly to allow teeth 340 to slide past engagement tips 346 as
the cell is expanded, but engagement tips 346 prevent post 338 from
moving in a direction towards the contracted state. Thus, once
expandable cell 330 is expanded, locking mechanism 336 prevents
contraction of the cell.
[0130] A similar design is illustrated in FIGS. 41A and 41B. This
design combines the expandable cell described with reference to
FIG. 40A and a locking mechanism of the type described in FIGS.
36A-36D. Thus, as the plurality of expandable cells 330 are moved
from the contracted state illustrated in FIG. 41A to the expanded
state illustrated in FIG. 41B, the wishbone style thin strut is
expanded. Simultaneously, prongs 276 are pulled from their
corresponding opening 280 to a position that prevents reentry of
fork 274 into opening 280. The locking mechanism may be designed
such that prongs 276 are withdrawn from and blocked from reentering
opening 280. Alternatively, prongs 276 may be designed for
interference with corresponding teeth or other interfering features
350 disposed along the outer limit of each opening 280 to prevent
return movement of prongs 276 into opening 280.
[0131] It also should be noted that expandable devices, such as
expandable tubulars, can be formed with a variety of cells and
locking mechanisms having differing configurations, such as changes
in size or type, as illustrated schematically in FIG. 42. For
example, by stacking cells of different length or eccentric offset
in a sheet or tube, it is possible to design an opening bias into
the structure. The expandable device may be designed to allow
certain rows of cells to open prior to other rows of cells or for
the cells to open in a predetermined pattern or at a predetermined
rate. In FIG. 42, for example, an expandable device 352 comprises
rows of expandable cells 354. However, different rows 354 have
cells of differing lengths, e.g. cells 356, 358 and 360. This
allows certain rows of cells to open prior to adjoining rows of
cells, because, at least with certain cell designs, the length of
the cell affects the force required to expand the cell.
Incorporating different rows of cells into an expandable device
allows the user to know the rate of expansion for a given
deployment force and facilitates the design of devices having cells
which open in a predetermined sequence. Additionally, the use of
different types of cells can improve compliance of the expandable
device when the deployment force is not uniform along the length of
the device.
[0132] It will be understood that the foregoing description is of
exemplary embodiments of this invention, and that the invention is
not limited to the specific forms shown. For example, the
expandable cells can be combined into a variety of tubulars and
other expandable structures; the size and shape of the expandable
cells and locking mechanisms can be adjusted; the types of material
utilized can be changed depending on the specific application; and
a variety of mechanisms may be used to expand the cells. Also, the
various cells can be formed by a variety of techniques including
laser cutting, jet cutting, water jet cutting and other formation
techniques. These and other modifications may be made in the design
and arrangement of the elements without departing from the scope of
the invention as expressed in the appended claims.
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