Note: Descriptions are shown in the official language in which they were submitted.
CA 02544701 2002-O1-14
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EXPANDABLE SAND SCREEN AND METHODS FOR USE
FIEhD OF THE INVENTION
This invention relates to equipment that can be
used in the drilling and completion of boreholes in an
underground formation and in the production of fluids from
such wells.
BACKGROUND OF THE INVENTION
Fluids such as oil, natural gas and water are
obtained from a subterranean geologic formation
(a ~~reservoir") by drilling a well that penetrates the
fluid-bearing formation. Once the well has been drilled to
a certain depth the borehole wall must be supported to
prevent collapse. Conventional well drilling methods
involve the installation of a casing string and cementing
between the casing and the borehole to provide support
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for the borehole structure. After cementing a casing string in
place, the drilling to greater depths can commence. After each
subsequent casing string is installed, the next drill bit must
pass through the inner diameter of the casing. In this manner
s each change in casing requires a reduction in the borehole
diameter. This repeated reduction in the borehole diameter
results in a requirement for very large initial borehole
diameters to permit a reasonable pipe diameter at the depth
where the wellbore penetrates the producing formation. The need
~o for larger boreholes and multiple casing strings results in the
use of more time, material and expense than if a uniform size
borehole could be drilled from the surface to the producing
formation.
~s Various methods have been developed to stabilize or
complete uncased boreholes. U.S. Patent No. 5,348,095 to
Worrall et al. discloses a method involving the radial expansion
of a casing string to a configuration with a larger diameter.
Very large forces are needed to impart the radial deformation
zo desired in this method. In an effort to decrease the forces
needed to expand the casing string, methods that involve
expanding a liner with longitudinal slots cut into it have been
proposed (U. S. Patents Nos. 5,366,012 and 5,667,011). These
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methods involve the radial deformation of the slotted liner into
a configuration having an increased diameter by running an
expansion mandrel through the slotted liner. Such methods still
require significant amounts of force to be applied throughout
s the entire length of the slotted liner.
In some drilling operations, another problem encountered is
the loss of drilling fluids into subterranean zones. The loss
of drilling fluids usually leads to increased expenses but also
to can result in a borehole collapse and a costly "fishing" job to
recover the drill string or other tools that were in the well.
Various additives, e.g. cottonseed hulls or synthetic fibers,
are commonly used within the drilling fluids to help seal off
loss circulation zones.
Furthermore, once a well is put in production an influx of
sand from the producing formation can lead to undesired fill
within the wellbore and can damage valves and other production
related equipment. There have been many attempted methods for
ao controlling sand. For example, some wells utilize sand screens
to prevent or restrict the inflow of sand and other particulate
matter from the formation into the production tubing. The
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annulus formed between the sand screen and the wellbore wall
is packed with a gravel material in a process called a
gravel pack.
The present invention is directed to overcoming,
or at least reducing the effects of one or more of the
problems set forth above, and can be useful in other
applications as well.
SU1~1ARY OF THE INVENTION
In one aspect of the present invention, a
technique is provided for controlling the influx of sand or
other particulates into a wellbore from a geological
formation. The technique utilizes an expandable member that
may be deployed at a desired location in a wellbore and then
expanded outwardly. When expanded, the device is better
able to facilitate flow while filtering particulate matter.
In accordance with a second broad aspect, the
invention provides a system for filtering in a wellbore
environment, comprising: at least one filter media defining
a plurality of perforations, the perforations being selected
to provide a predetermined flow regime therethrough.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will hereafter be described with
reference to the accompanying drawings, wherein like
reference numerals denote like elements, and:
Figures 1A and 1B are illustrations of the forces
imposed to make a bistable structure;
5
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Figure 2A and 2B show force-deflection curves of two
bistable structures;
s Figures 3A - 3F illustrate expanded and collapsed states of
three bistable cells with various thickness ratios;
Figures 4A and 4B illustrate a bistable expandable tubular
in its expanded and collapsed states;
~o
Figures 4C and 4D illustrate a bistable expandable tubular
in collapsed and expanded states within a wellbore;
Figures 5A and 5B illustrate an expandable packer type of
is deployment device;
Figures 6A and 6B illustrate a mechanical packer type of
deployment device;
zo Figures 7A - 7D illustrate an expandable swage type of
deployment device;
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Figures 8A - 8D illustrate a piston type of deployment
device;
Figures 9A and 9B illustrate a plug type of deployment
s device;
Figures 10A and 10B illustrate a ball type of deployment
device;
to Figure 11 is a schematic of a wellbore utilizing an
expandable bistable tubular;
Figure 12 illustrates a motor driven radial roller
deployment device;
Figure 13 illustrates a hydraulically driven radial roller
deployment device;
Figure 14 is a cross-sectional view of one embodiment of
ao the sand screen of the present invention;
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Figure 15 is a cross-sectional view of one embodiment of
the sand screen of the present invention;
Figure 16 is a cross-sectional view of one embodiment of
s the sand screen of the present invention;
Figure 17 is a perspective view of one embodiment of the
sand screen of the present invention;
Io Figure 18 is a cross-sectional view of one embodiment of
the sand screen of the present invention;
Figure 19 is a cross-sectional view of one embodiment of
the sand screen of the present invention;
IS
Figure 20 is a cross-sectional view of one embodiment of
the sand screen of the present invention;
Figure 21 is a side elevational view of a screen according
zo to one embodiment of the present invention;
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Figure 22 is a partial perspective view of a screen
according to one embodiment of the present invention;
s Figure 23 is a cross-sectional schematic view of one
embodiment of the present invention;
Figure 24 is a cross-sectional schematic view of one
embodiment of the present invention;
io
Figure 25 is a schematic view of an embodiment of filter
sheets for the present invention;
Figure 26 is a schematic view of one embodiment of filter
~s sheets that can be utilized with the device illustrated in
Figure 25;
Figure 27 is a partial cross-sectional view of an exemplary
filter layer;
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Figure 28 is a partial cross-sectional view of another
exemplary filter layer;
Figures 29A-B are cross-sectional views illustrating an
s exemplary technique for screen formation;
Figure 30 is a partial cross-sectional view of a screen
locking mechanism as part of one embodiment of the present
invention;
to
Figure 31 is a partial cross-sectional view of an
alternative screen locking mechanism;
Figure 32 is a partial cross-sectional view of another
is alternative screen locking mechanism;
Figure 33 is a partial cross-sectional view of a screen
utilizing a locking mechanism;
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Figure 34 is a cross-sectional, exploded view of an
alternate screen according to another embodiment of the present
invention;
s Figure 35 is a front view of a portion of exemplary filter
material for use with the embodiment illustrated in Figure 34;
and
Figure 36 is a front view of an exemplary filter sheet for
to use with screens, such as the screen illustrated in Figure 34.
GVhile 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
is 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 vn
the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the spirit and
zo scope of the invention as defined by the appended claims.
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DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
Bistable devices used in the present invention can take
advantage of a principle illustrated in Figures 1A and 1B.
Figure 1A shows a rod 10 fixed at each end to rigid supports 12.
s If the rod 10 is subjected to an axial force it begins to deform
as shown in Figure 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
to 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 i~
before deflecting to its new stable position.
is Bistable systems are characterized by a force deflection
curve such as those shown in Figures 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
zo 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.
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The force deflection curve for this example is symmetrical
and is illustrated in Figure 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 Figure 2B.
s 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.
io 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).
Instead of using the rigid supports as shown in Figures 1A
and 1B, a cell can be constructed where the restraint is
provided by curved struts connected at each end as shown in
Figures 3A - 3F. If both struts 21 and 22 have the same
2o thickness as shown in Figures 3A and 3B, the force deflection
curve is linear and the cell lengthens when compressed from its
open position Figure 3B to its closed position Figure 3A. If
the cell struts have different thicknesses, as shown in Figures
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3C - 3F, the cell has the force deflection characteristics shown
in Figure 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,
s 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, Figures 3C and 3D illustrated a thickness
~o ratio of approximately 3:1, and Figures 3E and 3F illustrate a
thickness ratio of approximately 6:1.
An expandable bore bistable tubular, such as casing, a
tube, a patch, or pipe, can be constructed with a series of
is circumferential bistable connected cells 23 as shown in Figures
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
Zo deflection characteristics and the longitudinal flexibility can
also be altered by the design of the cell shape. Figure 4A
illustrates an expandable bistable tubular 24 in its expanded
configuration while Figure 4B illustrates the expandable
14
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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
s 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 Figure 4C.
Upon placement of the bistable tubular 24 at a desired wellbore
location, it is expanded, as illustrated in Figure 4D.
io
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
is 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
2o 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
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length of bistable expandable tubular can be expanded from a
single point.
In like manner if radial compressive forces are exerted on
s 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
io tubular can be a reusable tool that is selectively changed
between the expanded state as shown in Figure 4A and the
collapsed state as shown in Figure 4B.
In the collapsed state, as in Figure 4B, the bistable
is 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.
2o In the expanded state, as in Figure 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
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properties and the geometric shape of the bistable cells can be
designed to give certain desired results.
One example of designing for certain desired results is an
s 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
io 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 encased section of the well. Figure 11
illustrates one example of this condition. A wellbore 40 is
drilled from the surface 42 and comprises a cased section 44 and
is 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
ao the well.
Bistable collars or connectors 24A (see Figure 4C) can be
designed to allow sections of the bistable expandable tubular to
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be joined together into a string of useful lengths using the
same principle as illustrated in Figure 4A and 4B. This
bistable connector 24A also incorporates a bistable cell design
that allows it to expand radially using the same mechanism as
s 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.
io 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
is two segments and the connector.
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
zo 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
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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.
s
A conveyance device 31 transports the bistable expandable
tubular lengths and bistable connectors into the wellbore and to
the correct position. (See Figures 4C and 4D). The conveyance
device may utilize one or more mechanisms such as wireline
to cable, coiled tubing, coiled tubing with wireline conductor,
drill pipe, tubing or casing.
A deployment device 33 can be incorporated into the overall
assembly to expand the bistable expandable tubular and
is connectors. (See Figures 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 sonically shaped device pulled or pushed
Zo through the tubing, a ball type apparatus or a rotary type
expander as further discussed below.
An inflatable packer element is shown in Figures 5A and 5B
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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 Figure 5A, the inflatable
packer element 25 is located inside the entire length, or a
s 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 Figure 5B. The
io 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
is 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
2o expandable tubular 24.
A mechanical packer element is shown in Figures 6A and 6B
and is a device with a deformable plastic element 26 that
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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
s 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 Figure 6A) to
to a final deployment diameter (see Figure 6B).
An expandable swage is shown in Figures 7A - 7D and
comprises a series of fingers 28 that are arranged radially
around a conical mandrel 30. Figures 7A and 7C show side and
is top views respectively. When the mandrel 30 is pushed or pulled
through the fingers 28 they expand radially outwards, as
illustrated in Figures 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.
A piston type apparatus is shown in Figures 8A - 8D and
comprises a series of pistons 32 facing radially outwardly and
used as a mechanism to expand the bistable expandable tubulars
21
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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. Figures 8A and
8C illustrate the pistons retracted while Figures 8B and 8D show
s the pistons extended. The piston type apparatus can be actuated
hydraulically, mechanically or electrically.
A plug type actuator is illustrated in Figures 9A and 9B
and comprises a plug 34 that is pushed or pulled through the
~o bistable expandable tubulars 24 or connectors as shown in Figure
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 Figure 9B.
is A ball type actuator is shown in Figures 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
zo 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
22
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cell geometry beyond the critical bistable point, allowing full
expansion to take place as shown in Figure 10B. Once the
bistable expandable tubulars and connectors are expanded, the
elastomer sleeve 38 and ball 36 are withdrawn.
s
Radial roller type actuators also can be used to expand the
bistable tubular sections. Figure 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
io 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 rollers) circumferentially inside the
is wellbore. The axis of the rollers) is such as to allow the
rollers) 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
ao 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
23
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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
s the rollers 60.
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
~o 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
~s from the bistable tubular by a conveyance device 68 that also
can be used to insert the tool.
Figure 13 illustrates a hydraulically driven radial roller
deployment device. The tool comprises one or more rollers 60
Zo 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.
24
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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
s 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
io 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.
is
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
ao 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.
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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
s 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.
~o
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
is 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
zo 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
26
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expense of drilling fluids can be reduced and the risk of losing
circulation and/or borehole collapse can be minimized.
Liners also can be used within wellbore tubulars for
s 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 (COz) readily reacts with any water
(HzO) that is present to form carbonic acid (HzC03). Other acids
io 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
is existing tubular to minimize the corrosive effects and to extend
the useful life of the wellbore tubulars.
Another exemplary application involves use of the bistable
tubular 24 as an expandable perforated liner. The open bistable
zo cells in the bistable expandable tubular allow unrestricted flow
from the formation while providing a structure to stabilize the
borehole.
27
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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
s 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
io reduce or eliminate the influx of sand from the producing zones,
even if no additional screen element is used.
The above described bistable expandable tubulars can be
made in a variety of manners such as: cutting appropriately
is 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
2o 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
28
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adjoining ends to form an expandable bistable device in its
expanded state and then compressing the device into its
collapsed state.
s 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.
to
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.
In Figures 14 through 20, an exemplary particulate screen
80, e.g. sand screen, is illustrated as formed of a tubular made
of bistable cells. The sand screen 80 has a tubular 82, formed
of bistable cells 23 as previously discussed, that provides the
2o structure to support a filter material 84 as well as the
necessary inflow openings through the base tubular that are a
part of the bistable cell 23 construction. The sand screen 80
has at least one filter 84 (or filter material) along at least a
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portion of its length. The filter 84 may be formed of a
material commonly used for sand screens and may be designed for
the specific requirements of the particular application (e. g.,
the mesh size, number of layers, material used, etc.). Further,
s the properties and design of the filter 84 allow it to at least
match the expansion ratio of the tubular 82. Folds, multiple
overlapping layers, or other design characteristics of the
filter 84 may be used to facilitate the expansion. The sand
screen 80 could be expanded as described herein and may include
io any form of bistable cell. In one embodiment of use, the sand
screen 80 is deployed on a run-in tool that includes an
expanding tool, as described above. The sand screen 80 is
positioned at the desired location (e.g., adjacent the area to
be filtered) and expanded. The sand screen 80 may expand such
is that it engages or contacts the walls of the well conduit (such
as the borehole) essentially eliminating or reducing any annulus
between the sand screen and the well conduit. In such a case
the need for a gravel pack may be reduced or eliminated.
2o Figures 14 and 15 illustrate alternative embodiments of the
sand screen 80 of the present invention. In the embodiment of
Figure 14, the filter material 84 has a plurality of folds 85 to
allow expansion of the tubular 82. The filter material 84 is
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connected to the tubular 82 (as by welding or other methods) at
various points about the tubular circumference. In the
embodiment of Figure 15, the filter material 84 is provided in
overlapping sheets 85A which are each attached at one edge so
s that one sheet of material 84 has a longitudinally extending
edge attached to the tubular 82 and overlaps an adjacent sheet
of filter material 84. As the tubular expands, the filter
sheets 85A slide over one another and still cover the full
expanded circumference of the tubular 82. In the embodiment of
to Figures 16 and 17, the filter material 84 is in the form of a
single sheet 85B attached to the tubular 82 in at least one
longitudinal location and wrapped around the tubular 82. Single
sheet 85B overlaps itself so that in the fully expanded state,
the full circumference of the tubular 82 is still covered by the
is filter material 84.
As illustrated in Figures 18 through 20, additional
alternative embodiments are similar to those of Figures 14
through 16 respectively but include a shroud 88. Shroud 88
zo encircles tubular 82 and filter 84 to protect the filter media
84 during shipping and deployment.
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In an alternative embodiment (shown in Figure 21), the sand
screen 80 has at least one section supporting a filter 84 and at
least one other section of the tubular supporting a seal
material 86. In the exemplary embodiment, multiple longitudinal
s filter sections are separated by seal sections. The seal
material 86 may comprise an elastomer or other useful seal
material and has an expansion ratio at least as great as the
tubular. V~lhen expanded, the seal material preferably seals
against the walls of a conduit in a well (e. g., the borehole
~o wall, the bottom end of a liner or a casing positioned in the
well, etc). Providing multiple sections with filter material 84
separated by sections having a seal material 86 thereon provides
isolated screen sections.
is In Figure 22 another embodiment of the sand screen is
illustrated in which at least one filter media 94 is positioned
between a pair of expandable tubes 90,92. The tubes 90,92 are
formed of bistable cells 23 and protect the filter media 94 from
damage. The filter media 94 may be formed from a variety of
zo filter media. The embodiment illustrated in Figure 22 uses a
relatively thin sheet of material, such as a foil material,
having perforations therein.
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As illustrated in Figures 23 and 24, filter media 94 may
comprise a single sheet 93 of filter media 94 (Figure 24) or a
plurality of sheets 95 of overlapping material (Figure 23). As
shown in the figures, the material may connect to one of the
s tubes 90,92 at a connection point 96 intermediate the edges of
the filter media 94. Alternatively, the filter media 94 may
connect to one of the tubes 90,92 at an edge thereof. However,
connecting the filter media 94 intermediate the edge allows each
edge to overlap at least an adjacent filter sheet or, in the
io case of a single sheet, to overlap itself. Figure 24
illustrates edges of the filter media 94 overlapping one
another. Note that the filter sheet may connect to either' the
base tube 90 or the outer tube 92.
is In Figure 25, a pair of filter sheets are positioned side-
by-side. The filter sheets are formed of a relatively thin
material, such as a metal foil, having perforations 98 therein.
The perforations may be formed in a variety of ways. One manner
of forming the perforations is with laser cutting techniques;
zo while an alternative method is to use a water jet cutting
technique. In the embodiment shown, the perforations in one of
the filter sheets are slots having a relatively high aspect
ratio. The other filter sheet has slots and holes. The slots
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of the second sheet are oriented at an angle to the slots of the
first filter sheet.
In Figure 26, the filter sheets are illustrated as
s overlapping one another to create a flow area 99 through the
overlapping filter sheets, due to the relative orientation of
the perforations 98. Note that the perforations 98 may have a
variety of shapes depending on the needs of the particular
application. Also, the amount of overlap and relative
to positioning and shape of the perforations may be used to provide
a desired flow path characteristic and flow path regime. For
example, the relative pressure drop through the screen about the
circumference or length of the screen may be predesigned by
selecting the desired flow path sizes and pattern overlap.
is Providing a pressure drop that varies along the length of the
sand screen, as an example, may provide for a more uniform
production boundary layer control and help reduce coning during
production. As an example, a portion of the sand screen may
provide for more restricted flow relative to another portion of
2o the sand screen to control the boundary layer approach to the
wellbore, thereby reducing coning and increasing production.
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Although shown as vertical and horizontal slots, the slots
may be oriented at any angle relative to the longitudinal
direction of the sand screen. For example, orienting the slots
at forty-five degrees to the longitudinal direction may provide
s greater manufacturing efficiency because the alternate sheets
may be mounted so that the resulting pattern has slots of
adjacent sheets oriented at ninety degrees to one another.
Similarly, rounded perforations may be used to reduce flat
surfaces that may tend to hang during expansion or for other
~o reasons. The possible shapes that may be used is virtually
unlimited and are selected depending upon the application. As
the filter sheets slide over one another during the expansion of
the tubings 90, 92, the sizes of the openings formed by the
overlap of the adjacent filter sheets changes. More than two
is filter sheets 94 may overlap one another so that, for example,
at least a portion of the filtering media may comprise three or
more layers of filter sheets.
In Figures 27 and 28, alternative embodiments for the
2o composition of the filter sheets, e.g. sheets 95, are
illustrated. The embodiment illustrated in Figure 27 uses
filter sheets having a central filter portion 100 formed of a
compact fibrous metal material (e.g., a free-wire mesh). The
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material forms multiple tortuous paths sandwiched between a pair
of foil sheets 101. In the embodiment of Figure 28, central
filter portion 100 has a woven-type material, such as a woven
Dutch twill filter material, positioned between a pair of foil
s sheets 101. Other filter media also may be used.
With reference to Figures 29A-B, an exemplary technique for
manufacturing an expandable sand screen 80 can be described.
Note that the manufacturing technique may be used to manufacture
to other expandable systems having multiple layers of expandable
conduits. Likewise, this manufacturing technique may be used to
manufacture non-expanding sand screens and similar equipment.
As shown in the figure, an inner conduit 102 is positioned on a
plate 103 having a layer of filter material 204 positioned
is thereon. Filter material 104 is positioned to reside between
the plate 103 and the inner conduit 102. In the case of an
expandable system, the inner conduit 102 and the plate 103 have
the slots or bistable cells formed thereon prior to assembly as
follows. With the conduit 102 positioned on or over the plate
zo 103 and with the filter material 104 interposed therebetween,
the plate and filter sheets are wrapped around the inner conduit
102 to the position shown in Figure 29B. The filter sheet may
cover all or some portion of the plate 103. Similarly, the
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filter sheet may cover all or some portion of the inner conduit
102 after wrapping.
In the embodiment shown in Figure 29B, the plate 103 (also
s referred to herein as the shroud) does not extend about the full
circumference of the conduit 102 leaving a gap or passageway 108
extending longitudinally along the screen 80. In other
embodiments, the filter material and/or the shroud extend about
the full circumference. Control lines, other types of conduits
io and equipment may be placed in the passageway 108. The filter
material 104 may be attached to the shroud prior to wrapping
such as by welding. Tn an alternative embodiment, the filter
media 104 is attached after wrapping along with the shroud/plate
103. The filter media 104 may extend beyond the shroud for
is connection to the conduit 102 or in other manners as deemed
convenient or advantageous depending on the design of the
screen, the presence or absence of the passageway 108 and other
design factors.
zo The screen 80 of Figures 29A-B may be formed of bistable
cells or of other expandable devices such as overlapping
longitudinal slots or corrugated tubing. In the case of an
expandable tubing formed of bistable cells, for example, the
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welds used for attaching the various components may be placed on
thick struts 22. The thick struts may be adapted so that they
do not undergo deformation during expansion to preserve the
integrity of the weld.
s
In alternative embodiments, sand screen 80 is manufactured
or formed in other ways. However, shroud 103 can still be
formed to extend only partially about the circumference of the
conduit 102, thereby forming passageway 108. The passageway
io size may be adjusted as desired to route control lines, form
alternate path conduits or for placement of equipment, such as
monitoring devices or other intelligent completion equipment.
Referring generally to Figures 30-32, an alternative
is embodiment is illustrated in which the filter material 84
includes a locking feature 109. As previously discussed,
certain embodiments use one or more overlapping sheets of filter
material 84 that slide over one another during expansion. In
some circumstances it is advantageous to lock the filter
2o material and the sand screen 80 in the expanded position. In
the embodiments of Figures 30-32, the locking feature 109 allows
the filter sheets 84 to slide over one another in a first
direction (the expanding direction) and prevents movement in a
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contracting direction. The alternative embodiments shown, as
examples, are ratchet teeth 110 (Figure 30), detents or bristles
112 (Figure 31), and vanes 114 (Figure 32) formed on or attached
to the filter media. Locking of the filter media 84 in the
s expanded position can be used to improve the collapse resistance
of the expanded sand screen 80.
In Figure 33, another type of locking mechanism 109 is
incorporated onto a portion of an expandable conduit. In this
io embodiment, the expandable conduit is formed of an inner tubular
82 having a portion 116 of the locking mechanism 209 (such as
one of the embodiments shown in Figures 30-32) formed thereon.
A shroud 88 surrounding the tubular 82 also has a portion 118 of
the locking mechanism 109 formed thereon. As the tubular and
~s shroud are expanded, the locking mechanism 109 locks the
expanded position of the expandable conduit. A filter media may
be placed between the tubular and the shroud, for example, on
either side of the locking mechanism 109. The locking mechanism
may be positioned about the full circumference of the tubular 82
ao and the shroud 88 or about a portion of the circumference.
Referring generally to Figures 34 through 36, another
embodiment of a particulate screen is illustrated and labeled as
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particulate screen 120. Particulate screen 120 is shown in
partially exploded form as having a filter material disposed
radially between expandable structures. As illustrated best in
Figure 34, an inner tube or base pipe 122 is circumferentially
s surrounded by an expanding base filter 124. Additionally, a
plurality of overlapping filter sheets 126, e.g. four
overlapping filter sheets 126, are disposed along the exterior
surface of base filter 124. A shroud 128 is disposed around
overlapping filter sheets 126 to secure base filter 124 and
~o overlapping filter sheets 126 between base pipe 122 and shroud
12 8 .
In this application, both base pipe 122 and shroud 128 are
designed for expansion to a larger diameter. For example, base
~s pipe 122 may comprise one or more bistable cells 130 that
facilitate the expansion from a contracted state to an expanded
state. Similarly, shroud 128 may comprise one or more bistable
cells 132 that facilitate expansion of the shroud from a
contracted to an expanded state.
zo
One technique for constructing shroud 128 is to form the
shroud in multiple components 134, such as halves that are split
generally axially. In this example, the two components 134 are
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connected to base pipe 122 at their respective ends 136. For
example, component ends 136 may be welded to base pipe 122
through base filter 124 by, for example, filet welds at
locations generally indicated by arrows 138.
Although overlapping filter sheets 126 may be positioned
between base pipe 122 and shroud 128 in a variety of ways, one
exemplary way is to secure each sheet 126 to shroud 128.
Opposed edges 140 of adjacent filter sheets 126 can be connected
~o to shroud 128 by, for example, a weld 142. By affixing opposed
edges 140, overlapping free ends 144 are able to slide past one
another as base pipe 122 and shroud 128 are expanded.
Overlapping filter sheets 126 may be formed from a variety
is of materials, such as a material 146, as illustrated best in
Figure 35. An exemplary woven material 146 is a woven metal
fabric having wires 148 woven more or less tightly depending on
the desired particle size to be filtered. One specific
exemplary material is a woven metal fabric woven in a twilled
ao dutch weave of overlapping wires 148, as illustrated in Figure
35.
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Another exemplary filter material 150 is illustrated in
Figure 36. Filter material 150 comprises a sheet 152 having a
plurality of openings 154 formed therethrough. For example,
openings 154 may be formed as a multiplicity of tiny slots
s disposed at a desired angle 156, such as a 45° angle.
If filter material 150 is utilized to form overlapping
filter sheets 126, the overlapping sheets typically are oriented
in opposite directions. Thus, the slots 154 of one filter sheet
io 126 intersect the slots 154 of the overlapping adjacent filter
sheet 126 to form a multiplicity of smaller openings for
filtering particulate matter. In the embodiment illustrated,
the sheets can be oriented such that the slots 154 of one filter
sheet 126 are oriented at approximately 90° with respect to slots
is 154 of the adjacent overlapping sheet.
With respect to base filter 124, the filter material is
generally wrapped around or disposed along the exterior surface
of base pipe 122. The material of base filter 124 may comprise
zo numerous types of filter material that typically are selected to
permit an expansion of the material and an increase in opening
or pore size during such expansion. Exemplary materials
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comprise meshes, such as metallic meshes, including woven and
non-woven designs.
The particular embodiments disclosed herein are
s illustrative only, as the invention may be modified and
practiced in different but equivalent manners apparent to those
skilled in the art having the benefit of the teachings herein.
Furthermore, no limitations are intended to the details of
construction or design herein shown, other than as described in
to the claims below. It is therefore evident that the particular
embodiments disclosed above may be altered or modified and all
such variations are considered within the scope and spirit of
the invention. Accordingly, the protection sought herein is as
set forth in the claims below.
IS
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