Note: Descriptions are shown in the official language in which they were submitted.
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VARIABLE FLOW RESISTANCE FOR USE WITH A
SUBTERRANEAN WELL
TECHNICAL FIELD
This disclosure relates generally to equipment utilized
and operations performed in conjunction with a subterranean
well and, in an example described herein, more particularly
provides for variably resisting flow.
BACKGROUND
Among the many reasons for variably resisting flow are
included: a) control of produced fluids, b) control over the
origin of produced fluids, c) prevention of formation
damage, d) conformance, e) control of injected fluids, f)
control over which zones receive injected fluids, g)
prevention of gas or water coning, h) stimulation, etc.
Therefore, it will be appreciated that improvements in the
art are continually needed.
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SUMMARY
In this disclosure, systems and methods are provided
which bring improvements to the art of variably resisting
flow of fluids in conjunction with well operations. One
example is described below in which a change in direction of
flow of fluids through a variable flow resistance system
changes a resistance to the flow. Another example is
described below in which a change in a structure changes the
flow resistance of the system.
In one described example, a variable flow resistance
system can include a structure which displaces in response
to a flow of a fluid composition. A resistance to the flow
of the fluid composition changes in response to a change in
a ratio of desired to undesired fluid in the fluid
composition.
In another example, a variable flow resistance system
can include a structure which rotates in response to flow of
a fluid composition, and a fluid switch which deflects the
fluid composition relative to at least two flow paths. In
this example also, a resistance to the flow of the fluid
composition through the system changes in response to a
change in a ratio of desired to undesired fluid in the fluid
composition.
In a further example, a variable flow resistance system
can include a chamber through which a fluid composition
flows, whereby a resistance to a flow of the fluid
composition through the chamber varies in response to a
change in a direction of the flow through the chamber, and a
material which swells in response to a decrease in a ratio
of desired to undesired fluid in the fluid composition.
In yet another example, a variable flow resistance
system can include at least two flow paths, whereby a
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resistance to a flow of a fluid composition through the
system changes in response to a change in a proportion of
the fluid composition which flows through the flow paths. In
this example, an airfoil changes a deflection of the flow of
the fluid composition relative to the flow paths in response
to a change in a ratio of desired to undesired fluid in the
fluid composition.
A further example comprises a method of variably
resisting flow in a subterranean well. The method can
include a structure displacing in response to a flow of a
fluid composition, and a resistance to the flow of the fluid
composition changing in response to a change in a ratio of
desired to undesired fluid in the fluid composition.
These and other features, advantages and benefits will
become apparent to one of ordinary skill in the art upon
careful consideration of the detailed description of
representative embodiments of the disclosure hereinbelow and
the accompanying drawings, in which similar elements are
indicated in the various figures using the same reference
numbers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a representative partially cross-sectional
view of a well system and associated method which can embody
principles of this disclosure.
FIG. 2 is a representative cross-sectional view of a
variable flow resistance system which can embody the
principles of this disclosure.
FIG. 3 is a representative cross-sectional view of the
variable flow resistance system, taken along line 3-3 of
FIG. 2.
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FIG. 4 is a representative cross-sectional view of the
variable flow resistance system, with rotational flow in a
chamber of the system.
FIGS. 5 & 6 are representative cross-sectional views of
another configuration of the variable flow resistance
system, resistance to flow being greater in FIG. 5 as
compared to FIG. 6.
FIG. 7 is a representative cross-sectional view of
another configuration of the variable flow resistance
system.
FIG. 8 is a representative cross-sectional view of the
FIG. 7 configuration, taken along line 8-8.
FIG. 9 is a representative cross-sectional view of the
variable flow resistance system, resistance to flow being
greater in FIG. 8 as compared to that in FIG. 9.
FIGS. 10 & 11 are representative cross-sectional views
of another configuration of the variable flow resistance
system, resistance to flow being greater in FIG. 11 as
compared to that in FIG. 10.
FIG. 12 is a representative cross-sectional view of
another configuration of the variable flow resistance
system.
FIG. 13 is a representative cross-sectional view of the
FIG. 12 configuration, taken along line 13-13.
FIG. 14 is a representative cross-sectional view of
another configuration of the variable flow resistance
system.
FIGS. 15 & 16 are representative cross-sectional views
of a fluid switch configuration which may be used with the
variable flow resistance system.
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FIGS. 17 & 18 are representative cross-sectional views
of another configuration of the variable flow resistance
system, FIG. 17 being taken along line 17-17 of FIG. 18.
FIG. 19 is a representative cross-sectional view of a
flow chamber which may be used with the variable flow
resistance system.
FIGS. 20-27 are representative cross-sectional views of
additional fluid switch configurations which may be used
with the variable flow resistance system.
DETAILED DESCRIPTION
Representatively illustrated in FIG. 1 is a system 10
for use with a well, which system can embody principles of
this disclosure. As depicted in FIG. 1, a wellbore 12 has a
generally vertical uncased section 14 extending downwardly
from casing 16, as well as a generally horizontal uncased
section 18 extending through an earth formation 20.
A tubular string 22 (such as a production tubing
string) is installed in the wellbore 12. Interconnected in
the tubular string 22 are multiple well screens 24, variable
flow resistance systems 25 and packers 26.
The packers 26 seal off an annulus 28 formed radially
between the tubular string 22 and the wellbore section 18.
In this manner, fluids 30 may be produced from multiple
intervals or zones of the formation 20 via isolated portions
of the annulus 28 between adjacent pairs of the packers 26.
Positioned between each adjacent pair of the packers
26, a well screen 24 and a variable flow resistance system
25 are interconnected in the tubular string 22. The well
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screen 24 filters the fluids 30 flowing into the tubular
string 22 from the annulus 28. The variable flow resistance
system 25 variably restricts flow of the fluids 30 into the
tubular string 22, based on certain characteristics of the
fluids.
At this point, it should be noted that the system 10 is
illustrated in the drawings and is described herein as
merely one example of a wide variety of systems in which the
principles of this disclosure can be utilized. It should be
clearly understood that the principles of this disclosure
are not limited at all to any of the details of the system
10, or components thereof, depicted in the drawings or
described herein.
For example, it is not necessary in keeping with the
principles of this disclosure for the wellbore 12 to include
a generally vertical wellbore section 14 or a generally
horizontal wellbore section 18. It is not necessary for
fluids 30 to be only produced from the formation 20 since,
in other examples, fluids could be injected into a
formation, fluids could be both injected into and produced
from a formation, etc.
It is not necessary for one each of the well screen 24
and variable flow resistance system 25 to be positioned
between each adjacent pair of the packers 26. It is not
necessary for a single variable flow resistance system 25 to
be used in conjunction with a single well screen 24. Any
number, arrangement and/or combination of these components
may be used.
It is not necessary for any variable flow resistance
system 25 to be used with a well screen 24. For example, in
injection operations, the injected fluid could be flowed
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through a variable flow resistance system 25, without also
flowing through a well screen 24.
It is not necessary for the well screens 24, variable
flow resistance systems 25, packers 26 or any other
components of the tubular string 22 to be positioned in
uncased sections 14, 18 of the wellbore 12. Any section of
the wellbore 12 may be cased or uncased, and any portion of
the tubular string 22 may be positioned in an uncased or
cased section of the wellbore, in keeping with the
principles of this disclosure.
It should be clearly understood, therefore, that this
disclosure describes how to make and use certain examples,
but the principles of the disclosure are not limited to any
details of those examples. Instead, those principles can be
applied to a variety of other examples using the knowledge
obtained from this disclosure.
It will be appreciated by those skilled in the art that
it would be beneficial to be able to regulate flow of the
fluids 30 into the tubular string 22 from each zone of the
formation 20, for example, to prevent water coning 32 or gas
coning 34 in the formation. Other uses for flow regulation
in a well include, but are not limited to, balancing
production from (or injection into) multiple zones,
minimizing production or injection of undesired fluids,
maximizing production or injection of desired fluids,
transmitting signals, etc.
In examples described below, resistance to flow through
the flow resistance systems 25 can be selectively varied, on
demand and/or in response to a particular condition. For
example, flow through the systems 25 could be relatively
restricted while the tubular string 22 is installed, and
during a gravel packing operation, but flow through the
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systems could be relatively unrestricted when producing the
fluid 30 from the formation 20. As another example, flow
through the systems 25 could be relatively restricted at
elevated temperature indicative of steam breakthrough in a
steam flooding operation, but flow through the systems could
be relatively unrestricted at reduced temperatures.
An example of the variable flow resistance systems 25
described more fully below can also increase resistance to
flow if a fluid velocity or density increases (e.g., to
thereby balance flow among zones, prevent water or gas
coning, etc.), or increase resistance to flow if a fluid
viscosity decreases (e.g., to thereby restrict flow of an
undesired fluid, such as water or gas, in an oil producing
well). Conversely, these variable flow resistance systems 25
can decrease resistance to flow if fluid velocity or density
decreases, or if fluid viscosity increases.
Whether a fluid is a desired or an undesired fluid
depends on the purpose of the production or injection
operation being conducted. For example, if it is desired to
produce oil from a well, but not to produce water or gas,
then oil is a desired fluid and water and gas are undesired
fluids. If it is desired to inject steam instead of water,
then steam is a desired fluid and water is an undesired
fluid. If it is desired to produce hydrocarbon gas and not
water, then hydrocarbon gas is a desired fluid and water is
an undesired fluid.
Note that, at downhole temperatures and pressures,
hydrocarbon gas can actually be completely or partially in
liquid phase. Thus, it should be understood that when the
term "gas" is used herein, supercritical, liquid and/or
gaseous phases are included within the scope of that term.
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Referring additionally now to FIG. 2, an enlarged scale
cross-sectional view of one of the variable flow resistance
systems 25 and a portion of one of the well screens 24 is
representatively illustrated. In this example, a fluid
composition 36 (which can include one or more fluids, such
as oil and water, liquid water and steam, oil and gas, gas
and water, oil, water and gas, etc.) flows into the well
screen 24, is thereby filtered, and then flows into an inlet
38 of the variable flow resistance system 25.
A fluid composition can include one or more undesired
or desired fluids. Both steam and liquid water can be
combined in a fluid composition. As another example, oil,
water and/or gas can be combined in a fluid composition.
Flow of the fluid composition 36 through the variable
flow resistance system 25 is resisted based on one or more
characteristics (such as viscosity, velocity, density, etc.)
of the fluid composition. The fluid composition 36 is then
discharged from the variable flow resistance system 25 to an
interior of the tubular string 22 via an outlet 40.
In other examples, the well screen 24 may not be used
in conjunction with the variable flow resistance system 25
(e.g., in injection operations), the fluid composition 36
could flow in an opposite direction through the various
elements of the well system 10 (e.g., in injection
operations), a single variable flow resistance system could
be used in conjunction with multiple well screens, multiple
variable flow resistance systems could be used with one or
more well screens, the fluid composition could be received
from or discharged into regions of a well other than an
annulus or a tubular string, the fluid composition could
flow through the variable flow resistance system prior to
flowing through the well screen, any other components could
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be interconnected upstream or downstream of the well screen
and/or variable flow resistance system, etc. Thus, it will
be appreciated that the principles of this disclosure are
not limited at all to the details of the example depicted in
FIG. 2 and described herein.
Although the well screen 24 depicted in FIG. 2 is of
the type known to those skilled in the art as a wire-wrapped
well screen, any other types or combinations of well screens
(such as sintered, expanded, pre-packed, wire mesh, etc.)
may be used in other examples. Additional components (such
as shrouds, shunt tubes, lines, instrumentation, sensors,
inflow control devices, etc.) may also be used, if desired.
The variable flow resistance system 25 is depicted in
simplified form in FIG. 2, but in a preferred example, the
system can include various passages and devices for
performing various functions, as described more fully below.
In addition, the system 25 preferably at least partially
extends circumferentially about the tubular string 22, or
the system may be formed in a wall of a tubular structure
interconnected as part of the tubular string.
In other examples, the system 25 may not extend
circumferentially about a tubular string or be formed in a
wall of a tubular structure. For example, the system 25
could be formed in a flat structure, etc. The system 25
could be in a separate housing that is attached to the
tubular string 22, or it could be oriented so that the axis
of the outlet 40 is parallel to the axis of the tubular
string. The system 25 could be on a logging string or
attached to a device that is not tubular in shape. Any
orientation or configuration of the system 25 may be used in
keeping with the principles of this disclosure.
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Referring additionally now to FIG. 3, a cross-sectional
view of the variable flow resistance system 25, taken along
line 3-3 of FIG. 2, is representatively illustrated. The
variable flow resistance system 25 example depicted in FIG.
3 may be used in the well system 10 of FIGS. 1 & 2, or it
may be used in other well systems in keeping with the
principles of this disclosure.
In FIG. 3, it may be seen that the fluid composition 36
flows from the inlet 38 to the outlet 40 via passage 44,
inlet flow paths 46, 48 and a flow chamber 50. The flow
paths 46, 48 are branches of the passage 44 and intersect
the chamber 50 at inlets 52, 54.
Although in FIG. 3 the flow paths 46, 48 diverge from
the inlet passage 44 by approximately the same angle, in
other examples the flow paths 46, 48 may not be symmetrical
with respect to the passage 44. For example, the flow path
48 could diverge from the inlet passage 44 by a smaller
angle as compared to the flow path 46, so that more of the
fluid composition 36 will flow through the flow path 48 to
the chamber 50, and vice versa.
A resistance to flow of the fluid composition 36
through the system 25 depends on proportions of the fluid
composition which flow into the chamber via the respective
flow paths 46, 48 and inlets 52, 54. As depicted in FIG. 3,
approximately half of the fluid composition 36 flows into
the chamber 50 via the flow path 46 and inlet 52, and about
half of the fluid composition flows into the chamber via the
flow path 48 and inlet 54.
In this situation, flow through the system 25 is
relatively unrestricted. The fluid composition 36 can
readily flow between various vane-type structures 56 in the
chamber 50 en route to the outlet 40.
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Referring additionally now to FIG. 4, the system 25 is
representatively illustrated in another configuration, in
which flow resistance through the system is increased, as
compared to the configuration of FIG. 3. This increase in
flow resistance of the system 25 can be due to a change in a
property of the fluid composition 36, due to a change in the
configuration of the system 25, etc.
A greater proportion of the fluid composition 36 flows
through the flow path 46 and into the chamber 50 via the
inlet 52, as compared to the proportion which flows into the
chamber via the inlet 54. When a majority of the fluid
composition 36 flows into the chamber 50 via the inlet 52,
the fluid composition tends to rotate counter-clockwise in
the chamber (as viewed in FIG. 4).
The structures 56 are designed to promote such
rotational flow in the chamber 50, and as a result, more
energy in the fluid composition 36 flow is dissipated. Thus,
resistance to flow through the system 25 is increased in the
FIG. 4 configuration as compared to the FIG. 3
configuration.
Although in FIGS. 3 & 4 the flow chamber 50 has
multiple inlets 52, 54, any number (including one) of inlets
may be used in keeping with the scope of this disclosure.
For example, in U.S. application serial no. 12/792117, filed
on 2 June 2010, a flow chamber is described which has only a
single inlet, but resistance to flow through the chamber
varies depending on via which flow path a majority of a
fluid composition enters the chamber.
Another configuration of the variable flow resistance
system 25 is representatively illustrated in FIGS. 5 & 6. In
this configuration, flow resistance through the system 25
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can be varied due to a change in a property of the fluid
composition 36.
In FIG. 5, the fluid composition 36 has a relatively
high velocity. As the fluid composition 36 flows through the
passage 44, it passes multiple chambers 64 formed in a side
of the passage. Each of the chambers 64 is in communication
with a pressure-operated fluid switch 66.
At elevated velocities of the fluid composition 36 in
the passage 44, a reduced pressure will be applied to the
fluid switch 66 as a result of the fluid composition flowing
past the chambers 64, and the fluid composition will be
influenced to flow toward the branch flow path 48, as
depicted in FIG. 5. A majority of the fluid composition 36
flows into the chamber 50 via the inlet 54, and flow
resistance through the system 25 is increased. At lower
velocities and increased viscosities, more of the fluid
composition 36 will flow into the chamber 50 via the inlet
52, and flow resistance through the system 25 is decreased
due to less rotational flow in the chamber.
In FIG. 6, rotational flow of the fluid composition 36
in the chamber 50 is reduced, and the resistance to flow
through the system 25 is, thus, also reduced. Note that, if
the velocity of the fluid composition 36 in the passage 44
is reduced, or if the viscosity of the fluid composition is
increased, a portion of the fluid composition can flow into
the chambers 64 and to the fluid switch 66, which influences
the fluid composition to flow more toward the flow path 46.
At relatively high velocities, low viscosity and/or
high density of the fluid composition 36, a majority of the
fluid composition will flow via the flow path 48 to the
chamber 50, as depicted in FIG. 5, and such flow will be
more restricted. At relatively low velocity, high viscosity
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and/or low density of the fluid composition 36, a majority
of the fluid composition will flow via the flow path 46 to
the chamber 50, as depicted in FIG. 6, and such flow will be
less restricted.
If oil is a desired fluid and water is an undesired
fluid, then it will be appreciated that the system 25 of
FIGS. 5 & 6 will result in less resistance to flow of the
fluid composition 36 through the system when a ratio of
desired to undesired fluid is increased, and greater
resistance to flow when the ratio of desired to undesired
fluid is decreased. This is due to oil having higher
viscosity and less density as compared to water. Due to its
higher viscosity, oil also generally flows at a slower
velocity as compared to water, for a given pressure
differential across the system 25.
However, in other examples, the chamber 50 and
structures 56 could be otherwise configured (e.g., reversed
from their FIGS. 5 & 6 configuration, as in the FIGS. 3 & 4
configuration), so that flow of a majority of the fluid
composition 36 through the flow path 46 is more restricted
as compared to flow of a majority of the fluid composition
through the flow path 48. An increased ratio of desired to
undesired fluid can result in greater or lesser restriction
to flow through the system 25, depending on its
configuration. Thus, the scope of this disclosure is not
limited at all to the details of the specific flow
resistance systems 25 described herein.
In the FIGS. 3 & 4 configuration, a majority of the
fluid composition 36 will continue to flow via one of the
flow paths 46, 48 (due to the Coanda effect), or will flow
relatively equally via both flow paths 46, 48, unless the
direction of the flow from the passage 44 is changed. In the
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FIGS. 5 & 6 configuration, the direction of the flow from
the passage 44 can be changed by means of the fluid switch
66, which influences the fluid composition 36 to flow toward
one of the two flow paths 46, 48. In other examples, greater
or fewer numbers of flow paths may be used, if desired.
In the further description below, additional techniques
for influencing the direction of flow of the fluid
composition 36 through the system 25, and variably resisting
the flow of the fluid composition, are described. These
techniques may be used in combination with the
configurations of FIGS. 3-6, or they may be used with other
types of variable flow resistance systems.
Referring additionally now to FIGS. 7-9, another
configuration of the variable flow resistance system 25 is
representatively illustrated. This configuration is similar
in some respects to the configuration of FIGS. 3-6, however,
instead of the flow chamber 50, the configuration of FIGS.
7-9 uses a structure 58 which displaces in response to a
change in a proportion of the fluid composition 36 which
flows through the flow paths 46, 48 (that is, a ratio of the
fluid composition which flows through one flow path and the
fluid composition which flows through the other flow path).
For example, in FIG. 8, a majority of the fluid
composition 36 flows via the flow path 48, and this flow
impinging on the structure 58 causes the structure to
displace to a position in which such flow is increasingly
restricted. Note that, in FIG. 8, the structure 58 itself
almost completely blocks the fluid composition 36 from
flowing to the outlet 40.
In FIG. 9, a majority of the fluid composition 36 flows
via the flow path 46 and, in response, the structure 58
displaces to a position in which flow restriction in the
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system 25 is reduced. The structure 58 does not block the
flow of the fluid composition 36 to the outlet 40 in FIG. 9
as much as it does in FIG. 8.
In other examples, the structure 58 itself may not
block the flow of the fluid composition 36, and the
structure could be biased toward the FIG. 8 and/or FIG. 9
position (e.g., using springs, compressed gas, other biasing
devices, etc.), thereby changing the proportion of the fluid
composition 36 which must flow through a particular flow
path 46, 48, in order to displace the structure. Preferably,
the fluid composition 36 does not have to exclusively flow
through only one of the flow paths 46, 48 in order to
displace the structure 58 to a particular position, but such
a design could be implemented, if desired.
The structure 58 is mounted via a connection 60.
Preferably, the connection 60 serves to secure the structure
58, and also to resist a pressure differential applied
across the structure from the flow paths 46, 48 to the
outlet 40. When the fluid composition 36 is flowing through
the system 25, this pressure differential can exist, and the
connection 60 can resist the resulting forces applied to the
structure 58, while still permitting the structure to
displace freely in response to a change in the proportion of
the flow via the flow paths 46, 48.
In the FIGS. 8 & 9 example, the connection 60 is
depicted as a pivoting or rotational connection. However, in
other examples, the connection 60 could be a rigid, sliding,
translating, or other type of connection, thereby allowing
for displacement of the structure 58 in any of
circumferential, axial, longitudinal, lateral, radial, etc.,
directions.
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In one example, the connection 60 could be a rigid
connection, with a flexible beam 62 extending between the
connection and the structure 58. The beam 62 could flex,
instead of the connection 60 rotating, in order to allow the
structure 58 to displace, and to provide a biasing force
toward the more restricting position of FIG. 8, toward the
less restricting position of FIG. 9, or toward any other
position (e.g., a position between the more restricting and
less restricting positions, etc.).
Another difference of the FIGS. 7-9 configuration and
the configurations of FIGS. 3-6 is that the FIGS. 7-9
configuration utilizes the fluid switch 66 with multiple
control passages 68, 70. In comparison, the FIGS. 3 & 4
configuration does not have a controlled fluid switch, and
the FIGS. 5 & 6 configuration utilizes the fluid switch 66
with a single control passage 68. However, it should be
understood that any fluid switch and any number of control
passages can be used with any variable flow resistance
system 25 configuration, in keeping with the scope of this
disclosure.
As depicted in FIG. 7, the fluid switch 66 directs the
fluid composition 36 flow toward the flow path 46 when flow
72 through the control passage 68 is toward the fluid
switch, and/or when flow 74 in the control passage 70 is
away from the fluid switch. The fluid switch 66 directs the
fluid composition 36 flow toward the flow path 48 when flow
72 through the control passage 68 is away from the fluid
switch, and/or when flow 74 in the control passage 70 is
toward the fluid switch.
Thus, since the proportion of the fluid composition 36
which flows through the flow paths 46, 48 can be changed by
the fluid switch 66, in response to the flows 72, 74 through
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the control passages 68, 70, it follows that the resistance
to flow of the fluid composition 36 through the system 25
can be changed by changing the flows through the control
passages. For this purpose, the control passages 68, 70 may
be connected to any of a variety of devices for influencing
the flows 72, 74 through the control passages.
For example, the chambers 64 of the FIGS. 5 & 6
configuration could be connected to the control passage 68
or 70, and another set of chambers, or another device could
be connected to the other control passage. The flows 72, 74
through the control passages 68, 70 could be automatically
changed (e.g., using the chambers 64, etc.) in response to
changes in one or more properties (such as density,
viscosity, velocity, etc.) of the fluid composition 36, the
flows could be controlled locally (e.g., in response to
sensor measurements, etc.), or the flows could be controlled
remotely (e.g., from the earth's surface, another remote
location, etc.). Any technique for controlling the flows 72,
74 through the control passages 68, 70 may be used, in
keeping with the scope of this disclosure.
Preferably, the flow 72 is toward the fluid switch 66,
and/or the flow 74 is away from the fluid switch, when the
fluid composition 36 has an increased ratio of desired to
undesired fluids, so that more of the fluid composition will
be directed by the fluid switch to flow toward the flow path
46, thereby reducing the resistance to flow through the
system 25. Conversely, the flow 72 is preferably away from
the fluid switch 66, and/or the flow 74 is preferably toward
the fluid switch, when the fluid composition 36 has a
decreased ratio of desired to undesired fluids, so that more
of the fluid composition will be directed by the fluid
switch to flow toward the flow path 48, thereby increasing
the resistance to flow through the system 25.
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Referring additionally now to FIGS. 10 & 11, another
configuration of the variable flow resistance system 25 is
representatively illustrated. In this configuration, the
structure 58 rotates about the connection 60, in order to
change between a less restricted flow position (FIG. 10) and
a more restricted flow position (FIG. 11).
As in the configuration of FIGS. 7-9, the configuration
of FIGS. 10 & 11 has the structure 58 exposed to flow in
both of the flow paths 46, 48. Depending on a proportion of
these flows, the structure 58 can displace to either of the
FIGS. 10 & 11 positions (or to any position in-between those
positions). The structure 58 in the FIGS. 7-11
configurations can be biased toward any position, or
releasably retained at any position, in order to adjust the
proportion of flows through the flow paths 46, 48 needed to
displace the structure to another position.
Referring additionally now to FIGS. 12 & 13, another
configuration of the variable flow resistance system 25 is
representatively illustrated. In this configuration, the
structure 58 is positioned in the flow chamber 50 connected
to the flow paths 46, 48.
In the FIGS. 12 & 13 example, a majority of the flow of
the fluid composition 36 through the flow path 46 results in
the structure 58 rotating about the connection 60 to a
position in which flow between the structures 56 (the
structures comprising circumferentially extending vanes in
this example) is not blocked by the structure 58. However,
if a majority of the flow is through the flow path 48 to the
flow chamber 50, the structure 58 will rotate to a position
in which the structure 58 does substantially block the flow
between the structures 56, thereby increasing the flow
resistance.
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Referring additionally now to FIG. 14, another
configuration of the variable flow resistance system 25 is
representatively illustrated. In this example, the flow path
46 connects to the chamber 50 in more of a radial, rather
than a tangential) direction, as compared to the
configuration of FIGS. 12 & 13.
In addition, the structures 56, 58 are spaced to allow
relatively direct flow of the fluid composition 36 from the
inlet 54 to the outlet 40. This configuration can be
especially beneficial where the fluid composition 36 is
directed by the fluid switch 66 toward the flow path 46 when
the fluid composition has an increased ratio of desired to
undesired fluids therein.
In this example, an increased proportion of the fluid
composition 36 flowing through the flow path 48 will cause
the flow to be more rotational in the chamber 50, thereby
dissipating more energy and increasingly restricting the
flow, and will cause the structure 58 to rotate to a
position in which flow between the structures 56 is more
restricted. This situation preferably occurs when the ratio
of desired to undesired fluids in the fluid composition 36
decreases.
Referring additionally now to FIGS. 15 & 16, additional
configurations of the fluid switch 66 are representatively
illustrated. The fluid switch 66 in these configurations has
a blocking device 76 which rotates about a connection 78 to
increasingly block flow through one of the flow paths 46, 48
when the fluid switch directs the flow toward the other flow
path. These fluid switch 66 configurations may be used in
any system 25 configuration.
In the FIG. 15 example, either or both of the control
passage flows 72, 74 influence the fluid composition 36 to
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flow toward the flow path 46. Due to this flow toward the
flow path 46 impinging on the blocking device 76, the
blocking device rotates to a position in which the other
flow path 48 is completely or partially blocked, thereby
influencing an even greater proportion of the fluid
composition to flow via the flow path 46, and not via the
flow path 48. However, if either or both of the control
passage flows 72, 74 influence the fluid composition 36 to
flow toward the flow path 48, this flow impinging on the
blocking device 76 will rotate the blocking device to a
position in which the other flow path 46 is completely or
partially blocked, thereby influencing an even greater
proportion of the fluid composition to flow via the flow
path 48, and not via the flow path 46.
In the FIG. 16 example, either or both of the control
passage flows 72, 74 influence the blocking device 76 to
increasingly block one of the flow paths 46, 48. Thus, an
increased proportion of the fluid composition 36 will flow
through the flow path 46, 48 which is less blocked by the
device 76. When either or both of the flows 72, 74 influence
the blocking device 76 to increasingly block the flow path
46, the blocking device rotates to a position in which the
other flow path 48 is not blocked, thereby influencing a
greater proportion of the fluid composition to flow via the
flow path 48, and not via the flow path 46. However, if
either or both of the control passage flows 72, 74 influence
the blocking device 76 to rotate toward the flow path 48,
the other flow path 46 will not be blocked, and a greater
proportion of the fluid composition 36 will flow via the
flow path 46, and not via the flow path 48.
By increasing the proportion of the fluid composition
36 which flows through the flow path 46 or 48, operation of
the system 25 is made more efficient. For example,
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resistance to flow through the system 25 can be readily
increased when an unacceptably low ratio of desired to
undesired fluids exists in the fluid composition 36, and
resistance to flow through the system can be readily
decreased when the fluid composition has a relatively high
ratio of desired to undesired fluids.
Referring additionally now to FIGS. 17 & 18, another
configuration of the system 25 is representatively
illustrated. This configuration is similar in some respects
to the configuration of FIGS. 12 & 13, in that the structure
58 rotates in the chamber 50 in order to change the
resistance to flow. The direction of rotation of the
structure 58 depends on through which of the flow paths 46
or 48 a greater proportion of the fluid composition 36
flows.
In the FIGS. 17 & 18 example, the structure 58 includes
vanes 80 on which the fluid composition 36 impinges. Thus,
rotational flow in the chamber 50 impinges on the vanes 80
and biases the structure 58 to rotate in the chamber.
When the structure 58 is in the position depicted in
FIGS. 17 & 18, openings 82 align with openings 84, and the
structure does not substantially block flow from the chamber
50. However, if the structure 58 rotates to a position in
which the openings 82, 84 are misaligned, then the structure
will increasingly block flow from the chamber 50 and
resistance to flow will be increased.
Although in certain examples described above, the
structure 58 displaces by pivoting or rotating, it will be
appreciated that the structure could be suitably designed to
displace in any direction to thereby change the flow
resistance through the system 25. In various examples, the
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structure 58 could displace in circumferential, axial,
longitudinal, lateral and/or radial directions.
Referring additionally now to FIG. 19, another
configuration of the chamber 50 is representatively
illustrated. The FIG. 19 chamber 50 may be used with any
configuration of the system 25.
One difference between the FIG. 19 chamber 50 and the
other chambers described herein is that a swellable material
86 is provided at the inlets 52, 54 to the chamber, and a
swellable material 88 is provided about the outlet 40.
Preferably, the swellable materials 86, 88 swell in response
to contact with an undesirable fluids (such as water or gas,
etc.) and do not swell in response to contact with desirable
fluids (such as liquid hydrocarbons, gas, etc.). However, in
other examples, the materials 86, 88 could swell in response
to contact with desirable fluids.
In the FIG. 19 example, the swellable materials 86 at
the inlets 52, 54 are shaped like vanes or airfoils, so that
the fluid composition 36 is influenced to flow more
rotationally (as indicated by arrows 36a) through the
chamber 50, instead of more radially (as indicated by arrows
36b), when the material swells. Since more energy is
dissipated when there is more rotational flow in the chamber
50, this results in more resistance to flow through the
system 25.
The swellable material 88 is positioned about the
outlet 40 so that, as the ratio of desired to undesired
fluid in the fluid composition 36 decreases, the material
will swell and thereby increasingly restrict flow through
the outlet. Thus, the swellable material 88 can increasingly
block flow through the system 25, in response to contact
with the undesired fluid.
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It will be appreciated that the swellable materials 86
change the direction of flow of the fluid composition 36
through the chamber 50 to thereby change the flow
resistance, and the swellable material 88 selectively blocks
flow through the system to thereby change the flow
resistance. In other examples, the swellable materials 86
could change the direction of flow at locations other than
the inlets 52, 54, and the swellable material 88 can block
flow at locations other than the outlet 40, in keeping with
the scope of this disclosure.
The swellable materials 86, 88 in the FIG. 19 example
allow for flow resistance to be increased as the ratio of
desired to undesired fluid in the fluid composition 36
decreases. However, in other examples, the swellable
materials 86, 88 could swell in response to contact with a
desired fluid, or the flow resistance through the system 25
could be decreased as the ratio of desired to undesired
fluid in the fluid composition 36 decreases.
The term "swell" and similar terms (such as
"swellable") are used herein to indicate an increase in
volume of a swellable material. Typically, this increase in
volume is due to incorporation of molecular components of an
activating agent into the swellable material itself, but
other swelling mechanisms or techniques may be used, if
desired. Note that swelling is not the same as expanding,
although a material may expand as a result of swelling.
The activating agent which causes swelling of the
swellable material can be a hydrocarbon fluid (such as oil
or gas, etc.), or a non-hydrocarbon fluid (such as water or
steam, etc.). In the well system 10, the swellable material
may swell when the fluid composition 36 comprises the
activating agent (e.g., when the activating agent enters the
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wellbore 12 from the formation 20 surrounding the wellbore,
when the activating agent is circulated to the system 25, or
when the activating agent is released downhole, etc.). In
response, the swellable materials 86, 88 swell and thereby
change the flow resistance through the system 25.
The activating agent which causes swelling of the
swellable material could be comprised in any type of fluid.
The activating agent could be naturally present in the well,
or it could be conveyed with the system 25, conveyed
separately or flowed into contact with the swellable material
in the well when desired. Any manner of contacting the
activating agent with the swellable material may be used in
keeping with the scope of this disclosure.
Various swellable materials are known to those skilled in
the art, which materials swell when contacted with water
and/or hydrocarbon fluid, so a comprehensive list of these
materials will not be presented here. Partial lists of
swellable materials may be found in U.S. Patent Nos. 3385367
and 7059415, and in U.S. Published Application No. 2004-
0020662.
As another alternative, the swellable material may have a
substantial portion of cavities therein which are compressed
or collapsed at surface conditions. Then, after being placed
in the well at a higher pressure, the material swells by the
cavities filling with fluid.
This type of apparatus and method might be used where it
is desired to expand the swellable material in the presence of
gas rather than oil or water. A suitable swellable material is
described in U.S. Published Application No. 2007-0257405.
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The swellable material used in the system 25 may swell
by diffusion of hydrocarbons into the swellable material, or
in the case of a water swellable material, by the water
being absorbed by a super-absorbent material (such as
cellulose, clay, etc.) and/or through osmotic activity with
a salt-like material. Hydrocarbon-, water- and gas-
swellable materials may be combined, if desired.
The swellable material could swell due to the presence
of ions in a fluid. For example, polymer hydrogels will
swell due to changes in the pH of a fluid, which is a
measure of the hydrogen ions in the fluid (or, equivalently,
the concentration of hydroxide, OH, ions in the fluid).
Swelling as a result of the salt ions in the fluid is also
possible. Such a swellable material could swell depending on
a concentration of chloride, sodium, calcium, and/or
potassium ions in the fluid.
It should, thus, be clearly understood that any
swellable material which swells when contacted by a
predetermined activating agent may be used in keeping with
the scope of this disclosure. The swellable material could
also swell in response to contact with any of multiple
activating agents. For example, the swellable material could
swell when contacted by hydrocarbon fluid and/or when
contacted by water and/or when contacted by certain ions.
Referring additionally now to FIGS. 20-27, additional
configurations of the fluid switch 66 are representatively
illustrated. These fluid switch 66 configurations may be
used with any configuration of the system 25.
In the FIG. 20 example, the fluid switch 66 includes an
airfoil 90. The airfoil 90 rotates about a pivot connection
92. Preferably, the airfoil 90 is biased (for example, using
a torsion spring, magnetic biasing devices, actuator, etc.),
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so that it initially directs flow of the fluid composition
36 toward one of the flow paths 46, 48. In FIG. 20, the
airfoil 90 is positioned to direct the fluid composition 36
toward the flow path 48.
It will be appreciated by those skilled in the art
that, as the velocity of the flow increases, a lift produced
by the airfoil 90 also increases, and eventually can
overcome the biasing force applied to the airfoil, allowing
the airfoil to pivot about the connection 92 to a position
in which the airfoil directs the fluid composition 36 toward
the other flow path 46. The lift produced by the airfoil 90
can also vary depending on other properties of the fluid
composition 36 (e.g., density, viscosity, etc.).
Thus, the airfoil 90 allows the fluid switch 66 to be
operated automatically, in response to changes in the
properties of the fluid composition 36. Instead of the
magnetic biasing device 94, the airfoil 90 itself could be
made of a magnetic material.
The magnetic biasing devices 94, 96, 98 can be used to
bias the airfoil 90 toward either or both of the positions
in which the airfoil directs the fluid composition 36 toward
the flow paths 46, 48. The magnetic biasing devices 96, 98
could be positioned further upstream or downstream from
their illustrated positions, and they can extend into the
flow paths 46, 48, if desired. The magnetic biasing devices
94, 96, 98 (or other types of biasing devices) may be used
to bias the airfoil 90 toward any position, in keeping with
the scope of this disclosure.
In the configuration of FIG. 21, multiple airfoils 90
are used. As illustrated, two of the airfoils 90 are used,
but it will be appreciated that any number of airfoils could
be used in other examples.
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The airfoils 90 may be constrained to pivot together
(e.g., with a mechanical linkage, synchronized stepper
motors, etc.), or the airfoils may be permitted to pivot
independently of each other. As depicted in FIG. 21, a
torsional biasing force 100 is applied to each of the
airfoils 90. This biasing force 100 could be applied by any
suitable means, such as, one or more rotary actuators,
torsion springs, biasing devices 96, 98, etc.).
In the configuration of FIG. 22, the multiple airfoils
90 are both laterally and longitudinally spaced apart from
each other. In addition, the airfoils 90 can be displaced in
both lateral and longitudinal directions 102, 104 (e.g.,
using linear actuators, etc.), in order to position the
airfoils as desired.
In the configuration of FIG. 23, the multiple airfoils
90 are longitudinally spaced apart. In some examples, the
airfoils 90 could be directly inline with each other.
In the FIG. 23 example, the upstream airfoil 90 directs
the flow of the fluid composition 36, so that it is
advantageously directed toward the downstream airfoil.
However, other purposes could be served by longitudinally
spacing apart the airfoils 90, in keeping with the scope of
this disclosure.
In the configuration of FIG. 24, airfoil-like surfaces
are formed on the walls of the fluid switch 66. In this
manner, the fluid composition 36 is preferentially directed
toward the flow path 48 at certain conditions (e.g., high
flow velocity, low viscosity, etc.). However, at other
conditions (e.g., low flow velocity, high viscosity, etc.),
the fluid composition 36 is able to flow relatively equally
to the flow paths 46, 48.
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In the FIG. 25 example, a wedge-shaped blockage 106 is
positioned upstream of the airfoil 90. The blockage 106
serves to influence the flow of the fluid composition 36
over the airfoil 90. The blockage 106 could also be a
magnetic device for applying a biasing force to the airfoil
90.
In the FIG. 26 example, cylindrical projections 108 are
positioned on opposite lateral sides of the fluid switch 66.
The cylindrical projections 108 serve to influence the flow
of the fluid composition 36 over the airfoil 90. The
cylindrical projections 108 could also be magnetic devices
(such as, magnetic biasing devices 96, 98) for applying a
biasing force to the airfoil 90.
In the FIG. 27 example, a cylindrical blockage 110 is
positioned upstream of the airfoil 90. The blockage 110
serves to influence the flow of the fluid composition 36
over the airfoil 90. The blockage 110 could also be a
magnetic device for applying a biasing force to the airfoil
90.
It may now be fully appreciated that this disclosure
provides significant advancements to the art of variably
resisting flow in conjunction with well operations. In
multiple examples described above, flow resistance can be
reliably and efficiently increased when there is a
relatively large ratio of desired to undesired fluid in the
fluid composition 36, and/or flow resistance can be
decreased when there is a reduced ratio of desired to
undesired fluid in the fluid composition.
A variable flow resistance system 25 for use with a
subterranean well is described above. In one example, the
system 25 includes a structure 58 which displaces in
response to a flow of a fluid composition 36, whereby a
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resistance to the flow of the fluid composition 36 changes
in response to a change in a ratio of desired to undesired
fluid in the fluid composition 36.
The structure 58 may be exposed to the flow of the
fluid composition 36 in multiple directions, and the
resistance to the flow can change in response to a change in
a proportion of the fluid composition 36 which flows in
those directions.
The structure 58 can be more biased in one direction by
the flow of the fluid composition 36 more in one direction,
and the structure 58 can be more biased in another direction
by the flow of the fluid composition 36 more in the second
direction.
The first and second directions may be opposite
directions. The directions can comprise at least one of the
group including circumferential, axial, longitudinal,
lateral, and radial directions.
The system 25 can include a fluid switch 66 which
directs the flow of the fluid composition 36 to at least two
flow paths 46, 48.
The structure 58 may be more biased in one direction by
the flow of the fluid composition 36 more through the first
flow path 46, and the structure may be more biased in a
another direction by the flow of the fluid composition 36
more through the second flow path 48.
The structure 58 may pivot or rotate, and thereby vary
the resistance to flow, in response to a change in a
proportion of the fluid composition 36 which flows through
the first and second flow paths 46, 48.
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The structure 58 may rotate, and thereby vary the
resistance to flow, in response to the change in the ratio
of desired to undesired fluids.
The fluid switch 66 can comprise a blocking device 76
which at least partially blocks the flow of the fluid
composition 36 through at least one of the first and second
flow paths 46, 48. The blocking device 76 may increasingly
block one of the first and second flow paths 46, 48, in
response to the flow of the fluid composition 36 toward the
other of the first and second flow paths 46, 48.
The fluid switch 66 may direct the flow of the fluid
composition 36 toward one of the first and second flow paths
46, 48 in response to the blocking device 76 increasingly
blocking the other of the first and second flow paths 46,
48.
The system 25 can include an airfoil 90 which deflects
the flow of the fluid composition 36 in response to the
change in the ratio of desired to undesired fluid.
The system 25 can include a material 86, 88 which
swells in response to a decrease in the ratio of desired to
undesired fluid, whereby the resistance to flow is
increased.
In some examples, the resistance to flow decreases in
response to an increase in the ratio of desired to undesired
fluid. In some examples, the resistance to flow increases in
response to a decrease in the ratio of desired to undesired
fluid.
Also described above is another variable flow
resistance system 25 example in which a structure 58 rotates
in response to flow of a fluid composition 36, and a fluid
switch 66 deflects the fluid composition 36 relative to at
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least first and second flow paths 46, 48, and a resistance
to the flow of the fluid composition 36 through the system
25 changes in response to a change in a ratio of desired to
undesired fluid in the fluid composition 36.
The structure 58 may be exposed to the flow of the
fluid composition 36 through the first and second flow paths
46, 48, and the resistance to the flow can change in
response to a change in a proportion of the fluid
composition 36 which flows through the first and second flow
paths 46, 48.
In another example, a variable flow resistance system
25 can include a chamber 50 through which a fluid
composition 36 flows, whereby a resistance to a flow of the
fluid composition 36 through the chamber 50 varies in
response to a change in a direction of the flow through the
chamber 50. A material 86, 88 swells in response to a
decrease in a ratio of desired to undesired fluid in the
fluid composition 36.
The resistance to the flow can increase or decrease
when the material 86, 88 swells.
The material 86, 88 may increasingly influence the
fluid composition 36 to flow spirally through the chamber 50
when the material 86, 88 swells.
The material 88 may increasingly block the flow of the
fluid composition 36 through the system 25 when the material
88 swells.
The material 86 may increasingly deflect the flow of
the fluid composition 36 when the material 36 swells.
The system 25 can also include a structure 25 which
displaces in response to the flow of the fluid composition
36, whereby the resistance to the flow of the fluid
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composition 36 increases in response to a decrease in the
ratio of desired to undesired fluid. The structure 58 may
rotate in response to the change in the ratio of desired to
undesired fluid.
Another variable flow resistance system 25 example
described above can include at least first and second flow
paths 46, 48, whereby a resistance to a flow of a fluid
composition 36 through the system 25 changes in response to
a change in a proportion of the fluid composition 36 which
flows through the first and second flow paths 46, 48. One or
more airfoils 90 may change a deflection of the flow of the
fluid composition 36 relative to the first and second flow
paths 46, 48 in response to a change in a ratio of desired
to undesired fluid in the fluid composition 36.
The airfoil 90 may rotate in response to the change in
the ratio of desired to undesired fluid in the fluid
composition 36.
The airfoil 90 may change the deflection in response to
a change in viscosity, velocity and/or density of the fluid
composition 36. =
The system 25 can include a magnetic biasing device 94,
96 or 98 which exerts a magnetic force on the airfoil 90,
whereby the airfoil 90 deflects the fluid composition 36
toward a corresponding one of the first and second flow
paths 46, 48. The system 25 can include first and second
magnetic biasing devices 94, 96 which exert magnetic forces
on the airfoil 90, whereby the airfoil 90 deflects the fluid
composition 36 toward respective ones of the first and
second flow paths 46, 48.
The system 25 can include a structure 58 which
displaces in response to the flow of the fluid composition
36, whereby the resistance to the flow of the fluid
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composition 36 increases in response to a decrease in the
ratio of desired to undesired fluid. The system 25 may
include a structure 58 which rotates in response to the
change in the ratio of desired to undesired fluid.
The system 25 can comprise multiple airfoils 90. The
airfoils 90 may be constrained to rotate together, or they
may be allowed to displace independently of each other. The
airfoils 90 may be displaceable laterally and longitudinally
relative to the first and second flow paths 46, 48. The
airfoils 90 may be laterally and/or longitudinally spaced
apart.
A method of variably resisting flow in a subterranean
well is also described above. In one example, the method can
include a structure 58 displacing in response to a flow of a
fluid composition 36, and a resistance to the flow of the
fluid composition 36 changing in response to a ratio of
desired to undesired fluid in the fluid composition
changing.
The method may include exposing the structure 58 to the
flow of the fluid composition 36 in at least first and
second directions. The resistance to the flow changing can
be further in response to a change in a proportion of the
fluid composition 36 which flows in the first and second
directions.
The structure 58 may be increasingly biased in a first
direction by the flow of the fluid composition 36
increasingly in the first direction, and the structure 58
may be increasingly biased in a second direction by the flow
of the fluid composition 36 increasingly in the second
direction.
The first direction may be opposite to the second
direction. The first and second directions may comprise any
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of circumferential, axial, longitudinal, lateral, and radial
directions.
The method can include a fluid switch 66 directing the
flow of the fluid composition 36 toward at least first and
second flow paths 46, 48. The structure 58 may be
increasingly biased in a first direction by the flow of the
fluid composition 36 increasingly through the first flow
path 46, and the structure 58 may be increasingly biased in
a second direction by the flow of the fluid composition 36
increasingly through the second flow path 48.
The structure 58 displacing may include the structure
58 pivoting or rotating, and thereby varying the resistance
to flow, in response to a change in a proportion of the
fluid composition 36 which flows through the first and
second flow paths 46, 48.
The structure 58 displacing may include the structure
58 rotating, and thereby varying the resistance to flow, in
response to the change in the ratio of desired to undesired
fluids.
The method may include a blocking device 76 of the
fluid switch 66 at least partially blocking the flow of the
fluid composition 36 through at least one of the first and
second flow paths 46, 48. The blocking device 76 can
increasingly block one of the first and second flow paths
46, 48, in response to the flow of the fluid composition
toward the other of the first and second flow paths.
The fluid switch 66 can direct the flow of the fluid
composition 36 toward one of the first and second flow paths
46, 48 in response to the blocking device 76 increasingly
blocking the other of the first and second flow paths 46,
48.
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The method may include an airfoil 90 deflecting the
flow of the fluid composition 36 in response to the ratio of
desired to undesired fluid changing.
The method may include a material 86, 88 swelling in
response to the ratio of desired to undesired fluid
decreasing. The resistance to the flow changing can include
the resistance to the flow increasing in response to the
material 86, 88 swelling.
The resistance to the flow changing can include the
resistance to the flow increasing or decreasing in response
to the ratio of desired to undesired fluid increasing.
Although various examples have been described above,
with each example having certain features, it should be
understood that it is not necessary for a particular feature
of one example to be used exclusively with that example.
Instead, any of the features described above and/or depicted
in the drawings can be combined with any of the examples, in
addition to or in substitution for any of the other features
of those examples. One example's features are not mutually
exclusive to another example's features. Instead, the scope
of this disclosure encompasses any combination of any of the
features.
It should be be understood that the various embodiments
described herein may be utilized in various orientations,
such as inclined, inverted, horizontal, vertical, etc., and
in various configurations, without departing from the
principles of this disclosure. The embodiments are
described merely as examples of useful applications of the
principles of the disclosure, which is not limited to any
specific details of these embodiments.
In the above description of the representative
examples, directional terms (such as "above," "below,"
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"upper," "lower," etc.) are used for convenience in
referring to the accompanying drawings. However, it should
be clearly understood that the scope of this disclosure is
not limited to any particular directions described herein.
Of course, a person skilled in the art would, upon a
careful consideration of the above description of
representative embodiments of the disclosure, readily
appreciate that many modifications, additions,
substitutions, deletions, and other changes may be made to
the specific embodiments, and such changes are contemplated
by the principles of this disclosure. Accordingly, the
foregoing detailed description is to be clearly understood
as being given by way of illustration and example only, the
spirit and scope of the invention being limited solely by
the appended claims and their equivalents.
