SERIES CONFIGURED VARIABLE FLOW RESTRICTORS FOR USE
IN 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 below, more particularly
provides a series configuration of variable flow
restrictors.
BACKGROUND
In a hydrocarbon production well, it is many times
beneficial to be able to regulate flow of fluids from an
earth formation into a wellbore. A variety of purposes may
be served by such regulation, including prevention of water
or gas coning, minimizing sand production, minimizing water
and/or gas production, maximizing oil and/or gas production,
balancing production among zones, etc.
In an injection well, it is typically desirable to
evenly inject water, steam, gas, etc., into multiple zones,
so that hydrocarbons are displaced evenly through an earth
formation, without the injected fluid prematurely breaking
through to a production wellbore. Thus, the ability to
regulate flow of fluids from a wellbore into an earth
formation can also be beneficial for injection wells.
Therefore, it will be appreciated that advancements in
the art of controlling fluid flow in a well would be
desirable in the circumstances mentioned above, and such
advancements would also be beneficial in a wide variety of
other circumstances.
SUMMARY
In the disclosure below, a variable flow resistance
system is provided which brings improvements to the art of
regulating fluid flow in wells. One example is described
below in which resistance to flow through a vortex device is
dependent on a rotation of a fluid composition as it enters
the vortex device. Another example is described, in which
multiple vortex devices are connected in series.
In one aspect, the disclosure provides to the art a
variable flow resistance system for use in a subterranean
well. The system can include a vortex device through which
a fluid composition flows. A resistance to flow of the
fluid composition through the vortex device is dependent on
a rotation of the fluid composition at an inlet to the
vortex device.
In another aspect, a variable flow resistance system
described below can include a first vortex device having an
outlet, and a second vortex device which receives a fluid
composition from the outlet of the first vortex device. A
resistance to flow of the fluid composition through the
second vortex device is dependent on a rotation of the fluid
composition at the outlet of the first vortex device.
In yet another aspect, a variable flow resistance
system can include a first vortex device which causes
increased rotation of a fluid composition at an outlet of
the first vortex device in response to an increase in a
velocity of the fluid composition, and a second vortex
device which receives the fluid composition from the outlet
of the first vortex device. A resistance to flow of the
fluid composition through the second vortex device is
dependent on the rotation of the fluid composition at the
outlet of the first vortex device.
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 examples below 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 schematic partially cross-sectional view of
a well system which can embody principles of the present
disclosure .
FIG. 2 is an enlarged scale schematic cross-sectional
view of a well screen and a variable flow resistance system
which may be used in the well system of FIG. 1 .
FIGS. 3A & B are schematic "unrolled" cross-sectional
views of one configuration of the variable flow resistance
system, taken along line 3-3 of FIG. 2 .
FIG. 4 is a schematic cross-sectional view of another
configuration of the variable flow resistance system.
FIG. 5 is a schematic cross-sectional of the variable
flow resistance system of FIG. 4 , taken along line 5-5.
FIGS. 6A & B are schematic cross-sectional views the
variable flow resistance system of FIG. 4 , depicting changes
in flow resistance resulting from changes in characteristics
of a fluid composition.
DETAILED DESCRIPTION
Representatively illustrated in FIG. 1 is a well system
10 which 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
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 well system
10 is illustrated in the drawings and is described herein as
merely one example of a wide variety of well 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 well 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
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, etc.
Examples of the variable flow resistance systems 25
described more fully below can provide these benefits by
increasing resistance to flow if a fluid velocity increases
beyond a selected level (e.g., to thereby balance flow among
zones, prevent water or gas coning, etc.), and/or increasing
resistance to flow if a fluid viscosity decreases below a
selected level (e.g., to thereby restrict flow of an
undesired fluid, such as water or gas, in an oil producing
well ).
As used herein, the term "viscosity" is used to
indicate any of the rheological properties including
kinematic viscosity, yield strength, viscoplasticity ,
surface tension, wettability, etc.
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 produce gas from a well, but
not to produce water or oil, the gas is a desired fluid, and
water and oil are undesired fluids. If it is desired to
inject steam into a formation, but not to inject water, then
steam is a desired fluid and water is an undesired fluid.
If gas is being flowed, it can be difficult to restrict
flow of the gas using conventional techniques, which
typically involve interposing small diameter passages,
orifices, etc. in the gas flow. Unfortunately, these
devices can have an increased volumetric flow rate when gas
is flowing instead of oil or another fluid, and can result
in erosion problems.
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, condensate
and/or gaseous phases are included within the scope of that
term.
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 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, 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
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 can at least partially extend
circumf erentially 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
circumf erentially 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.
Referring additionally now to FIGS. 3A & B , a more
detailed cross-sectional view of one example of the system
25 is representatively illustrated. The system 25 is
depicted in FIGS. 3A & B as if it is "unrolled" from its
circumf erentially extending configuration to a generally
planar configuration.
As described above, the fluid composition 36 enters the
system 25 via the inlet 38, and exits the system via the
outlet 40. A resistance to flow of the fluid composition 36
through the system 25 varies based on one or more
characteristics of the fluid composition.
The inlet 38, the outlet 40, and a flow passage 42 and
flow chamber 44 through which the fluid composition 36 flows
between the inlet and the outlet, are elements of a vortex
device 46 which restricts flow of the fluid composition
based on certain characteristics of the fluid composition.
Rotational flow of the fluid composition 36 increases in the
chamber 44, thereby increasing restriction to flow through
the chamber, for example, when a velocity of the fluid
composition increases, when a viscosity of the fluid
composition decreases and/or when a ratio of desired fluid
to undesired fluid in the fluid composition decreases.
As depicted in FIG. 3A, the chamber 44 is generally
cylindrical-shaped, and the flow passage 42 intersects the
chamber tangentially , so that fluid entering the chamber via
the inlet 48 tends to flow clockwise (as viewed in FIG. 3A)
about the outlet 40. A bypass passage 50 intersects the
passage 42 downstream of the inlet 38, and the bypass
passage also intersects the chamber 44 tangentially.
However, fluid entering the chamber 44 through the bypass
passage 50 via an inlet 52 tends to flow counterclockwise
(as viewed in FIG. 3A) about the outlet 40.
In FIG. 3A, a relatively high velocity and/or low
viscosity fluid composition 36 flows through the flow
passage 42 from the system inlet 38 to the flow chamber 44.
In contrast, a relatively low velocity and/or high viscosity
fluid composition 36 flows through the flow passage 42 to
the chamber 44 in FIG. 3B.
Only a small proportion of the fluid composition 36
flows to the chamber 44 via the bypass passage 50 in FIG.
3A. Thus, a substantial proportion of the fluid composition
36 rotates in the chamber 44, spiraling with increasing
rotational velocity toward the outlet 40. Note that the
rotation of the fluid composition 36 at the outlet 40 will
increase as the velocity of the fluid composition entering
the inlet 38 increases, and as a viscosity of the fluid
composition decreases.
A substantially larger proportion of the fluid
composition flows to the chamber 44 via the bypass passage
50 in FIG. 3B. In this example, the flows entering the
chamber 44 via the inlets 48, 52 are about equal. These
flows effectively "cancel" or counteract each other, so that
there is relatively little rotational flow of the fluid
composition 36 in the chamber 44.
It will be appreciated that the much more circuitous
flow path taken by the fluid composition 36 in the example
of FIG. 3A consumes more of the fluid composition's energy
at the same flow rate and, thus, results in more resistance
to flow, as compared to the much more direct flow path taken
by the fluid composition in the example of FIG. 3B. If oil
is a desired fluid, and water and/or gas are undesired
fluids, then it will be appreciated that the variable flow
resistance system 25 of FIGS. 3A & B will provide less
resistance to flow of the fluid composition 36 when it has
an increased ratio of desired to undesired fluid therein,
and will provide greater resistance to flow when the fluid
composition has a decreased ratio of desired to undesired
fluid therein.
Since the chamber 44 in this example has a cylindrical
shape with a central outlet 40, and the fluid composition 36
(at least in FIG. 3A) spirals about the chamber, increasing
in velocity as it nears the outlet, driven by a pressure
differential from the inlet 44 to the outlet, the chamber
may be referred to as a "vortex" chamber.
Circular flow inducing structures 54 are used in the
chamber 44 in the configuration of FIGS. 3A & B . The
structures 54 operate to maintain circular flow of the fluid
composition 36 about the outlet 40, or at least to impede
inward flow of the fluid composition toward the outlet, when
the fluid composition does flow circularly about the outlet.
Openings 56 in the structures 54 permit the fluid
composition 36 to eventually flow inward to the outlet 40.
As discussed above, in FIG. 3A, the vortex device 46 is
depicted in a situation in which an increased velocity
and/or reduced viscosity of the fluid composition 36 results
in a substantial proportion of the fluid composition flowing
into the chamber 44 via the inlet 48. The fluid composition
36, thus, spirals about the outlet 40 in the chamber 44, and
a resistance to flow through the vortex device 46 increases.
A reduced viscosity can be due to a relatively low ratio of
desired fluid to undesired fluid in the fluid composition
36.
Relatively little of the fluid composition 36 flows
into the chamber 44 via the inlet 52 in FIG. 3A, because the
flow passage 50 is branched from the flow passage 42 in a
manner such that most of the fluid composition remains in
the flow passage 42. At relatively high velocities and/or
low viscosities, the fluid composition 36 tends to flow past
the flow passage 50.
In FIG. 3B, a velocity of the fluid composition 36 has
decreased and/or a viscosity of the fluid composition has
increased, and as a result, proportionately more of the
fluid composition flows from the passage 42 and via the
passage 50 to the inlet 52. The increased viscosity of the
fluid composition 36 may be due to an increased ratio of
desired to undesired fluids in the fluid composition.
Since, in FIG. 3B, the flows into the chamber 4 4 from
the two inlets 4 8 , 5 2 are oppositely directed (or at least
the flow of the fluid composition through the inlet 5 2
opposes the flow through the inlet 4 8 ) , they counteract each
other. Thus, the fluid composition 3 6 flows more directly
to the outlet 4 0 and a resistance to flow through the vortex
device 4 6 is decreased, and the fluid composition has
reduced (or no) rotation at the outlet 4 0 .
Referring additionally now to FIG. 4 , another
configuration of the variable flow resistance system 2 5 is
representatively illustrated. In this configuration, the
vortex device 4 6 is used in series with two additional
vortex devices 5 8 , 6 0 . Although three vortex devices 4 6 ,
5 8 , 6 0 are depicted in FIG. 4 , it will be appreciated that
any number of vortex devices may be connected in series, in
keeping with the principles of this disclosure.
An outlet 6 2 of the vortex device 4 6 corresponds to an
inlet of the vortex device 5 8 , and an outlet 6 4 of the
vortex device 5 8 corresponds to an inlet of the vortex
device 6 0 . The fluid composition 3 6 flows from the system
2 5 inlet 3 8 to the chamber 4 4 , from the chamber 4 4 to the
vortex device 5 8 via the outlet/inlet 6 2 , from the
outlet/inlet 6 2 to a vortex chamber 6 6 of the vortex device
5 8 , from the chamber 6 6 to the vortex device 6 0 via the
outlet/inlet 6 4 , from the outlet/inlet 6 4 to a vortex
chamber 6 8 of the vortex device 6 0 , and from the chamber 6 8
to the outlet 4 0 of the system 2 5 .
Each of the vortex devices 5 8 , 6 0 includes two passages
7 0 , 7 2 and 7 4 , 7 6 , respectively, which function somewhat
similar to the passages 4 2 , 5 0 of the vortex device 4 6 .
However, the proportions of the fluid composition 3 6 which
flows through each of the passages 7 0 , 7 2 and 7 4 , 7 6 varies
based on a rotation of the fluid composition as it enters
the respective vortex device 58, 60, as described more fully
below.
Referring additionally now to FIG. 5 , a cross-sectional
view of the variable flow resistance system 25 is
representatively illustrated, as viewed along line 5-5 of
FIG. 4 . In this view, the manner in which the outlet/inlet
62 and outlet/inlet 64 provide fluid communication between
the vortex devices 46, 58, 60 can be readily seen.
In FIG. 5 , it may also be seen that the vortex devices
46, 58, 60 are "stacked" in a compact manner, alternating
orientation back and forth. However, it will be appreciated
that the vortex devices 46, 58, 60 could be otherwise
arranged, in keeping with the principles of this disclosure.
Referring additionally now to FIGS. 6A & B , the
variable flow resistance system 25 of FIGS. 4 & 5 is
depicted, with a relatively low viscosity and/or high
velocity fluid composition 36 flowing through the system in
FIG. 6A, and with a relatively high viscosity and/or low
velocity fluid composition flowing through the system in
FIG. 6B. These examples demonstrate how the resistance to
flow through the system 25 varies based on certain
characteristics of the fluid composition 36.
In FIG. 6A, significant spiraling flow of the fluid
composition 36 is present in the vortex device 46 (similar
to that described above in relation to FIG. 3A) . As a
result, the fluid composition 36 is rotating significantly
when it flows from the chamber 44 to the vortex device 58
via the outlet/inlet 62.
This rotational flow of the fluid composition 36 causes
a greater proportion of the fluid composition to flow
through the passage 70, as compared to the proportion of the
fluid composition which flows through the passage 72. The
manner in which the rotating fluid composition 36 impinges
on the curved walls of the passages 70, 72 at their
intersection with the outlet/inlet 62 causes this difference
in the proportions of the fluid composition which flows
through each of the passages.
Since a greater proportion of the fluid composition 36
flows into the chamber 66 of the vortex device 58 via the
passage 70, the fluid composition rotates within the chamber
66, similar to the manner in which the fluid composition
flows spirally through the chamber 44 of the vortex device
46. This spiraling flow of the fluid composition 36 through
the chamber 66 generates resistance to flow, with the
resistance to flow increasing with increased rotational flow
of the fluid composition in the chamber.
The fluid composition 36 rotates as it exits the
chamber 66 via the outlet/inlet 64. This rotational flow of
the fluid composition 36 causes a greater proportion of the
fluid composition to flow through the passage 74, as
compared to the proportion of the fluid composition which
flows through the passage 76. Similar to that described
above for the vortex chamber 58, the manner in which the
rotating fluid composition 36 impinges on the curved walls
of the passages 74, 76 at their intersection with the
outlet/inlet 64 causes this difference in the proportions of
the fluid composition which flows through each of the
passages .
Since a greater proportion of the fluid composition 36
flows into the chamber 68 of the vortex device 60 via the
passage 74, the fluid composition rotates within the chamber
68, similar to the manner in which the fluid composition
flows spirally through the chamber 66 of the vortex device
58. This spiraling flow of the fluid composition 36 through
the chamber 68 generates resistance to flow, with the
resistance to flow increasing with increased rotational flow
of the fluid composition in the chamber.
Thus, with the relatively high velocity and/or low
viscosity fluid composition 36 in FIG. 6A, rotational flow
and resistance to flow is increased in each of the vortex
devices 46, 58, 60, so that overall flow resistance is much
greater than that which would have been provided by only the
single vortex device 46. In addition, the rotational flow
through the chambers 66, 68 of the vortex devices 58, 60 is
due to the rotational flow of the fluid composition 36 at
each of the outlet/inlets 62, 64.
In FIG. 6B, a relatively high viscosity and/or low
velocity fluid composition 36 flows through the system 25.
Note that rotational flow of the fluid composition 36 in
each of the chambers 44, 66, 68 is significantly reduced,
and so the resistance to flow of the fluid composition
through the chambers is also significantly reduced. Thus,
the resistance to flow of the relatively high viscosity
and/or low velocity fluid composition 36 is much less in
FIG. 6B, as compared to the resistance to flow of the
relatively low viscosity and/or high velocity fluid
composition in FIG. 6A.
Note that any of the features of any of the
configurations of the system 25 described above may be
included in any of the other configurations of the system
and, thus, it should be understood that these features are
not exclusive to any one particular configuration of the
system. The system 25 can be used in any type of well
system (e.g., not only in the well system 10), and for
accomplishing various purposes in various well operations,
including but not limited to injection, stimulation,
completion, production, conformance, drilling operations,
etc .
It will be appreciated that the system 25 of FIGS. 4-6B
provides significant advancements to the art of controlling
flow in a well. The resistance to flow of the fluid
composition 36 through the system 25 can be substantially
increased by connecting the vortex devices 46, 58, 60 in
series, and by resisting flow of the fluid composition in
response to its rotation as it passes from one vortex device
to the next.
The above disclosure provides to the art a variable
flow resistance system 25 for use in a subterranean well.
The system 25 can include a vortex device 58 or 60 through
which a fluid composition 36 flows. A resistance to flow of
the fluid composition 36 through the vortex device 58 or 60
is dependent on a rotation of the fluid composition 36 at an
inlet 62 or 64 to the vortex device 58 or 60.
The resistance to flow of the fluid composition 36
through the vortex device 58 or 60 can increase in response
to an increased rotation of the fluid composition 36 at the
inlet 62 or 64 to the vortex device 58 or 60.
The rotation of the fluid composition 36 at the inlet
62 or 64 can increase in response to a decrease in viscosity
of the fluid composition 36.
The rotation of the fluid composition 36 at the inlet
62 or 64 can increase in response to an increase in velocity
of the fluid composition 36.
The rotation of the fluid composition 36 at the inlet
62 or 64 can increase in response to a decrease in a ratio
of desired to undesired fluid in the fluid composition 36.
An outlet 64 of the vortex device 58 can comprise an
inlet 64 of another vortex device 60. The inlet 64 of the
vortex device 60 can comprise an outlet 64 of another vortex
device 58.
The vortex device 58 can comprise at least first and
second passages 70, 72 which receive the fluid composition
36 from an outlet 62 of another vortex device 46. A
difference in proportions of the fluid composition 36 which
flows through the respective first and second passages 70,
72 is dependent on the rotation of the fluid composition 36
at the outlet 62. The difference in the proportions of the
fluid composition 36 which flows through the first and
second passages 70, 72 may increase in response to an
increase in velocity of the fluid composition 36.
Rotation of the fluid composition 36 in a vortex
chamber 66 increases in response to an increase in the
difference in the proportions of the fluid composition 36
which flows through the first and second passages 70, 72.
The above disclosure also describes a variable flow
resistance system 25 which can include a first vortex 46
device having an outlet 62, and a second vortex device 58
which receives a fluid composition 36 from the outlet 62 of
the first vortex device 46. A resistance to flow of the
fluid composition 36 through the second vortex device 58 can
be dependent on a rotation of the fluid composition 36 at
the outlet 62 of the first vortex device 46.
The rotation of the fluid composition 36 at the outlet
62 may increase in response to a decrease in viscosity of
the fluid composition 36, in response to an increase in
velocity of the fluid composition 36 and/or in response to a
decrease in a ratio of desired to undesired fluid in the
fluid composition 36.
The resistance to flow of the fluid composition 36
through the second vortex device 58 can increase in response
to an increase in the rotation of the fluid composition 36
at the outlet 62 of the first vortex device 46.
An outlet 64 of the second vortex device 58 can
comprise an inlet 64 of a third vortex device 60.
The second vortex device 58 can include at least first
and second passages 70, 72 which receive the fluid
composition 36 from the outlet 62 of the first vortex device
46. A difference in proportions of the fluid composition 36
which flow through the respective first and second passages
70, 72 is dependent on the rotation of the fluid composition
36 at the outlet 62 of the first vortex device 46.
The difference in the proportions of the fluid
composition 36 which flows through the first and second
passages 70, 72 may increase in response to an increase in
velocity of the fluid composition 36.
Rotation of the fluid composition 36 in a vortex
chamber 66 of the second vortex device 58 may increase in
response to an increase in the difference in the proportions
of the fluid composition 36 which flows through the first
and second passages 70, 72.
The above disclosure also describes a variable flow
resistance system 25 which can include a first vortex device
46 which causes increased rotation of a fluid composition 36
at an outlet 62 of the first vortex device 46 in response to
an increase in a velocity of the fluid composition 36, and a
second vortex device 58 which receives the fluid composition
36 from the outlet 62 of the first vortex device 46. A
resistance to flow of the fluid composition 36 through the
second vortex device 58 may be dependent on the rotation of
the fluid composition 36 at the outlet 62 of the first
vortex device 46.
It is to be understood that the various examples
described above may be utilized in various orientations,
such as inclined, inverted, horizontal, vertical, etc., and
in various configurations, without departing from the
principles of the present disclosure. The embodiments
illustrated in the drawings are depicted and described
merely as examples of useful applications of the principles
of the disclosure, which are not limited to any specific
details of these embodiments.
Of course, a person skilled in the art would, upon a
careful consideration of the above description of
representative embodiments, readily appreciate that many
modifications, additions, substitutions, deletions, and
other changes may be made to these specific embodiments, and
such changes are within the scope of the principles of the
present 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 present invention being limited solely by the
appended claims and their equivalents.

WHAT IS CLAIMED IS:
1 . A variable flow resistance system for use in a
subterranean well, the system comprising:
a vortex device through which a fluid composition
flows; and
wherein a resistance to flow of the fluid composition
through the vortex device is dependent on a rotation of the
fluid composition at an inlet to the vortex device.
2 . The system of claim 1 , wherein the resistance to
flow of the fluid composition through the vortex device
increases in response to an increased rotation of the fluid
composition at the inlet to the vortex device.
3 . The system of claim 1 , wherein the rotation of the
fluid composition at the inlet increases in response to a
decrease in viscosity of the fluid composition.
4 . The system of claim 1 , wherein the rotation of the
fluid composition at the inlet increases in response to an
increase in velocity of the fluid composition.
5 . The system of claim 1 , wherein the rotation of the
fluid composition at the inlet increases in response to a
decrease in a ratio of desired to undesired fluid in the
fluid composition.
6 . The system of claim 1 , wherein an outlet of the
vortex device comprises an inlet of another vortex device,
7 . The system of claim 1 , wherein the inlet of the
vortex device comprises an outlet of another vortex device,
8 . The system of claim 1 , wherein the vortex device
comprises at least first and second passages which receive
the fluid composition from an outlet of another vortex
device, and wherein a difference in proportions of the fluid
composition which flows through the respective first and
second passages is dependent on the rotation of the fluid
composition at the outlet.
9 . The system of claim 8 , wherein the difference in
the proportions of the fluid composition which flows through
the first and second passages increases in response to an
increase in velocity of the fluid composition.
10. The system of claim 8 , wherein rotation of the
fluid composition in a vortex chamber increases in response
to an increase in the difference in the proportions of the
fluid composition which flows through the first and second
passages .
11. A variable flow resistance system for use in a
subterranean well, the system comprising:
a first vortex device having an outlet; and
a second vortex device which receives a fluid
composition from the outlet of the first vortex device, a
resistance to flow of the fluid composition through the
second vortex device being dependent on a rotation of the
fluid composition at the outlet of the first vortex device.
12. The system of claim 11, wherein the rotation of
the fluid composition at the outlet increases in response to
a decrease in viscosity of the fluid composition.
13. The system of claim 11, wherein the rotation of
the fluid composition at the outlet increases in response to
an increase in velocity of the fluid composition.
14. The system of claim 11, wherein the rotation of
the fluid composition at the outlet increases in response to
a decrease in a ratio of desired to undesired fluid in the
fluid composition.
15. The system of claim 11, wherein the resistance to
flow of the fluid composition through the second vortex
device increases in response to an increase in the rotation
of the fluid composition at the outlet of the first vortex
device .
16. The system of claim 11, wherein an outlet of the
second vortex device comprises an inlet of a third vortex
device .
17. The system of claim 11, wherein the second vortex
device comprises at least first and second passages which
receive the fluid composition from the outlet of the first
vortex device, and wherein a difference in proportions of
the fluid composition which flows through the respective
first and second passages is dependent on the rotation of
the fluid composition at the outlet of the first vortex
device .
18. The system of claim 17, wherein the difference in
the proportions of the fluid composition which flows through
the first and second passages increases in response to an
increase in velocity of the fluid composition.
19. The system of claim 17, wherein rotation of the
fluid composition in a vortex chamber of the second vortex
device increases in response to an increase in the
difference in the proportions of the fluid composition which
flows through the first and second passages.
20. A variable flow resistance system for use in a
subterranean well, the system comprising:
a first vortex device which causes increased rotation
of a fluid composition at an outlet of the first vortex
device in response to an increase in a velocity of the fluid
composition; and
a second vortex device which receives the fluid
composition from the outlet of the first vortex device, a
resistance to flow of the fluid composition through the
second vortex device being dependent on the rotation of the
fluid composition at the outlet of the first vortex device.
21. The system of claim 20, wherein the resistance to
flow of the fluid composition through the second vortex
device increases in response to an increase in the rotation
of the fluid composition at the outlet of the first vortex
device .
22. The system of claim 20, wherein an outlet of the
second vortex device comprises an inlet of a third vortex
device .
23. The system of claim 20, wherein the second vortex
device comprises at least first and second passages which
receive the fluid composition from the outlet of the first
vortex device, and wherein a difference in proportions of
the fluid composition which flows through the respective
first and second passages is dependent on the rotation of
the fluid composition at the outlet of the first vortex
device .
24. The system of claim 23, wherein the difference in
the proportions of the fluid composition which flows through
the first and second passages increases in response to the
increase in the velocity of the fluid composition.
25. The system of claim 23, wherein rotation of the
fluid composition in a vortex chamber of the second vortex
device increases in response to an increase in the
difference in the proportions of the fluid composition which
flows through the first and second passages.