VARIABLE FLOW RESTRICTOR 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 variable flow restrictor.
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 production, balancing
production among zones, etc.
Therefore, it will be appreciated that advancements in
the art of variably restricting 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
variably restricting fluid flow in a well. One example is
described below in which a flow chamber is provided with
structures which cause a restriction to flow through the
chamber to increase as a ratio of undesired to desired fluid
in a fluid composition increases.
In one aspect, this disclosure provides to the art a
variable flow resistance system for use in a subterranean
well. The system can include a flow chamber through which a
fluid composition flows. The chamber has at least one
inlet, an outlet, and at least one structure spirally
oriented relative to the outlet. The structure induces
spiral flow of the fluid composition about the outlet.
In another aspect, a variable flow resistance system
for use in a subterranean well can include a flow chamber
including an outlet, at least one structure which induces
spiral flow of a fluid composition about the outlet, and at
least one other structure which impedes a change in
direction of flow of the fluid composition radially toward
the outlet.
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 cross-sectional view of a
portion of the well system.
FIGS. 3A & B are further enlarged scale cross-sectional
views of a variable flow resistance system, taken along line
3-3 of FIG. 2 , with FIG. 3A depicting relatively high
velocity, low density flow through the system, and FIG. 3B
depicting relatively low velocity, high density flow through
the system.
FIG. 4 is a cross-sectional view of another
configuration of the variable flow resistance system.
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.), 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 ).
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 .
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.
Referring additionally now to FIG. 2 , an enlarged scale
cross-sectional view of one of the variable flow resistance
systems 2 5 and a portion of one of the well screens 2 4 is
representatively illustrated. In this example, a fluid
composition 3 6 (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 2 4 , is thereby filtered, and then flows into an inlet
3 8 of the variable flow resistance system 2 5 .
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 preferably at least partially
extends 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 , more
detailed cross-sectional views of one example of the system
25 is representatively illustrated. The system 25 is
depicted in FIGS. 3A & B as if it is planar in
configuration, but the system could instead extend
circumf erentially , such as in a sidewall of tubular member,
if desired.
FIG. 3A depicts the variable flow resistance system 25
with the fluid composition 36 flowing through a flow chamber
42 between the inlet 38 and the outlet 40. In FIG. 3A, the
fluid composition 36 has a relatively low viscosity and/or a
relatively high velocity. For example, if gas or water is
an undesired fluid and oil is a desired fluid, then the
fluid composition 36 in FIG. 3A has a relatively high ratio
of undesired fluid to desired fluid.
Note that the flow chamber 42 is provided with
structures 44 which induce a spiraling flow of the fluid
composition 36 about the outlet 40. That is, the fluid
composition 36 is made to flow somewhat circularly about,
and somewhat radially toward, the outlet 40.
Preferably, the structures 44 also impede a change in
direction of the fluid composition 36 radially toward the
outlet 40. Thus, although the spiral flow of the fluid
composition 36 induced by the structures 44 does have both a
circular and a radial component, the structures preferably
impede an increase in the radial component.
In the example of FIG. 3A, the structures 44 are spaced
apart from each other in the direction of flow of the fluid
composition 36. The spacing between the structures 44
preferably decreases incrementally in the direction of flow
of the fluid composition 36.
Two entrances 46 to the chamber 42 are depicted in FIG.
3A, with each entrance having a series of the spaced apart
structures 44 associated therewith. However, it will be
appreciated that any number of entrances 46 and structures
44 may be provided in keeping with the principles of this
disclosure .
Additional structures 48 are provided in the chamber 42
for impeding a change toward radial flow of the fluid
composition 36. As depicted in FIG. 3A, the structures 48
are circumf erentially and radially spaced apart from each
other .
The spacings between the structures 44, 48 do
eventually allow the fluid composition 36 to flow to the
outlet 40, but energy is dissipated due to the spiraling and
circular flow of the fluid composition about the outlet, and
so a relatively large resistance to flow is experienced by
the fluid composition. As the viscosity of the fluid
composition 36 decreases and/or as the velocity of the fluid
composition increases (e.g., due to a decreased ratio of
desired to undesired fluids in the fluid composition), this
resistance to flow will increase. Conversely, As the
viscosity of the fluid composition 36 increases and/or as
the velocity of the fluid composition decreases (e.g., due
to an increased ratio of desired to undesired fluids in the
fluid composition), this resistance to flow will decrease.
In FIG. 3B, the system 25 is depicted with such an
increased ratio of desired to undesired fluids in the fluid
composition 36. Having a higher viscosity and/or lower
velocity, the fluid composition 36 is able to more readily
flow through the spacings between the structures 44, 48.
In this manner, the fluid composition 36 flows much
more directly to the outlet 40 in the FIG. 3B example, as
compared to the FIG. 3A example. This is some spiral flow
of the fluid composition in the FIG. 3B example, but it is
much less than that in the FIG. 3A example. Thus, the
energy dissipation and resistance to flow is much less in
the FIG. 3B example, as compared to the FIG. 3A example.
Referring additionally now to FIG. 4 , another
configuration of the variable flow resistance system 25 is
representatively illustrated. In this configuration, there
are many more entrances 46 to the chamber 42 as compared to
the configuration of FIGS. 3A & B , and there are two
radially spaced apart sets of the spiral flow-inducing
structures 44. Thus, it will be appreciated that a wide
variety of different configurations of variable flow
resistance systems may be constructed, without departing
from the principles of this disclosure.
Note that the entrances 46 gradually narrow in the
direction of flow of the fluid composition 36. This
narrowing of flow area increases the velocity of the fluid
composition 36 somewhat.
As with configuration of FIGS. 3A & B , the resistance
to flow through the system 25 of FIG. 4 will increase as the
viscosity of the fluid composition 36 decreases and/or as
the velocity of the fluid composition increases.
Conversely, the resistance to flow through the system 25 of
FIG. 4 will decrease as the viscosity of the fluid
composition 36 increases and/or as the velocity of the fluid
composition decreases.
In each of the configurations described above, the
structures 44 and/or 48 may be formed as vanes or as
recesses on one or more walls of the chamber 42. If formed
as vanes, the structures 44 and/or 48 may extend outwardly
from the chamber 42 wall(s). If formed as recesses, the
structures 44 and/or 48 may extend inwardly from the chamber
42 wall(s). The functions of inducing a desired direction
of flow of the fluid composition 36, or of resisting a
change in direction of the fluid composition flow, may be
performed with any types, numbers, spacings or
configurations of structures.
It may now be fully appreciated that the above
disclosure provides significant advancements to the art of
variably restricting flow of fluid in a well. Preferably,
the variable flow resistance system 25 examples described
above operate autonomously, automatically and without any
moving parts to reliably regulate flow between a formation
20 and an interior of a tubular string 22.
In one aspect, the above disclosure describes a
variable flow resistance system 25 for use in a subterranean
well. The system 25 can include a flow chamber 42 through
which a fluid composition 36 flows. The chamber 42 has at
least one inlet 38, an outlet 40, and at least one structure
44 spirally oriented relative to the outlet 40, whereby the
structure 44 induces spiral flow of the fluid composition 36
about the outlet 40.
In another aspect, a variable flow resistance system 25
described above comprises a flow chamber 42 including an
outlet 40, at least one structure 44 which induces spiral
flow of a fluid composition 36 about the outlet 40, and at
least one other structure 48 which impedes a change in
direction of flow of the fluid composition 36 radially
toward the outlet 40.
The fluid composition 36 preferably flows through the
flow chamber 42 in the well.
The structure 48 increasingly impedes the change in
direction radially toward the outlet 40 in response to at
least one of a ) increased velocity of the fluid composition
36, b ) decreased viscosity of the fluid composition 36, and
c ) a reduced ratio of desired fluid to undesired fluid in
the fluid composition 36.
The structure 44 and/or 48 can comprises at least one
of a vane and a recess. The structure 44 and/or 48 can
project at least one of inwardly and outwardly relative to a
wall of the chamber 42.
The structure 44 and/or 48 can comprise multiple spaced
apart structures. A spacing between adjacent structures 44
may decrease in a direction of spiral flow of the fluid
composition 36.
The fluid composition 36 preferably flows more directly
to the outlet 40 as a viscosity of the fluid composition 36
increases, as a velocity of the fluid composition 36
decreases, and/or as a ratio of desired fluid to undesired
fluid in the fluid composition 36 increases.
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.
In the above description of the representative examples
of the disclosure, directional terms, such as "above,"
"below," "upper," "lower," etc., are used for convenience in
referring to the accompanying drawings. In general,
"above," "upper," "upward" and similar terms refer to a
direction toward the earth's surface along a wellbore, and
"below," "lower," "downward" and similar terms refer to a
direction away from the earth's surface along the wellbore.
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 flow chamber through which a fluid composition flows,
the chamber having at least one inlet, an outlet, and at
least one structure spirally oriented relative to the
outlet, whereby the structure induces spiral flow of the
fluid composition about the outlet.
2 . The system of claim 1 , wherein the fluid
composition flows through the flow chamber in the well.
3 . The system of claim 1 , wherein the structure
impedes a change in direction of flow of the fluid
composition radially toward the outlet.
4 . The system of claim 3 , wherein the structure
increasingly impedes the change in direction radially toward
the outlet in response to at least one of a ) increased
velocity of the fluid composition, b ) decreased viscosity of
the fluid composition, and c ) a reduced ratio of desired
fluid to undesired fluid in the fluid composition.
5 . The system of claim 1 , wherein the structure
comprises at least one of a vane and a recess.
6 . The system of claim 1 , wherein the structure
projects at least one of inwardly and outwardly relative
a wall of the chamber.
7 . The system of claim 1 , wherein the at least one
structure comprises multiple spaced apart structures.
8 . The system of claim 7 , wherein a spacing between
adjacent structures decreases in a direction of spiral flow
of the fluid composition.
9 . The system of claim 1 , wherein the fluid
composition flows more directly from the inlet to the outlet
as a viscosity of the fluid composition increases.
10. The system of claim 1 , wherein the fluid
composition flows more directly from the inlet to the outlet
as a velocity of the fluid composition decreases.
11. The system of claim 1 , wherein the fluid
composition flows more directly from the inlet to the outlet
as a ratio of desired fluid to undesired fluid in the fluid
composition increases.
12. A variable flow resistance system for use in a
subterranean well, the system comprising:
a flow chamber including an outlet, at least one first
structure which induces spiral flow of a fluid composition
about the outlet, and at least one second structure which
impedes a change in direction of flow of the fluid
composition radially toward the outlet.
13. The system of claim 12, wherein the fluid
composition flows through the flow chamber in the well
14. The system of claim 12, wherein the second
structure increasingly impedes the change in direction
radially toward the outlet in response to at least one of a )
increased velocity of the fluid composition, b ) decreased
viscosity of the fluid composition, and c ) a reduced ratio
of desired fluid to undesired fluid in the fluid
composition .
15. The system of claim 12, wherein the first
structure comprises at least one of a vane and a recess.
16. The system of claim 12, wherein the second
structure comprises at least one of a vane and a recess.
17. The system of claim 12, wherein the first
structure projects at least one of inwardly and outwardly
relative to a wall of the chamber.
18. The system of claim 12, wherein the second
structure projects at least one of inwardly and outwardly
relative to a wall of the chamber.
19. The system of claim 12, wherein the at least
second structure comprises multiple spaced apart second
structures .
20. The system of claim 12, wherein the at least one
first structure comprises multiple spaced apart first
structures .
21. The system of claim 20, wherein a spacing between
adjacent first structures decreases in a direction of spiral
flow of the fluid composition.
22. The system of claim 12, wherein the fluid
composition flows more directly to the outlet as a viscosity
of the fluid composition increases.
23. The system of claim 12, wherein the fluid
composition flows more directly to the outlet as a velocity
of the fluid composition decreases.
24. The system of claim 12, wherein the fluid
composition flows more directly from to the outlet as a
ratio of desired fluid to undesired fluid in the fluid
composition increases.