SELF-RELEASING PLUG 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 flow control system with a self-releasing plug.
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 flow control system is
provided which brings improvements to the art of regulating
fluid flow in wells. One example is described below in
which a flow control system is used in conjunction with a
variable flow resistance system. Another example is
described below in which a flow control system is used in
conjunction with an inflow control device.
In one aspect, the disclosure provides to the art a
flow control system for use in a subterranean well. The
system can include a flow chamber through which a fluid
composition flows, and a plug which is released in response
to an increase in a ratio of undesired fluid to desired
fluid in the fluid composition.
In another aspect, a flow control system described
below can include a flow chamber through which a fluid
composition flows, a plug and a structure which supports the
plug, but which releases the plug in response to degrading
of the structure by the fluid composition.
In yet another aspect, a flow control system can
include a flow chamber through which a fluid composition
flows, and a plug which is released in response to an
increase in a velocity of the fluid composition in the flow
chamber.
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" plan views of one
configuration of the variable flow resistance system, taken
along line 3-3 of FIG. 2 .
FIGS. 4A & B are schematic plan views of another
configuration of the variable flow resistance system.
FIGS. 5A-C are schematic plan views of another
configuration of the variable flow resistance system.
FIGS. 6 is a schematic plan view of yet another
configuration of the variable flow resistance system.
FIG. 7 is a schematic plan views of another
configuration of the variable flow resistance system.
FIG. 8 is a schematic cross-sectional view of a well
screen and an inflow control device which may be used in the
well system of FIG. 1 .
FIGS. 9A & B are schematic plan views of another
configuration of the inflow control device.
FIGS. 10A & B are schematic plan views of yet another
configuration of the inflow control device.
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.
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 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 3 6 through the variable
flow resistance system 2 5 is resisted based on one or more
characteristics (such as viscosity, velocity, etc.) of the
fluid composition. The fluid composition 3 6 is then
discharged from the variable flow resistance system 2 5 to an
interior of the tubular string 2 2 via an outlet 4 0 .
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,
and/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.
In FIG. 3A, a relatively high velocity and/or low
viscosity fluid composition 36 flows through a flow passage
42 from the system inlet 38 to an inlet 44 of a flow chamber
46. The flow passage 42 has an abrupt change in direction
48 just upstream of the inlet 44. The abrupt change in
direction 48 is illustrated as a relatively small radius
ninety degree curve in the flow passage 42, but other types
of direction changes may be used, if desired.
As depicted in FIG. 3A, the chamber 46 is generally
cylindrical-shaped and, prior to the abrupt change in
direction 48, the flow passage 42 directs the fluid
composition 36 to flow generally tangentially relative to
the chamber. Because of the relatively high velocity and/or
low viscosity of the fluid composition 36, it does not
closely follow the abrupt change in direction 48, but
instead continues into the chamber 46 via the inlet 44 in a
direction which is substantially angled (see angle A in FIG.
3A) relative to a straight direction 50 from the inlet 44 to
the outlet 40. The fluid composition 36 will, thus, flow
circuitously from the inlet 44 to the outlet 40, eventually
spiraling inward to the outlet.
In contrast, a relatively low velocity and/or high
viscosity fluid composition 36 flows through the flow
passage 42 to the chamber inlet 44 in FIG. 3B. Note that
the fluid composition 36 in this example more closely
follows the abrupt change in direction 48 of the flow
passage 42 and, therefore, flows through the inlet 44 into
the chamber 46 in a direction which is only slightly angled
(see angle a in FIG. 3B) relative to the straight direction
50 from the inlet 44 to the outlet 40. The fluid
composition 36 in this example will, thus, flow much more
directly from the inlet 44 to the outlet 40.
Note that, as depicted in FIG. 3B, the fluid
composition 36 also exits the chamber 46 via the outlet 40
in a direction which is only slightly angled relative to the
straight direction 50 from the inlet 44 to the outlet 40.
Thus, the fluid composition 36 exits the chamber 46 in a
direction which changes based on velocity, viscosity, and/or
the ratio of desired fluid to undesired fluid in the fluid
composition.
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 46 has a generally cylindrical shape
as depicted in the examples of FIGS. 3A & B , the straight
direction 50 from the inlet 44 to the outlet 40 is in a
radial direction. The flow passage 42 upstream of the
abrupt change in direction 48 is directed generally
tangential relative to the chamber 46 (i.e., perpendicular
to a line extending radially from the center of the
chamber) . However, the chamber 46 is not necessarily
cylindrical-shaped and the straight direction 50 from the
inlet 44 to the outlet 40 is not necessarily in a radial
direction, in keeping with the principles of this
disclosure .
Since the chamber 46 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.
Referring additionally now to FIGS. 4A & B , another
configuration of the variable flow resistance system 25 is
representatively illustrated. The configuration of FIGS. 4A
& B is similar in many respects to the configuration of
FIGS. 3A & B , but differs at least in that the flow passage
42 extends much more in a radial direction relative to the
chamber 46 upstream of the abrupt change in direction 48,
and the abrupt change in direction influences the fluid
composition 36 to flow away from the straight direction 50
from the inlet 44 to the outlet 40.
In FIG. 4A, a relatively high viscosity and/or low
velocity fluid composition 36 is influenced by the abrupt
change in direction 48 to flow into the chamber 46 in a
direction away from the straight direction 50 (e.g., at a
relatively large angle A to the straight direction). Thus,
the fluid composition 36 will flow circuitously about the
chamber 46 prior to exiting via the outlet 40.
Note that this is the opposite of the situation
described above for FIG. 3B, in which the relatively high
viscosity and/or low velocity fluid composition 36 enters
the chamber 46 via the inlet 44 in a direction which is only
slightly angled relative to the straight direction 50 from
the inlet to the outlet 40. However, a similarity of the
FIGS. 3B & 4A configurations is that the fluid composition
36 tends to change direction with the abrupt change in
direction 48 in the flow passage 42.
In contrast, a relatively high velocity and/or low
viscosity fluid composition 36 flows through the flow
passage 42 to the chamber inlet 44 in FIG. 4B. Note that
the fluid composition 36 in this example does not closely
follow the abrupt change in direction 48 of the flow passage
42 and, therefore, flows through the inlet 44 into the
chamber 46 in a direction which is angled only slightly
relative to the straight direction 50 from the inlet 44 to
the outlet 40. The fluid composition 36 in this example
will, thus, flow much more directly from the inlet 44 to the
outlet 40.
It will be appreciated that the much more circuitous
flow path taken by the fluid composition 36 in the example
of FIG. 4A 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. 4B. If gas
or steam is a desired fluid, and water and/or oil are
undesired fluids, then it will be appreciated that the
variable flow resistance system 25 of FIGS. 4A & 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.
Referring additionally now to FIGS. 5A & B , another
configuration of the variable flow resistance system 25 is
representatively illustrated. In this configuration, a flow
control system 52 is used which shares some of the elements
of the variable flow resistance system 25. The flow control
system 52 desirably shuts off flow through the variable flow
resistance system 25 when an unacceptably high ratio of
undesired fluid to desired fluid flows through the chamber
46, when a particular undesired fluid flows through the
chamber and/or when the fluid composition 36 flows through
the chamber at a velocity which is above a predetermined
acceptable level.
In FIG. 5A, it may be seen that the flow control system
25 includes a plug 54 in the form of a ball. Other types of
plugs (such as cylindrical, flat, or otherwise shaped plugs,
plugs with seals thereon, etc.) may be used, if desired.
The plug 54 is retained in a central position relative
to the chamber 46 by means of a support structure 56. The
structure 56 releasably supports the plug 54. The structure
56 may be made of a material which relatively quickly
corrodes when contacted by a particular undesired fluid (for
example, the structure could be made of cobalt, which
corrodes when in contact with salt water) . The structure 56
may be made of a material which relatively quickly erodes
when a high velocity fluid impinges on the material (for
example, the structure could be made of aluminum, etc.).
However, it should be understood that any material may be
used for the structure 56 in keeping with the principles of
this disclosure.
In FIG. 5B, it may be seen that the structure 56 has
been degraded by exposure to a relatively high velocity
fluid composition 36 in the chamber 46, by an undesired
fluid in the fluid composition, and/or by an increased ratio
of undesired to desired fluids in the fluid composition.
The plug 54 has been released from the degraded structure 56
and now sealingly engages a seat 58 located somewhat
upstream of the outlet 40.
Flow through the chamber 46 is now prevented by the
sealing engagement between the plug 54 and the seat 58. It
will be appreciated that this flow prevention is beneficial,
in that it prevents production of the undesired fluid
through the chamber 46, it prevents production of
unacceptably high velocity fluid through the chamber, etc.
In circumstances in which unacceptably high levels of
undesired fluid are being produced through the variable flow
resistance system 25, it may be more beneficial to
completely shut off flow through the chamber 46, rather than
merely increase the resistance to flow through the chamber.
The flow control system 52 accomplishes this result
automatically, without the need for human intervention, in
response to sustained flow of undesired fluid through the
chamber 46, in response to sustained high velocity flow
through the chamber, etc.
Of course, the material of the structure 56 can be
conveniently selected and dimensioned to cause release of
the plug 54 in response to certain levels of undesired
fluids, high velocity flow, etc., and/or exposure of the
structure to the undesired fluids and/or high velocity flow
for certain periods of time. For example, the structure 56
could be configured to release the plug 54 only after a
certain number of days or weeks of exposure to a certain
undesired fluid, or to an unacceptably high velocity flow.
In FIG. 5C, the flow control system 52 is provided with
a latch device 60 which prevents the plug 54 from displacing
away from the seat, or back into the chamber 46. The latch
device 60 can also be configured to seal against the plug
54, so that reverse flow (e.g., from the outlet 40 to the
inlet 44) is prevented.
Referring additionally now to FIG. 6 , the system 25 is
representatively illustrated after the plug 54 has been
released (as in FIG. 5B), but with a pressure differential
being applied from the outlet 40 to the inlet 38. This
would be the case if reverse flow through the chamber 46
were to be attempted.
As depicted in FIG. 6 , another seat 62 can be provided
for sealing engagement with the plug 54, to thereby prevent
reverse flow through the chamber 46 after the plug has been
released. The passage 42 can also be dimensioned to prevent
the plug 54 from being displaced out of the chamber 46.
Referring additionally now to FIG. 7 , another
configuration is representatively illustrated. In this
configuration, the passage 42 is dimensioned so that the
plug 54 can be displaced out of the chamber 46. This
configuration may be useful in circumstances in which it is
desired to be able to restore flow through the chamber 46,
even after the plug 54 has been released. Flow through the
chamber 46 could be restored by using reverse flow through
the chamber to displace the plug 54 out of the chamber.
Referring additionally now to FIG. 8 , another
configuration is representatively illustrated in which the
flow control system 52 is used in conjunction with an inflow
control device 64. Instead of the variable flow resistance
system 25, the inflow control device 64 includes a fixed
flow restrictor 66 which restricts flow of the fluid
composition 36 into the tubular string 22.
The configuration of FIG. 8 operates in a manner
similar to that described above for the configurations of
FIGS. 5A-7. However, the chamber 46 is not necessarily a
"vortex" chamber. The structure 56 can release the plug 54
for sealing engagement with the seat 58 to prevent flow
through the chamber 46 when a particular undesired fluid is
flowed through the chamber, when an increased ratio of
undesired to desired fluids is in the fluid composition 36,
etc .
Referring additionally now to FIGS. 9A & B , another
configuration of the inflow control device 64 is
representatively illustrated. In this configuration, a
bypass passage 66 intersects the flow passage 42 upstream of
the chamber 46. The bypass passage 66 is used to bias the
fluid composition 36 to flow more toward another bypass
passage 68 (which bypasses the chamber 46) when the fluid
composition has a relatively high viscosity, low velocity
and/or a relatively high ratio of desired to undesired fluid
therein, or to flow more toward the chamber 46 when the
fluid composition has a relatively low viscosity, high
velocity and/or a relatively low ratio of desired to
undesired fluid therein.
In FIG. 9A, the fluid composition 36 has a relatively
high viscosity, low velocity and/or a relatively high ratio
of desired to undesired fluid therein. A significant
portion of the fluid composition 36 flows through the bypass
passage 66 and impinges on the fluid composition flowing
through the passage 42. This causes a substantial portion
(preferably a majority) of the fluid composition 36 to flow
through the bypass passage 68, and so relatively little of
the fluid composition flows through the chamber 46.
In FIG. 9B, the fluid composition 36 has a relatively
low viscosity, high velocity and/or a relatively low ratio
of desired to undesired fluid therein. Relatively little of
the fluid composition 36 flows through the bypass passage
66, and so the fluid composition is not biased significantly
to flow through the other bypass passage 68. As a result, a
substantial portion (preferably a majority) of the fluid
composition 36 flows through the chamber 46.
It will be appreciated that, with a substantial portion
of the fluid composition 36 flowing through the chamber 46,
the structure 56 will be more readily eroded or corroded by
the fluid composition. In this manner, the relatively low
viscosity, high velocity and/or a relatively low ratio of
desired to undesired fluid of the fluid composition 36 will
cause the structure 56 to degrade and release the plug 54,
thereby preventing flow through the outlet 40.
Although in the examples depicted in FIGS. 3A-9B, only
a single inlet 44 is used for admitting the fluid
composition 36 into the chamber 46, in other examples
multiple inlets could be provided, if desired. The fluid
composition 36 could flow into the chamber 46 via multiple
inlets 44 simultaneously or separately. For example,
different inlets 44 could be used for when the fluid
composition 36 has corresponding different characteristics
(such as different velocities, viscosities, etc.).
Referring additionally now to FIGS. 10A & B , another
configuration of the variable flow resistance system 25 is
representatively illustrated. The system 25 of FIGS. 10A &
B is similar in many respects to the systems of FIGS. 3A-4B,
but differs at least in that one or more structures 72 are
included in the chamber 46. As depicted in FIGS. 10A & B ,
the structure 72 may be considered as a single structure
having one or more breaks or openings 74 therein, or as
multiple structures separated by the breaks or openings.
Another difference in the configuration of FIGS. 10A &
B is that two inlets 76, 78 are provided for flowing the
fluid composition 36 into the chamber 46. When the fluid
composition 36 has an increased ratio of undesired to
desired fluids therein, an increased proportion of the fluid
composition flows into the chamber 46 via the inlet 76.
When the fluid composition 36 has a decreased ratio of
undesired to desired fluids therein, an increased proportion
of the fluid composition flows into the chamber 46 via the
inlet 78. A similar configuration of inlets to a vortex
chamber is described in US patent application serial no.
12/792146, filed on 2 June 2010, the entire disclosure of
which is incorporated herein by this reference.
The structure 72 induces any portion of the fluid
composition 36 which flows circularly about the chamber 46,
and has a relatively high velocity, high density or low
viscosity, to continue to flow circularly about the chamber,
but at least one of the openings 74 permits more direct flow
of the fluid composition from the inlet 78 to the outlet 40.
Thus, when the fluid composition 36 enters the other inlet
76, it initially flows circularly in the chamber 46 about
the outlet 40, and the structure 72 increasingly resists or
impedes a change in direction of the flow of the fluid
composition toward the outlet, as the velocity and/or
density of the fluid composition increases, and/or as a
viscosity of the fluid composition decreases. The openings
74, however, permit the fluid composition 36 to gradually
flow spirally inward to the outlet 40.
In FIG. 10A, a relatively high velocity, low viscosity
and/or high density fluid composition 36 enters the chamber
46 via the inlet 76. Some of the fluid composition 36 may
also enter the chamber 46 via the inlet 78, but in this
example, a substantial majority of the fluid composition
enters via the inlet 76, thereby flowing tangential to the
flow chamber 46 initially (i.e., at an angle of 0 degrees
relative to a tangent to the outer circumference of the flow
chamber) .
Upon entering the chamber 46, the fluid composition 36
initially flows circularly about the outlet 40. For most of
its path about the outlet 40, the fluid composition 36 is
prevented, or at least impeded, from changing direction and
flowing radially toward the outlet by the structure 72. The
openings 74 do, however, gradually allow portions of the
fluid composition 36 to spiral radially inward toward the
outlet 40.
In FIG. 10B, a relatively low velocity, high viscosity
and/or low density fluid composition 36 enters the chamber
46 via the inlet 78. Some of the fluid composition 36 may
also enter the chamber 46 via the inlet 76, but in this
example, a substantial majority of the fluid composition
enters via the inlet 78, thereby flowing radially through
the flow chamber 46 (i.e., at an angle of 90 degrees
relative to a tangent to the outer circumference of the flow
chamber) .
One of the openings 74 allows the fluid composition 36
to flow more directly from the inlet 78 to the outlet 40.
Thus, radial flow of the fluid composition 36 toward the
outlet 40 in this example is not resisted or impeded
significantly by the structure 72.
If a portion of the relatively low velocity, high
viscosity and/or low density fluid composition 36 should
flow circularly about the outlet 40 in FIG. 10B, the
openings 74 will allow the fluid composition to readily
change direction and flow more directly toward the outlet.
Indeed, as a viscosity of the fluid composition 36
increases, or as a velocity of the fluid composition
decreases, the structures 72 in this situation will
increasingly impede the circular flow of the fluid
composition 36 about the chamber 46, enabling the fluid
composition to more readily change direction and flow
through the openings 74.
Note that it is not necessary for multiple openings 74
to be provided in the structure 72, since the fluid
composition 36 could flow more directly from the inlet 78 to
the outlet 40 via a single opening, and a single opening
could also allow flow from the inlet 76 to gradually spiral
inwardly toward the outlet. Any number of openings 74 (or
other areas of low resistance to radial flow) could be
provided in keeping with the principles of this disclosure.
Furthermore, it is not necessary for one of the
openings 74 to be positioned directly between the inlet 78
and the outlet 40. The openings 74 in the structure 72 can
provide for more direct flow of the fluid composition 36
from the inlet 78 to the outlet 40, even if some circular
flow of the fluid composition about the structure is needed
for the fluid composition to flow inward through one of the
openings .
It will be appreciated that the more circuitous flow of
the fluid composition 36 in the FIG. 10A example results in
more energy being consumed at the same flow rate and,
therefore, more resistance to flow of the fluid composition
as compared to the example of FIG. 10B. 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. 10A & 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.
It will also be appreciated that the fluid composition
36 rotates more about the outlet 40 in the FIG. 10A example,
as compared to the FIG. 10B example. Thus, the support
structure 56 can more readily be eroded, corroded or
otherwise degraded by the flow of the fluid composition 36
in the FIG. 10A example (having an increased ratio of
undesired to desired fluids therein), as compared to the
FIG. 10B example (having a decreased ratio of undesired to
desired fluid in the fluid composition) .
Note that it is not necessary for the plug 54 to be
rigidly secured by the support structure 56 in any of the
configurations of the variable flow resistance system 25
described above. Instead, the support structure 56 could
somewhat loosely retain the plug 54 relative to the chamber
46. In such a situation, the loose retention of the plug 54
could allow it to displace (e.g., linearly, rotationally ,
etc.) somewhat in response to the flow of the fluid
composition 36 through the chamber 46.
In the configurations of FIGS. 3A-4B and 10A & B ,
increased rotational flow of the fluid composition 36 in the
chamber 46 due to an increased ratio of undesired to desired
fluid in the fluid composition could cause increased
rotational displacement of the plug 54 in response. Such
increased rotational displacement of the plug 54 can cause
increased fatigue, wear, erosion, etc., of the support
structure 56 and/or an interface between the plug and the
support structure, thereby causing an increased rate of
breakage or other degradation of the support structure.
In other examples (such as the example of FIGS. 9A &
B), increased vibration, oscillation, etc. of the plug 54
can cause increased fatigue, wear, erosion, etc., of the
support structure 56 and/or an interface between the plug
and the support structure, thereby causing an increased rate
of degradation of the support structure. Thus, an increased
ratio of undesired to desired fluids in the fluid
composition 36 can lead to quicker breakage or otherwise
degrading of the support structure 56.
Although various configurations of the variable flow
resistance system 25 and inflow control device 64 have been
described above, with each configuration having certain
features which are different from the other configurations,
it should be clearly understood that those features are not
mutually exclusive. Instead, any of the features of any of
the configurations of the system 25 and device 64 described
above may be used with any of the other configurations.
It may now be fully appreciated that the above
disclosure provides a number of advancements to the art of
controlling fluid flow in a well. The flow control system
52 can operate automatically, without human intervention
required, to shut off flow of a fluid composition 36 having
relatively low viscosity, high velocity and/or a relatively
low ratio of desired to undesired fluid. These advantages
are obtained, even though the system 52 is relatively
straightforward in design, easily and economically
constructed, and robust in operation.
The above disclosure provides to the art a flow control
system 52 for use in a subterranean well. The system 52 can
include a flow chamber 46 through which a fluid composition
36 flows, and a plug 54 which is released in response to an
increase in a ratio of undesired fluid to desired fluid in
the fluid composition 36.
The plug 54 can be released automatically in response
to the increase in the ratio of undesired to desired fluid.
The increase in the ratio of undesired to desired fluid may
cause degradation, breakage, erosion and/or corrosion of a
structure 56 which supports the plug 54.
The plug 54, when released, may prevent flow through
the flow chamber 46, or prevent flow from an inlet 38 to an
outlet 40 of the flow chamber 46.
The increase in the ratio of undesired to desired fluid
in the fluid composition 36 can result from an increase in
water or gas in the fluid composition 36.
The increase in the ratio of undesired to desired fluid
in the fluid composition 36 can result in an increase in a
velocity of the fluid composition 36 in the flow chamber 46.
Also described above is a flow control system 52 which
includes a flow chamber 46 through which a fluid composition
36 flows, a plug 54, and a structure 56 which supports the
plug 54, but which releases the plug 54 in response to
degrading of the structure 56 by the fluid composition 36.
The structure 56 may be degraded in response to an
increase in a ratio of undesired fluid to desired fluid in
the fluid composition 36.
The plug 54 may be released automatically in response
to the degrading of the structure 56.
An increase in a ratio of undesired fluid to desired
fluid in the fluid composition 36 can cause degradation,
breakage, erosion and/or corrosion of the structure 56.
The plug 54, when released, may prevent flow from an
outlet 40 of the flow chamber 46.
The degrading of the structure 56 may result from an
increase in water in the fluid composition 36 and/or from an
increase in a velocity of the fluid composition 36 in the
flow chamber 46.
Another flow control system 52 described above can
include a flow chamber 46 through which a fluid composition
36 flows, and a plug 54 which is released in response to an
increase in a velocity of the fluid composition 36 in the
flow chamber 46.
The plug 54 can be released automatically in response
to the increase in the velocity of the fluid composition 36.
The increase in velocity of the fluid composition 36 may
cause degradation, breakage, erosion and/or corrosion of a
structure 56 which supports the plug 54.
The increase in velocity of the fluid composition 36
may result from an increase in water and/or gas in the fluid
composition 36, and/or from an increase in a ratio of
undesired fluid to desired fluid in the fluid composition
36.
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 flow control system for use in a subterranean
well, the system comprising:
a flow chamber through which a fluid composition flows;
and
a plug which is released in response to an increase in
a ratio of undesired fluid to desired fluid in the fluid
composition .
2 . The system of claim 1 , wherein the plug is
released automatically in response to the increase in the
ratio of undesired to desired fluid.
3 . The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid causes degradation of a
structure which supports the plug.
4 . The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid causes corrosion of a
structure which supports the plug.
5 . The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid causes erosion of a
structure which supports the plug.
6 . The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid causes breakage of a
structure which supports the plug.
7 . The system of claim 1 , wherein the plug, when
released, prevents flow through the flow chamber.
8 . The system of claim 1 , wherein the plug, when
released, prevents flow from an inlet to an outlet of the
flow chamber.
9 . The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid in the fluid composition
results from an increase in water in the fluid composition.
10. The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid in the fluid composition
results in an increase in a velocity of the fluid
composition in the flow chamber.
11. The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid in the fluid composition
results from an increase in gas in the fluid composition.
12. A flow control system for use in a subterranean
well, the system comprising:
a flow chamber through which a fluid composition flows;
a plug; and
a structure which supports the plug, but which releases
the plug in response to degrading of the structure by the
fluid composition.
13. The system of claim 12, wherein the structure is
degraded in response to an increase in a ratio of undesired
fluid to desired fluid in the fluid composition.
14. The system of claim 12, wherein the plug is
released automatically in response to the degrading of the
structure .
15. The system of claim 12, wherein an increase in a
ratio of undesired fluid to desired fluid in the fluid
composition causes erosion of the structure.
16. The system of claim 12, wherein an increase in a
ratio of undesired fluid to desired fluid in the fluid
composition causes corrosion of the structure.
17. The system of claim 12, wherein an increase in a
ratio of undesired fluid to desired fluid in the fluid
composition causes breakage of the structure.
18. The system of claim 12, wherein the plug, when
released, prevents flow through the flow chamber.
19. The system of claim 12, wherein the plug, when
released, prevents flow from an outlet of the flow chamber.
20. The system of claim 12, wherein the degrading of
the structure results from an increase in water in the fluid
composition .
21. The system of claim 12, wherein the degrading of
the structure results from an increase in a velocity of the
fluid composition in the flow chamber.
22. The system of claim 12, wherein the degrading of
the structure results from an increase in gas in the fluid
composition .
23. A flow control system for use in a subterranean
well, the system comprising:
a flow chamber through which a fluid composition flows;
and
a plug which is released in response to an increase in
a velocity of the fluid composition in the flow chamber.
24. The system of claim 23, wherein the plug is
released automatically in response to the increase in the
velocity of the fluid composition.
25. The system of claim 23, wherein the increase in
velocity of the fluid composition causes erosion of a
structure which supports the plug.
26. The system of claim 23, wherein the increase in
velocity of the fluid composition causes corrosion of a
structure which supports the plug.
27. The system of claim 23, wherein the increase in
velocity of the fluid composition causes breakage of a
structure which supports the plug.
28. The system of claim 23, wherein the increase in
velocity of the fluid composition causes degradation of a
structure which supports the plug.
29. The system o f claim 23, wherein the plug, when
released, prevents flow through the flow chamber.
30. The system o f claim 23, wherein the plug, when
released, prevents flow from an inlet to an outlet o f the
flow chamber.
31. The system o f claim 23, wherein the increase in
velocity o f the fluid composition results from an increase
in water in the fluid composition.
32. The system o f claim 23, wherein the increase
the velocity o f the fluid composition results from an
increase in a ratio o f undesired fluid to desired fluid
the fluid composition.
33. The system o f claim 23, wherein the increase in
velocity o f the fluid composition results from an increase
in gas in the fluid composition.