PREVENTING FLOW OF UNDESIRED FLUID THROUGH A
VARIABLE FLOW RESISTANCE SYSTEM IN A 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 for preventing flow of undesired fluid through a
variable flow resistance system.
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 in
which flow through the variable flow resistance system is
completely prevented when an unacceptable level of undesired
fluid is flowed through the system.
In one aspect, a flow control system for use with a
subterranean well can include a flow chamber through which a
fluid composition flows, and a closure device which is
biased toward a closed position in which the closure device
prevents flow through the flow chamber. The closure device
can be displaced to the closed position 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 can include a
closure device and a structure which prevents the closure
device from being displaced to a closed position in which
the closure device prevents flow through the flow chamber.
The fluid composition can flow through the structure to an
outlet of 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 representative partially cross-sectional
view of a well system which can embody principles of this
disclosure .
FIG. 2 is an enlarged scale representative crosssectional
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 representative "unrolled" plan views
of one configuration of the variable flow resistance system,
taken along line 3-3 of FIG. 2 .
FIGS. 4A & B are representative plan views of another
configuration of the variable flow resistance system.
FIG. 5 is a representative cross-sectional view of a
well screen and a flow control system which may be used in
the well system of FIG. 1 .
FIG. 6 is a representative cross-sectional view of
another example of the flow control system.
FIG. 7 is a representative perspective view of another
example of the flow control 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.), 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, visco-plasticity ,
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 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 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 dissipates 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 dissipates 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 FIG. 5 , another
configuration is representatively illustrated in which a
flow control system 52 is used with the variable flow
resistance system 25. The control system 52 includes certain
elements of the variable flow resistance system 25 (such as,
the flow chamber 46, outlet 40, etc.), along with a closure
device 54 and a structure 56, to prevent flow into the
tubular string 22 when an unacceptable level of undesired
fluid has been flowed through the system.
The structure 56 supports the closure device 54 away
from the outlet 40, until sufficient undesired fluid has
been flowed through the chamber 46 to degrade the structure.
In additional examples described below, the structure 56
resists a biasing force applied to the closure device 54,
with the biasing force biasing the closure device toward the
outlet 40.
The closure device 54 depicted in FIG. 5 has a
cylindrical shape, and is somewhat larger in diameter than
the outlet 40, so that when the closure device is released,
it will cover and prevent flow through the outlet. However,
other types of closure devices (e.g., flappers, etc.) may be
used in keeping with the scope of this disclosure.
The closure device 54 may be provided with a seal or
sealing surface for sealingly engaging a sealing surface
(e.g., a seat) about the outlet 40. Any manner of sealing
with the closure device 54 may be used, in keeping with the
scope of this disclosure.
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.
The structure 56 can degrade (e.g., erode, corrode,
break, dissolve, disintegrate, etc.) more rapidly when the
fluid composition 36 flows circuitously through the chamber
46. Thus, the structure 56 could degrade more rapidly in the
relatively high velocity and/or low viscosity situation
depicted in FIG. 3A, or in the relatively high viscosity
and/or low velocity situation depicted in FIG. 4A.
However, note that the chamber 46 is not necessarily a
"vortex" chamber. In some examples, the structure 56 can
release the closure device 54 for displacement to its closed
position when a particular undesired fluid is flowed through
the chamber 46, when an increased ratio of undesired to
desired fluids is in the fluid composition 36, etc., whether
or not the fluid composition 36 flows circuitously through
the chamber.
Note that, as depicted in FIG. 5 , the structure 56
encircles the outlet 40, and the fluid composition 36 flows
through the structure to the outlet. Openings 58 in the wall
of the generally tubular structure 56 are provided for this
purpose. In other examples, the fluid composition 36 may not
flow through the structure 56, or the fluid composition may
flow otherwise through the structure (e.g., via grooves or
slots in the structure, the structure could be porous,
etc .).
Referring additionally now to FIG. 6 , another example
of the flow control device 52 is representatively
illustrated at an enlarged scale. In this example, a biasing
device 60 (such as a coil spring, Belleville washers, shape
memory element, etc.) biases the closure device 54 toward
its closed position.
The structure 56 is interposed between the closure
device 54 and a wall of the chamber 46, thereby preventing
the closure device from displacing to its closed position.
However, when the structure 56 is sufficiently degraded
(e.g., in response to a ratio of undesired to desired fluids
being sufficiently large, in response to a sufficient volume
of undesired fluid being flowed through the system, etc.),
the structure will no longer be able to resist the biasing
force exerted by the biasing device, and the closure device
54 will be permitted to displace to its closed position,
thereby preventing flow through the chamber 46.
Referring additionally now to FIG. 7 , another example
of the flow control system 52 is representatively
illustrated in perspective view, with an upper wall of the
chamber 46 removed for viewing the interior of the chamber.
In this example, the biasing device 60 encircles an upper
portion of the closure device 54 .
The structure 56 prevents the closure device 54 from
displacing to its closed position. The biasing device 60
exerts a biasing force on the closure device 54 , biasing the
closure device toward the closed position, but the biasing
force is resisted by the structure 56 , until the structure
is sufficiently degraded.
Although in the examples depicted in FIGS. 3A-7 , 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.).
Although various configurations of the variable flow
resistance system 25 and flow control system 52 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 systems 25 , 52 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 5 2 is relatively
straightforward in design, easily and economically
constructed, and robust in operation.
The above disclosure provides to the art a flow control
system 5 2 for use with a subterranean well. In one example,
the system 5 2 can include a flow chamber 4 6 through which a
fluid composition 3 6 flows, and a closure device 5 4 which is
biased toward a closed position in which the closure device
5 4 prevents flow through the flow chamber 4 6 . The closure
device 5 4 can be displaced to the closed position in
response to an increase in a ratio of undesired fluid to
desired fluid in the fluid composition 3 6 .
A biasing device 6 0 may bias the closure device 5 4
toward the closed position.
The closure device 5 4 may displace 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 of a structure 5 6 which resists
displacement of the closure device 5 4 .
The fluid composition 3 6 may flow through the structure
5 6 to an outlet 4 0 of the flow chamber 4 6 .
The structure 5 6 may encircle an outlet 4 0 of the flow
chamber 4 6 .
The increase in the ratio of undesired to desired fluid
may cause corrosion, erosion and/or breakage of the
structure 5 6 .
The closure device 5 6 , when released, can prevent flow
to an outlet 4 0 of the flow chamber 4 6 .
The increase in the ratio of undesired to desired fluid
in the fluid composition 36 may 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 may 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
example in which a structure 56 prevents a closure device 54
from being displaced to a closed position in which the
closure device 54 prevents flow of a fluid composition 36
through a flow chamber 46, and in which the fluid
composition 36 flows through the structure 56 to an outlet
40 of the flow chamber 46.
Although various examples have been described above,
with each example having certain features, it should be
understood that it is not necessary for a particular feature
of one example to be used exclusively with that example.
Instead, any of the features described above and/or depicted
in the drawings can be combined with any of the examples, in
addition to or in substitution for any of the other features
of those examples. One example's features are not mutually
exclusive to another example's features. Instead, the scope
of this disclosure encompasses any combination of any of the
features .
Although each example described above includes a
certain combination of features, it should be understood
that it is not necessary for all features of an example to
be used. Instead, any of the features described above can be
used, without any other particular feature or features also
being used.
It should be understood that the various embodiments
described herein may be utilized in various orientations,
such as inclined, inverted, horizontal, vertical, etc., and
in various configurations, without departing from the
principles of this disclosure. The embodiments are described
merely as examples of useful applications of the principles
of the disclosure, which is not limited to any specific
details of these embodiments.
In the above description of the representative
examples, directional terms (such as "above," "below,"
"upper," "lower," etc.) are used for convenience in
referring to the accompanying drawings. However, it should
be clearly understood that the scope of this disclosure is
not limited to any particular directions described herein.
The terms "including," "includes," "comprising,"
"comprises," and similar terms are used in a non-limiting
sense in this specification. For example, if a system,
method, apparatus, device, etc., is described as "including"
a certain feature or element, the system, method, apparatus,
device, etc., can include that feature or element, and can
also include other features or elements. Similarly, the term
"comprises" is considered to mean "comprises, but is not
limited to."
Of course, a person skilled in the art would, upon a
careful consideration of the above description of
representative embodiments of the disclosure, readily
appreciate that many modifications, additions,
substitutions, deletions, and other changes may be made to
the specific embodiments, and such changes are contemplated
by the principles of this disclosure. Accordingly, the
foregoing detailed description is to be clearly understood
as being given by way of illustration and example only, the
spirit and scope of the invention being limited solely by
the appended claims and their equivalents.
WHAT IS CLAIMED IS:
1 . A flow control system for use with a subterranean
well, the system comprising:
a flow chamber through which a fluid composition flows;
and
a closure device which is biased toward a closed
position in which the closure device prevents flow through
the flow chamber, the closure device being displaced to the
closed position 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 a biasing device
biases the closure device toward the closed position.
3 . The system of claim 1 , wherein the closure device
displaces automatically in response to the increase in the
ratio of undesired to desired fluid.
4 . The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid causes degradation of a
structure which resists displacement of the closure device.
5 . The system of claim 4 , wherein the fluid
composition flows through the structure to an outlet of the
flow chamber.
6 . The system of claim 4 , wherein the structure
encircles an outlet of the flow chamber.
7 . The system of claim 4 , wherein the increase in the
ratio of undesired to desired fluid causes corrosion of the
structure .
8 . The system of claim 4 , wherein the increase in the
ratio of undesired to desired fluid causes erosion of the
structure .
9 . The system of claim 1 , wherein the increase in the
ratio of undesired to desired fluid causes breakage of the
structure .
10. The system of claim 1 , wherein the closure device,
when released, prevents flow to an outlet of 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 water in the fluid composition.
12. 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.
13. 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.
14. A flow control system for use in a subterranean
well, the system comprising:
a flow chamber through which a fluid composition flows;
a closure device; and
a structure which prevents the closure device from
being displaced to a closed position in which the closure
device prevents flow through the flow chamber, and
wherein the fluid composition flows through the
structure to an outlet of the flow chamber.
15. The system of claim 14, wherein the closure device
displaces to the closed position in response to degradation
of the structure by the fluid composition.
16. The system of claim 14, wherein the structure is
degraded in response to an increase in a ratio of undesired
fluid to desired fluid in the fluid composition.
17. The system of claim 14, wherein the closure device
is released automatically in response to the degrading of
the structure.
18. The system of claim 14, wherein an increase in a
ratio of undesired fluid to desired fluid in the fluid
composition causes erosion of the structure.
19. The system of claim 14, wherein an increase in a
ratio of undesired fluid to desired fluid in the fluid
composition causes corrosion of the structure.
20. The system of claim 14, wherein an increase
ratio of undesired fluid to desired fluid in the fluid
composition causes breakage of the structure.
21. The system of claim 14, further comprising a
biasing device which biases the closure device toward the
closed position.
22. The system of claim 14, wherein the degrading of
the structure results from an increase in water in the fluid
composition .
23. The system of claim 14, wherein the degrading of
the structure results from an increase in a velocity of the
fluid composition in the flow chamber .
24. The system of claim 14, wherein the degrading of
the structure results from an increase in gas in the fluid
composition .
25. The system of claim 14, wherein the structure
encircles the outlet.