TITLE:
AUTONOMOUS FLUID CONTROL DEVICE HAVING A RECIPROCATING
VALVE FOR DOWNHOLE FLUID SELECTION
Inventors: Stephen Greci
Citizenship: USA
Residence:
4416 San Mateo Lane
McKinney, Texas 75070
CROSS-REFERENCE TO RELATED APPLICATIONS
None.
FIELD OF INVENTION
[0001] The invention relates generally to methods and apparatus for selective
control of fluid flow from a formation in a hydrocarbon bearing subterranean formation
into a production string in a wellbore. More particularly, the invention relates to methods
and apparatus for controlling the flow of fluid based on some characteristic of the fluid
flow, such as viscosity, by utilizing a reciprocating member, such as a hollow-bore piston
having a screen covering or choke at one end of the bore, the reciprocating member
moved to an open position by the force of a flowing fluid depending on a characteristic of
the fluid, for example, by the force of a relatively higher viscosity fluid.
BACKGROUND OF INVENTION
[0002] During the completion of a well that traverses a hydrocarbon bearing
subterranean formation, production tubing and various equipment are installed in the well
to enable safe and efficient production of the fluids. For example, to prevent the
production of particulate material from an unconsolidated or loosely consolidated
subterranean formation, certain completions include one or more sand control screens
positioned proximate the desired production intervals. In other completions, to control the
flow rate of production fluids into the production tubing, it is common practice to install
one or more inflow control devices with the completion string.
[0003] Production from any given production tubing section can often have
multiple fluid components, such as natural gas, oil and water, with the production fluid
changing in proportional composition over time. Thereby, as the proportion of fluid
components changes, the fluid flow characteristics will likewise change. For example,
when the production fluid has a proportionately higher amount of natural gas, the
viscosity of the fluid will be lower and density of the fluid will be lower than when the
fluid has a proportionately higher amount of oil. It is often desirable to reduce or prevent
the production of one constituent in favor of another. For example, in an oil-producing
well, it may be desired to reduce or eliminate natural gas production and to maximize oil
production. While various downhole tools have been utilized for controlling the flow of
fluids based on their desirability, a need has arisen for a flow control system for
controlling the inflow of fluids that is reliable in a variety of flow conditions. Further, a
need has arisen for a flow control system that operates autonomously, that is, in response
to changing conditions downhole and without requiring signals from the surface by the
operator. Similar issues arise with regard to injection situations, with flow of fluids going
into instead of out of the formation.
SUMMARY OF THE INVENTION
[0004] The invention presents an apparatus and method for autonomously
controlling flow of fluid in a subterranean well, wherein a fluid characteristic of the fluid
flow changes over time. In one embodiment, an autonomous reciprocating member has a
fluid flow passageway there through and a primary outlet and at least one secondary
outlet. A flow restrictor, such as a choke or screen, is positioned to restrict, for example, a
relatively higher viscosity fluid flow through the primary outlet of the reciprocating
member. A vortex chamber having a primary inlet and at least one secondary inlet is
adjacent the reciprocating member. The reciprocating member moves between a first
position wherein fluid flow is directed primarily through the primary outlet of the
reciprocating member and into the primary inlet of the vortex assembly, and a second
position wherein fluid flow is directed primarily through the at least one secondary outlet
of the reciprocating member and into the at least one secondary inlet of the vortex
assembly.
[0005] The reciprocating member moves in response to changes in the fluid
characteristic. For example, when the fluid is of relatively low viscosity, it flows through
the reciprocating member passageway, the reciprocating member primary outlet and
restrictor relatively freely. In the first position, the secondary outlets of the reciprocating
member are substantially blocked. As the fluid changes to a higher viscosity, fluid flow is
restricted by the restrictor and the reciprocating member is moved to the second position
by the resulting pressure. In the second position, the secondary outlets of the
reciprocating member are no longer blocked and fluid now flows relatively freely through
them.
[0006] The movement of the reciprocating member alters the fluid flow pattern
in the adjacent vortex chamber. In the first position, when fluid flows primarily through
the primary outlet, the fluid is directed tangentially into the vortex, causing spiraling
flow, increased fluid velocity and a greater pressure drop across the vortex. In the second
position, fluid flow is directed such that the resulting fluid flow in the vortex is primarily
radial, the velocity is reduced and the pressure drop across the vortex is reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] For a more complete understanding of the features and advantages of the
present invention, reference is now made to the detailed description of the invention
along with the accompanying figures in which corresponding numerals in the different
figures refer to corresponding parts and in which:
[0008] Figure 1 is a schematic illustration of a well system including a plurality
of autonomous fluid flow control systems according to an embodiment of the invention;
[0009] Figure 2 is a top view schematic of an autonomous fluid flow control
device utilizing a vortex assembly and autonomously reciprocating assembly embodying
principles of the present invention;
[0010] Figure 3 is a detail view of an embodiment of the reciprocating assembly
in a first position embodying principles of the present invention;
[0010] Figure 4 is a top view schematic of an alternate embodiment of the
invention; and
[0012] Figure 5 is a top view schematic of an alternate embodiment of the
invention.
[0013] It should be understood by those skilled in the art that the use of
directional terms such as above, below, upper, lower, upward, downward and the like are
used in relation to the illustrative embodiments as they are depicted in the figures, the
upward direction being toward the top of the corresponding figure and the downward
direction being toward the bottom of the corresponding figure. Where this is not the case
and a term is being used to indicate a required orientation, the Specification will state or
make such clear. Upstream and downstream are used to indicate location or direction in
relation to the surface, where upstream indicates relative position or movement towards
the surface along the wellbore and downstream indicates relative position or movement
further away from the surface along the wellbore.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0014] While the making and using of various embodiments of the present
invention are discussed in detail below, a practitioner of the art will appreciate that the
present invention provides applicable inventive concepts which can be embodied in a
variety of specific contexts. The specific embodiments discussed herein are illustrative of
specific ways to make and use the invention and do not limit the scope of the present
invention.
[0015] Descriptions of fluid flow control using autonomous flow control devices
and their application can be found in the following U.S. Patents and Patent Applications,
each of which are hereby incorporated herein in their entirety for all purposes: U.S.
Patent No. 7,404,416, entitled "Apparatus and Method For Creating Pulsating Fluid
Flow, And Method of Manufacture For the Apparatus," to Schultz, filed 3/25/2004; U.S.
Patent No. 6,976,507, entitled "Apparatus for Creating Pulsating Fluid Flow," to Webb,
filed 2/8/2005; U.S. Patent Application Serial No. 12/635612, entitled "Fluid Flow
Control Device," to Schultz, filed 12/10/2009; U.S. Patent Application Serial No.
12/770568, entitled "Method and Apparatus for Controlling Fluid Flow Using Movable
Flow Diverter Assembly," to Dykstra, filed 4/29/2010; U.S. Patent Application Serial No.
12/700685, entitled "Method and Apparatus for Autonomous Downhole Fluid Selection
With Pathway Dependent Resistance System," to Dykstra, filed 2/4/2010; U.S. Patent
Application Serial No. 12/750476, entitled "Tubular Embedded Nozzle Assembly for
Controlling the Flow Rate of Fluids Downhole," to Syed, filed 3/30/2010; U.S. Patent
Application Serial No. 12/791993, entitled "Flow Path Control Based on Fluid
Characteristics to Thereby Variably Resist Flow in a Subterranean Well," to Dykstra,
filed 6/2/2010; U.S. Patent Application Serial No. 12/792095, entitled "Alternating Flow
Resistance Increases and Decreases for Propagating Pressure Pulses in a Subterranean
Well," to Fripp, filed 6/2/2010; U.S. Patent Application Serial No. 12/7921 17, entitled
"Variable Flow Resistance System for Use in a Subterranean Well," to Fripp, filed
6/2/2010; U.S. Patent Application Serial No. 12/792146, entitled "Variable Flow
Resistance System With Circulation Inducing Structure Therein to Variably Resist Flow
in a Subterranean Well," to Dykstra, filed 6/2/2010; U.S. Patent Application Serial No.
12/879846, entitled "Series Configured Variable Flow Restrictors For Use In A
Subterranean Well," to Dykstra, filed 9/10/2010; U.S. Patent Application Serial No.
12/869836, entitled "Variable Flow Restrictor For Use In A Subterranean Well," to
Holderman, filed 8/27/2010; U.S. Patent Application Serial No. 12/958625, entitled "A
Device For Directing The Flow Of A Fluid Using A Pressure Switch," to Dykstra, filed
12/2/2010; U.S. Patent Application Serial No. 12/974212, entitled "An Exit Assembly
With a Fluid Director for Inducing and Impeding Rotational Flow of a Fluid," to Dykstra,
filed 12/21/2010; U.S. Patent Application Serial No. 12/983144, entitled "Cross-Flow
Fluidic Oscillators for use with a Subterranean Well ," to Schultz, filed 12/31/2010; U.S.
Patent Application Serial No. 12/966772, entitled "Downhole Fluid Flow Control System
and Method Having Direction Dependent Flow Resistance," to Jean-Marc Lopez, filed
12/13/2010; U.S. Patent Application Serial No. 12/983153, entitled "Fluidic Oscillators
For Use With A Subterranean Well (includes vortex)," to Schultz, filed 12/31/2010; U.S.
Patent Application Serial No. 13/084025, entitled "Active Control for the Autonomous
Valve," to Fripp, filed 4/1 1/201 1; U.S. Patent Application Serial No. 61/473,700, entitled
"Moving Fluid Selectors for the Autonomous Valve," to Fripp, filed 4/8/201 1; U.S.
Patent Application Serial No. 61/473,699, entitled "Sticky Switch for the Autonomous
Valve," to Fripp, filed 4/8/201 1; and U.S. Patent Application Serial No. 13/100006,
entitled "Centrifugal Fluid Separator," to Fripp, filed 5/3/201 1.
[0016] Figure 1 is a schematic illustration of a well system, indicated generally
10, including a plurality of autonomous flow control systems embodying principles of the
present invention. A wellbore 12 extends through various earth strata. Wellbore 12 has a
substantially vertical section 14, the upper portion of which has installed therein a casing
string 16. Wellbore 12 also has a substantially deviated section 18, shown as horizontal,
which extends through a hydrocarbon-bearing subterranean formation 20. As illustrated,
substantially horizontal section 18 of wellbore 12 is open hole. While shown here in an
open hole, horizontal section of a wellbore, the invention will work in any orientation,
and in open or cased hole. The invention will also work equally well with injection
systems, as will be discussed supra.
[0017] Positioned within wellbore 12 and extending from the surface is a tubing
string 22. Tubing string 22 provides a conduit for fluids to travel from formation 20
upstream to the surface. Positioned within tubing string 22 in the various production
intervals adjacent to formation 20 are a plurality of autonomous flow control systems 25
and a plurality of production tubing sections 24. At either end of each production tubing
section 24 is a packer 26 that provides a fluid seal between tubing string 22 and the wall
of wellbore 12. The space in-between each pair of adjacent packers 26 defines a
production interval.
[0018] In the illustrated embodiment, each of the production tubing sections 24
includes sand control capability. Sand control screen elements or filter media associated
with production tubing sections 24 are designed to allow fluids to flow therethrough but
prevent particulate matter of sufficient size from flowing therethrough. While the
invention does not need to have a sand control screen associated with it, if one is used,
then the exact design of the screen element associated with fluid flow control systems is
not critical to the present invention. There are many designs for sand control screens that
are well known in the industry, and will not be discussed here in detail. Also, a protective
outer shroud having a plurality of perforations therethrough may be positioned around the
exterior of any such filter medium.
[0019] Through use of the flow control systems 25 of the present invention in
one or more production intervals, some control over the volume and composition of the
produced fluids is enabled. For example, in an oil production operation if an undesired
fluid component, such as water, steam, carbon dioxide, or natural gas, is entering one of
the production intervals, the flow control system in that interval will autonomously
restrict or resist production of fluid from that interval.
[0020] The term "natural gas" or "gas" as used herein means a mixture of
hydrocarbons (and varying quantities of non-hydrocarbons) that exist in a gaseous phase
at room temperature and pressure. The term does not indicate that the natural gas is in a
gaseous phase at the downhole location of the inventive systems. Indeed, it is to be
understood that the flow control system is for use in locations where the pressure and
temperature are such that natural gas will be in a mostly liquefied state, though other
components may be present and some components may be in a gaseous state. The
inventive concept will work with liquids or gases or when both are present.
[0021] The fluid flowing into the production tubing section 24 typically
comprises more than one fluid component. Typical components are natural gas, oil,
water, steam or carbon dioxide. Steam and carbon dioxide are commonly used as
injection fluids to drive the hydrocarbon towards the production tubular, whereas natural
gas, oil and water are typically found in situ in the formation. The proportion of these
components in the fluid flowing into each production tubing section 24 will vary over
time and based on conditions within the formation and wellbore. Likewise, the
composition of the fluid flowing into the various production tubing sections throughout
the length of the entire production string can vary significantly from section to section.
The flow control system is designed to reduce or restrict production from any particular
interval when it has a higher proportion of an undesired component.
[0022) Accordingly, when a production interval corresponding to a particular
one of the flow control systems produces a greater proportion of an undesired fluid
component, the flow control system in that interval will restrict or resist production flow
from that interval. Thus, the other production intervals which are producing a greater
proportion of desired fluid component, in this case oil, will contribute more to the
production stream entering tubing string 22. In particular, the flow rate from formation 20
to tubing string 22 will be less where the fluid must flow through a flow control system
(rather than simply flowing into the tubing string). Stated another way, the flow control
system creates a flow restriction on the fluid.
[0023] Though Figure 1 depicts one flow control system in each production
interval, it should be understood that any number of systems of the present invention can
be deployed within a production interval without departing from the principles of the
present invention. Likewise, the inventive flow control systems do not have to be
associated with every production interval. They may only be present in some of the
production intervals in the wellbore or may be in the tubing passageway to address
multiple production intervals.
[0024] Figure 2 is a top plan view of a fluid control device 30 according to an
embodiment of the invention showing fluid flow paths there through. The fluid control
device 30 has a reciprocating assembly 40 for directing fluid flow into a fluid flow
system 80.
[0025] A preferred embodiment of the fluid flow chamber 80 is seen in Figure 2.
The chamber is a vortex chamber 82, having a peripheral wall 84, a top surface (not
shown), and a bottom surface 86 sloped to induce a rotational or spiral flow. Fluid flows
through the vortex outlet 88, typically located proximate the center of the bottom surface
86. The fluid flow system 80 can include additional features. For example, directional
elements 90 can be added, such as vanes, grooves, etc. In the embodiment seen in Figure
2, the fluid flow system has multiple inlets, namely, a primary inlet 92, and two
secondary inlets 94. The inlets can be passageways, as shown.
[0026] Primary inlet 92 directs fluid flow into the vortex chamber 82 to induce
spiral or centrifugal flow in the chamber. In a preferred embodiment, the primary inlet 92
directs flow into the vortex chamber tangentially to increase such flow. Consequently,
there is a greater pressure drop across the chamber (from the chamber inlets to the
chamber outlet). Fluid flow along the primary inlet 92 and through the vortex chamber 82
is seen in Figure 2 as solid arrows for ease of reference.
[0027] The secondary inlets 94, conversely, are designed to direct fluid into the
vortex chamber 82 to inhibit, or result in relatively less spiral or centrifugal flow. In the
embodiment shown in Figure 2, the secondary inlets 94 direct flow into the vortex
chamber 82 in opposing flow paths, such that the flows tend to interfere or "cancel each
other out" and inhibit centrifugal flow. Instead, the fluid directed through the secondary
inlets 94 flows through the vortex outlet 88 with no or minimal spiraling. Preferably, the
fluid flow from the secondary inlets 94 flows radially through the vortex chamber 82.
Flow directed through the secondary inlets 94 produces a relatively lower pressure drop
across the chamber. Fluid flow along the secondary inlets 94 and then through the vortex
chamber 82 are shown ion dashed arrows for ease of reference.
[0028] The reciprocating assembly 40 is shown in a preferred embodiment in
Figures 2-4. Figure 3 is a detailed view of the reciprocating assembly in a first position
wherein fluid flow is directed into the fluid flow chamber to create a relatively higher
pressure drop across the chamber. For example, in a vortex chamber as shown, when the
reciprocating assembly is in the first position, fluid is directed into the vortex chamber 82
through the primary inlet 92, preferably tangentially, to create a centrifugal flow about
the chamber as indicated by the solid arrows. Figure 4 is a detailed view of the
reciprocating assembly in a second position, wherein fluid flow is directed into the fluid
flow chamber 82 to create a relatively low pressure drop across the chamber. For
example, in a vortex chamber as shown, when the reciprocating assembly is in the second
position, fluid is directed into the vortex chamber 82 through the secondary inlets 94 to
inhibit spiral or centrifugal flow through the chamber. Such flow preferably induces
radial flow through the chamber 82, as indicated by the dashed arrows.
[0029] In the preferred embodiment seen in Figure 2-4, the reciprocating
assembly 40 includes a reciprocating member 42, such as piston 44. The piston 44
defines a reciprocating member passageway 46, such as the hollow-bore shown. The
piston 44 reciprocates within cylinder 48. The piston 44 is biased towards the first
position, as shown in Figures 2 and 3, by a biasing member 50, such as a spring. Other
biasing mechanisms are known in the art. Seals 52 can be provided to prevent or reduce
flow around the piston and can be mounted in the cylinder walls, as shown, or on the
piston periphery. The reciprocating member 42 moves to a second position, such as when
piston 44 is in the position seen in Figure 4.
[0030] The reciprocating member 42 defines at least one fluid flow passageway
46 there through. In the preferred embodiment the passageway 46 is a hollow-bore
passageway through the piston. Fluid flow enters the reciprocating member passageway
and flows toward the fluid flow system 80. The hollow-bore passageway 46 leads to
multiple outlets. The primary outlet 54 has a flow restrictor 56 positioned to restrict fluid
flow through the primary outlet. The flow restrictor 56 can be a choke, a screen, or other
mechanism, as is known in the art. The flow restrictor is shown positioned over the end
of the primary outlet but can be positioned elsewhere, such as within the outlet
passageway. The flow restrictor 56 is designed to allow fluid flow there through when the
fluid is of a relatively low viscosity, such as water or natural gas. The flow restrictor 56
restricts or prevents flow there through when the fluid is of relatively higher viscosity,
such as oil, for example. In the first position, flow through secondary outlets 58 is
restricted or prevented. For example, in the embodiment shown, flow through the
secondary outlets 58 is restricted by the wall of the cylinder 48. Figure 3 shows the fluid
"F" flowing into the reciprocating member passageway and through the primary outlet 54
and restrictor 56.
[0031] In Figure 4, the reciprocating member is in the second position. The
piston 44 has moved along the cylinder 48, compressing the biasing member 50. Fluid
flow is now allowed along secondary outlets 58. As can be seen, fluid F flowing through
the piston 44 is now directed through the secondary outlets 58 and into the secondary
inlets 94 of the fluid flow system 80.
[0032] Movement of the reciprocating member 42 is autonomous and dependent
on a characteristic of the fluid flowing there through, which is expected to vary over time
during use. In the preferred embodiment shown, when the fluid is of a low viscosity, it
simply flows through the reciprocating member with relatively little resistance provided
by the restrictor and the reciprocating member remains in the first position. When the
characteristic of the fluid changes, for example to a higher viscosity, the restrictor 56
restricts fluid flow, raising fluid pressure behind the restrictor, and resulting in movement
of the reciprocating member to the second position. In the second position, fluid flows
primarily through secondary outlets, such as secondary outlets 58. Although some fluid
may flow through the restrictor 56 and through inlet 92 of the vortex assembly, fluid flow
is such that it will not induce significant (or any) centrifugal or spiraling flow in the
chamber. In a preferred embodiment, a portion of the reciprocating member, such as the
restrictor 56, moves adjacent to or into the inlet 92, further reducing or preventing flow
through the primary inlet 92.
[0033] As the fluid characteristic changes again, for example to a relatively
lower viscosity, the biasing member returns the reciprocating member to its first position.
Thus the changing characteristic of the fluid or fluid flow autonomously changes the
position of the reciprocating member and alters the flow path through the fluid flow
system 80.
[0034] Alternate embodiments of the reciprocating member passageway can
include multiple passageways arranged through the reciprocating member, along grooves
or indentations along the exterior of the reciprocating member, etc. The secondary
passageway(s) can be radial, as shown, or take other forms as to provide an alternate fluid
flow path as the reciprocating member moves. Similarly, the reciprocating member 42 is
shown as a piston, but can take alternative forms, such as a sliding member, reciprocating
ball, etc., as will be recognized by those of skill in the art.
[0035] It is specifically asserted that the reciprocating assembly can be used with
alternate fluid flow systems 80. The incorporated references provide examples of such
flow systems.
[0036] Figures 5 and 6 are alternate exemplary embodiments of fluid flow
systems 80 which can be used in conjunction with the reciprocating assembly described
herein. In Figure 5, the fluid flow system 80, with vortex chamber 82, vortex outlet 88
and directional elements 90, has a single inlet 98. Fluid flow is directed through the
primary outlet 56 of the reciprocating piston 44, and tangentially into the vortex chamber
82, as indicated by solid arrows. When the piston 44 is in the second position, as seen in
Figure 5, the fluid flows through secondary outlet 58 and is directed such that it flows
substantially radially through the vortex chamber 82. Thus the same or similar flow
patterns are achieved with a different design.
[0037] In Figure 6, when the fluid is of a relatively low viscosity, fluid flow is
directed through the piston 44, along passageway 46, through the primary outlet 54 and
restrictor 56, and into a primary inlet 92 of the vortex assembly, thereby inducing spiral
or centrifugal flow in the vortex chamber. When the fluid changes characteristics, such
as to a high viscosity, the piston 44 is moved to the second position, and fluid flows
primarily through the secondary outlet 58 and into the secondary inlet 94 of the fluid flow
assembly. Thus, the relatively higher viscosity fluid is directed, as indicated by the
dashed arrows, primarily radially through the vortex chamber 82 and through vortex
outlet 88.
[0038] It can be seen that the inventive features herein can be utilized with
various fluid flow systems 80, having single or multiple inlets, single or multiple outlets,
etc., as will be understood by those of skill in the art.
[0039] The description above of the assembly in use is provided in an exemplary
embodiment wherein production fluid from the formation is directed through the
assembly. The production fluid can flow through screens, passageways, tubular sections,
annular passageways, etc., before and after flowing through the assembly. The assembly
can also be used for injection and other completion activities, as explained in
incorporated references and as understood by those of skill in the art. The exemplary use
is described in terms of restricting fluid flow such as water of natural gas and allowing
flow of oil. The invention can be used to restrict fluid flow based on viscosity or other
fluid characteristics, and can be used to restrict flow of an undesired fluid while allowing
flow of a desired fluid. For example, water flow can be restricted while natural gas flow
is allowed, etc. In injection uses, for example, steam can be allowed while water is
restricted.
[0040] The invention can also be used with other flow control systems, such as
inflow control devices, sliding sleeves, and other flow control devices that are already
well known in the industry. The inventive system can be either parallel with or in series
with these other flow control systems.
[0041] While this invention has been described with reference to illustrative
embodiments, this description is not intended to be construed in a limiting sense. Various
modifications and combinations of the illustrative embodiments as well as other
embodiments of the invention, will be apparent to persons skilled in the art upon
reference to the description. It is, therefore, intended that the appended claims encompass
any such modifications or embodiments.
It is claimed:
1. An apparatus for autonomously controlling flow of fluid in a subterranean well,
wherein a fluid characteristic of the fluid flow changes over time, comprising:
a vortex assembly defining a vortex chamber and having a primary inlet and at
least one secondary inlet;
an autonomous reciprocating assembly having a reciprocating member, the
reciprocating member defining a fluid flow passageway and having a primary outlet and
at least one secondary outlet; and
the reciprocating assembly movable between a first position wherein fluid flow is
directed primarily through the primary outlet of the reciprocating member and into the
primary inlet of the vortex assembly, and a second position wherein fluid flow is directed
primarily through the at least one secondary outlet of the reciprocating member and into
the at least one secondary inlet of the vortex assembly, the reciprocating member
movable in response to changes in the fluid characteristic.
2. An apparatus as in claim 1, further comprising a flow restrictor positioned to
restrict fluid flow through the primary outlet of the reciprocating member.
3. An apparatus as in claim 2, wherein the restrictor includes a viscosity dependent
choke.
4. An apparatus as in claim 2, wherein the restrictor includes a viscosity dependent
screen.
5. An apparatus as in claim 1, wherein the reciprocating member is a reciprocating
piston positioned in a cylinder.
6. An apparatus as in claim 5, wherein the primary outlet is positioned at a first end
of the piston.
7. An apparatus as in claim 6, wherein the restrictor is positioned at the first end of
the piston.
8. An apparatus as in claim 1, wherein the secondary outlet includes multiple outlet
passageways.
9. An apparatus as in claim 1, wherein the primary inlet of the vortex assembly is
positioned to induce fluid flowing there through primarily into a spiral flow in the vortex
chamber.
10. An apparatus as in claim 1, wherein the at least one secondary inlet to the vortex
chamber includes two opposed secondary inlets.
11. An apparatus as in claim 1, wherein the characteristic of the fluid which changes
over time is viscosity.
12. An apparatus as in claim 1, further comprising a downhole tool, the vortex
assembly positioned in the downhole tool.
13. A method for controlling fluid flow in a subterranean well having a wellbore
extending there through, the method comprising the steps of:
flowing fluid through a downhole tool;
flowing fluid through an autonomous reciprocating member and through a
restrictor attached thereto;
flowing fluid into a vortex chamber positioned in the downhole tool, thereby
creating a flow pattern in the vortex chamber;
moving the autonomous reciprocating member in response to a change in a
characteristic of the fluid; and
altering the fluid flow pattern through the vortex chamber in response to moving
the autonomous reciprocating member.
14. A method as in claim 13, wherein the step of flowing fluid into a vortex chamber
further includes the step of flowing fluid primarily through a tangential inlet of the vortex
chamber.
15. A method as in claim 13, wherein the step of altering the fluid flow pattern further
comprises the step of altering the fluid flow pattern from primarily centrifugal to
primarily radial flow in the vortex chamber.
16. A method as in claim 13, further comprising the step of preventing fluid flow
through a primary inlet to the vortex chamber.
17. A method as in claim 13, wherein the step of moving the autonomous
reciprocating member results in reduced fluid flow through the restrictor.
18. A method as in claim 17, wherein the autonomous reciprocating member has a
primary outlet and multiple secondary outlets, and moving the autonomous reciprocating
member results in fluid flow primarily through the secondary outlets.
19. A method as in claim 13, wherein the fluid characteristic is viscosity.
20. A method as in claim 13, wherein the step of moving the autonomous
reciprocating member further comprises the step of moving the autonomous reciprocating
member alternately toward a closed position and toward an open position in response to
changes in fluid characteristic over time.