Note: Descriptions are shown in the official language in which they were submitted.
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TITLE:
AUTONOMOUS FLUID CONTROL SYSTEM HAVING A FLUID DIODE
CROSS-REFERENCE TO RELATED APPLICATIONS
None.
FIELD OF INVENTION
[0001] The invention relates to apparatus and methods for autonomously
controlling fluid flow through a system using a fluid diode. More
specifically, the
invention relates to using a fluid diode defined by an orifice having a high
resistance side
and a low resistance side.
BACKGROUND OF INVENTION
[0002] Some wellbore servicing tools provide a plurality of fluid flow
paths
between the interior of the wellbore servicing tool and the wellbore. However,
fluid
transfer through such a plurality of fluid flow paths may occur in an
undesirable and/or
non-homogeneous manner. The variation in fluid transfer through the plurality
of fluid
flow paths may be attributable to variances in the fluid conditions of an
associated
hydrocarbon formation and/or may be attributable to operational conditions of
the
wellbore servicing tool, such as a fluid flow path being unintentionally
restricted by
particulate matter.
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SUMMARY OF THE INVENTION
[0003] The invention provides apparatus and methods for autonomously
controlling fluid flow in a subterranean well, and in particular for providing
a fluid diode
to create a relatively high resistance to fluid flow in one direction and a
relatively low
resistance to fluid flowing in the opposite direction. The diode is positioned
in a fluid
passageway and has opposing high resistance and low resistance entries. The
low
resistance entry providing a relatively low resistance to fluid flowing into
the diode
through the low resistance entry. The high resistance entry providing a
relatively high
resistance to fluid flowing into the diode through the high resistance entry.
In a preferred
embodiment, the high resistance entry has a concave, annular surface
surrounding an
orifice and the low resistance entry has a substantially conical surface. The
entries can
have a common orifice. In one embodiment, the concave, annular surface of the
high
resistance entry extends longitudinally beyond the plane of the orifice. That
is, a portion
of a fluid flowing through the diode from the high resistance side will flow
longitudinally
past, but not through, the orifice, before being turned by the concave,
annular surface. In
a preferred embodiment, the fluid will flow in eddies adjacent the concave,
annular
surface.
[0004] The apparatus and method can be used in conjunction with other
autonomous flow control systems, including those having flow control
assemblies and
vortex assemblies. The invention can be used in production, injection and
other servicing
operations of a subterranean wellbore. The invention can be positioned to
provide
relatively higher resistance to fluid flow as it moves towards or away from
the surface.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0005] 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:
[0006] 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;
Figure 2 is a cross-sectional view of a fluid diode of a preferred embodiment
of the
invention,
[0007] Figure 3 is a flow diagram representative of a fluid flowing into
the fluid
diode through the high resistance entry;
[0008] Figure 4 is a flow diagram representative of a fluid flowing into
the fluid
diode through the low resistance entry;
[0009] Figures 5A-C are exemplary embodiments of fluid diodes according to
the
invention;
[0010] Figure 6 is a cross-sectional view of an alternate embodiment of a
fluid
diode according to an aspect of the invention; and
[0011] Figure 7 is a schematic diagram of an exemplary fluid control
system 59
having a fluid diode according to aspects of the invention.
[0012] 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
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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. "Uphole," "downhole" are used to indicate location or direction in
relation to
the surface, where uphole indicates relative position or movement towards the
surface
along the wellbore and downhole indicates relative position or movement
further away
from the surface along the wellbore, regardless of the wellbore orientation
(unless
otherwise made clear).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0013] 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.
[0014] 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,
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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.
[0015] 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 fluid 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.
[0016] 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.
[0017] The fluid flowing into the production tubing section 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.
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[0018] The invention provides a method and apparatus for use of a fluid
diode in a
passageway to provide a relatively high resistance to fluid flow through a
passageway in
one direction while providing a relatively low resistance to fluid flow in the
opposite
direction. It is envisioned that such relative restriction of fluid flow can
be used in any
operation where fluid flow is desired in one direction and undesired in the
opposite
direction. For example, during production of hydrocarbons from the wellbore,
fluid
typically flows from the wellbore, into the tubing string, and thence uphole
towards the
surface. However, if flow is reversed for some reason, a fluid diode, or
series of diodes,
will restrict flow in the reverse direction. The diodes can be used similarly
in injection
operations to restrict fluid flow uphole. Persons of skill in the art will
recognize other
uses where restriction of flow in one direction is preferable.
[0019] Figure 2 is a cross-sectional view of a fluid diode of a preferred
embodiment of the invention. The fluid diode 100 is positioned in a fluid
passageway
102 defined by a passageway wall 101. The passageway 102 can be positioned in
a
downhole tool, tubing string, as part of a larger autonomous fluid control
system, in
series with additional fluid diodes, or individually.
[0020] The fluid diode 100 has a high resistance entry 104 and a low
resistance
entry 106. The low resistance entry 104, in the preferred embodiment shown,
has a
substantially conical surface 108 narrowing from a large diameter end 110 to a
small
diameter end 112 and terminating at an orifice 114. The substantially conical
surface is
preferably manufactured such that it is, in fact, conical; however, the
surface can instead
vary from truly conical, such as made of a plurality of flat surfaces arranged
to provide a
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cone-like narrowing. The high resistance entry 106 narrows from a large
diameter end
116 to a small diameter end 118 and terminates at an orifice 114. In the
preferred
embodiment shown, the orifice 114 for the high and low resistance ends is
coincident. In
other embodiments, the orifices can be separate. The orifice 114, high
resistance entry
106 and low resistance entry 104 are preferably centered on the longitudinal
axis 103 of
the passageway 102. The orifice 114 lies in a plane 115. Preferably the plane
115 is
normal to the longitudinal axis 103.
[0021] The high resistance entry 106 preferably includes a concave surface
120.
The concave surface 120 is annular, extending around the orifice 114. In a
preferred
embodiment, as seen in Figure 2, the concave surface 120 curves along an arc
through
more than 90 degrees. Here, "arc" does not require that the surface be a
segment of a
circle; the surface seen in Figure 2 is not circular, for example. The concave
surface can
be a segment of a circle, ellipse, etc., or irregular. The concave surface
extends
longitudinally from one side of the plane 115 of the orifice 114 to another.
For purposes
of discussion, the concave surface 120 extends longitudinally from a point
upstream of
the plane of the orifice (when fluid is flowing into the high resistance entry
106) to a
furthest extent downstream from the place of the orifice. That is, the concave
surface
extends longitudinally beyond the plane of the orifice. The furthest extent
downstream of
the concave surface 120 is indicated by dashed line 121. In the embodiment
shown, the
longitudinal extent of the conical surface 108 overlaps with the longitudinal
extent of the
concave surface 120.
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[0022] In use, fluid F can flow either direction through the diode 100.
When fluid
flows into the diode through the low resistance entry 104, as indicated by the
solid arrow
in Figure 2, the diode provides a lower resistance to fluid flow than when
fluid flows into
the diode through the high resistance entry 106, as indicated by the dashed
arrow in
Figure 2. In a typical use, fluid flow in the low resistance direction is
preferred, such as
for production of well fluid. If flow is reversed, such that it flows through
the diode from
the high resistance entry, flow is restricted.
[0023] Figure 3 is a flow diagram representative of a fluid F flowing into
the fluid
diode 100 through the high resistance entry 106. Figure 4 is a flow diagram
representative of a fluid F flowing into the diode 100 through the low
resistance entry
104. The flow lines shown are velocity flow lines. Where fluid enters from the
high
resistance side, as in Figure 3, a portion of the fluid flow is directed
substantially radially,
toward the axis 103. The fluid flow through the orifice 114 is substantially
restricted or
slowed, and total fluid flow across the diode is similarly restricted. The
pressure drop
across the diode is correspondingly relatively higher. In a preferred
embodiment, eddies
122 are created adjacent the concave surface of the high resistance entry.
Where fluid
enters the diode from the low resistance side, as in Figure 4, fluid flows
through the diode
with relatively lower resistance, with a corresponding lower pressure drop
across the
diode.
[0024] The following data is exemplary in nature and generated from
computer
modeling of a diode similar to that in Figure 2-4. The pressure drops across
the diode and
resistance to fluid flow is dependent on the direction of fluid flow through
the diode.
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Water at a flow rate of 0.2 kg per second experienced a pressure drop across
the diode of
approximately 4200Pa when flowing into the diode from the high resistance
side. Water
flowing the opposite direction, from the low resistance side, only experienced
a pressure
drop of approximately 2005Pa. Similarly, air having a density of 1.3 kg per
cubic meter
and at the same flow rate, experienced a pressure drop of 400psi when flowing
in the
restricted direction and only a 218psi pressure drop in the unrestricted
direction. Finally,
gas modeled at 150 kg per cubic meter and at the same flow rate, experienced a
pressure
drop of 5 psi in the restricted direction and 2 psi in the unrestricted
direction. These data
points are exemplary only.
[0025] Figures 5A-C are exemplary embodiments of fluid diodes according to
the
invention. Figures 5A-C show alternate profiles for the concave, annular
surface 120 of
the fluid diode 100. In Figure 5A, the profile is similar to that in Figure 2,
wherein the
concave surface 120 curves through more than 90 degrees, has a comparatively
deep
"pocket," and extends to a point at 121 past the plane 115 of the orifice 114.
Figure 5B is
similar, however, the concave surface 120 is shallower. In Figure 5C the
concave surface
120 curves through 90 degrees and does not extend longitudinally past the
orifice plane
115. The design of Figure 5A is presently preferred and provides the greatest
pressure
drop when flow is in the restricted direction. Using modeling techniques, the
pressure
drops across the diodes in Figures 5A-C were 4200Pa, 3980Pa and 3208Pa,
respectively.
Additionally, the high resistance entry can take other shapes, such as curved
surfaces
having additional curvatures to the concave surface shown, concave surfaces
which vary
from the exact curvature shown, a plurality of flat surfaces which provide a
substantially
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similar concave surface when taken in the aggregate, or even having a
rectangular cross-
section. Further, the passageway can have round, rectangular, or other cross-
sectional
shape.
[0026] Figure 6 is a cross-sectional view of an alternate embodiment of a
fluid
diode according to an aspect of the invention. Figure 6 shows an alternate
embodiment
wherein the orifice 114a of the high resistance entry 106 is not coincident
with the orifice
114b of the low resistance entry 104. A relatively narrow conduit 124 connects
the
orifices.
[0027] Figure 7 is a schematic diagram of an exemplary fluid control
system 59
having a fluid diode according to aspects of the invention. The fluid control
system 59 is
explained in detail in references which are incorporated herein by reference
and will not
be described in detail here. The fluid control system is designed for fluid
flow in the
direction indicated by the double arrows, F. Fluid, such as production fluid,
enters the
fluid control system 59, flows through the passageways 62 and 64 of the flow
control
assembly 60, exits through outlets 68 and 70. Fluid then flows into the vortex
assembly
80 through an inlet 84 or 86, by optional directional elements 90, through
vortex chamber
82 and out of the vortex outlet 88. Fluid then flows downstream (which in this
embodiment is uphole), such as to the surface. While flow in this direction is
preferred
and typical, the fluid diode of the invention can be used in conjunction with
or as part of
the flow control system to restrict or prevent reverse fluid flow through the
system. As
indicated, one or more fluid diodes 100 can be employed at locations along the
system,
upstream or downstream from the system.
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[00281 In a preferred embodiment, fluid diodes 100 are arranged in series,
such
that the fluid flow passes through a plurality of diodes. For example, two
diodes 100 are
seen downstream of the vortex assembly 80 in Figure 7. As discussed above,
when fluid
flows through the high resistance side of the diode, a greater pressure drop
is realized
across the diode than when flow is in the opposite direction. However, the
pressure drop
across a plurality of diodes will be greater still. It is preferred that a
plurality of diodes in
series be used to create a much greater total pressure drop across the
plurality of diodes.
In such a manner, the reverse flow through the system can be substantially
restricted.
[0029] The diode explained herein can be used in conjunction with the
various
flow control systems, assemblies and devices described in the incorporated
references as
will be understood by those of skill in the art.
[0030] 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.
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. 12/791993, entitled "Flow Path Control Based on Fluid
Characteristics to Thereby Variably Resist Flow in a Subterranean Well," to
Dykstra,
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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. 12/792117,
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. 12983144, 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 4/11/2011; U.S. Patent Application Serial No.
61/473,700, entitled
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"Moving Fluid Selectors for the Autonomous Valve," to Fripp, filed 4/8/2011;
U.S.
Patent Application Serial No. 61/473,699, entitled "Sticky Switch for the
Autonomous
Valve," to Fripp, filed 4/8/2011; and U.S. Patent Application Serial No.
13/100006,
entitled "Centrifugal Fluid Separator," to Fripp, filed 5/3/2011.
[0031] 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.
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