Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
DEVICE AND METHOD FOR GAS LIFT OF A RESERVOIR FLUID
FIELD OF THE INVENTION
[0001] The present invention relates to lifting reservoir fluid in the
production tubing of an
oil and gas well.
BACKGROUND OF THE INVENTION
[0002] Artificial lift technologies are used to enhance the production
rate of a reservoir fluid
from an oil and gas well, particularly when the prevailing natural reservoir
pressure is
insufficient to lift the reservoir fluid in the downhole production tubing to
the well head.
[0003] A gas lift valve or mandrel may be installed in a side pocket of
the production tubing.
A surface pump injects gas under high pressure from a surface source into the
annular space
between the production tubing and the well wall. The gas enters the production
tubing via the
gas lift valve in the form of bubbles. The bubbles mix with the reservoir
fluid in the production
tubing such that the resulting mixture has a lower density that the reservoir
fluid. The relatively
buoyant bubbles may also provide a "scrubbing" effect that helps lift the
reservoir fluid in the
production tubing.
[0004] A jet pump may be installed in a production tubing. A surface pump
injects a power
fluid into the annular space between the production tubing and the well wall.
The power fluid
enters the jet pump through side openings of the production tubing and flows
through an
internal nozzle of the jet pump to create a low fluid pressure zone that draws
reservoir fluid up
a lower portion of the production tubing. The reservoir fluid commingles with
the power fluid,
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Date Recue/Date Received 2020-09-30
and flows up the production tubing. Alternatively, the surface pump may inject
power fluid
into a downhole tube, such that the commingled fluid flows up the annular
space.
[0005] These artificial lift technologies require equipment to supply
external energy to
supplement the natural reservoir pressure, which adds cost and complexity to
the well system.
Accordingly, there remains a need in the art for technology to lift reservoir
fluid in an oil and
gas well without the need for such equipment.
SUMMARY OF THE INVENTION
[0006] In one aspect, the present invention comprises a method for
lifting a reservoir fluid
in an oil and gas well. The method comprises the step of allowing the
reservoir fluid to flow in
an axial uphole direction through an internal flow path of a production tubing
disposed in the
well. The internal flow path comprises a "Venturi profile" having a transverse
cross-sectional
area that gradually decreases in the axial uphole direction to a throat. The
Venturi profile is
configured to flash out a free gas phase from the reservoir fluid as the
reservoir fluid flows in
the axial uphole direction through the Venturi profile, such that the
reservoir fluid comprises
the free gas phase and a liquid phase. The internal flow path further
comprises a "diffusion
profile" disposed above the throat of the Venturi profile, and having a
transverse cross-
sectional area that gradually increases in the axial uphole direction. The
diffusion profile is
configured to condense the free gas phase into the liquid phase as the
reservoir fluid flows in
the axial uphole direction through the diffusion profile. In embodiments of
the method,
pressure of the reservoir fluid in the internal flow path is not increased by
energy added from
any man-made equipment. In embodiments of the method, the internal flow path
is configured
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such that the reservoir fluid has a pressure at a location above the throat
that is sufficient to lift
the reservoir fluid to a surface location of the well.
[0007] In another aspect, the present invention comprises a device for
lifting a reservoir
fluid in an oil and gas well. The device comprises a tubular member for
forming a portion of a
production tubing disposed in the well. The tubular member defines an internal
flow path for
flow of the reservoir fluid. The internal flow path extends in an axial uphole
direction from at
least one lower inlet port to an upper outlet port. The internal flow path
comprises a Venturi
profile and a diffusion profile, as described above.
[0008] In another aspect, the present invention comprise a system for
lifting a reservoir
fluid in an oil and gas well. The system comprises a production tubing
disposed in the well and
defining an internal flow path for flow of the reservoir fluid. The internal
flow path extends in
an axial uphole direction form at least one lower inlet port. The internal
flow path comprises a
Venturi profile and a diffusion profile, as described above.
[0009] In embodiments of the method, device, and system of the present
invention (as
described above), the at least one lower inlet port may comprise a plurality
of lower inlet ports.
In embodiments, the plurality of lower inlet ports may be transversely spaced
apart from each
other. In embodiments, the at least one inlet port has an axial length to
transverse dimension
ratio of at least about 9 to 1. In embodiments, the internal flow path further
comprises an inlet
chamber profile disposed axially between the at least one inlet port and the
Venturi profile,
and having a transverse cross-sectional area that gradually decreases in the
axial uphole
direction.
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[0010] The present invention may be used to enhance production of the
reservoir fluid from
the oil and gas well, solely under the influence of natural reservoir pressure
¨ that is, without
the need for equipment supplying external energy. The flashing out of the free
gas reduces the
density of the reservoir fluid in a region above the Venturi profile, and at a
well depth below
which the gas would naturally flash out of the reservoir fluid. This reduces
the hydrostatic head
of the column of reservoir fluid in the production tubing, and thereby
provides a gas-lift effect.
The condensing of the free gas into the liquid phase may help to maintain the
pressure of the
reservoir fluid for flow to the well head, such that the gas-lift effect is
minimally impacted or
not impacted by the free gas in the internal flow path.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In the drawings, which form part of the specification, like
elements may be assigned
like reference numerals. The drawings are not necessarily to scale, with the
emphasis instead
placed upon the principles of the present invention. Additionally, each of the
embodiments
depicted are but one of a number of possible arrangements utilizing the
fundamental concepts
of the present invention.
[0012] Figure 1 shows an axial medial cross-sectional view of an
embodiment of a system
of the present invention for lifting a reservoir fluid in an oil and gas well.
[0013] Figure 2 shows an axial medial cross-sectional view of an
embodiment of a device
installed in the system of Figure 1, when isolated from the system.
[0014] Figure 3 shows a perspective view of the device of Figure 2.
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[0015] Figures 4 to 7 show axial medial cross-sectional views of
alternative embodiments
of the inlet chamber section for the device of Figure 2. Figure 4 is a first
alternative
embodiment. Figure 5 is a second alternative embodiment. Figure 6 is a third
alternative
embodiment. Figure 7 is a fourth alternative embodiment.
[0016] Figures 8A and 8B show axial medial cross-sectional views of a first
embodiment
of a throat section for the device of Figure 2. Figure 8A shows the entire
throat section. Figure
8B shows region 'I' of Figure 8A.
[0017] Figures 9A and 9B show axial medial cross-sectional views of a second
embodiment
of a throat section for the device of Figure 2. Figure 9A shows the entire
throat section. Figure
.. 9B shows region 'I' of Figure 9A.
[0018] Figure 10A shows an example of a relationship between density and
pressure of
hydrocarbon components of a reservoir fluid, used in a computational fluid
dynamics (CFD)
model. Figure 10B shows an example of a relationship between specific heat and
pressure of
hydrocarbon components of a reservoir fluid, including an average specific
heat used in a
computational fluid dynamics (CFD) model.
[0019] Figures 11A to 11D show the results of a computational fluid
dynamics (CFD)
model of a multiphase reservoir fluid flowing at a steady state through the
device of Figure 2
under simulated well conditions. Figure 11A shows the reservoir fluid velocity
and
streamlines. Figure 11B shows the reservoir fluid pressure. Figure 11C shows
the reservoir
fluid gas volume fraction. Figure 11D shows the reservoir fluid density.
Figure 11E shows the
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effect of the Venturi profile and the throat diameter thereof on reservoir
fluid pressure over the
well depth.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0020] The present invention relates to lifting reservoir fluid in an
oil and gas well. Any
term or expression not expressly defined herein shall have its commonly
accepted definition
understood by a person skilled in the art.
[0021] System for Gas Lift. Figure 1 shows an embodiment of system 10 of
the present
invention including production tubing 12 and sealing element 14, disposed
within an oil and
gas well with a wall formed by casing 16 (or alternatively by geological
formation 18 if the
well were uncased). Axis "A" denotes the "axial" direction parallel to the
central axis of the
well and production tubing 12, which is vertical in the drawing plane of
Figure 1. Axis "T"
denotes a "transverse" direction perpendicular to the axial direction, which
is horizontal in the
drawing plane of Figure 1.
[0022] Production tubing 12 extends axially upwardly to convey reservoir
fluid to a well
head (not shown) at the ground surface. Sealing element 14 (e.g., a packer)
seals the annular
space between production tubing 12 and casing 16, thus dividing the well into
an upper well
portion 20 and a lower well portion 22. Casing 16 is perforated to allow
reservoir fluid of
producing zone 24 to enter lower well portion 22.
[0023] Production tubing 12 includes an upper portion 26 and a lower portion
formed by
device 28 of the present invention. Device 28 forms the lower terminus of
production tubing
12 in this embodiment; production tubing 12 may extend below device 28 in
other
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embodiments. Thus, it will be understood that "upper" and "lower" describe
relative axial
positions of portion 26 and device 28 of production tubing 12, and do not
indicate axial
extremities of production tubing 12.
[0024] Device. Figures 2 and 3 show device 28 in isolation. Device 28
includes a tubular
member formed in this embodiment from a housing 30, inlet port section 32,
inlet chamber
section 34, throat section 36, and diffuser chamber section 38. These separate
parts facilitate
manufacturing of device 28, and servicing and modification of device 28. For
example,
different embodiments of sections 32, 34, 36, 38 may be interchanged with a
single housing
30 to modify flow characteristics of the tubular member for different well
conditions. These
parts of the tubular member may be made of a corrosion-resistant alloy steel,
or any other
material suitable for conditions in the well. The tubular member may be formed
by a single
monolithic part in other embodiments.
[0025] The embodiment of device 28 shown in Figure 2 is assembled by
inserting inlet
chamber section 34 up into housing 30 to abut against a lower internal
shoulder thereof. Inlet
.. port section 32 is secured to housing 30 by a threaded connection. Throat
section 36 is inserted
down into housing 30 to abut against the upper end of inlet chamber section
34. Diffuser
chamber section 38 is secured to housing 30 by a threaded connection. Diffuser
chamber
section 38 defines a threaded box end for attachment to upper portion 26 of
production tubing
12 (see Figure 1). 0-ring seals 40, 42, 44, 46 seal between inner wall of
housing 30 and outer
walls of sections 32, 34, 36, and 38. Threaded connections of sections 32 and
38 with housing
are tightened using wrenches applied to flats 48, 50 formed on sections 32,
38, respectively
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(see Figure 3). For scale, in this embodiment, the tubular member has an axial
length of about
16.66 inches and a transverse outer diameter of about 1.84 inches.
[0026] Internal flow path. The tubular member defines axial internal
flow path 54 for the
reservoir fluid. Internal flow path 54 extends in the axial uphole direction
from at least one
lower inlet port 56 to upper outlet port 58. Lower inlet ports 56 allow
reservoir fluid in lower
well portion 22 to flow into internal flow path 54. Upper outlet port 58
allows reservoir fluid
in internal flow path 54 to flow into upper portion 26 of production tubing
12. In this
embodiment, lower inlet ports 56 extend axially up from the lower terminus of
the tubular
member; in other embodiments, lower inlet ports 56 may extend transversely
inward from a
side wall of the tubular member, in which case the tubular member may extend
below lower
inlet ports 56. Thus, it will be understood that "lower" describes an axial
position of inlet ports
56 relative to upper outlet port 58, and does not indicate a lower extremity
of the tubular
member.
[0027] Inlet port section. In the embodiment shown in Figure 2, inlet
port section 32
defines a central lower inlet port 56a substantially coinciding transversely
with the central axis
of inlet port section 32, which is surrounded by ten peripheral lower inlet
ports 56b arranged
in a circle in a transverse cross-section of inlet port section 32 (see Figure
3). Each lower inlet
port 56 has an aspect ratio of at least about about 9 to 1, as defined by the
ratio of its axial
length (about 2.28 inches) to its transverse dimension (i.e., diameter of
about 0.25 inches). This
configuration and proportion of inlet ports 56 may allow for an evenly
distributed flow of
reservoir fluid, with minimal vorticity within inlet chamber section 34. In
other embodiments,
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inlet port section 32 may define a different number of lower inlet ports 56,
with a different
geometry and arrangement.
[0028] Inlet chamber section. Inlet chamber section 34 defines an inlet
chamber profile
that has an inner diameter that gradually decreases in the axial direction
from inlet port section
32 to throat section 36. Inlet chamber section 34 may help to minimize
vorticity and flow
separation of the reservoir fluid as it flows in the axial uphole direction
toward throat section
36.
[0029] In this embodiment, inlet chamber section 34 is closed to flow of
any fluid, except
for reservoir fluid that enters from lower well portion 22 via lower inlet
ports 56. These are the
only openings defined by the tubular member of device 28 that permit fluid
communication
into internal flow path 54 below the Venturi profile of throat section 36, as
described below.
Accordingly, the reservoir fluid does not commingle with any other fluid as it
flows up toward
the Venturi profile of throat section 36.
[0030] In the embodiment shown in Figure 2, inlet chamber section 34 has
an axial length
of about 2.25 inches. The inner wall of inlet chamber section 34 transitions
from an inlet
diameter of about 1.4 inches to an outlet diameter of about 0.58 inches
according to quadratic
curve of the form 'y = ax2 + bx + c', where 'x' and 'y' are axial and
transverse coordinates,
respectively, and 'a', 'b', and 'c' are coefficients. The upper end of inlet
chamber section 34
defines a recess that receives the lower end of throat section 36, allowing
inlet chamber section
34 to be used with throat sections 36 of different inner diameters at their
lower ends.
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[0031] Figures 4 to 7 show alternative embodiments of inlet chamber
section 34 that are
interchangeable with the embodiment shown in Figure 2. The embodiments have
the same
axial length of 2.25 inches and maximum inner diameter of about 1.4 inches as
the embodiment
shown in Figure 2. In Figure 4, inner wall of inlet chamber section 34 defines
a lower frustro-
conical portion with an axial length of about 1.5 inches, and an upper
cylindrical portion with
an axial length and inner diameter of about 0.75 inches. The upper cylindrical
portion may help
to minimize vorticity below throat section 36.
[0032] In Figure 5, inner wall of inlet chamber section 34 is entirely
conical, thus avoiding
the angular change of the embodiment shown in Figure 4.
[0033] In Figure 6, inlet chamber section 34 is adapted specifically for
use with the
embodiment of throat section 36 shown in Figures 8A and 8B. The upper end of
inlet chamber
section 34 is complementary in shape to the lower end of throat section 36
shown in Figure
8A. Further, inlet chamber section 34 has an inner diameter of 0.75 inches at
its upper outlet
that matches the inlet diameter 'D' of throat section 36 shown in Figure 8B.
Accordingly, when
.. the upper end of inlet chamber section 34 and the lower end of throat
section 36 abut against
each other, internal flow path 54 transitions smoothly between sections 34, 36
without any
abrupt change of angle or inner diameter.
[0034] In Figure 7, inlet chamber section 34 includes a central element
defining a central
channel for transverse alignment with central lower inlet port 56a defined by
inlet port section
32. The central element and inner wall of inlet chamber section 34 define
therebetween a
plurality of peripheral channels for transverse alignment with a different one
of peripheral
Date Recue/Date Received 2020-09-30
lower inlet ports 56b defined by inlet port section 32. At the upper end of
inlet chamber section
34, the central channel and peripheral channels converge to a single nozzle-
like outlet.
[0035] Throat section. Throat section 36 defines a Venturi profile for
flashing out a free
gas phase of the reservoir fluid. "Venturi profile" refers to the transverse
cross-sectional area
of internal flow path 54 gradually decreasing in the uphole axial direction
toward throat 60. In
accordance with Bernoulli's principle, when an incompressible reservoir fluid
flows at a steady
state through the Venturi profile, the reservoir fluid velocity is higher and
the reservoir fluid
pressure is lower in a region at and above throat 60, than in the region
immediately below
throat 60.
[0036] "Flash out" refers to a fraction of the hydrocarbon components of
the reservoir fluid
transforming from a higher density supercritical liquid phase to a lower
density free gas phase,
resulting in the reservoir fluid having both a liquid phase and a free gas
phase. Figure 10A
shows an example of a model relationship between density and pressure of a
mixture of
hydrocarbon components in a typical reservoir fluid from a well in the
Duvernay Formation in
western Alberta, Canada. At higher pressures, the reservoir fluid is a single
supercritical liquid
phase. As the reservoir fluid pressure decreases to about 18.0 MPa (gauge) in
this example,
some of the lighter (i.e., lower molecular weight) hydrocarbon components
vaporize, and the
reservoir fluid transforms into a two-phase fluid including a free gas phase
and a liquid phase.
The pressure at which this phase transition occurs will vary depending on the
hydrocarbon
components present and their relative proportions within the reservoir fluid.
[0037] Returning to Figure 8A, above the Venturi profile, throat section
36 also defines a
diffusion profile for condensing the free gas into the liquid phase of the
reservoir fluid.
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"Diffusion profile" refers to the transverse cross-sectional area of internal
flow path 54
gradually increasing in the uphole axial direction away from throat 60. As the
reservoir fluid
flows at a steady state through the diffusion profile, the reservoir fluid
velocity gradually
decreases, and the reservoir fluid pressure gradually increases in the uphole
axial direction
sufficiently to condense the free gas phase back to the liquid phase.
[0038] The Venturi profile and diffusion profile may be configured by
persons of ordinary
skill in the art to achieve the below objectives, by appropriate selection of
dimensional
parameters such as axial length 'L', diffusing angle 'alp', throat diameter
'd' and inlet diameter
'D' (see Figures 8A to 9B). The Venturi profile below throat 60 should limit
the reservoir fluid
pressure drop so that the reservoir fluid has sufficient energy to flow
through throat 60 without
choking. Throat 60 should result in a reservoir fluid pressure drop that is
effective to "flash
out" a free gas phase from the reservoir fluid. In this regard, a phase-
pressure relationship such
as shown in the example of Figure 10A will indicate the "flash out" pressure
for a particular
reservoir fluid, which may be used for the design of the Venturi profile. The
diffusion profile
above throat 60 should allow for gradual recovery of reservoir fluid pressure,
sufficient to
condense the free gas phase back into the liquid phase, and to maintain a
sufficient production
rate of the reservoir fluid in production tubing 12.
[0039] As an example, in the embodiment shown in Figures 2, 8A, and 8B, throat
section
36 has an axial length 'L' of about 4.44 inches, and a diffusing angle 'ocip'
of about 3 . The inner
.. wall of throat section 36 transitions from inlet diameter 'D' of about 0.75
inches to throat
diameter 'd' of about 0.185 inches according to ellipsoidal function, over an
axial inlet distance
equal to throat diameter 'd'.
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[0040] As another example, in the alternative embodiment shown in Figures 9A
and 9B,
throat section 36 has the same axial length 'L', diffusing angle 'alp', and
throat diameter 'd' as
the embodiment shown in Figures 8A and 8B, but a smaller inlet diameter 'D' of
about 0.58
inches, and a longer axial inlet distance of 0.5 times the inlet diameter 'D',
for a less abrupt
curvature and longer axial transition to throat 60.
[0041] Diffuser chamber section. Diffuser chamber section 38 continues
the diffusion
profile defined in part by throat section 36. Accordingly, diffuser chamber
section 38 has an
inner diameter that gradually increases in the axial direction from throat
section 36 to upper
outlet port 58. Preferably, diffuser chamber section 38 allows for a flow of
reservoir fluid with
minimal vorticity and flow separation as the reservoir fluid flows toward
upper outlet port 58.
[0042] Method for Gas Lift. Device 28 may be used in a method to lift a
reservoir fluid in
an oil and gas well. The method may be used to produce the reservoir fluid
from the well under
"natural reservoir pressure" ¨ i.e., the pressure of the reservoir fluid is
not supplemented by
energy added from any man-made equipment such as a pump.
[0043] Referring to Figure 1, device 28 is attached to upper portion 26 of
production tubing
12 with sealing element 14 in an unexpanded state. Production tubing 12 is
lowered into casing
16, until lower inlet ports 56 are in the vicinity of producing zone 24.
Sealing element 14 is
expanded to seal against casing 16 as shown in Figure 1. Reservoir fluid from
producing zone
24 flows through perforations of casing 16 into lower well portion 22. Under
influence of
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Date Recue/Date Received 2020-09-30
natural reservoir pressure, reservoir fluid flows through lower inlet ports 56
of device 28 into
internal flow path 54.
[0044] A computational fluid dynamics (CFD) model of device 28 shown in Figure
2
predicts a "gas-lift" effect as the reservoir fluid flows at a steady state
through internal flow
path 54. ANSYS CFX 18.0 (2018) TM software was used to model internal flow
path 54 using
a finite element approach. OLI Studio 9.6 TM software was used to model the
reservoir fluid as
a continuous (i.e., without bubbles) multiphase fluid of emulsion (liquid
condensate of
hydrocarbons), water (brine), and gas (gaseous hydrocarbons), with pressure-
dependent
density for water (brine), and for hydrocarbon components according to the
relationship shown
in Figure 10A, and an assumed average specific heat of 2900 kJ/[kg=K] for
hydrocarbon
components based on the relationship shown in Figure 10B. The modeled
reservoir fluid has a
flash point pressure of about 18.0 MPa (gauge) at 100 C, at which lighter
hydrocarbon
components "flash out." The boundary conditions (i.e., depth dependent
temperature and
pressure) were selected to simulate conditions expected in a well in the
Montney Formation of
Alberta and British Columbia, Canada. The flow bottom hole pressure (FBHP) was
set at 18.5
MPa at lower inlet ports 56 of device 28 assuming an installation depth of
about 3157 meters.
The bulk mass flow rate of reservoir fluid was set at 0.658 kg/s with a water-
to-oil ratio (WOR)
of 0.067. The pressure of the separator at the well head was set to 5 MPa.
[0045] Figures 11A, 11B, 11C and 11D show the CFD model predictions of
reservoir fluid
velocity, pressure, gas volume fraction (GVF), and density, respectively, as
the reservoir fluid
flows at a steady state in the axial uphole direction through internal flow
path 54. For Figure
11C, "gas volume fraction" or "GVF" refers to the ratio of the volume of the
gas phase (if any)
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Date Recue/Date Received 2020-09-30
of the reservoir fluid, to the volume of the gas phase (if any) and liquid
phase of the reservoir
fluid volume, expressed as decimal fraction. Figure 11A shows that the
reservoir fluid flows
with minimal turbulence throughout most of internal flow path 54.
[0046] As the reservoir fluid flows upward through the Venturi profile
of internal flow path
54, the reservoir fluid velocity increases to a maximum of about 83.3 m/s
(Figure 11A), and
the reservoir fluid velocity pressure decreases to a minimum of about 16.75
MPa (gauge)
(Figure 11B) at a location slightly above throat 60. This causes lighter
hydrocarbons
components of the reservoir fluid to "flash out", thereby increasing the
reservoir fluid GVF to
a maximum of 0.147 (Figure 11C), and decreasing the reservoir fluid density to
a minimum of
472 kg/m3 (Figure 11D) at this location. Device 28 allows the "flash out"
phenomenon to occur
at greater depth in the well than would otherwise occur in the absence of
device 28. Further,
the reduction in density of the reservoir fluid reduces the hydrostatic head
of the column of
reservoir fluid in production tubing 12. Accordingly, the device produces a
"gas-lift" effect
that allows for increased production of reservoir fluid from the well.
[0047] As the reservoir fluid continues to flow upward through the
diffusion profile of
internal flow path 54, the reservoir fluid velocity gradually decreases
(Figure 11A), and the
reservoir fluid gradually increases to 18.117 MPa (Figure 11B) at upper outlet
port 58. Almost
all or all of the free gas phase condenses to the liquid phase at a location
substantially below
upper outlet port 58 (see Figure 11C at the point labelled "re-condensation").
Accordingly, the
gas-lift effect is nor impacted or only minimally impacted by free gas above
the upper outlet
port 58.
Date Recue/Date Received 2020-09-30
[0048] In the foregoing example, the throat diameter 'd' is set to 0.185
inches. Figure 11E
shows the effect of modifying the throat section 36 with a section having no
Venturi profile,
or a throat diameter of 0.165 inches, as predicted by the CFD model. In the
case of no Venturi
profile, the predicted reservoir fluid pressure at the well head is only 4.8
MPa. As this is less
than the modeled pressure of 5 MPa at the well head separator, the well would
be non-
producing. In the case of a throat section 36 having a throat diameter of
0.165 inches, the throat
section 36 results in reservoir fluid pressure drop being so large, that the
predicted reservoir
pressure at the well head is only 4.4 MPa. Again, the well would be non-
producing. If the
throat diameter is further decreased, throat section 36 may choke the flow of
reservoir fluid.
[0049] Interpretation. The corresponding structures, materials, acts, and
equivalents of all
means or steps plus function elements in the claims appended to this
specification are intended
to include any structure, material, or act for performing the function in
combination with other
claimed elements as specifically claimed.
[0050] References in the specification to "one embodiment", "an
embodiment", etc.,
indicate that the embodiment described may include a particular aspect,
feature, structure, or
characteristic, but not every embodiment necessarily includes that aspect,
feature, structure, or
characteristic. Moreover, such phrases may, but do not necessarily, refer to
the same
embodiment referred to in other portions of the specification. Further, when a
particular aspect,
feature, structure, or characteristic is described in connection with an
embodiment, it is within
the knowledge of one skilled in the art to affect or connect such module,
aspect, feature,
structure, or characteristic with other embodiments, whether or not explicitly
described. In
other words, any module, element or feature may be combined with any other
element or
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Date Recue/Date Received 2020-09-30
feature in different embodiments, unless there is an obvious or inherent
incompatibility, or it
is specifically excluded.
[0051] It is further noted that the claims may be drafted to exclude any
optional element.
As such, this statement is intended to serve as antecedent basis for the use
of exclusive
terminology, such as "solely," "only," and the like, in connection with the
recitation of claim
elements or use of a "negative" limitation. The terms "preferably,"
"preferred," "prefer,"
"optionally," "may," and similar terms are used to indicate that an item,
condition or step being
referred to is an optional (not required) feature of the invention.
[0052] The singular forms "a," "an," and "the" include the plural
reference unless the
context clearly dictates otherwise. The term "and/or" means any one of the
items, any
combination of the items, or all of the items with which this term is
associated. The phrase
"one or more" is readily understood by one of skill in the art, particularly
when read in context
of its usage.
[0053] The term "about" can refer to a variation of 5%, 10%, 20%, or
25% of the
value specified. For example, "about 50" percent can in some embodiments carry
a variation
from 45 to 55 percent. For integer ranges, the term "about" can include one or
two integers
greater than and/or less than a recited integer at each end of the range.
Unless indicated
otherwise herein, the term "about" is intended to include values and ranges
proximate to the
recited range that are equivalent in terms of the functionality of the
composition, or the
embodiment.
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[0054] As will be understood by one skilled in the art, for any and all
purposes, particularly
in terms of providing a written description, all ranges recited herein also
encompass any and
all possible sub-ranges and combinations of sub-ranges thereof, as well as the
individual values
making up the range, particularly integer values. A recited range includes
each specific value,
integer, decimal, or identity within the range. Any listed range can be easily
recognized as
sufficiently describing and enabling the same range being broken down into at
least equal
halves, thirds, quarters, fifths, or tenths. As a non-limiting example, each
range discussed
herein can be readily broken down into a lower third, middle third and upper
third, etc.
[0055] As will also be understood by one skilled in the art, all language
such as "up to", "at
least", "greater than", "less than", "more than", "or more", and the like,
include the number
recited and such terms refer to ranges that can be subsequently broken down
into sub-ranges
as discussed above. In the same manner, all ratios recited herein also include
all sub-ratios
falling within the broader ratio.
18
Date Recue/Date Received 2020-09-30
