U.S. patent application number 16/386028 was filed with the patent office on 2019-08-08 for synthetic target material for shaped charge performance evaluation, powdered metal.
This patent application is currently assigned to Hunting Titan, Inc.. The applicant listed for this patent is Hunting Titan, Inc.. Invention is credited to Laura Montoya Ashton, Ian Douglas Rudnik, Christopher Brian Sokolove, Morgan Tompkins.
Application Number | 20190242866 16/386028 |
Document ID | / |
Family ID | 55400716 |
Filed Date | 2019-08-08 |
United States Patent
Application |
20190242866 |
Kind Code |
A1 |
Rudnik; Ian Douglas ; et
al. |
August 8, 2019 |
Synthetic Target Material for Shaped Charge Performance Evaluation,
Powdered Metal
Abstract
A shaped charge target apparatus and method for using a target
composed of synthetic material, thereby allowing for repeatable
testing at a variety of density and hardness values.
Inventors: |
Rudnik; Ian Douglas;
(Vassar, MI) ; Sokolove; Christopher Brian;
(Midlothian, TX) ; Montoya Ashton; Laura; (Ithaca,
NY) ; Tompkins; Morgan; (Tijeras, NM) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hunting Titan, Inc. |
Pampa |
TX |
US |
|
|
Assignee: |
Hunting Titan, Inc.
Pampa
TX
|
Family ID: |
55400716 |
Appl. No.: |
16/386028 |
Filed: |
April 16, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15506195 |
Feb 23, 2017 |
10309952 |
|
|
PCT/US15/47581 |
Aug 28, 2015 |
|
|
|
16386028 |
|
|
|
|
62043072 |
Aug 28, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F41J 1/08 20130101; G01N
3/40 20130101; G01N 33/227 20130101; E21B 43/119 20130101; G01N
3/08 20130101; F42B 35/00 20130101; E21B 43/117 20130101; F42B 1/02
20130101 |
International
Class: |
G01N 33/22 20060101
G01N033/22; F41J 1/08 20060101 F41J001/08; G01N 3/40 20060101
G01N003/40; G01N 3/08 20060101 G01N003/08; E21B 43/117 20060101
E21B043/117; F42B 35/00 20060101 F42B035/00; E21B 43/119 20060101
E21B043/119 |
Claims
1. A method for testing a shaped charge comprising: pressing a
powdered material into a disc; sintering the disc; placing the disc
proximate to a shaped charge; and firing the shaped charge into the
disc.
2. The method of claim 1, wherein the disc is between 1 and 4
inches diameter.
3. The method of claim 1, further comprising placing a metal plate
between the shaped charge and the disc.
4. The method of claim 1, further comprising hardness testing the
disc.
5. The method of claim 1, further comprising stacking one or more
discs underneath the first disc to form a plurality of discs.
6. The method of claim 5, further comprising placing the plurality
discs in a test fixture.
7. The method of claim 6, further comprising saturating the
plurality of discs with a fluid.
8. The method of claim 7, further comprising applying a compressive
radial stress to the plurality of discs.
9. The method of claim 7, further comprising applying a compressive
axial stress to the plurality of discs.
10. The method of claim 1, wherein the powdered material including
a wax powdered component.
11. A shaped charge test apparatus comprising: a first end cap
adapted to accept a shaped charge; a second end cap; and a body
containing a hollow cylindrical interior holding a plurality of
synthetic target discs.
12. The shaped charge test apparatus of claim 11 further comprising
a first reservoir within the body contains a first fluid.
13. The shaped charge test apparatus of claim 11 further comprising
a second reservoir within the first end cap containing a second
fluid.
14. The shaped charge test apparatus of claim 11 wherein the
synthetic target discs are composed of sintered powdered
material.
15. The shaped charge test apparatus of claim 14 wherein the
powdered material is composed of a metallic powder.
16. The shaped charge test apparatus of claim 11 wherein a shape
charge is oriented to fire through the second fluid and the
plurality of synthetic target discs.
17. The shaped charge test apparatus of claim 11 wherein the second
end cap has a through opening.
18. A shaped charge test apparatus comprising: a cylindrical
fixture with a hollow portion adapted for accepting a plurality of
synthetic target cylinders about its outer surface, and having a
hallow annulus adapted to accept a perforating gun.
19. The apparatus of claim 18 wherein the plurality of synthetic
target cylinders are perpendicular to the outer surface of the
cylindrical fixture.
20. The apparatus of claim 18 wherein each synthetic target
cylinder further comprises a plurality of synthetic targets stacked
inside.
21. The apparatus of claim 20, wherein each synthetic target
comprises a sintered powdered material in a cylindrical shape.
22. The apparatus of claim 21, wherein the sintered powdered
material comprises powdered iron.
23. The apparatus of claim 21, wherein the sintered powdered
material comprises powdered carbon.
24. The apparatus of claim 21, wherein the sintered powdered
material comprises powdered copper.
25. The apparatus of claim 21, wherein the sintered powdered
material comprises powdered molybdenum.
26. The apparatus of claim 21, wherein the sintered powdered
material comprises a density of approximately 3.34 g/cc and a
hardness of approximately 61.1 HRP.
27. The apparatus of claim 21, wherein the sintered powdered
material comprises a density of approximately 4.35 g/cc and a
hardness of approximately 70.3 HRP.
28. The apparatus of claim 21, wherein the sintered powdered
material comprises a density of approximately 4.69 g/cc and a
hardness of approximately 75.4 HRP.
29. The apparatus of claim 21, wherein the sintered powdered
material comprises a density of approximately 5.34 g/cc and a
hardness of approximately 92.2 HRP.
30. The apparatus of claim 21, wherein the sintered powdered
material comprises a density range of 2.7 g/cc to 8 g/cc.
31. The apparatus of claim 21, wherein the sintered powdered
material comprises a hardness range of 48.8593 HRP to 128.1844 HRP.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Non-provisional
application Ser. No. 15/506,195 filed Feb. 23, 2017, which is a 371
of International Application No. PCT/US15/47581, filed Aug. 28,
2015, which claims priority to U.S. Provisional Application No.
62/043,072, filed Aug. 28, 2014.
FIELD
[0002] The invention generally relates to methods and apparatus for
testing shaped charges. More particularly, the invention relates to
the use of shape charge targets composed of synthetic
materials.
BACKGROUND OF THE INVENTION
[0003] Generally, when completing a subterranean well for the
production of fluids, minerals, or gases from underground
reservoirs, several types of tubulars are placed downhole as part
of the drilling, exploration, and completions process. These
tubulars can include casing, tubing, pipes, liners, and devices
conveyed downhole by tubulars of various types. Each well is
unique, so combinations of different tubulars may be lowered into a
well for a multitude of purposes.
[0004] A subsurface or subterranean well transits one or more
formations. The formation is a body of rock or strata that contains
one or more compositions. The formation is treated as a continuous
body. Hydrocarbon deposits may exist within the formation.
Typically a wellbore is drilled from a surface location, placing a
hole into a formation of interest. Completion equipment is placed
downhole after drilling, including casing, tubing, and other
downhole equipment as needed. Perforating the casing and the
formation with a perforating gun is a well known method in the art
for accessing hydrocarbon deposits within a formation from a
wellbore.
[0005] Explosively perforating the formation using a shaped charge
is a widely known method for completing an oil well. A shaped
charge is a term of art for a device that when detonated generates
a focused explosive output. This is achieved in part by the
geometry of the explosive in conjunction with an adjacent liner.
Generally, a shaped charge includes a metal case that contains an
explosive material with a concave shape and has a thin metal liner
on the inner surface of the explosive material. Many materials are
used for the liner including brass, copper, tungsten, and lead.
When the explosive detonates the liner metal is compressed into a
super-heated, super pressurized jet that can penetrate metal,
concrete, and rock.
[0006] A perforating gun has a gun body. The gun body typically is
composed of metal and is cylindrical in shape. Within a typical gun
tube is a charge holder or carrier tube, which is a tube that is
designed to hold the actual shaped charges. The charge holder
contains cutouts called charge holes where the shaped charges are
placed.
[0007] A shaped charge is typically detonated by a booster or
igniter. Shaped charges may be detonated by electrical igniters,
pressure activated igniters, or detonating cord. One way to ignite
several shaped charges is to connect a common detonating cord that
is placed proximate to the igniter of each shaped charge. The
detonating cord is comprised of material that explodes upon
ignition. The energy of the exploding detonating cord can ignite
shaped charges that are properly placed proximate to the detonating
cord. Often a series of shaped charges may be daisy chained
together using detonating cord.
[0008] Shaped charges are tested to ensure quality control as well
as determine performance characteristics. A common test is to place
a shaped charge on top of a plate and concrete cylinder. A steel
jacket may surround the concrete cylinder. The test setup is
typically located in a bunker for safety reasons. The shaped charge
is then detonated remotely from a control station. The concrete
cylinder is then opened up to determine the depth of the
penetration as well as the deviation of the hole from the center of
the cylinder. One problem with this method is that the concrete is
always curing and is therefore not shelf stable for long periods of
time. A further problem with concrete targets is that its
properties (such as compressive strength and density) in general
are difficult to control, resulting in inconsistent test data.
Concrete is also too soft to gauge shaped charge performance in
hard rock applications.
[0009] Natural rock targets are also commonly used for testing for
improved accuracy of down hole charge performance. Berea sandstone
is one of the most common natural rock targets. These rock targets
are generally expensive. Moreover, availability of specific
examples is sometimes limited. Rock targets also require
complicated confinement designs to simulate the natural stresses in
oil and gas producing formations.
[0010] Solid steel targets are used for targets. One problem with a
steel target is that it is non-porous. An explosive jet passing
through a porous medium versus a non-porous one may exhibit
significant differences. This results in test data that is not
always applicable to the field. Also, steel has a high compressive
strength that makes it not suitable for simulating medium or soft
formations.
[0011] Aluminum targets are also used to test shaped charges.
Aluminum has the same problem as steel in that it is non-porous.
Another problem with aluminum is that it may react with the
materials in the high explosive jet. These reactions may result in
disruption of the jet and erratic penetration patterns. Both of
these problems result in inconsistent test data that does not
always apply to field conditions.
SUMMARY OF EXAMPLES OF THE INVENTION
[0012] An example of the invention may include a shaped charge
target puck comprising a powdered material, wherein the powder is
pressed into a cylindrical shape and then sintered. A variation of
the example may include the powdered material comprising powdered
iron, powdered carbon, powdered copper, or powdered molybdenum, or
any combination of the identified materials. A variation of the
example may include the target comprising a density of
approximately 3.34 g/cc with a hardness of approximately 61.1 HRP,
approximately 4.35 g/cc with a hardness of approximately 70.3 HRP,
approximately 4.69 g/cc with a hardness of approximately 75.4 HRP,
or approximately 5.34 g/cc with a hardness of approximately 92.2
HRP. A variation of the example may include the target comprising a
density range of 2.7 g/cc to 8 g/cc. A variation of the example may
include the target comprising a hardness range of 48.8593 HRP to
128.1844 HRP.
[0013] Another example of the invention may include a method for
testing a shaped charge comprising pressing a powdered material
into a disc, sintering the disc, placing the disc proximate to a
shaped charge, and firing the shaped charge into the disc. A
variation of the example may include the disc being between 1 and 4
inches diameter. The example may further comprise placing a metal
plate between the shaped charge and the disc. The example may
further comprise hardness testing the disc. The example may further
comprise stacking one or more discs underneath the first disc to
form a plurality of discs. The example may further comprise placing
the plurality discs in a test fixture. The example may further
comprise saturating the plurality of discs with a fluid. The
example may further comprise applying a compressive radial stress
to the plurality of discs. The example may further comprise
applying a compressive axial stress to the plurality of discs. A
variation of the example may include the powdered material
including a powdered wax component that is burned off during the
sintering process. A variation of the example may include the
powdered material including lubricating additives that burns off
during the sintering process.
[0014] Another example of the invention may include a shaped charge
test apparatus comprising a first end cap adapted to accept a
shaped charge, a second end cap, and a body containing a hollow
cylindrical interior adapted for accepting a plurality of synthetic
target discs. The example may further comprise a first reservoir
within the body adapted to contain a first fluid. The example may
further comprise a second reservoir within the first end cap
adapted to contain a second fluid. The example may further comprise
synthetic target discs being composed of sintered powdered
material. The example may include the powdered material being
composed of a metallic powder. The example may further include the
second end cap having a through opening. The example may further
include a shape charge being oriented to fire through the second
fluid and the plurality of synthetic target discs.
[0015] Another example of the invention may include a shaped charge
test apparatus comprising a cylindrical fixture with a hollow
portion adapted for accepting a plurality of synthetic target
cylinders about its outer surface, and having a hallow annulus
adapted to accept a perforating gun. A variation of the example may
include the plurality of synthetic target cylinders located
perpendicular to the outer surface of the cylindrical fixture. A
variation of the example may include each synthetic target cylinder
further comprises a plurality of synthetic targets stacked inside.
Furthermore, each synthetic target may comprise a powdered
material, wherein the powder is pressed into a cylindrical shape
and then sintered. A variation of the example may include the
powdered material comprising powdered iron, powdered carbon,
powdered copper, or powdered molybdenum, or any combination of the
identified materials. A variation of the example may include the
powdered material comprising a density of approximately 3.34 g/cc
with a hardness of approximately 61.1 HRP, approximately 4.35 g/cc
with a hardness of approximately 70.3 HRP, approximately 4.69 g/cc
with a hardness of approximately 75.4 HRP, or approximately 5.34
g/cc with a hardness of approximately 92.2 HRP. A variation of the
example may include the powdered material comprising a density
range of 2.7 g/cc to 8 g/cc. A variation of the example may include
the powdered material comprising a hardness range of 48.8593 HRP to
128.1844 HRP.
DESCRIPTION OF THE DRAWINGS
[0016] For a thorough understanding of the present invention,
reference is made to the following detailed description of the
preferred embodiments, taken in conjunction with the accompanying
drawings in which reference numbers designate like or similar
elements throughout the several figures. Briefly:
[0017] FIG. 1 is a shaped charge.
[0018] FIGS. 2A, 2B, and 2C are different views of a synthetic
target.
[0019] FIG. 3 is a cross section of a perforating gun.
[0020] FIG. 4 is shaped charge test setup.
[0021] FIG. 5 is a perforating gun test setup.
[0022] FIG. 6 is a shaped charge test setup.
DETAILED DESCRIPTION OF EXAMPLES OF THE INVENTION
[0023] In the following description, certain terms have been used
for brevity, clarity, and examples. No unnecessary limitations are
implied and such terms are used for descriptive purposes only and
are intended to be broadly construed. The different apparatus and
method steps described herein may be used alone or in combination
with other systems and method steps. It is to be expected that
various equivalents, alternatives, and modifications are possible
within the scope of the appended claims.
[0024] Referring to an example shown in FIG. 1, a shaped charge 12
includes a shaped charge case 28 that holds the energetic material
26 and the liner 27. The shaped charge case 28 typically is
composed of a high strength metal, such as alloy steel. The liner
27 is usually composed of a powdered metal that is either pressed
or stamped into place. The metals used in liner 27 may include
brass, copper, tungsten, and lead. The retainer fitting 30 is
secured to the end fitting 46 of the shaped charge case 28 by
snapping into place over a flange on end fitting 46. The entire
assembly 40 includes shaped charge 12 combined with retainer
fitting 30. Alternatively, the fitting 30 could be threaded onto
the charge case 18, secured with adhesive, snapped around the full
length of the charge case, or formed integrally with the charge
case. The fitting 30 could also be secured to the charge case 18
using set screws, roll pins, or any other mechanical attachment
mechanisms. Alternatively, shaped charge case 28 could be
integrally formed to retaining fitting 30. This would result in a
single component, thus reducing cost and complexity.
[0025] An example synthetic target is shown in FIGS. 2A, 2B, and
2C. The synthetic target 101 in this example is approximately two
inches in diameter and one inch in depth. The depth and the
diameter may vary. Other dimensions may include a four inch
diameter disc with a two inch depth. The synthetic target 101 can
be composed of metal powder. The synthetic target 101 may be
composed of a combination of metal and ceramic powders. The powder
used could include one or more of the elements iron, carbon,
copper, and molybdenum. The powder is pressed into the shape of a
disk. The pressed synthetic target 101 is then sintered in an inert
atmosphere. Afterwards it may be allowed to furnace cool. The
indicator 102 designates the top surface of the synthetic target
101 for testing and quality control purposes. The side pressed down
on, in this case the top surface with the indicator 102, may
exhibit a different hardness value than the bottom surface. In this
example the synthetic target 101 is shaped as a disk or puck,
however it may be shaped in any number of configurations, including
rectangular, square, oval, or any other configuration
necessary.
[0026] An example of a powder mix for the synthetic target 101 may
include North American Hoganas R 12 Fe with 10% RXM 100 Cu powder
plus 1.5% Mo (-325 mesh), +1.5% graphite, and Asbury 1651+0.75%
Acrawax X atomized lubricant powder. Wax and lubricating additives
can be used in the powder mix. Common examples of lubricating
additives include carbon or graphite. The wax and lubricating
additives make the powder metal easier to process. Furthermore,
during the sintering process the wax and lubricating additives burn
off and create voids in the synthetic target 101. These voids give
the synthetic target 101 its low density and high porosity if that
is desired. The range of likely densities sought for the synthetic
targets is between 2.7 and 8.0 g/cc. The potential hardness values
associated with that range of density is from 40 to 150 HRP.
[0027] An important advantage of synthetic targets over concrete is
that they are shelf stable. Synthetic targets can be stored for
long periods of time without changing their performance. However,
concrete continues to cure, thus making it stronger and harder with
time.
[0028] An advantage of using synthetic targets is that it the
density and hardness are easily changed in order to accommodate
specific testing requirements. For example, a pressed density of
3.5 g/cc may result in a sintered density of 3.56 g/cc and a
Brinell hardness of 23.3 HB 10/500. Another example may include a
pressed density of 4.4 g/cc, resulting in a sintered density of
4.34 g/cc and a Brinell hardness of 43.2 HB 10/500. Another example
may include a pressed density of 5.0 g/cc, resulting in a sintered
density of 4.84 g/cc and a Brinell hardness of 56.7 HB 10/500.
Another example may include a pressed density of 5.6 g/cc,
resulting in a sintered density of 5.4 g/cc and a Brinell hardness
of 71.8 HB 10/500. These examples provide the ability to evaluate
shaped charge performance across a broad range of formation
stresses and naturally occurring rocks with differing
properties.
[0029] In some applications Rockwell Hardness P (HRP) is a better
measurement of hardness for synthetic targets. In at least one
example, a measured density of 3.34 g/cc corresponds to an average
measured hardness of approximately 61.1 HRP. In at least another
example, a measured density of 4.35 g/cc corresponds to an average
measured hardness of approximately 70.3 HRP. In at least another
example, a measured density of 4.69 g/cc corresponds to an average
measured hardness of approximately 75.4 HRP. In at least another
example, a measured density of 5.34 g/cc corresponds to an average
measured hardness of approximately 92.2 HRP. In another example the
density may range from 2.7 g/cc to 8 g/cc, corresponding to a range
of hardness of approximately 48.8593 HRP to 128.1844 HRP.
[0030] Referring to an example shown in FIG. 3, a typical
perforating gun 10 comprises a gun body 11 that houses the shaped
charges 12. The gun body 11 contains end fittings 16 and 20 which
secure the charge holder 18 into place. The charge holder 18 in
this example is a charge tube and has charge holes 23 that are
openings where shaped charges 12 may be placed. The charge holder
18 has retainer cutouts 31 that are adapted to fit a retainer
fitting 30 in a predetermined orientation. The gun body 11 has
threaded ends 14 that allow it to be connected to a series of
perforating guns 10 or to other downhole equipment depending on the
job requirements. In this example the retainer fitting 30 is
separate from the charge holder 18, however in another variation of
the embodiment that retainer fittings 30 may be integral to the
charge holder 18. Each shaped charge 12 has an associated retainer
fitting 30 that secures each shaped charge 12 to the charge holder
18 and the detonating cord 32. The detonating cord 32 runs the
majority of the length of the gun body 11 beginning at end cap 48
and ending at end cap 49. The detonating cord 32 wraps around the
charge holder 18 as shown to accommodate the different orientations
of the shaped charges 12. In this embodiment, the shaped charges 12
have an orientation that is rotated 60 degrees about the center
axis of the gun body 11 from one shaped charge to the next. Other
orientations may include a zero angle, where all of the shaped
charges 12 are lined up. Other orientations may have different
angles between each shaped charge 12. This example using a 60
degree phase is illustrative and not intended to be limiting in
this regard.
[0031] Referring to FIG. 4, a shaped charge 50 is tested with a
test fixture 61 to simulate perforating in downhole conditions. In
this test setup the shaped charge 50 may be secured to a piece of
casing 53, simulating the perforating gun casing that is penetrated
during the perforating event. A fluid barrier 55 is created wherein
a void in the test fixture 61 is filled with a fluid. This
simulates the fluid existing in the annulus between the perforating
gun and the downhole casing. In this case the fluid may include
water, drilling mud, or other fluids or combinations of fluids of
interest that may be found downhole. A metallic barrier 62
simulates the casing. A concrete barrier 56 simulates the presence
of concrete between the casing and the formation. The formation
material 59 is comprised of one of more cylindrical synthetic
target segments 63. These segments may be the same hardness or a
variety of hardness values to simulate different formations. The
formation material 59 may be sealed and filled with a fluid to
saturate the synthetic target segments 63. The fluid used to
saturate the formation material 59 may include water, mineral
spirits, paint thinner, or some other fluid or combinations of
fluids.
[0032] The test fixture 61 contains a body 57, a top cap 54, and a
bottom cap 60. The bottom cap 60 may have an opening to atmosphere
or it may be sealed with a base plate. The base plate may have a
hole that may include threads or some other mechanism for adapting
the hole to a fitting. The test fixture 61 may include a fluid
space 58 that wraps around the test fixture in 360 degrees. The
fluid space 58 may be pressurized in order to apply a radial
pressure against the formation material 59.
[0033] Another test setup is illustrated in FIG. 5 wherein an
existing perforating gun 82 is placed inside a piece of well casing
80 with test specimens 81 attached externally. In this example the
test specimens 81 may be hollow to allow synthetic target segments
63 to be stacked inside. However, the test specimens 81 may also be
a solid piece of metal or a solid synthetic target. The test
specimens 81 may attach to the well casing 80 of the perforating
gun 81. The attaching means may include threads, clips,
interference fit, or some type of adhesive. Once the test specimens
81 are in place the perforating gun 82 fires, sending the explosive
energy of each shaped charge through the well casing 80 and into
each test specimen 81. This test setup allows for a full up gun
system test.
[0034] Another test setup may include a shaped charge attached to a
synthetic target as shown in FIG. 6. In this setup a detonating
cord 91 is attached to a shaped charge 92. The shaped charge 92 is
then flush with standoff 93. The standoff 93 may be a hollow
cylinder spacer or a solid material. The standoff 93 may include a
liquid, gas, or solid barrier for the shaped chare 92 to perforate.
A scallop plate 94 is below the standoff. The scallop plate 94
simulates the outer casing of a perforating gun. A clearance means
95 is located below the scallop plate 94. The clearance means 95
may include a cylindrical or square device that may be hollowed and
filled with water, gas or a solid material. The clearance means 95
simulates that distance inside a wellbore between the casing and
the perforating gun. The wellbore is typically full of water, oil,
drilling fluids, or some combination of fluids. The clearance means
95 may be filled with any fluid or combination of fluids that may
exist in a wellbore. The casing of a wellbore is simulated using a
steel plate 96. A synthetic target 97 is then located below the
steel plate 96. The synthetic target 97, as disclosed herein, may
be composed of a variety of materials at a variety of densities,
porosities, or hardness.
[0035] In the test setup show in in FIG. 6 a shaped charge 92 is
detonated by a detonating cord 91. The explosive blast of the
shaped charge 92 will penetrate the standoff 93, the scallop plate
94, the clearance means 95, the steel plate 96, and the synthetic
target 97. In this example only one synthetic is shown, however
synthetic targets could be stacked in order to make a longer
distance of material for the shaped charge 92 to penetrate. The
entire setup may be fastened together using tape, adhesives, a
mechanical device to hold the items 91-97 together, or some
combination thereof.
[0036] Although the invention has been described in terms of
particular embodiments which are set forth in detail, it should be
understood that this is by illustration only and that the invention
is not necessarily limited thereto. Alternative embodiments and
operating techniques will become apparent to those of ordinary
skill in the art in view of the present disclosure. Accordingly,
modifications of the invention are contemplated which may be made
without departing from the spirit of the claimed invention.
* * * * *