U.S. patent application number 13/712534 was filed with the patent office on 2014-06-12 for devices and methods for conveying a tool along a wellbore.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. The applicant listed for this patent is BAKER HUGHES INCORPORATED. Invention is credited to John G. Evans, Jeffery B. McMeans, Steven R. Radford.
Application Number | 20140158369 13/712534 |
Document ID | / |
Family ID | 50879707 |
Filed Date | 2014-06-12 |
United States Patent
Application |
20140158369 |
Kind Code |
A1 |
Radford; Steven R. ; et
al. |
June 12, 2014 |
DEVICES AND METHODS FOR CONVEYING A TOOL ALONG A WELLBORE
Abstract
An apparatus for flowing a tool string along a wellbore tubular
includes a flow restrictor having a diametrically expanded position
and a diametrically retracted position. The flow restrictor
sealingly engages the wellbore tubular when in the diametrically
expanded position. The apparatus also includes a joint connected to
the flow restrictor. The joint actuates the flow restrictor between
the expanded position to the retracted position while moving
between an open and a closed position.
Inventors: |
Radford; Steven R.; (The
Woodlands, TX) ; McMeans; Jeffery B.; (Spring,
TX) ; Evans; John G.; (The Woodlands, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BAKER HUGHES INCORPORATED |
Houston |
TX |
US |
|
|
Assignee: |
BAKER HUGHES INCORPORATED
HOUSTON
TX
|
Family ID: |
50879707 |
Appl. No.: |
13/712534 |
Filed: |
December 12, 2012 |
Current U.S.
Class: |
166/373 ;
166/316; 166/319; 166/332.1 |
Current CPC
Class: |
E21B 23/10 20130101;
E21B 34/14 20130101 |
Class at
Publication: |
166/373 ;
166/316; 166/319; 166/332.1 |
International
Class: |
E21B 34/06 20060101
E21B034/06; E21B 34/14 20060101 E21B034/14; E21B 34/08 20060101
E21B034/08 |
Claims
1. An apparatus for flowing a tool string along a wellbore tubular,
comprising: a flow restrictor having a diametrically expanded
position and a diametrically retracted position, wherein the flow
restrictor sealingly engages the wellbore tubular when in the
diametrically expanded position; and a joint connected to the flow
restrictor, the joint actuating the flow restrictor between the
expanded position and the retracted position while moving between
an open and a closed position.
2. The apparatus of claim 1, wherein the flow restrictor expands to
engage an inner surface of the wellbore tubular in response to a
pressure applied by a fluid flowing in the wellbore tubular.
3. The apparatus of claim 1 wherein the joint moves between the
open position and the closed position in response to a preset value
of applied tension; and further comprising a conveyance device
connected to the joint, the conveyance device being configured to
apply at least the preset value of the applied tension to the
joint.
4. The apparatus of claim 3, wherein the conveyance device is one
of: (i) a wireline, (ii) a slickline, and (iii) an e-line.
5. The apparatus of claim 3, wherein the joint includes a first
section in sliding engagement with a second section, and further
comprising at least one link having an end connected to the first
section, wherein the at least one link radially rotates when the
first section moves relative to the second section.
6. The apparatus of claim 5, wherein the flow restrictor includes a
support and a ring slidably disposed on the body, the ring being
connected to one of: (i) the at least one link, and (ii) the first
section of the slip joint.
7. The apparatus of claim 6, wherein the flow restrictor further
includes at least one radially projecting petal coupled to the
support, wherein the ring slides over the at least one radially
projecting petal when the joint moves between the open and the
closed position.
8. The apparatus of claim 6, wherein the flow restrictor further
includes a sail coupled to the support, wherein the ring slides
over the sail when the joint moves between the open and the closed
position.
9. The apparatus of claim 5, wherein the flow restrictor includes a
shell enclosing the at least one link.
10. The apparatus of claim 1, wherein the joint includes a first
section in sliding engagement with a second section, wherein the
flow restrictor includes a bellows having an upper end connected to
the first section of the slip joint and a lower end connected to
the second section of the slip joint, and wherein the bellows
diametrically expands when the first section of the slip joint
slides toward the second section of the slip joint.
11. The apparatus of claim 1, further comprising a liner lining the
flow restrictor, the liner being coupled to the joint, wherein the
joint extracts the liner from the flow restrictor while moving from
the closed position to the open position.
12. A method for flowing a tool string along a wellbore tubular,
comprising: disposing a flow restrictor and the tool string into
the wellbore tubular, wherein the flow restrictor has a
diametrically expanded position and a diametrically retracted
position; pumping fluid into the wellbore tubular; propelling the
flow restrictor and the tool string through the wellbore by
sealingly engaging a surface of the wellbore tubular with the flow
restrictor in the diametrically expanded position; actuating the
flow restrictor from the expanded position to the retracted
position by applying a tension force on a joint connected to the
flow restrictor; and retrieving the flow restrictor from the
wellbore tubular while the flow restrictor is in the retracted
position.
13. The method of claim 12, further comprising expanding the flow
restrictor to engage an inner surface of the wellbore tubular using
a pressure applied by the fluid flowing in the wellbore
tubular.
14. The method of claim 12 further comprising connecting a
conveyance device to the joint, and using the conveyance device to
apply at least a preset value of tension to move the joint between
the open position and the closed position.
15. The method of claim 12, wherein the joint includes a first
section in sliding engagement with a second section, and wherein
the tension force applied to the first section actuates the flow
restrictor to the retracted position.
16. The method of claim 12, wherein the flow restrictor includes at
least one of: (i) at least one radially projecting petal, (ii) a
sail, (iii) a shell and (iv) a bellows.
17. The method of claim 12, further diametrically expanding the
flow restrictor by using at least one link connected to the
joint.
18. The method of claim 12, wherein a liner lining the flow
restrictor, and further comprising extracting the liner from the
flow restrictor while moving from joint from the closed position to
the open position.
Description
BACKGROUND OF THE DISCLOSURE
[0001] 1. Field of the Disclosure
[0002] This disclosure relates generally to method and devices for
conveying tools along a wellbore.
[0003] 2. Background of the Art
[0004] During the drilling, completion, workover, and remediation
of a hydrocarbon-producing wellbore, it may be necessary to convey
a tool string to one or more target depths along that wellbore. One
conventional method for conveying a tool string along a wellbore is
a "pump down" operation. A "pump down" operation typically involves
pumping a liquid (e.g., water) to propel a tool string along a
wellbore tubular in the wellbore. The tool string may include "swab
cups" or other fixed annular rings or fins that resist fluid flow.
For wellbores that have extended non-vertical sections, a
significant amount of fluid must flow past the swab cups at a high
flow rate in order to provide this propulsive force.
[0005] In some aspects, the present disclosure addresses the need
for devices and methods that can reduce the amount of fluid needed
for pump down operations.
SUMMARY OF THE DISCLOSURE
[0006] In one aspect, the present disclosure provides an apparatus
for flowing a tool string along a wellbore tubular. The apparatus
may include a flow restrictor having a diametrically expanded
position and a diametrically retracted position. The flow
restrictor sealingly engages the wellbore tubular when in the
diametrically expanded position. The apparatus also includes a
joint connected to the flow restrictor. The joint actuates the flow
restrictor between the expanded position and the retracted position
while moving between an open and a closed position.
[0007] In another aspect, the present disclosure provides a method
for flowing a tool string along a wellbore tubular. The method may
include disposing a flow restrictor and the tool string into the
wellbore tubular, wherein the flow restrictor has a diametrically
expanded position and a diametrically retracted position; pumping
fluid into the wellbore tubular; propelling the flow restrictor and
the tool string through the wellbore by sealingly engaging a
surface of the wellbore tubular with the flow restrictor in the
diametrically expanded position; actuating the flow restrictor from
the expanded position to the retracted position by applying a
tension force on a joint connected to the flow restrictor; and
retrieving the flow restrictor from the wellbore tubular while the
flow restrictor is in the retracted position.
[0008] Examples of certain features of the disclosure have been
summarized rather broadly in order that the detailed description
thereof that follows may be better understood and in order that the
contributions they represent to the art may be appreciated. There
are, of course, additional features of the disclosure that will be
described hereinafter and which will form the subject of the claims
appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] For a detailed understanding of the present disclosure,
reference should be made to the following detailed description of
the embodiments, taken in conjunction with the accompanying
drawings, in which like elements have been given like numerals,
wherein:
[0010] FIG. 1 illustrates a well that may use flow tools in
accordance with the present disclosure;
[0011] FIG. 2 schematically illustrates a flow tool made in
accordance with one embodiment of the present disclosure;
[0012] FIG. 3 schematically illustrates an embodiment of a flow
tool made in accordance with one embodiment of the present
disclosure that uses petals as a flow restrictor;
[0013] FIG. 4 schematically illustrates an embodiment of a flow
tool made in accordance with one embodiment of the present
disclosure that uses a sail as a flow restrictor;
[0014] FIGS. 5 and 6 schematically illustrate an embodiment of a
flow tool made in accordance with one embodiment of the present
disclosure that uses a flexible shell as a flow restrictor;
[0015] FIGS. 7 and 8 schematically illustrate an embodiment of a
flow tool made in accordance with one embodiment of the present
disclosure that uses bellows as a flow restrictor;
[0016] FIG. 9 schematically illustrates an embodiment of a slip
joint for use with bellows; and
[0017] FIG. 10 schematically illustrates an embodiment of a slip
joint for use with an umbrella-type of flow restrictor.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0018] In aspects, the present disclosure provides methods and
devices that can reduce the amount of fluid used while conveying a
tool along a wellbore. FIG. 1 illustrates an exemplary wellbore 10
that has been drilled through the earth 12 and into formations 14,
16 from which it is desired to produce hydrocarbons. The wellbore
10 may be cased by metal casing, as is known in the art. The
wellbore 10 may have a vertical leg 17 and a non-vertical leg 19.
While leg 19 is shown substantially horizontal, a non-vertical leg
may be inclined between a vertical and horizontal. The wellbore 10
has a wellbore tubular 20 that extends downwardly from a wellhead
24 at the surface 26 of the wellbore 10. The wellbore tubular 20
may be formed of known wellbore tubulars such as drill string,
jointed pipe, coiled tubing, or production tubing. The wellbore
tubular 20 defines an internal axial flowbore 28 along its length.
An annulus 30 is defined between the production assembly 20 and the
wellbore casing.
[0019] Also shown in FIG. 1 is a tool string 40 configured to
perform one or more selected operations in the wellbore 10. The
tool string 40 may include perforating guns, packers, bridge plugs,
circulating subs, casing collar locators, formation evaluation
tools, casing or pipe evaluation tools, wellbore evaluation tools,
frac tools, well treatment equipment, and/or other tools used in
the course of completing, recompleting, logging, evaluating,
remediating, or working over the wellbore 10. The tool string 40
may be tethered to a non-rigid conveyance device 42 such as a
wireline (power and data), an e-line (power only), or a slickline
(no power or data). The non-rigid conveyance 42 may be a flexible
cable that has sufficient tensile strength to pull the tool string
40 out of the wellbore 10. A fluid mover 44 may be used to pump
pressurized fluid into the wellbore tubular 20. The fluid mover 44
may be a pump for pumping water, drilling mud, or any other
suitable liquid carrier into the flow bore 28 of the tubing 20.
This fluid may return via the annulus 30 to the surface. The tool
string 40 may include one or more flow tools that use adjustable
flow restrictors to selectively block fluid flow along the wellbore
tubular 20. Specifically, these flow tools can open to propel the
tool string 40 into the wellbore 10 and then close while retrieving
the tool string 40 out of the wellbore 10. Illustrative embodiments
are discussed in connection with FIGS. 2-9 below.
[0020] Referring to FIG. 2, there is shown one embodiment of a flow
tool 50 in accordance with the present disclosure. The flow tool 50
may be connected to a tool string 52 that is configured to perform
one or more desired well operations. The flow tool 50 may include a
variable diameter flow restrictor 54 that is actuated by a slip
joint 56. Centralizers 59, which may be bow springs, ribs or
stands, may be used to center the flow tool 50 in the wellbore
tubular 20. The flow restrictor 54 is an annular-shaped member that
can diametrically expand and retract to block flow along an annulus
55 between the wellbore tubular 20 and the flow tool 50. In the
diametrically expanded condition, the flow restrictor 54 may be
approximately the same diameter as an inner diameter of a wellbore
tubular 20 and form a sliding seal with the adjacent wellbore wall
21. This form of contact may be referred to a hydraulic sealing
engagement or simply `sealing engagement,` but does not require
physical contact between adjacent surfaces. Rather, fluid flow is
sufficiently restricted to generate pressure differential
sufficient to propel the flow tool 50 along the wellbore. A space
or gap may separate the flow restrictor 54 partially or completely
along a circumference during a sealing engagement. This seal allows
the relatively higher pressure uphole of the flow tool 50 to propel
the tool string 52 through the wellbore tubular. Moreover, the seal
may be compliant in that the flow restrictor 54 may bend or deform
as needed to pass through obstructions along the flow bore 20 and
expand once the obstruction has been passed. It should be
understood that the seal need not be a fluid-tight seal and that
some fluid flow may still occur through the seal.
[0021] Referring now to FIGS. 2 and 3, there is shown a flow tool
50 that uses flow restrictor 54 formed as petals 62. The petals 62
may be segmented pie-shaped members that are circumferentially
arrayed around a body or support 64. The support 64 may be a
mandrel, a tube, a rod, or other suitable support member. The
petals 62 may be interleaved and fixed at one end to the support
64. Thus, the petals 62 rotate about the fixed end when opening.
When open, the petals 62 form a basket shape that captures flowing
fluids. The petals 62 may be formed of a metal, an elastomeric
material (e.g., rubber), and/or a composite material. As seen in
FIG. 2, in some embodiments, the flow tool 50 may also include a
liner 58 that lines the radially inner surface of the petals 62.
The liner 58, which may also be connected to the slip joint 56,
catches debris and other material that may otherwise become lodged
in the petals 62.
[0022] FIG. 4 shows an embodiment of a flow tool 50 that is similar
to that shown in FIGS. 2 and 3. However, in the FIG. 4 embodiment,
the flow restrictor 54 is formed as a sail 72 (or canopy) that is
fixed to the support 64. The sail 72 may include pleats for folding
into a compact condition. In embodiments, the sail 72 may include
rigid or semi-rigid support members 74 such as rods that assist in
the sail 72 having a pre-defined shape (e.g., annular) when opened.
The sail 72 may open in an umbrella-type fashion with the concave
side facing the downwardly flowing fluid. The sail 72 may be formed
of pliant materials such as fabric, cloth, an elastomer, or
suitable material.
[0023] Referring to FIGS. 2-4, the petals 62 or the sail 72 may be
closed using a ring 66 that may be pulled around the petals 62. The
ring 66 may be disposed on the outer surface of the support 64 such
that the ring 66 can slide axially over the petals 62 or the sail
72. In the first position shown in FIG. 2, the ring 66 may be
positioned near the support 64 so that the petals 62 or the sail 72
are free to expand diametrically. In the second position shown in
FIG. 4, the ring 66 slides over and compacts the petals 62 or the
sail 72.
[0024] Referring to FIG. 4, in embodiments, the slip joint 56 may
be used to axially slide the ring 66 between the first position at
the support 64 and the second position around the petals 62 or the
sail 72. The slip joint 56 may be a tubular assembly that can
axially lengthen and shorten depending on the amount of applied
tension. In some arrangements, the slip joint 54 may be a
telescoping type device that has an upper section 78 that is
connected to a lower section 80. The upper and lower sections 78,
80 may slide relative to one another. The upper section 78 may be
connected to the conveyance device 42 (FIG. 2) and the lower
section may be connected to the ring 66 using one or more links 82.
The links 82 may pass through slots (not shown) or other suitable
openings in the petals 62 or the sail 72. The ring 66 may also be
axially displaced by other arrangements such as tethers or cables
that go over the sail 72. When the joint 56 is in the axially
shortened condition, the ring 66 is near or at the support 64.
Axial movement of the upper section 78 away from the lower section
80 pulls the links 72 away from the lower section 80 and slips over
the ring 66 and retracts the flow petals 62 or the sail 72.
[0025] The slip joint 56 may also be configured to pull the liner
58 out of the petals 62 or the sail 72 before either of these
features are closed. For example, the liner 58 may be connected by
a suitable linkage or wire to the upper section 78. The connection
may be arranged that the liner 58 is moved before the petals 62 or
sail 72 are closed.
[0026] Depending on the application, additional features may be
used to facilitate the opening and closing of the flow restrictor
50. For example, biasing elements such as springs may be used to
urge the slip joint 56 to either the open or the closed position.
Similarly, biasing elements may be used to urge the flow restrictor
50 to either the diametrically expanded or the diametrically
retracted condition. These biasing elements may be used to
establish a force value (e.g., tension, pressure, etc.) that must
be exceeded for an action to occur or to provide additional force
for moving or shifting to a particular position or condition.
[0027] An exemplary mode of use will be described in connection
with FIGS. 1-4. To begin, the flow tool 50 and the tool string 52
are inserted into the wellbore tubular 20 (FIG. 1). The tool string
52 may be coupled to a conveyance device such as a wireline 24.
Initially, the lower section 80 positions the ring 66 such that the
petals 62 are free to radiate outward and obstruct the flowing
fluid. The flow tool 50 and the tool string 52 may travel primarily
under the force of gravity down the vertical section 17 and then
enter the horizontal section 19. Because no fluid is being pumped
into the wellbore tubular 20 during this initial descent, the
petals 62 remain in a generally retracted condition. After entry
into the horizontal section 19, or when gravity can no longer move
the tool string 52, a fluid, such as water, is pumped into the
wellbore tubular 20 using a fluid mover 44 (FIG. 1). The flowing
fluid causes the petals 62 to rotate radially outward and contact
the adjacent wellbore tubular surface 21. This fluid obstruction
generates a pressure differential that propels the tool string 52
along the wellbore tubular 20. When the tool string 52 is
positioned at the desired depth along the wellbore, the fluid
circulation is stopped and one or more desired well operations may
commence.
[0028] After one or more desired well operations are completed, a
tension is applied to the wireline 42. When the tension exceeds the
activation level of the slip joint 56, the slip joint 56 axially
lengthens. This lengthening is caused by the upper section 78
moving away from the lower section 80 and the petals 62. As the
upper section 78 slides upward, the connected links 82 pull the
ring 66 over the outer surfaces of the petals 64, which collapses
the petals 64 into a radially compact closed position. At this
stage, the tool string 52 and the flow tool 50 may be retrieved
from the wellbore. It should be appreciated that the sail 72 of the
FIG. 4 embodiment may also be deployed in a similar manner.
[0029] Referring now to FIG. 5, there is shown another flow tool 50
according to the present disclosure wherein a flow restrictor is
formed as a shell. The flow tool 50 may include expandable members
102, a shell 104 enclosing the expandable members 102, and a slip
joint 56. The expandable members 102 may be rods, arms, plates,
strips, bands, tubes, or other like structures that are suitable
for displacing the shell 104 radially outward. In one arrangement,
the expandable members 102 may include one or more
circumferentially arrayed link assemblies 106 that extend radially
outward when compressed. The link assemblies 106 may include pair
hinged links that are connected between the upper section 78 of the
slip joint 56 and the lower section 80 of the slip joint 56. The
shell 104 may be shaped as a sleeve that is connected at the upper
end to the upper section 78 and the lower section 80 using suitable
fastening elements such as bands 108. The shell 104 may be formed
of a pliant material; e.g., a sheet of a rubber-type material that
includes woven fabric layers or other flexible material suitable
for downhole use. In some embodiments, the outer surface of the
shell 104 may include features such as ribs 110 to enhance a
sealing contact with an adjacent wellbore tubular surface. Also,
the shell 104 may include rigid or semi-rigid support members such
as rods (not shown) that assist the shell 104 to have a pre-defined
shape (e.g., annular) when opened.
[0030] When the slip joint 56 closes, the links 106 rotate as they
are pushed together and move to an extreme outer diametrical
position, which expands the shell 104 to a diametrically enlarged
position. When the slip joint 56 opens, the links 106 are pulled
apart and radially retract toward the slip joint 56. FIG. 6 shows
the links 106 in a diametrically retracted condition where the slip
joint 56 is open and the expandable members 102 are diametrically
retracted.
[0031] Referring now to FIG. 7, there is shown yet another
embodiment of a flow tool 50 in accordance with the present
disclosure wherein the flow restrictor is formed as bellows. The
flow tool 50 may include bellows 120, and a slip joint 56. The
bellows 120 may include a foldable sleeve 122 made of a suitable
flexible material. Fastening elements 124 may be used to attach the
distal ends of the bellows 120 to the slip joint upper and lower
sections 78, 80, respectively. When the slip joint 56 is an axially
shortened condition (closed), the bellows 120 is folded and
compressed, which causes the material of the sleeve 122 to radially
expand and obstruct the fluid flow path between the pump down tool
50 and an adjacent wellbore tubular wall. When a preset amount of
tension is applied, the upper section 78 and the lower section 80
of the slip joint 56 move axially away from one another. This
relative motion causes the slip joint 56 to radially lengthen and
unfold the bellows 120, which causes a minimal flow obstruction
along the flow tool 50 as shown in FIG. 8.
[0032] Referring now to FIG. 9, there is shown an embodiment of a
slip joint 56 that may be used to actuate the bellows 120. The flow
tool 50 may include bellows 120, and a slip joint 56. The bellows
120 is shown in the de-activated position wherein fluid flow
through the annulus 55 is only minimally blocked. This de-activated
position is associated with the slip joint 56 being in an open
position, i.e., axially lengthened. The slip joint 56 includes an
upper section 78 that may be formed as a cylinder 130 and a lower
section 80 can includes a piston 132 that reciprocates in the
cylinder 130. A shaft 134 may connect the piston 132 to the lower
end of the tool string 40. In some embodiments, the slip joint 56
may include a biasing element 136 to urge or push the piston 132
toward a desired position (e.g., open or closed). The biasing
element 136 may be a coiled spring, leaf spring, spring washers, or
other similar structure for applying a biasing force to the piston
132. In FIG. 9, the biasing element 136 is shown pushing the piston
132 uphole, which would tend to close the slip joint 56 and
maintain the bellows 120 in the diametrically expanded,
flow-blocking condition. Thus, applying a tension force on the
conveyance device 42 (FIG. 1) overcomes the spring force of the
biasing element 136, which opens the slip joint 56 and closes
retracts the bellows 120.
[0033] Referring now to FIG. 10, there is shown an embodiment of a
slip joint 56 that may be used to actuate a sail, petals, or other
umbrella-type of flow restrictors that spread and retract
circumferentially. The flow tool 50 may include a variable diameter
umbrella-type flow restrictor 150 and a slip joint 56. The flow
restrictor 150 is shown in the activated position wherein fluid
flow through the annulus 55 is substantially blocked. This
activated position is associated with the slip joint 56 being in a
closed position, i.e., axially shortened. The slip joint 56
includes an upper section 78 that may be formed as a cylinder 130
and a lower section 80 can includes a piston 132 that reciprocates
in the cylinder 130. A shaft 134 may connect the piston 132 to the
lower end of the tool string 40. In some embodiments, the slip
joint 56 may include a biasing element 136 to urge or push the
piston 132 toward a desired position (e.g., open or closed). The
biasing element 136 may be a coiled spring, leaf spring, spring
washers, or other similar structure for applying a biasing force to
the piston 132. An expander 152 may be used to expand and retract
the flow restrictor 150. An expander 152 may be connected to the
upper section 78 and slide along an inner surface of the flow
restrictor 150. The flow restrictor 150 is connected at one end to
the lower section 80.
[0034] In FIG. 10, the biasing element 136 is shown pushing the
piston 132 uphole, which would tend to close the slip joint 56 and
maintain the flow restrictor 150 in the diametrically expanded,
flow-blocking condition. When the expander 152 slides axially away
from the free end of the flow restrictor 150 to the connected end
of the flow restrictor 150, the flow restrictor 150 expands
diametrically outward. This action is due to the ramp-like
interaction between the flow restrictor 150 and the expander 152.
The expander 152 may be connected to the flow restrictor 150. For
example, the expander 152 may ride along slots or rails formed on
the flow restrictor 150. Applying a tension force on the conveyance
device 42 (FIG. 1) overcomes the spring force of the biasing
element 136, which opens the slip joint 56 and allows the flow
restrictor 150 to retract. Biasing elements (not shown) may be used
to bias the flow restrictor 150 to the closed position.
[0035] While the present disclosure discusses a hydrocarbon
producing well, the present teachings may also be used with other
types of wells (e.g., geothermal wells, water wells, etc.) While
the foregoing disclosure is directed to the one mode embodiments of
the disclosure, various modifications will be apparent to those
skilled in the art. It is intended that all variations within the
scope of the appended claims be embraced by the foregoing
disclosure.
* * * * *