U.S. patent application number 16/670567 was filed with the patent office on 2021-05-06 for buoyancy assist tool with debris barrier.
The applicant listed for this patent is Halliburton Energy Services, Inc.. Invention is credited to Mayur Narain Ahuja, Lonnie Carl Helms, Rajesh Parameshwaraiah, Ishwar Dilip Patil, Min Mark Yuan.
Application Number | 20210131222 16/670567 |
Document ID | / |
Family ID | 1000005535235 |
Filed Date | 2021-05-06 |
United States Patent
Application |
20210131222 |
Kind Code |
A1 |
Helms; Lonnie Carl ; et
al. |
May 6, 2021 |
BUOYANCY ASSIST TOOL WITH DEBRIS BARRIER
Abstract
A downhole apparatus comprises a casing string with a removable
plug therein to block flow therethrough. A flow barrier is
positioned in the casing below the removable plug and the removable
plug and the flow barrier defining a buoyancy chamber therebetween.
A debris barrier positioned above the removable plug includes a
frangible disk. A stretchable connecting ring is connected to the
frangible disk and to the casing.
Inventors: |
Helms; Lonnie Carl; (Humble,
TX) ; Yuan; Min Mark; (Katy, TX) ; Ahuja;
Mayur Narain; (Friendswood, TX) ; Patil; Ishwar
Dilip; (Spring, TX) ; Parameshwaraiah; Rajesh;
(Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Halliburton Energy Services, Inc. |
Houston |
TX |
US |
|
|
Family ID: |
1000005535235 |
Appl. No.: |
16/670567 |
Filed: |
October 31, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 34/063 20130101;
E21B 33/1208 20130101 |
International
Class: |
E21B 34/06 20060101
E21B034/06; E21B 33/12 20060101 E21B033/12 |
Claims
1. A downhole apparatus comprising: a casing string; a degradable
plug positioned in the casing string to block flow therethrough; a
flow barrier positioned in the casing string below the degradable
plug, the degradable plug and the flow barrier defining a buoyancy
chamber therebetween; and a debris barrier positioned above the
degradable plug, the debris barrier comprising: a frangible disk
configured to break into pieces and pass through the casing string
upon removal of the plug from the casing string; and a stretchable
connecting ring connected to the frangible disk and to the casing
string, the debris barrier and degradable plug defining a fluid
chamber containing a fluid therebetween.
2. The downhole apparatus of claim 1, the fluid in the fluid
chamber comprising a degrading fluid.
3. The downhole apparatus of claim 2, further comprising a plug
housing connected in the casing string, the degradable plug fixed
in the plug housing.
4. The downhole apparatus of claim 2, further comprising a membrane
positioned across an upper end of the degradable plug.
5. The downhole apparatus of claim 2, the stretchable ring
comprising an elastomeric ring.
6. The downhole apparatus of claim 2, the stretchable ring
configured to tear and disconnect the debris barrier from the
casing string.
7. (canceled)
8. A downhole apparatus comprising: an outer case connected at
upper and lower ends in a casing string; a degradable plug
positioned in the outer case; a flow barrier connected in the
casing string below the degradable plug, the degradable plug and
flow barrier defining a buoyancy chamber therebetween; and a debris
barrier mounted in the outer case above the degradable plug, the
debris barrier comprising a frangible disk and a flexible
connecting ring connecting the frangible disk to the outer case,
the debris barrier and degradable plug defining a fluid chamber
therebetween.
9. The downhole apparatus of claim 8, further comprising: a plug
housing connected in the outer case, the plug housing and the outer
case defining an annulus therebetween; and a rupture disk
positioned in a port defined in the outer case, the port positioned
to communicate fluid from the fluid chamber into the annulus, the
plug housing having openings therethrough to communicate the fluid
to the degradable plug, the flexible connecting ring configured to
tear and disconnect the frangible disk from the outer case after
the rupture disk ruptures.
10. The downhole apparatus of claim 9, the frangible disk
configured to break into small fragments after the flexible
connecting ring tears away from the outer case.
11. The downhole apparatus of claim 8, the flexible connecting ring
comprising an elastomeric connecting ring.
12. The downhole apparatus of claim 8, the frangible disk
comprising a dome-shaped frangible disk.
13. The downhole apparatus of claim 8, the frangible disk
comprising an upward-facing concave disk.
14. The downhole apparatus of claim 8 further comprising an
impermeable membrane stretched across upper and lower ends of the
degradable plug.
15. A downhole apparatus comprising: a casing string; an outer case
connected to and forming a part of the casing string; a plug
housing connected in the outer case; a degradable plug fixed in the
outer case and positioned to block flow therethrough; and a debris
barrier connected in the casing string above the degradable plug,
the debris barrier and degradable plug defining a fluid chamber
containing a degrading fluid therebetween, the debris barrier
comprising: a flexible connecting ring; and a frangible disk
connected to the flexible connecting ring.
16. The downhole apparatus of claim 15, further comprising a flow
barrier connected in the casing string below the degradable plug,
the degradable plug and flow barrier defining a buoyancy chamber
therebetween.
17. The downhole apparatus of claim 15, the flexible connecting
ring configured to tear and disconnect the frangible disk from the
outer case as a result of fluid pressure acting on the frangible
disk.
18. The downhole apparatus of claim 17, the outer case having a
port communicated with an annulus defined by and between the plug
housing and the outer case, the port having a rupture disk therein,
the debris barrier configured to apply downward pressure to the
fluid in the fluid chamber to rupture the rupture disk and urge the
degrading fluid through the port.
19. The downhole apparatus of claim 15, the flexible connecting
ring comprising an elastomeric connecting ring.
20. The downhole apparatus of claim 19, the frangible disk
comprising a phenolic disk.
Description
[0001] The length of deviated or horizontal sections in wellbores
is such that it is sometimes difficult to run well casing to the
desired depth due to high casing drag. Long lengths of casing
create significant friction and thus problems in getting casing to
the toe of the wellbore. Creating a buoyant chamber in the casing
utilizing air or a fluid lighter than the wellbore fluid can reduce
the drag making it easier to overcome the friction and run the
casing to the desired final depth.
DESCRIPTION OF THE DRAWINGS
[0002] FIG. 1 is a schematic view of an exemplary wellbore with a
well casing including a buoyancy chamber therein.
[0003] FIG. 2 is a cross section of a buoyancy assist tool of the
current disclosure.
[0004] FIG. 3 is a cross section of a buoyancy assist tool of FIG.
2 after the plug has degraded and the plug and debris barrier
removed from the buoyancy assist tool.
[0005] FIG. 4 is an enlarged view of the debris barrier.
[0006] FIG. 5 is an enlarged view of the connection for the
connecting ring and disk of the debris barrier.
[0007] FIG. 6 is a cross section of an additional embodiment of a
buoyancy assist tool of the current disclosure.
[0008] FIG. 7 is a cross section of a buoyancy assist tool of FIG.
6 after the plug has degraded and the plug and debris barrier
removed from the buoyancy assist tool.
[0009] FIG. 8 is an enlarged view of the debris barrier of FIG.
6.
[0010] FIG. 9 is an enlarged view of the connection for the
connecting ring and disk of the debris barrier of FIG. 6.
DESCRIPTION
[0011] The following description and directional terms such as
above, below, upper, lower, uphole, downhole, etc., are used for
convenience in referring to the accompanying drawings. One who is
skilled in the art will recognize that such directional language
refers to locations in the well, either closer or farther from the
wellhead and the various embodiments of the inventions described
and disclosed here may be utilized in various orientations such as
inclined, deviated, horizontal and vertical.
[0012] Referring to the drawings, a downhole apparatus 10 is
positioned in a wellbore 12. Wellbore 12 includes a vertical
portion 14 and a deviated or horizontal portion 16. Apparatus 10
comprises a casing string 18 which is made up of a plurality of
casing joints 20. Casing joints 20 may have inner diameter or bore
22 which defines a central flow path 24 therethrough. Well casing
18 defines a buoyancy chamber 26 with upper end or boundary 28 and
lower end or boundary 30. Buoyancy chamber 26 will be filled with a
buoyant fluid which may be a gas such as nitrogen, carbon dioxide,
or air but other gases may also be suitable. The buoyant fluid may
also be a liquid such as water or diesel fuel or other like liquid.
The important aspect is that the buoyant fluid has a lower specific
gravity than the well fluid in the wellbore 12 in which casing 18
is run. The choice of gas or liquid, and which one of these is used
is a factor of the well conditions and the amount of buoyancy
desired.
[0013] Lower boundary 30 may comprise a float device such as a
float shoe or float collar 32. As is known, such float devices will
generally allow fluid flow downwardly therethrough but will prevent
flow upwardly into the casing. The float devices are generally
one-way check valves. The float device 32 is thus a fluid barrier
that will be configured such that it will hold the buoyant fluid in
the buoyancy chamber 26 until additional pressure is applied after
the release of the buoyancy fluid from the buoyancy chamber. The
upper boundary 28 is defined by a buoyancy assist tool as described
herein.
[0014] Buoyancy assist tool 34 includes an outer case 36 defining
flow path 37 therethrough that is connectable in casing string 18.
Buoyancy assist tool 34 comprises a plug assembly 38 that is
connected to and positioned in outer case 36. Buoyancy assist tool
34 has upper end 40 and lower end 42. Buoyancy assist tool 34 is
connectable in the casing string at the upper and lower ends 40 and
42 thereof and forms a part of the casing string 18 lowered into
wellbore 12.
[0015] Outer case 36 comprises an upper outer case 44 and a lower
outer case 46. A connecting shield 48 is connected to and extends
between upper outer case 44 and lower outer case 46. Outer case 36
and plug assembly 38 define an annular space 50 therebetween.
[0016] Plug assembly 38 has upper end 52 and lower end 54. Plug
assembly 38 is connected to upper outer case 44 at the upper end 52
thereof and to lower outer case 46 at the lower end 54 thereof. The
plug assembly may be threadedly connected or connected by other
means known in the art. Plug assembly 38 may comprise a plug
housing 56 with upper and lower ends 52 and 54 which are the upper
and lower ends of the plug assembly 38. A degradable plug or
degradable core 58 is fixed in housing 56. Degradable core 58 has
upper end 57 and lower end 59, which may be for example coincident
with the upper and lower ends 52 and 54 of plug housing 56. The
degradable core may be a matrix of sand and salt but can be other
degradable substances that can be degraded with fluids or other
means once the casing string 18 is lowered into the wellbore to a
desired location in the well. Plug housing 56 has a plurality of
housing ports 60 defined through the wall thereof. Housing ports 60
communicate the annular space 50 with the degradable plug or core
58 so that fluid passing therethrough can contact degradable plug
58 and can degrade the plug to remove it from plug housing 56 to
create a full bore flow path therethrough.
[0017] Buoyancy assist tool 34 may include an upper impermeable
membrane 62 positioned across upper end 57 of degradable plug 58
and a lower impermeable membrane 63 positioned across the lower end
59 of degradable plug 58. Membranes 62 and 63 will prevent fluid
thereabove from contacting the degradable plug at the upper end of
the plug assembly 38 prior to the time casing string 18 is placed
at the desired location in wellbore 12. Likewise, the impermeable
membrane 63 will prevent fluid in the buoyancy chamber 26 from
contacting the degradable plug 58 until such time as degradation of
the plug is desired. Upon degradation of the plug 58 the membranes
62 and 63 will be easily ruptured by fluid flowing through the
casing string 18, including outer case 36.
[0018] Plug housing 56 has an inner surface 64 defining a diameter
66 and has an outer surface 68. In the embodiment described
diameter 66 is a diameter that is no smaller than an inner diameter
of casing string 18 such that upon the degradation of plug 58
buoyancy assist tool 34 provides no greater restriction to the
passage of well tools therethrough than that which already exists
as a result of the inner diameter of the casing string 18.
[0019] Upper end 40 of buoyancy assist tool 34 is likewise the
upper end of upper outer case 44. Upper outer case 44 has a lower
end 70. Plug assembly 38 is connected at its upper end 52 to the
lower end 70 of upper outer case 44. Outer surface 68 of plug
housing 56 may have a groove 67 with an O-ring seal 69 therein to
sealingly engage an inner surface of upper outer case 44. Upper
outer case 44 has inner surface 72 which defines an inner diameter
74 that is a minimum inner diameter of upper outer case 44. Upper
outer case 44 has a port 76 therethrough. Inner diameter 74 is a
diameter that is no smaller than an inner diameter of casing string
18 such that upon the degradation of plug 58 buoyancy assist tool
34 provides no greater restriction to the passage of well tools
therethrough than that which already exists as a result of the
inner diameter of the casing string 18.
[0020] A rupture disc or other rupturable membrane 78 is positioned
in port 76 in upper outer case 44. Rupture disc 78 will prevent
flow through port 76 until a desired or pre-determined pressure is
reached in casing string 18. Upon reaching the predetermined
pressure the rupture disc 78 will rupture and fluid will be
communicated from casing string 18 through port 76 into annular
space 50. Fluid will pass from annular space 50 through housing
ports 60 and will contact the degradable plug 58. The fluid passing
therethrough may be referred to as a degrading fluid. The degrading
fluid may be any fluid utilized to degrade the degradable plug and
may be water or other degrading fluid.
[0021] The degrading fluid is in fluid chamber 84, which has upper
end 86 and lower end 88. Upper membrane 62 prevents the fluid in
fluid chamber 84 from contacting degradable plug 58 prior to the
rupturing of rupture disc 78. Upper outer case 44 may be a
two-piece outer case comprising an upper portion 80 that is
threadedly and sealingly connected to lower portion 82. Lower
portion 82 connects to plug assembly 38 as shown in the figures.
Upper outer case 44 may define fluid chamber 84 which is a closed
fluid chamber 84. Fluid chamber 84 has a debris barrier 85 that
extends across upper end 86 thereof. Fluid in fluid chamber 84 is
thus trapped between debris barrier 85 and the upper membrane 62.
There are certain formations in which it is not desirable to pump
water. In those instances oil or another fluid other than water may
be utilized to fracture or otherwise treat the formation. Where,
for example, water is the degrading fluid, but not the treatment
fluid, water will be contained in the fluid chamber 84 such that
upon reaching the appropriate position in the well oil or other
fluid may be pumped through the casing string 18 so that the water
in fluid chamber 84 will contact the degradable plug 58 as further
described herein. The water in fluid chamber 84 passes into and
from annular space 50 through ports 60 in plug housing plug and
will contact the degradable plug 58 until it is degraded or
dissolved.
[0022] Lower outer case 46 has upper end 90 and a lower end which
is the lower end 42 of buoyancy assist tool 34. Upper end 90 of
lower outer case 46 is connected to lower end 54 of plug assembly
38. Outer surface 68 of plug housing 56 may have a groove 91 with
an O-ring seal 93 therein to sealingly engage lower outer case 46.
Lower outer case 46 has inner surface 92 defining an inner diameter
94. Inner diameter 94 is a diameter that is no smaller than an
inner diameter of casing string 18 such that upon the degradation
of plug 58 buoyancy assist tool 34 provides no greater restriction
to the passage of well tools therethrough than that which already
exists as a result of the inner diameter of the casing string
18.
[0023] Connecting sleeve 48 has upper end 102 and lower end 104.
Connecting sleeve 48 is connected at its upper end 102 to an outer
surface of upper outer case 44 and is connected at its lower end
104 to an outer surface of lower outer case 46. O-ring seals 105
may be positioned in grooves in the outer surfaces of the upper and
lower outer cases 44 and 46 respectively to sealingly engage an
inner surface 106 of connecting shield 48. Inner surface 106 of
connecting shield 48 defines an inner diameter 108. An annular
passageway 110 is defined by and between upper outer case 44 and
connecting shield 48. Annular passageway 110 communicates fluid
delivered through port 76 into annular space 50. Fluid is
communicated through ports 60 so that it will contact degradable
plug 58 to dissolve or degrade the plug.
[0024] Debris barrier 85 is a multiple-piece debris barrier, and in
the embodiment described is a two-piece debris barrier. Debris
barrier 85 has a connecting ring 120, which is a flexible
connecting ring 120. A frangible disk 122 is connected to flexible
connecting ring 120. Frangible disk 122 in the embodiment shown is
an upward facing concave frangible disk. Flexible connecting ring
120 is stretchable and will stretch when a downward push is applied
to frangible disk 122. Flexible connecting ring 120 comprises an
annular ring 124 with a tongue 126 extending radially inwardly
therefrom. Tongue 126 is bonded or otherwise connected to frangible
disk 122 and annular ring 124 is bonded or otherwise connected to
outer case 36. Connecting ring 120 thus connects frangible disk 122
to outer case 36. The connecting ring 120 may be, for example an
elastomeric ring and the frangible disk 122 a brittle disk
comprised of, for example, a phenolic material, ceramic, tempered
glass or other brittle material that will break into small
pieces.
[0025] In operation casing string 18 is lowered into wellbore 12 to
a desired location. Running a casing such as casing 18 in deviated
wells and long horizontal wells often results in significantly
increased drag forces and may cause a casing string to become stuck
before reaching the desired location in the wellbore. For example,
when the casing produces more drag forces than the available weight
to slide the casing down the well, the casing may become stuck. If
too much force is applied to the casing string 18 damage may occur.
The buoyancy assist tool 34 as described herein alleviates some of
the issues and at the same time provides for a full bore passageway
so that other tools or objects such as, for example production
packers, perforating guns and service tools may pass therethrough
without obstruction after well casing 18 has reached the desired
depth. When well casing 18 is lowered into wellbore 12 buoyancy
chamber 26 will aid in the proper placement since it will reduce
friction as the casing 18 is lowered into horizontal portion 16 to
the desired location.
[0026] Once the casing string 18 has reached the desired position
in the wellbore, pressure is increased and fluid pumped through the
casing string 18. The pressure will cause debris barrier 85 to
apply a downward pressure to the fluid in chamber 84 until at a
predetermined pressure rupture disc 78 bursts. Connecting ring 120
will stretch and the frangible disk 122 will apply downward
pressure to the fluid in chamber 84. Once rupture disk 78 busts,
degrading fluid from fluid chamber 84 will pass through port 76
into passageway 110 and into annular space 50. Fluid will pass from
annular space 50 through ports 60 and will contact the degradable
plug 58. A sufficient quantity of the degrading fluid will be
utilized to degrade degradable plug 58 so that it will be
completely removed from plug housing 56.
[0027] Typically, once the degradation process reaches a certain
level, the degradable plug 58 will break up, and at that point both
of upper and lower membranes 62 and 63 will likewise be broken, and
the pieces thereof along with pieces of the degradable plug will
pass through casing string 18. The pressure in the casing string 18
will cause the debris barrier 85 to break into small pieces that
will pass through the casing string and through the float equipment
at the end of the casing string 18. Any large pieces that exist
will break when they reach the float equipment into pieces that
will pass therethrough.
[0028] An additional embodiment of a debris barrier is shown
connected in outer case 36 in FIG. 6. Debris barrier 130 comprises
connecting ring 132 that is a flexible connecting ring 132. A
frangible disk 134 is connected to flexible connecting ring 132.
Frangible disk 134 in the embodiment shown is an upward facing
concave frangible disk. Frangible disk 134 is deeper than frangible
disk 122 and may comprise a dome-shaped frangible disk with a
rounded bottom portion 136 and an attachment leg 138 extending
therefrom. Flexible connecting ring 132 is stretchable and will
stretch when a downward push is applied to frangible disk 134.
Flexible connecting ring 132 comprises an annular ring 140 with a
tongue 142 extending radially inwardly therefrom. Tongue 142 is
bonded or otherwise connected to frangible disk 134 and annular
ring 140 is bonded or otherwise connected to outer case 36.
Connecting ring 132 thus connects frangible disk 134 to outer case
36. The connecting ring 132 may be, for example an elastomeric ring
and the frangible disk 134 a brittle disk comprised of, for
example, a phenolic material, ceramic, tempered glass or other
brittle material that will break into small pieces.
[0029] In operation casing string 18 is lowered into wellbore 12 to
a desired location. Running a casing such as casing 18 in deviated
wells and long horizontal wells often results in significantly
increased drag forces and may cause a casing string to become stuck
before reaching the desired location in the wellbore. For example,
when the casing produces more drag forces than the available weight
to slide the casing down the well, the casing may become stuck. If
too much force is applied to the casing string 18 damage may occur.
The buoyancy assist tool 34 as described herein alleviates some of
the issues and at the same time provides for a full bore passageway
so that other tools or objects such as, for example production
packers, perforating guns and service tools may pass therethrough
without obstruction after well casing 18 has reached the desired
depth. When well casing 18 is lowered into wellbore 12 buoyancy
chamber 26 will aid in the proper placement since it will reduce
friction as the casing 18 is lowered into horizontal portion 16 to
the desired location.
[0030] Once the casing string 18 has reached the desired position
in the wellbore, pressure is increased and fluid pumped through the
casing string 18. The pressure will cause debris barrier 130 to
apply a downward pressure to the fluid in chamber 84 until at a
predetermined pressure rupture disc 78 bursts. Connecting ring 132
will stretch and the frangible disk 134 will apply downward
pressure to the fluid in chamber 84. Once rupture disk 78 bursts,
degrading fluid from fluid chamber 84 will pass through port 76
into passageway 110 and into annular space 50. Fluid will pass from
annular space 50 through ports 60 and will contact the degradable
plug 58. A sufficient quantity of the degrading fluid will be
utilized to degrade degradable plug 58 so that it will be
completely removed from plug housing 56.
[0031] As described above, once the degradation process reaches a
certain level, the degradable plug 58 will break up, and at that
point both of upper and lower membranes 62 and 63 will likewise be
broken, and the pieces thereof along with pieces of the degradable
plug will pass through casing string 18. The pressure in the casing
string 18 will cause the debris barrier 130 to break into small
pieces that will pass through the casing string and through the
float equipment at the end of the casing string 18. Any large
pieces that exist will break when they reach the float equipment
into pieces that will pass therethrough.
[0032] A downhole apparatus comprises a casing string and a
removable plug positioned in the casing string to block flow
therethrough. A flow barrier is positioned in the casing below the
removable plug, and the removable plug and the flow barrier define
a buoyancy chamber therebetween. A debris barrier is positioned
above the removable plug. The debris barrier comprises a frangible
disk and a stretchable connecting ring connected to the frangible
disk and to the casing. The debris barrier and removable plug
define a fluid chamber therebetween. In one embodiment the
removable plug comprises a degradable plug and the fluid in the
fluid chamber is a degrading fluid.
[0033] A plug housing is connected in the casing string, and the
degradable plug is fixed in the plug housing. A membrane may be
positioned across an upper end of the degradable plug. In one
embodiment the stretchable ring is an elastomeric ring. The
stretchable ring is configured to tear and disconnect the debris
barrier from the casing. The frangible disk is configured to break
into pieces and pass through the casing upon removal of the
removable plug from the casing.
[0034] A downhole apparatus comprises an outer case connected at
upper and lower ends in a casing string. A degradable plug is
positioned in the outer case string and a flow barrier connected in
the casing string below the degradable plug. The degradable plug
and flow barrier define a buoyancy chamber therebetween. A debris
barrier is mounted in the outer case above the degradable plug. The
debris barrier comprises a frangible disk and a flexible connecting
ring connecting the frangible disk to the outer case. A plug
housing is connected in the outer case. The plug housing and the
outer case define an annulus therebetween, and a rupture disk is
positioned in a port defined in the outer case. The port is
positioned to communicate fluid from the fluid chamber into the
annulus. The plug housing has openings therethrough to communicate
the fluid to the degradable plug.
[0035] The flexible outer ring is configured to tear and disconnect
the frangible disk from the outer case after the rupture disk
ruptures. The frangible disk is configured to break into small
fragments after the flexible connecting ring tears away from the
outer case. In one embodiment the flexible connecting ring
comprises an elastomeric connecting ring. The frangible disk
comprises in one embodiment an upward facing concave disk and in
one example a dome-shaped frangible disk.
[0036] A downhole apparatus comprises a casing string and an outer
case connected to and forming a part of the casing string. A plug
housing is connected in the outer case and a degradable plug is
fixed in the plug housing and positioned to block flow therethrough
and to block flow through the outer case. A debris barrier is
connected in the casing string above the degradable plug. The
debris barrier and degradable plug define a fluid chamber
therebetween. The debris barrier comprises a flexible connecting
ring and a frangible disk connected to the flexible connecting
ring.
[0037] A flow barrier may be connected in the casing string below
the degradable plug. The degradable plug and flow barrier define a
buoyancy chamber therebetween. The flexible connecting ring is
configured to tear and disconnect the frangible disk from the outer
case as a result of fluid pressure acting on the frangible disk.
The outer case has a port communicated with an annulus defined by
and between the plug housing and the outer case. The port has a
rupture disk therein. The debris barrier is configured to apply
downward pressure to the fluid in the fluid chamber to rupture the
disk and urge the degrading fluid through the port. The flexible
connecting ring comprises in one embodiment an elastomeric
connecting ring. The frangible disk is a brittle disk that may
comprise, for example, a phenolic disk.
[0038] Thus it is seen that the apparatus and methods of the
present invention readily achieve the ends and advantages mentioned
as well as those inherent therein. While certain preferred
embodiments of the invention have been illustrated and described
for purposes of the present disclosure, numerous changes in the
arrangement and construction of parts and steps may be made by
those skilled in the art, which changes are encompassed within the
scope and spirit of the present invention.
* * * * *