Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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. CEMENTING APPAR~TUS
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. This application relates to improved apparatus for use in
placing cement at a desired location within the annulus
between a casing string and a well bore. More
5 particularly, in one of its novel aspects, it relates to
,; improvements in apparatus of this general type which
includes an inflatable packer for closing off the annulus
beneath the location in which the cement is to be placed.
d Apparatus of this general type is frequently used in
lO stage cementing - i.e., in placing cement sequentially at
successively higher locations within the annulus. Typical
apparatus of this type includes a so-called stage collar
connected in the casing string adjacent each location and
I having one or more ports through which cement may be
15 circulated from the casing string into the annulus. A
first tubular member or opening sleeve is disposed within
the bore of the collar and initially connected to the
collar in an upper position in which it is disposed over
the port to close it. Following placement of cement at the
20 lower stage, a plug is lowered through the casing onto a
seat on the sleeve, and fluid pressure is introduced into
the casing string above the plug to shear the connection of
. the sleeve to the collar and lower it to a position to open
the port. At this time, cement may be circulated
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.!.' downwardly through the casing an~ out the port into the
annulus.
The apparatus also includes another tubular member or
~rclosing sleeve which is disposed within the bore of the
collar above the opening sleeve and releasably connected to
the collar in an upper position in which it is above the
ports. Following circulation of cement through the port,
a second plug is lowered onto the closing sleeve and fluid
pressure is introduced into the casing above the plug to
'~10 shear the connection of the closing sleeve to the collar
,,
and move it downwardly to a position over the ports to
x~close it. At this time, additional cement may be placed at
other locations thereabove through similar apparatus.
~There are occasions in which it is necessary or at
,!~'15 least desirable to inflate a packer beneath the ports in
.order to close the annulus below the location at which
s-cement is to be placed. For example, it may be necessary
to prevent the cement from entering a lost circulation zone
~i~of the well bore beneath the zone in which cement is to be
placed, or, it may be necessary to protect a slotted liner
connected to the casing string below the collar.
~ or this latter purpose, it has been proposed to
provide such apparatus with a packer element including an
~'inflatable sleeve of elastomeric material beneath the port,
and to inflate the sleeve by means of pressure fluid
.~introduced through the casing string into passageway means
-~connecting with a space between the collar and sleeve.
~More particularly, as shown in Patent No. 3,948,322, it has
Ibeen proposed to lower a plug onto a sleeve which is
i~30 initially releasably connected to the collar in a position
,closing the connection of the passageway means to the bore,
Iand then introduce pressure fluid into the casing above the
plug in order to shear the connection and thus open the
connection of the passageway means to the bore, whereby the
*U.S. Patent No. 2
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PATENT
DAVE, OO9CIP
fluid may be supplied to the space to inflate the sleeve.
When the sleeve has been inflated, pressure fluid is
retained in the sleeve to hold the sleeve inflated by means
-~ of a one-way valve in the passageway means.
- 5 At this time, the pressure of the fluid in the casing
string above the plug is increased in order to release
shearable means connecting another sleeve to the collar and
move it to a position opening the ports in the collar.
When cement has been circulated through the open ports,
another plug is lowered onto still another sleeve in order
- to release its shearable connection to the collar and thus
lower it to a position closing the port.
Since the passageway means leading to the space
between the collar and packer sleeve remains open to the
15 pressure fluid in the casing strinq, as the opening sleeve
is moved to open the side ports and cement is circulated
through them into the annulus, the increased pressure is
free to pass through the one way valve into the space, and,
if the squeeze pressure on the cement is high, damaging the
20 packing element. Also, of course, this apparatus is
relatively expensive and time consuming to use since it
requires the application of three separate levels of
pressure to inflate the packer, open the ports and close
the ports. Still further, due to the arrangement of its
25 sleeves and the passageway means leading to the space
3 within the packing element, the apparatus is not only of
complex and expensive construction but also of such
thickness as to either or both increase its outside
diameter and decrease its inside diameter, making it
30 difficult if not impossible to use in "tight" holes. The
construction is further complicated by arrangement of the
packing element which is fixed at its lower end and thus
requires still another sleeve at its upper end slidable
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, over the outer diameter of the collar to form the
passageway means into the space withill the sleeve.
The apparatus of Patent No. 4,421,165, which was an
apparent attempt to simplify the construction of Patent No.
~r~ 5 3,948,322, includes a packing element disposed about a
`.? lower extension of the collar and having passageway means
leading to the spacing between the extensions and sleeve
which opens to the casing string at its lower end. More
particularly, the passageway means is normally closed by a
shearable closure extending into the bore of the extension
^ and adapted to be opened by a first plug lowered through
; the casing string to shear off the inner end of the
. closure. Thus, when the plug has bottomed out and pressure
in the casing string is increased, the packing element is
lS inflated following completion of the first stage. At this
time, with pressure contained in the space to maintain the
packer inflated, additional plugs are lowered and pressure
suitably applied thereabove in order to sequentially lower
a first sleeve to open the ports in the collar above the
packer, circulate cement through the ports in order to
place it in the annulus above the packer, and lower the
second sleeve to close the ports.
Although this apparatus protects the packer against
over-pressurization, and is an improvement upon the
apparatus of Patent No. 3,948,322 in this respect, it
nevertheless requires lowering of a third plug in order to
initially prepare the packer for inflation. Also, and as
in the case of the prior apparatus, the sleeve of the
packer element is fixed at its lower end and thus requires
! 30 a slidable sleeve at its upper end. Still further, the
apparatus is necessarily long and expensive to manufacture.
Accordingly this invention seeks to provide apparatus of
this general type which overcomes these and other problems
with the prior apparatus.
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*U.S. Patent No. -4
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Further this invention seeks to provide such
apparatus in which the packer is not only protected against
over-pressurization, but also prepared for inflation
without the need for lowering and pressurizing a third
plug.
- Still further this invention seeks to provide such
apparatus which is of minimum thickness between its inner
; and outer diameters, which requires less sleeves and other
ports whlch require the maintenance of dynamic seals and
which is of relatively short length.
Further still the invention seeks to provide such
apparatus in which the inflatable sleeve of the packer
~ element is fixed and supported at its upper end so that
:;;; its lower end may be raised over a receded diameter
` 15 portion of the collar as the sleeve is inflated.
- These and other aspects are accomplished, in
.i accordance with the illustrated embodiment of the
;i' invention, by apparatus which includes, as in prior
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apparatus of this type, a body or collar having a bore
through it which is connectible as part of the casing
~- string and ports connecting the bore with its outer side,
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and a packing element including an inflatable sleeve
surrounding the body below the ports, with the body having
~` passageway means therein connecting its bore with the space
~ 25 between the sleeve and body. More particularly, in
~rf accordance with the novel aspects of this invention, it
also includes a tubular member or opening sleeve which has
~ a bore therethrough as well as an upwardly facing seat and
¦ passageway means therein connecting its bore with the outer
side, the member being disposed within the bore of the body
or collar for vertical reciprocation between an upper
position in which it is releasably connected to the body
~ and in which it closes the port in the body and its
j passageway connects with the passageway means in the body,
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and a lower position in which it opens the port, a5 well as
a plug lowerable throu.-Jh the casing string into a landed
position on the seat on the opening sleeve, and having a
port therethrough and means thereabout for sealably
`~ S engaging the bore of the member, when landed on the seat,
- to connect the port in the plug and thus the casing string
thereabove with the passageway means in the member. More
particularly, the member has means thereon for closing the
; passageway means, but adapted to be moved to open position
by the plug, as the plug is landed, whereby pressure fluid
in the casing string above the plug may be supplied to the
~- space in order to inflate the sleeve of the packer element
into engagement with the well bore beneath the port, and
when the packer has been inflated, release the connection
15 of the member to the body and move the tubular member to
its lower position to open the port and thus permit cement
to be circulated through the open port in the body and into
the annulus above the inflated sleeve, the tubular member
and bore of the body having means for holding the member in
20 its lower position.
More particularly, a means is provided for closing the
,l passageway means in order to contain such pressure fluid
A~! within the space and prevent the supply thereto of
additional pressure fluid in the casing string above the
25 plug following inflation of the sleeve. Thus, it is
possible to avoid damage to the packer by squeeze pressure
on the cement as it is circulated through the ports and
~ into the annulus, without the need for an additional plug
3 -- i.e., with only the single plug lowered into the tubular
~ 30 member or opening sleeve which opens the passageway means
¦ leading to the space between the packer sleeve and body and
then opens the ports in the body.
In accordance with one embodiment of the invention,
the shear means connecting the member to the body is
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-- shearable in response to flui~ pressure in the casing
string above the plug which is greater than that which was
required to inflate the sleeve, and the means for closing
the passageway means comprises means for sealing between an
;~; 5 imperforate portion of the outer side of the member and the
bore of the body above and below the connection of the
passageway means in the body upon movement of the member to
its lower position. Preferably, the sealing means is
: sealably slidable along equal diameter portions so that
10 there is no risk of fluid lock above the passageway means
leading to the space between the packing element and body
as the opening sleeve is lowered.
In accordance with another embodiment of the
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g~ invention, the means for closing the passageway means
15 comprises valve means which includes a valve member
installed in the body for movement between positions
`~j opening and closing the passageway means in the body, means
holding the valve member in open position, and means
responsive to the supply of the passageway means of
20 pressure fluid to inflate the sleeve for releasing the
holding means and moving the valve member to closed
position in which it is held by the fluid pressure in the
space regardless of fluid pressure supplied to the casing.
^~ More particularly, the valve means also includes an
25 additional valve member installed in the body for movement
between positions opening and closing passageway means in
the body upstream of the first mentioned valve member,
means urging the additional valve member to closed position
3 but yieldable to permit the additional valve member to be
30 moved to open position in response to the supply of said
pressure fluid to the passageway means for inflating the
sleeve, and means for locking said additional valve member
i in its closed position when returned thereto by said urging
means upon the reduction of pressure fluid.
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':,
- In the preferred and illustrated embodiment of the
invention, the body has a lower reduced outer diameter
portion, the sleeve is fixed to the upper end of the upper
body portion to surround the lower portion, and the packing
element also includes a ring on the lower end of the sleeve
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sealably slidable along the lower body portion. Thus, as
the packer is inflated and expanded, the ring moves
~ upwardly along the reduced outer diameter portion of the
,~ body so as to minimize the radial thickness required to
accommodate the packer by virtue of the fact that it does
' not have to slidably move over the upper enlarged diameter
x- portion of the body in which the tubular member or opening
sleeve is contained. More particularly, the sleeve is made
.~ of an elastomeric material and has metal strips extending
' 15 between its upper and lower ends, and the ring and lower
,~ portions of the body have means which are engageable with
one another as the ring is raised to hold the sleeve in its
expanded or set position, whereby due to the metal
reinforcement of the sleeve, the packer may remain in its
,c 20 expanded or set position even though pressure fluid is lost
in the space between the packer and body.
As in the case of prior apparatus of this type, it
also includes another tubular member or closing sleeve
which is vertically reciprocal within the bore of the body
above the first-mentioned tubular member or opening sleeve
between an upper position in which it opens the ports in
the body, during circulation of cement through the ports,
and a lower position in which it closes the ports following
~; circulation of cement. Shear means releasably connects the
3G other tubular member or closing sleeve in its upper
position, and another plug is lowerable through the casing
S` string and into a landed position on the other member,
i whereby pressure above it is effective to release the shear
~ means and lower the other member to its closing position,
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- the other member being located and held in its lower
position by suitable means.
~In its preferred embodiment, the means by which the
- connection of the passageway means in the tubular member is
closed comprises a closure mounted in the passageway means
;~and extending into the bore of the member in order to be
engaged and thereby removed from the passageway means by
;the plug as it is lowered into landed position.
`The disclosed embodiments of the invention also
contemplate that, in the event pressure fluid is not able
to shear the connection of the first tubular member to the
;~body and move it to its lower open position, a pipe string
may be lowered through the casing string and onto the seat
in the plug and sealed with respect thereto above the port
to permit pressure fluid to be circulated downwardly
therethrough and into the port and a downward force to be
applied by the pipe string to the pluq to shear the
connection of the member to the body and lower the member
to its lower position. In addition to permitting this
downward force to be applied to the plug, the lower end of
the pipe string permits pressure fluid to be supplied to
the packer, which of course would not be possible by merely
dropping a ball or other closure onto the plug.
In apparatus of the type described, the opening sleeve
is a relatively long tubular member which is releasably
connected to the bore of the body in its upper position by
!shear pins. Due to its length, and the resulting large
area of frictional resistance between it and the bore of
the body, it may be difficult to shear its connection to
the body and lower it to port opening position in response
to the desired pressure level. In any event, its movement,
and thus the opening of the ports, and, in one embodiment
of the invention, closing of the passageway means leading
to the packer, is rather unreliable, thus raising the risk
2~2~ 93~ PATENT
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- of over pressurizing the packinq element before the sleeve is released to open the port. It is therefore still
another object of this invention to provide such apparatus
in which the movement of the opening is more reliable.
~, 5 This and other aspects are accomplished, in apparatus
-~ made in accordance with the first embodiment of the
~,~ invention, by an opening plug which comprises an outer plug
~;~ body having a bore therein and disposable within the bore
.h' of the tubular member for landing on the seat thereof, and
~ 10 an inner plug body having a bore therein and disposable
~A`' within the bore of the outer plug body for moving between
;~ upper and lower positions therein, the port means in the
, plug comprising ports in each of the inner and outer plug
; bodies connecting their bores with their outer sides and
means being provided for sealing between the first and
~ second plug bodies and between the outer plug body and the
-~ bore of the member so as to connect the ports and thus
~; connect the port means with the passageway means in the
member when the inner plug body is in its upper position,
the space between the lower ends of the plugs being vented
to permit the inner plug body to be lowered. More
particularly, means are provided for holding said inner
plug body in its upper position but releasable, in response
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to an increase in fluid pressure above the plug above that
required to inflate the sleeve, but less than required to
move the opening sleeve to its lower position, so as to
lower the inner plug body to its lower position, and for
sealing between the plug bodies to close the connection
between their ports and thus close the port means when the
inner plug body is moved to its lower position. Due to its
short length, the release and lowering of the inner plug
body is more predictable, thus permitting the passageway
~ means to be closed before the opening sleeve is lowered, so
f as to prevent over pressurizing the packing element.
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.
There is a further risk, in the use of apparatus of
this general type, that the closing sleeve will not fully
move down to its lower position, or will not, for some
other reason, be locked in its lower position. In this
case, the closing plug must be held down on the sleeve with
pressure above it to prevent heavier cement in the annulus
. from flowing through the ports and back into the casing.
. Then, when the cement in the annulus has hardened, and
, pressure above is reduced, the casing may contract and
.~ 10 leave spaces or voids between the outer side and the inner
wall of the cement column. It is therefore yet a further
object of this invention to provide apparatus of this
general type in which heavier cement will be contained
~ beneath the plug, even though the opening sleeve is not
.~l 15 locked down in its lower position, and without having to
~: hold pressure above the plug.
7 This further aspect is accomplished, in accordance
with another novel aspect of this invention, by apparatus
of this general type in which a means is provided for
20 connecting the plug to the closing sleeve as the plug is
lowered into its bore, so as to permit said plug to
reciprocate within said bore between a lower position in
which it is landed on the seat of the closing sleeve and an
upper position in which it is raised from the seat, and in
25 which means are provided on the plug which sealably engages
the bore of the closing sleeve in the upper position of the
plug, but is removed from the bore to open a flow path
between the plug and the opening sleeve as the plug is
lowered toward its landed position. More particularly, as
30 illustrated, the connecting means comprises a groove about
one of said bore of the closing sleeve and outer side of
the plug, and expandable and retractable locking means
~ carried by the other of the bore of the closing sleeve and
', outer side of the plug for moving into the groove as the
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'' plug is lowered into the bore of the closing sleeve, the groove
, being of a length to permit said plug to reciprocate between its
upper position and lower landed position and thus permit cement
to intermittently flow therepast to equalize pressure above and
below the plug until the plug moves upwardly to its upper
,,' position in the bore of the sleeve to close it. Finally, the
`- opening sleeve is free to move upwardly beyond its position until
it engages a shoulder on the bore of the body thus limiting
, upward movement of the sleeve and body to contain cement
" 10 therebelow.
~' Thus in one of its broader aspects the invention as claimed
provides apparatus for use in placing cement at a desired
, location within the annulus between a casing string and a well
,~, bore, comprising a body having a bore therethrough which is
t' 15 connectable as part of the casing string for lowering therewith
into the well bore and a port connecting its bore with its outer
. .,
~;, side, a packing element including an inflatable sleeve
surrounding the body below the port, the body having passageway
means therein connecting its bore with a space between the sleeve
',' 20 and body. A tubular member has a bore therethrough with an
upwardly facing seat thereabout and passageway means therein
~ connecting its bore with its outer side, the member is disposed
:~ within the bore of the body for vertical reciprocation between an
,~ upper position in which it closes the port in the body and its
passageway means connects with the passageway means in the body
and a lower position in which it opens the port and closes the
, passageway means in each of the member and body. Shear means
releasably connects the tubular member to the body in its upper
position. A plug is lowerable through the casing string into a
~, 30 landed position on the seat in the member, the plug having port
means therethrough and being sealably engageable with the bore of
the member, when landed on the seat, to connect the port means
and thus the casing string thereabove with the passageway means
in the member. The member having means thereon for closing its
passageway means but adapted to be moved to open position by the
plug, as the plug is landed. Thus pressure fluid in the casing
string above the plug may be supplied to the space in order to
¦ inflate and expand the sleeve, of the packing element into
~ 12
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- engagement with the well bore beneath the port and then shear the
releasable connection of the member to the body and move the
member to its lower position in which cement may be circulated
through the open port in the body and into the annulus above the
` 5 inflated sleeve. ~eans on the member and body is provided for
locating and holding the member in the lower position.
The invention in another broad claimed aspect pertains to a
method of placing a column of cement at a desired location
between a casing string and a well bore by means of a stage
;, 10 collar comprising a body having a bore therethrough connected to
'~ a pipe string, a sleeve reciprocable within the bore between a
~,; first position in which it is releasably connected to the body to
close a port in the body connecting its bore with its outer side
and a second position in which it opens the port to permit cement
,i15 to be circulated therethrough and, an inflatable packer element
mounted on the body beneath the port with its interior
connectable to the bore of the body by passageway means, having
L' valve means therein which is normally closed but which is adapted
to open in response to the supply of pressure fluid in the pipe
string for inflating the packing element and then close when the
,~ packing element is inflated to the desired pressure in order to
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~ contain pressure in and prevent the supply of additional pressure
-s
~- to the packing element. The method includes the steps of
... .
lowering the stage collar body with the pipe string to dispose
the packing element beneath the desired location within the well
bore, supplying fluid pressure to the pipe string and through the
~ passageway means in order to open and then close the valve means
', to inflate the packing element and raising fluid pressure in the
pipe string to a level above that for inflating the packer in
.~30 order to release the sleeve from its connection to the body and
move it to its position opening the port.
~: In the drawings, wherein like reference characters are used
throughout to designate like parts:
,,i~ Figs. lA and lB are views partly in elevation and partly in
~- 35 vertical section of the upper and lower ends of the apparatus,
with the packer shown in deflated position and broken away or
,, discontinued intermediate its upper and lower ends and the
,~i tubular member or opening sleeve in its upper position closing
12A
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the ports in the body or collar of the apparatus;
. Figs. 2A and 2B are partial vertical sectional views of the
upper and lower ends of the apparatus, similar to Figs. lA and
. lB, but upon lowering of an opening plug onto a seal in the
; S tubular member to move the closure in the passageway means of the
first tubular position to open position and thereby permit
pressure fluid above the plug to be circulated into the
passageway means leading to the space between the packing sleeve
and body in order to inflate the packer into engagement with the
well bore in which the apparatus is disposed;
.- Fig. 3 is a full sectional view of the upper end
~'.: of the apparatus, but upon the continued application of fluid
pressure to the casing string above the plug to cause the
connection of the upper member to the body to be sheared
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and the member to be lowered to open side ports in the
body, whereby cement may be circulated through the side
ports into the annulus abo~e the inflated packer;
Fig. 4 is a partial vertical sectional view similar to
Fig. 3, but following placement of cement in the annulus
~t',~ above the packer, and lowering of another plug onto another
tubular member or closing sleeve mounted in the bore of the
body above the opening sleeve, and upon application of
pressure fluid to the string above the other plug to shear
i~10 the connection of the closing sleeve to the body and move
the opening sleeve downwardly with the plugs to a position
in which it closes the side port;
Fig. 5 is a vertical sectional view of the apparatus
showing the lower end of a pipe string lowered through the
casing string and seated upon the plug seated on the first
tubular member and sealed with respect to it above the port
in the plug, so that pressure fluid may be circulated
-downwardly through the pipe string slacked off to release
the connection of the tubular member to the body and lower
the tubular member to a position opening the side ports, as
shown in Fig. 3;
Fig. 6 is a vertical sectional view of a modified and
preferred version of an opening plug lowered onto a seat in
the opening sleeve, with the inner plug body thereof in its
upper position with respect to the outer plug body to
connect the port means of the plug with the sleeve to
permit inflation of the packer;
Fig. 7 is a view similar to Fig. 6, but upon lowering
of the inner plug body to close the port means and thus the
passageway means following inflation of the packer;
Fig. 8 is a partial vertical section view of the
alternative embodiment of the apparatus, with the packer
~shown in inflated position following the supply thereof to
.~
~pressure fluid through the valve means disposed within the
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r passageway means of the body of the apparatus at the
locations indicated by circles;
Figs. 9A, 9B and 9C are enlarged sectional views of
the valve means shown diagrammatically in the circled parts
of Fig. 8, and as seen along broken lines 9--9 thereof,
~i~ includiny upper and lower valve members shiftable between
positions opening and closing the passageway means, the
upper valve member being shown in closed and open positions
and the lower valve member in open position in Figs. 9A and
9B, prior to and during the supply of packer inflating
pressure, respectively, and the lower valve member being
~; shown in closed position in Fig. 9B, following inflation of
~h~ the packer, to prevent the escape from or the supply of
additional pressure fluid to the packer;
Fig. 10 is a vertical sectional view of an alternative
version of a closing sleeve having a closing plug landed
thereon, with the plug and closing sleeve lowered in
response to pressure thereabove to move the lower end of
the closing sleeve into sealed engagement with the opening
sleeve in order to close the cement circulating port in the
body of the apparatus; and
Fig. 11 is a view similar to Fig. 10, but showing the
opening sleeve raised to its upper limited position within
the body to open the port, following failure to lock to the
body in its lower positions, and with the plug raised
within the sleeve to contain cement beneath the plug.
With reference now to the details of the above
described drawings, the embodiment of the overall apparatus
shown in Figs. lA, lB, 2A and 2B includes a body indicated
in its entirety by reference character 10 and connectable
in a pipe string (not shown) to permit it to be lowered
into a well bore, such as casing string 9 shown in Figs. 2A
¦ and 2B,.although as used herein, "well bore" means either
an open hole or a cased hole. The body, known as a
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PATENT
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"collar" in the art of stage cementing, has a bore 11
forming a continuation of the pipe string and includes an
upper pipe 12 having a sub 13 at its upper end for
connection to the lower end of an upper portion of the pipe
string, an intermediate pipe 15 threadedly connected at its
upper end to the lower end of the upper pipe 12, and a
lower pipe 16 threadedly connected to the pipe 15 and
extending downwardly therefrom for connection at its lower
end to the upper end of the lower portion of the pipe
string. The upper pipe 12 of the body has ports 14 formed
therein connecting the bore of the body with its outer side
and thus with the annulus about the body, and the
intermediate pipe 15 has one or more passageways 17 formed
therein to connect its upper with its lower end.
The outer diameter of the lower pipe 16 of the body is
of reduced outer diameter and a packing element indicated
in its entirety by reference character 18 mounted about the
lower pipe is shown to comprise an outer sleeve 19 of
elastomeric material extending between a sleeve 20A at its
upper end for threaded connection to the outer diameter of
the lower end of intermediate pipe 15, a sleeve 20B on its
lower end connected to a ring 21 which is sealably slidable
along the lower pipe 16 of the reduced outer diameter
portion of the body. As previously described, the sleeve
is reinforced by vertically extending metal strips 22
disposed within it and fixed at their upper ends to the
sleeve 20A and at their lower ends to the sleeve 20B. More
particularly, the pacXing elements also include an inner
sleeve 23 of elastomeric material on the inner side of the
metal strips and extending between a head 24 at its upper
end mounted within upper sleeve 20A and a head 25 at its
lower end mounted within lower sleeve 20B. Reference is
made to my Canadian patent application, Serial No.
615,237 filed September 29, 1989, and assigned to the
~5
2 ~
PATENT
DAVE, OO9CIP
assignee of the present application, for a more detailed
description of a packing element of this construction.
As shown, the inner sleeve 23 is spaced outwardly from
the outer diameter of the reduced diameter portion of the
- 5 body to provide an annular space between them connecting at
its upper end with passageway means 17, whereby, as will be
described, inflating pressure fluid may be introduced into
the space to inflate the sleeves and thus the metal strips
16 of the body to permit the outer sleeve to be expanded
into sealing engagement with the well bore in which the
casing string is suspended. As shown, the lower end of the
passageway means 17 connects with this space so as to
permit pressure fluid to be supplied thereto, all in a
manner to be described below.
The apparatus further includes a first tubular member
or opening sleeve which is indicated in its entirety by
reference character 30 and which includes a first outer
pipe 31 which is disposed within and slidable vertically
with respect to the bore 11 of the body 10, and a second
inner pipe 32 which is threadedly connected to the inner
diameter of the pipe 31 intermediate its upper and lower
ends with its lower end seated upon a flange 33 at the
lower end of the pipe 31. As shown in Fig. lA, the tubular
member 30 is held in an upper position, wherein it is
disposed over the ports 14 by means of one or more shear
pins 34 releasably connecting it to the body 10. More
particularly, seal rings 35 and 36 are carried about the
outer diameter of the pipe 31 for sealably engaging the
bore of the body above and below the ports when the first
tubular member 30 is in its raised position. Additional
seal rings 37 and 38 are carried about the outer diameter
of the pipe 31 in position to sealably engage an annular
space 39 between the pipes 12 and 15 of the body at the
upper end of the passageway means 17 as well as above and
16
, -.. . , . .. ,. - ;:. i;, , , , . - . . - , ,: . . . .. , . -
. L ~ ~ r
PATENT
DAVE, OO9CIP
below ports 40 in the outer pipe 31 which fluidly connect
an annular space about the inner diameter of pipe 32 with
the space.
Another port 41 is formed in the inner pipe 32 of the
tubular member to connect the bore 43 of the member 30 with
space 39, and a seal ring 42 is carried about the inner
pipe for sealably engaging the inner diameter of the outer
pipe 31 below the port 40 in the outer pipe and the port 41
in the inner pipe. Thus, in the upper position of the
member 30, the port 41 is fluidly connected to the port 40
and thus to the space 39 at the upper end of the passageway
means 17. The port 41 in the tubular member is initially
closed by a closure or knock-off plug 45 whose inner end
projects inwardly of the bore 43 below an upwardly facing
seat 44 at the upper end of the bore.
The apparatus further includes an opening plug 50
which, as shown in Figs. 2A and 2B, is adapted to be
lowered downwardly through the casing string and into a
position in which a shoulder 44A thereabout lands on the
seat 44, as shown in more detail in Fig. 3. The plug has
a lower closed end and ports 57 through the side thereof
connecting its bore above the closed end with its outer
side below the shoulder 44A. More particularly, seal rings
52 and 53 are carried about the outer side of the plug 50
for sealably engaging the upper and lower portions of the
bore 43 in member 30 and thus above and below the ports 57
as well as the port 41 of the tubular member. The lower
end of the larger outer diameter portion of the plug is
thus adapted to engage and remove the outer end of the
closure 45 to thereby shear it off to open the port 41 for
fluidly connecting the bore of the plug and the casing
string thereabove with the upper end of passageway means
17. As shown in Fig. 2A, the outer end of the closure has
been sheared from its inner reduced end in passageway 41
2 ~h t~ h ~J ~J
PATENT
DAVE, OO9CIP
and has fallen into a space betwe~n the outer side of the
plug and the inner side of the tubular member.
With the casing string above the plug 50 thus fluidly
connected with the passageway means 17, pressure fluid may
be supplied downwardly through the casing string and into
the pacXing element for inflating it into sealing
engagement with the casing 9, as shown in Fig. 2B. As also
shown, the plug carries lips about its lower end which
permit it to be pumped downwardly through the casing string
into landed position on the tubular member. It should be
understood, however, that the plug could instead be lowered
into seated position merely by its weight.
After the fluid pressure has inflated the packer, as
shown in Fig. 2B, it is effective to shear the pins 34 and
thus releas~ the tubular member 30 for lowering with
respect to the body. Thus, as fluid pressure continues to
be applied to the plug landed on the tubular member, the
lower end 60 of the outer pipe of the tubular member lands
upon a seat 61 formed on a reduced inner diameter portion
of the intermediate pipe 15 of the body so as to locate the
tubular member in its opening position in which its upper
end has moved below the port 14 in the body. At this time,
a snap ring 62 or the like carried about the upper pipe of
the tubular member engages within a groove 63 about the
inner diameter of the body 10 to hold the tubular member
down in its open position.
When the first tubular member has moved to its lower
position, the O-ring 36 thereabout will sealably engage the
bore of the body above the space 39, while the O-ring 37
carried thereabout will sealably engage the bore of the
body beneath the space, thereby closing the fluid
connection between the upper end of the passageway means 17
and the port 40 and thus, through the port 41, with the
casing string above the plug. As a consequence, pressure
18
PATENT
DAVE,009CIP
fluid is captured and contained within the space within the
packing element to maintain it inflated. As previously
mentioned, each of seal rings 36, 37 and 38 are of equal
outer diameter, thereby avoiding the possibility of a fluid
lock as the member 30 moves to its lower position. At this
time, cement may be circulated downwardly through the pipe
string and into the body for passage outwardly through the
ports 14 and thus into the annulus between the casing
string and the well bore above the inflated packer.
10Following placement of the cement in the annulus, the
ports 14 may be closed by means of a second tubular member
or closing sleeve 70 disposed within the bore of the body
above the opening sleeve 30. As shown, this tubular member
is releasably connected to the body in the upper position
15of Fig. 3 by means of shear pins 71, and includes a sub 72
threadedly connected to the upper end of the pipe 73 to
form an upwardly facing seat 74 at its upper end.
Following placement of cement within the annulus, the ports
14 may be closed by the lowering of a second plug 75
through the casing string and onto a landed position on the
seat 74, as shown in Fig. 4. Thus, with the plug so
disposed, pressure f]uid above it will shear the pin 71 and
move the second sleev~ downwardly into a position in which
its lower end closes the ports 14. As shown, the plug
carries wings which permit it to be pumped down into seated
position.
As shown, seal rings 76 are carried about the upper
end of the second tubular member for sealably engaging the
bore of the body above the shear pin 71, and other seal
rings 77 are carried about the reduced lower end 78 of the
second member for sealably engaging the enlarged upper end
of the first tubular member 30 or opening sleeve as the
closing sleeve is lowered into the closing position of Fig.
4. The closing sleeve is located in its lower position by
19
2~J~ ~t~
PATENT
DAVE,009CIP
the landing of the reduced lower end upon a shoulder 79
formed on the enlarged inner diameter portion of the upper
end of the first tubular member. The closing sleeve is
held in its lower closing position by means of snap ring ~0
carried about it for engaging a shoulder at the upper end
of a recess 81 formed in the bore of the body.
As closing sleeve 70 moves downwardly to the position
shown in Fig. 4 closing opening 14, seal rings 77 will move
into sealing engagement with the upper end of opening
sleeve 30 and immediately trap the cement inside the
sleeves, forming a pressure lock that would prevent any
further downward movement of the closing sleeve. To keep
this from happening, means are provided to release cement
from inside the sleeves when the pressure of the cement
exceeds a preselected amount. In the embodiment shown,
such means comprises a spring loaded check valve 54 located
in a passageway in inner pipe 32 connecting the inside of
opening sleeve 30 to the bore of the intermediate pipe 15.
The check valve will allow sufficient cement to flow out of
the sleeves to allow the closing sleeve to move to the
closed position shown in Fig. 4.
Fig. 5 shows the upper portion of the apparatus in the
same position it is shown in Fig. 2A -- i.e., upon lowering
of the plug 50 into seated position on the first tubular
member or opening sleeve so as to shear the closure of the
port 41 and thus open the bore of the plug to the upper end
of the passageway means 17 leading to the space between the
packing element and lower body portion. As previously
described, however, it may be found that, following
inflation of the packer, the pressure of the fluid in the
casing string above the plug is not sufficient to shear
pins 34 and thus move the first tubular member downwardly
to open the ports 14. Thus, in accordance with another
novel aspect of the present invention, a pipe string such
',
,,: .... . .......... ., , ~ ,,. .. . .. ,. , . . ~ . ~ .
.: : , . : :
2 ~! .L'J' ~ .
PATENT
DAVE, OO9CIP
':
as drill pipe so has been lowered within the casing string
to land at its lower end upon the plug 50. ~ore
particularly, the lower end of the pipe string 90 has a
shoulder, such as conically shaped shoulder 91 for landing
- 5 upon a shoulder, such as seat 44 at the upper end of the
plug, whereby the weight of the pipe string may be slacked
off to impose a downward force on the plug sufficient to
shear the pins and thus lower member 30. The lower end of
the pipe string also has a lower extension 92 which fits
closely within the bore of the plug and which has a seal
ring 93 carried thereabout for sealably engaging the bore
above the port 41 therein, thereby permitting fluid
pressure to be held on the packing element so as to
maintain it inflated as the plug and thus the first tubular
member are forced downwardly. Obviously, upon opening of
the ports 14, the pipe string 90 may be removed, and cement
may be circulated through the ports into the annulus, and
the closing sleeve subsequently lowered to close the ports.
As previously mentioned, difficulty may be
encountered, in the use of the above described apparatus,
in causing the opening sleeve 30 to move downwardly to and
remain at its lower position in order to close passageway
17 for containing inflating pressure within the packer, in
which case it may be found desirable to use an opening plug
constructed in accordance with the alternative embodiment
of the invention, shown in Figs. 6 and 7. Thus, the
modified opening plug, which is indicated in its entirety
by reference character 100, comprises an outer plug body
101 which is similar in construction to the opening plug 50
shown and described in connection with the prior figures of
the drawings, as well as an inner plug body 102 disposable
within a bore 103 in the outer plug body for movement
between its upper position of Fig. 6 and its lower posltion
of Fig. 7. As in t,he prior described plug, the outer plug
~1
. ., ' '' ' ' . . ' ~: ', '
', ' ' ~ ' ' ~ ' ;' ' : ''.''
~ ~ 2 ~ c~ ~
PATENT
DAVE,009CIP
body 101 includes a shoulder 104 adapted to land on the
seat ~4 on the bore of the opening sleeve 30, and carries
an 0-ring 105 thereabout for sealably engaging within the
bore 43 in the opening sleeve beneath the seat 44 thereof,
and another 0-ring 106 about a reduced diameter portion 109
thereof for sealably engaging within the reduced bore in
the lower end of the opening sleeve below ports 108 therein
which connect its bore 103 with its outer side and which in
turn is connected with the port 41 in the inner side o~ the
opening sleeve leading to the port 40 in the outer side
thereof, and thus the space 39 at the upper end of the
passageway 17 leading to the packer.
The inner plug body 102 also has a port llO formed
therein which, in the upper position of the inner plug body
shown in Fig. 6, is disposed opposite the port 108 formed
in the outer plug body, the ports 108 and 110 thus forming
port means connecting bore 111 in the inner plug body with
the outer side of the inner plug body, and thus ultimately
with the passageway means 17. O-rings 112 and 113 are
carried about the bore 103 of the outer plug body for
sealably engaging the outer side of the inner plug body
above and below the ports 110 therein when the inner body
is in its upper position, thereby confining flow of
pressure fluid within the casing string above the plug for
flow through the port means.
The inner plug body is initially held in its upper
position by means of a shear pin 114 mounted in the outer
plug body and extending into a recess in the inner plug
body. This shear pin is so designed as to shear in
response to the supply of fluid within the pipe string
above the plug at the pressure above that for inflating the
packer. Upon shearing of the pin 114, the inner plug body
is forced downwardly to the lower position of Fig. 7
wherein its lower end lands on the lower end of the bore in
22
2 ~
PATENT
DAVE,009CIP
the outer plug body. At this time, the outer ends of ports
110 are disposed between O~ring 113 and another 0-ring 115
carried within the bore 103 of the outer plug body beneath
the 0-ring 113. As shown, ports 116 are formed in the
lower end of the outer plug body to vent the space beneath
the lower end of the inner plug body and the lower end of
the bore in the outer plug body and thus permit the inner
plug body to be moved downwardly.
When the inner plug body has been so lowered, the
connection of the port means to passageway means 17 is
closed so as to prevent pressure fluid from escaping from
within the inflated packer, and the higher pressure to be
applied in the casing upon lowering of the opening sleeve
and circulation of cement out into the annulus from
entering and thereby over inflating the packer. As
previously described, due to the short length of the inner
plug body, and thus the relatively short length of sliding
engagement between the inner and outer plug bodies, the
downward movement of the inner plug body to close the port
means in the plug 100 is relatively reliable. More
particularly, the plug 100 thus serves to close the port
means and thus close the passageway 17 whether or not the
inner sleeve is fully lowered to and held in its lower
position.
25The embodiment of the overall apparatus shown in Fig.
8 is similar in many respects to that of the overall
apparatus shown in Figs. lA, lB, 2A and 2B in that it has
been lowered on a pipe string into a casing 9 to dispose it
at a level in which a column of cement is to be applied
between the string and the bore of the outer casing 9.
Thus, similarly to the previously described apparatus, that
shown in Fig. 8 includes a tubular body 120 having
circulating ports (not shown) formed therein connecting the -
:-
23 ~-
.
3'f~
PATENT
DAVE, OO9CIP
bore 121 of the body with its outer side and thus with the
an~ulus about the body.
More particularly, the outer diameter of the lower end
of the body is reduced, and a packing element 122 is
mounted thereabout includ~s an outer sleeve of elastomeric
material as in the apparatus previously described such that
further detail is not necessary. Thus, the inner sleeve of
the packing element is spaced outwardly from the outer
diameter of the reduced portion of the body to provide an
annular space ~etween them connecting at its upper end with
passageway means 123 formed in the outer body and
connecting at its upper end with an annular space 124 to
which fluid pressure means may be applied for the purpose
of inflating the packer. As will be described to follow,
this alternative embodiment of the apparatus differs from
the previously described apparatus in the manner in which
! pressure fluid within the pipe string is supplied to the
passageway 17 for inflating the packer and then contained
within the pac~er to maintain it inflated as well as to
prevent the supply of pressure at a higher level through
the passageway means to the packer, which might otherwise
over inflate and thus damage the packer.
Similarly to the previously described apparatus, that
of Fig. 8 includes an opening sleeve or first tubular
member 125 which is reciprocal within the bore of the body
120 between an upper position, as shown in Fig. 8, wherein
it closes the circulating ports (not shown) in the body as
well as connection with a space 124 within the body at the
upper end of the passageway means 123 leading to the
packer. The apparatus further includes a closing plug 126
which is landed within the bore of the lower end of the
opening sleeve 125 so as to connect port means therethrough
with ports through the tubular member leading to the space
124. As in the case of the previously described apparatus,
~4
:
PATENT
DAVE, OO9CIP
lowering of the plug 126 into the position of Fig. 8 has
sheared a clociure 127 over the inner end of the port in the
opening sleeve so that pressure fluid in the pipe string
above the plug 126 will flow through the port means in the
plug as well as the port in the openiny sleeve and thus
into the passageway means 17 for the purpose of inflating
the packer.
As described in connection with the prior apparatus,
when the packer has been inflated, as shown in Fig. 8,
additional fluid pressure in the pipe string above the plug
is intended to lower it and thus the opening sleeve to its
lower position for closing the passageway means. For this
purpose, a seal ring 128 carried about the outer side of
the opening sleeve is so disposed as to be lowered to a
position above the space 124, while another O-ring 129
about the sleeve has been lowered beneath the space 124,
the imperforate portion of the opening sleeve intermediate
the rings 128 and 129, thus closing off the upper end of
the passageway means 17. However, in accordance with the
embodiment of the apparatus shown in Fig. 8, valve means
are provided in the body for closing the passageway means
to not only contain pressure within the inflated packer,
but also prevent the introduction to the packer of still
higher pressure within the pipe string, automatically in
response to the inflation of the packer at the desired
pressure level and whether or not the O-rings 128 and 129
are properly positioned, and thus without reliance upon the
intended operation of the opening sleeve. Thus, if
desired, the O-rings 128 and 129 may be eliminated since
they serve only as a secondary means of closing the
passageway means.
For this purpose, valve means in the form of upper and
lower valve members 130 and 131 are instalied in the body
120 for controlling flow through the passageway means 123.
.. . . .. . . .. .
2 ~ 2
PATENT
DAVE,009CIP
Thus, as shown in Figs. sA to 9C, the upper valve member
130 is disposed within a bore 132 formed in the body to
connect at its left-hand end with an upper segment 17A of
the passageway means downstream of the space 124 and at its
opposite end with the outer side of the body. The lower
valve member 1~1 is disposed within a bore 133 formed in
the body to connect intermediate its ends with an
intermediate segment 17B of the passageway 17 and at its
right-hand end with the outer side of the body. The upper
end of the passageway means segment 17B connects with the
bore 132 toward its left end and thus toward its connection
with the passageway segment 17A. The bore 133 also
connects with a lower seyment 17C of the passageway means
which leads to the space within the sleeve of the packer,
15 the connection of the segment 17C with the bore 133 being
disposed to the right of its connection with the lower end
of the passageway siegment 17B. As shown in Fig. 9A, the
valve member 130 is initially urged by a coil spring to the
left and held by a shear pin in a position closing the
passageway 17 prior to the supply of pressure at a level
for inflating the packer. At this same time, the lower
valve member 131 is also held by a shear pin in the
position shown in Fig. 9A so as to connect the passageway
segments 17B and 17C with one another. For this purpose,
the valve member 131 has spaced left and right-hand heads
131A and 131B, each carrying seal rings for sealably
engaging the bore 133 as the valve member 131 reciprocates
therein. When the valve member 131 is held in its left
position, the head 131A is to the left of passageway
30 segment 17B and the head 131B is to the right of the
passageway segment 17C, thus connecting them to open the
passageway beneath the valve member 130.
The valve member 130 includes a head 130~ at its left
end which is spring pressed to the closed position shown in
.- . ,. ,,, .. , . .... , ~
,,,~ . , ". : . ... , ... ,, , .~ .. , . ... .- . ~.,
3 ~
PATENT
D~VE,009CIP
Fig. 9 and held therein by a shear pin which is adapted to
` shear in response to the supply of fluid pressure to the
passageway 17 during inflation of the packer. ~s the pin
is sheared, the valve member 130 is urged to the right-hand
position shown in Fig. 9B so as to connect passageway
segment 17A with passageway segment 17B of the passageway
means, thus permitting pressure fluid to pass into segment
17C and through the passageway means into the packer for
inflating it.
10An additional passageway 146 is formed in the body of
the apparatus to connect the space between the packer
sleeve and the body with the left-hand end of the bore 133,
whereby pressure in the space is effective over the left-
hand end of the head 131A of the valve member 131 to shear
the pin holding it open and then urge it to the right, thus
to the position shown in Fig. 9C for closing the passageway
means when the packer has been inflated. At this time, as
shown in Fig. 9C, one of the 0-rings about the head 131A
sealably engages the bore 133 intermediate its connection
with the passageway segments 17B and 17C, thus preventing
communication between the passageway segments 17B and 17C.
As a result, the valve member 131 will contain pressure
within the packer to hold it inflated and cannot be urged
from the right-hand open position of Fig. 9C, regardless of
the pressure which might be applied thereto through the
passageway means 17 upstream of it.
When pressure in the pipe string is relieved, the
upper valve member 130 will be urged to the right and thus
back to the position shown in Fig. 9A. It will then be
held in such position by means of a ring adapted to be
urged to a cocked position as the rod on the right-hand end
of the valve member 130 is withdrawn from within the ring.
This then will lock the upper valve member 130 in its
27
- . . . . ~ . . ..
P~TENT
DAVE, OO9CIP
closed position, thus providing a secondary closure for the
passageway means.
As previously described, the alternative form of
closing sleeve and closing plug shown in Figs. lo and 11,
S and indicated in their entireties by reference characters
220 and 221, respectively, are of such construction as to
prevent the substantial return of cement from the annulus
through the circulating ports 14 even though the closing
sleeve is not lowered and locked in its closing position.
As in the case of the closing sleeve 70, sleeve 220 is
disposed within the bore of the body 10 and carries an
o-ring 226 thereabout for sealably reciprocating therein
above the opening sleeve 30. This closing is initially
retained in its upper position by means of shear pins 222
releasably connecting it to the body. The closing sleeve
has a seat 223 at its upper end, and the closing plug 221
has a shoulder 224 which is adapted to land on the seat as
well as wings above the shoulder which permit it to be
pumped downwardly to seated position. When the plug is so
landed, fluid pressure thereabove is effective to shear the
pins 222, and thus move the closing sleeve downwardly with
it toward closing position. As in the case of the closing
sleeve 70, the lower end of sleeve 220 has a reduced
diameter portion carrying o-rings 225 thereabout for
sliding into and sealably engaging the enlarged diameter of
the upper end of the bore in opening sleeve 30, thereby
closing the circulating ports.
As in the case of the sleeve 70, sleeve 220 carries an
expandable locking ring 227 thereabout which is intended to
move outwardly into a groove 223 about the bore of the body
as the sleeve is lowered into a landed position on a
shoulder 230 within the bore of the opening sleeve 30.
However, as shown in Fig. 10, the locking means may not,
for one or more various reasons, move into a position
28
~ ~ 2 ~
PATENT
D~VE, OO9CIP
beneath the upper end o~ the groove 228, or even if it is
lowered to the position, expand outwardly into the groove,
-in any event failing to be locked in its lower closing
position. Unless locked in this lower position, the
.;5 closing sleeve would be forced upwardly due to the
downwardly facing differential pressure area between the
seal rings 225 and 226, thus permitting cement within the
annulus to flow through the ports 14 into the bore of the
body 10 beneath the closing plug 221. Consequently, unless
the closing sleeve was held downwardly by pressure above
the plug as the cement column hardened, cement would be
free to flow upwardly within the pipe string. I~owever,
and, as previously described, the lowering of pressure
above the plug following hardening of the cement may permit
contraction of the casing and void between it and the
cement column.
As also previously described, however, the closing
sleeve and plug are provided with means for retaining the
plug in a position closing the bore through the closing
sleeve, while the cement column hardens so that there is no
need to maintain and then reduce pressure above the plug.
For this purpose, an expandable locking ring 230 is carried
within a groove 231 about the closing plug beneath the
landing shoulder 224 thereon, so that the closing plug is
lowered into the bore of the closing sleeve beneath the
seat 223, the locking ring 230 is adapted to expand
outwardly into a groove 232 formed about the bore of the
closing sleeve beneath the seat 223. More particularly, an
o-ring 233 is carried about the closing plug beneath the
locking ring 230 in position to sealably engage the bore of
the closing sleeve when the closing plug is locked down in
the closing sleeve by engagement of the locking ring 230
with the upper end of the groove 232. In this way, cement
which may circulate back through the ports 14 and into the
29
PATENT
DAVE, OO9CIP
bore of the closing sleeve be~eath the plug is retained
despite the failure of the closing sleeve to move to its
locked position within the bore of the body.
As shown, the groove 232 is of such length that it
permits the locking ring 230 to move downwardly within it
to a position in which the o-ring 233 is removed from
sealing position within the bore of the closing sleeve. At
this time, the landing shoulder 224 about the closing plug
is above the seat 223 so as to form a bypass between the
plug and sleeve thus permitting f luid beneath the plug to
flow therethrough into the bore of the body above the
closing sleeve. Thus, as the closing sleeve is moved
downwardly with the plug due to pressure thereabove, the
movement of its lower end into the upper enlarged bore of
the opening sleeve 30 will prevent displacement of further
cement through the circulating ports 14, whereby pressure
beneath the plug will cause it to rise, as shown in Fig.
10, to relieve the build up in pressure. Then, pressure
acting upon the upwardly facing differential area between
the O-rings 225 and 226 will force the closing sleeve
downwardly, thus again building up a higher pressure below
the plug, the plug thus continuing to shuttle or
reciprocate these short distances until cement has been
circulated through the ports 14 into the annulus between
the stage collar and well bore, following which the plug
will then be moved upwardly to its position shown in Fig.
11 for closing the bore through the closing sleeve. At
this time, the upper end of the closing sleeve is free to
move upwardly until its upper end engages a shoulder 234 in
the bore of the body, thus limiting further upward movement
of the closing sleeve and closing plug. -
As shown, the locking ring 230 has a lower conical
surface about its outer side to permit it to be contracted
.
,t r~
PATENT
DAVE,009CIP
inwardly as it engages and slides downwardly over the seat
223 on the upper end of the closing sleeve.
From the foregoing it will be seen that this invention
is one well adapted to attain all of the ends and objects
hereinabove set forth, together with other advantages which
are obvious and which are inherent to the apparatus.
It will be understood that certain features and
subcombinations are of utility and may be employed without
reference to other features and subcombinations. This is
contemplated by and is within the scope of the claims.
As many possible embodiments may be made of the
invention without departing from the scope thereof, it is
to be understood that all matter herein set forth or shown
in the accompanying drawings is to be interpreted as
illustrative and not in a limiting sense.
