Note: Descriptions are shown in the official language in which they were submitted.
J ~38~
Background Of The Invention
1. Field Of The Invention
The present invention relates generally to bridge plugs,
and more particularly, but not by way of limitation, to a
retrievable bridge plug suitable for setting inside the bore
of a string of drill pipe to aid in the control of a well
that is flowing out of control.
2. Description Of The Prior Art
Bridge plugs are packing devices which are generally
used to completely seal the bore of a string of pipe. Most
commonly, bridge plugs are utilized to block the bore of a
string of casing in a well.
Bridge plugs are typically set by engaging the bore of
the pipe string with a set of slips and then mechanically or
hydraulically setting a packer against the bore.
During the drilling of a well, a string of drill pipe
with the drill bit connected to the lower end thereof
extends down into a well bore and is rotated to extend the
depth of the well bore.
If the drilling operator loses control of the fluids in
the well bore, i.e., a blowout occurs, the well will ini-
tially be brought under control by shearing the drill pipe
near the surface with the shear rams, and removing the upper
portion of drill pipe and closing in the well above the
sheared off upper end of the drill pipe. Well fluids may
continue to flow upward through the drill pipe and through
the well bore, which outward flow up through the well is
~ ~ 1938~
controlled through the choke line.
In order to bring the well back under control, it is
necessary at some point to remove the damaged upper portion
of the drill pipe and reconnect new drill pipe segments
thereto.
Accordingly, it is desirable to have a bridge plug which
could be set in drill pipe to stop the flow up through the
drill pipe so that the damaged upper portions of the drill
pipe could be removed and replaced with new drill pipe
segments.
Summary Of The Invention
The present invention provides such a bridge plug appa-
ratus for sealing off the bore of a damaged string of drill
pipe, and also provides related methods for controlling well
flow.
A retrievable bridge plug apparatus in accordance with
the present invention includes a packer mandrel assembly
having a longitudinal mandrel bore defined therein with a
barrier blocking the mandrel bore. The packer mandrel
assembly has a bypass port disposed radially through a wall
thereof and communicated with the mandrel bore below the
barrier.
A packer is disposed on the packer mandrel assembly for
sealing between the packer mandrel assembly and the bore of
the drill pipe string below the bypass port upon engagement
of the packer with an internal upset of the drill pipe
string and subsequent application of upward force to the
3 8 ~
packer mandrel assembly.
A bypass sleeve is slidably disposed about the packer
mandrel assembly and movable longitudinally relative to the
packer mandrel assembly between an open position wherein the
bypass port is open and a closed position wherein the bypass
port is closed. The bypass sleeve is fixed against rota-
tional movement relative to the packer mandrel assembly.
A rotating case assembly is operably associated with the
packer mandrel assembly and bypass sleeve. The case assem-
bly is threadedly engaged with the bypass sleeve so that
upon rotation of the rotating case assembly relative to the
packer mandrel assembly the bypass sleeve is selectively
moved between its opened and closed positions.
A thrust bearing is provided between the packer mandrel
assembly and the rotating case assembly for permitting rota-
tion of the rotating case assembly relative to the packer
mandrel assembly while simultaneously applying a sufficient
upward force on the packer mandrel assembly from the rotat-
ing case assembly to maintain the packer sealed against the
drill pipe bore.
The barrier and bypass port in the packer mandrel assem-
bly, the bypass sleeve, the rotating case assembly, and the
thrust bearing means can be collectively defined as a selec-
tively positionable bypass means of the bridge plug
apparatus. The bypass means performs several functions. It
prevents fillup of the work string to which the bridge plug
apparatus is attached as the work string and the bridge
~1 ~938~
plug apparatus are run into position in the drill pipe
string. Further, the bypass means communicates the
pipe bore below the packer with a low pressure zone
above the packer through the mandrel bore prior to
sealing the packer against the drill pipe bore.
Further, the bypass means isolates the pipe bore below
the packer from the low pressure zone above the packer
after the packer is sealed against the drill pipe bore.
Finally, the bypass means serves to recommunicate the
drill pipe bore below the packer with the low pressure
zone above the packer through the mandrel bore to
balance pressure across the packer prior to unsetting
of the packer and retrieval of the bridge- plug
apparatus.
In accordance with a broad aspect, the invention
relates to a retrievable bridge plug apparatus for
sealing a pipe bore in a pipe string, comprising:
a packer mandrel assembly having a longitudinal
mandrel bore defined therethrough;
packer means, disposed on said packer mandrel
assembly, for sealing between said packer mandrel
assembly and said pipe bore in said pipe string upon
engagement of said packer means with an internal upset
of said pipe string and subsequent application of
upward force to said packer mandrel assembly; and
selectively positionable bypass means for:
preventing fill-up of a work string attached to
said bridge plug apparatus as said work string and said
bridge plug apparatus are run into position in said
pipe string;
communicating said pipe bore below said packer
means with a low pressure zone above said packer means
through said mandrel bore prior to sealing said packer
means against said pipe bore;
isolating said pipe bore below said packer means
from said low pressure zone above said packer means
g~ 3 ~
-4a-
after sealing said packer means against said pipe bore;
and
recommunicating said pipe bore below said packer
means with said low pressure zone above said packer
means through said mandrel bore to balance pressure
across said packer means prior to unsetting said packer
means.
Brief Description of the Drawings
Numerous objects, features and advantages of the
present invention will be readily apparent to those
skilled in the art upon a reading of the following
disclosure when taken in conjunction with the
accompanying drawings.
FIG. 1 is a schematic illustration of a string
of drill pipe in a well bore hole after the upper end
of the drill pipe has been sheared by the shear rams.
FIG. 2 is a schematic illustration similar to
FIG. 1 showing the bridge plug apparatus of the present
invention having been lowered into the drill pipe
string on a snubbing unit work string and having been
set in place within the drill pipe string to seal
across the bore of the drill pipe.
FIGS. 3A-3J comprise an elevation right side
only sectioned view of a first embodiment of the bridge
plug appara-
336
tus of the present invention. The apparatus is illustratedin a position prior to expansion of the packer and with the
bypass port in an open position. The bypass means of the
bridge plug is shown in its open position and is constructed
to bypass into the annulus between the snubbing unit work
string and the drill pipe bore.
FIG. 4 is a laid out view of the upper J-slot of FIG. 3B
which connects the overshot to the rotating case assembly.
FIG. 5 is a laid out view of the lower J-slot of FIG. 3G
which interconnects the collet with the packer mandrel
assembly.
FIGS. 6A-6K comprise an elevation right side only sec-
tioned view of an alternative embodiment of the bridge plug
apparatus of the present invention. In the embodiment of
FIGS. 6A-6K the bypass means is shown in FIG. 6E in an open
position, and bypasses fluid up into the interior of the
snubbing unit work string.
FIG. 7 is an elevation sectioned view of a typical joint
between segments of drill pipe illustrating more precisely
the typical configuration of the internal upset within the
drill pipe bore.
Detailed Description Of The Preferred Embodiments
Referring now to the drawings, and particularly to FIGS.
1 and 2, the general structure of an oil well is there sche-
matically illustrated, along with the placement of the drill
pipe bridge plug apparatus of the present invention within
such a well to control the flow of fluid up through the
~1938~3
drill pipe.
In FIG. 1, a typical oil or gas well 10 is schematically
illustrated. A well bore 12 has been drilled down through
the earth's surface 14 by a drill bit (not shown) located on
the lower end of a string of drill pipe 16. A length of
surface casing 18 has been set in the bore hole 12.
A blowout preventer stack 20 is mounted on the surface
casing 18. In FIG. 1, the shear rams 22 of the blowout pre-
venter stack 20 have been used to shear off the drill pipe
string 16 thus creating a damaged upper end 24 of the drill
pipe string 16.
Well fluids are schematically illustrated by the arrows
such as 26 flowing upward through the pipe bore 28 of drill
pipe string 16 and through the annulus 30 defined between
well bore 12 and drill pipe string 16. The flow of these
upwardly flowing fluids is permitted by the choke line 32
having valve means 34 therein through which the flow can be
controlled.
Schematically illustrated in FIG. 1 is a typical inter-
nal upset 36 of the pipe bore 28. The true configuration of
such an upset is best seen in FIG. 7 which illustrates a
connection between two joints of a typical form of drill
pipe utilized in the oil field. The joint illustrated in
FIG. 7 is a Hydril PH-4~ drill pipe. As is apparent in FIG.
7, near the ends of each drill pipe segment the pipe wall
has an increased thickness thus defining a minimum diameter
pipe bore 38 adjacent the joint, with an enlarged diameter
3 8 ~
drill pipe bore 40 throughout most of the length of each
joint, and with tapered transitional shoulders such as 36
and 42 at the lower and upper ends of the reduced diameter
bore 38. It is the lower transitional shoulder 36 which is
utilized for purposes of the present invention as an inter-
nal upset of the pipe bore 28 against which a bridge plug
can be set.
Although the internal upset 36 illustrated in FIG. 7 is
integrally formed on one of the sections of drill pipe, it
will be understood that the term internal upset can
generally be used to describe any downwardly facing surface
defined internally within the pipe string which could be
used to engage a structure like the collet of drill pipe
bridge plug apparatus 48 further described below.
A snubbing unit 44 is schematically illustrated as being
mounted above the blowout preventer stack 20. As seen in
FIG. 2, a snubbing unit work string 46 having the bridge
plug apparatus 48 of the present invention connected to a
lower end thereof has been lowered through the snubbing unit
44 into the drill pipe bore 28. The bridge plug apparatus
48 has been set within the drill pipe bore 28 and against
the internal upset 36 thereof to seal the pipe bore 28. The
snubbing unit 44 permits the snubbing unit work string 46 to
be lowered therethrough while maintaining a seal about the
work string 46 so that any upward flow of fluids is still
controlled by the choke line 32 and valve means 34.
Turning now to FIGS. 3A-3J, the details of construction
~1933~
--8--
of a preferred embodiment of the drill pipe bridge plug
apparatus 48 will be described.
The bridge plug apparatus 48 includes a packer mandrel
assembly 50 (see FIGS. 3C-3J) having a longitudinal mandrel
bore 52 defined therein with a barrier 54 (see FIG. 3E)
blocking the mandrel bore 52. The packer mandrel assembly
50 has a bypass port 56 disposed radially through a wall 58
thereof and communicated with the mandrel bore 52 below the
barrier 54.
The packer mandrel assembly 50 includes a number of com-
ponents fixedly connected together. Beginning at the upper
end of packer mandrel assembly 50 in FIG. 3C, the assembly
50 includes a differential piston 60, an upper mandrel 62, a
bypass body 64, a packer mandrel 66, a connector 68, and a
bottom guide 70.
The differential piston 60 and upper mandrel 62 are
threadedly connected at 72 (see FIG. 3C) with a seal 74
therebetween, and with a set screw 76 for locking the
threaded connection 72. The differential piston 60 carries
an outer 0-ring seal 61 which sealingly engages the rotating
case assembly as is further described below.
The upper mandrel 62 and bypass body 64 are threadedly
connected at 78 (see FIG. 3E) with the set screw 80 locking
the same.
A bypass seal assembly 82 is carried by bypass body 64
and held in place between the lower end 84 of upper mandrel
62 and an upward facing shoulder 86 of bypass body 64. An
3 8 S
o-ring seal 88 seals between the bypass body 64 and the
bypass seal assembly 82.
The bypass port 56 is disposed through the wall 58 of
bypass body 64 just below the bypass seal assembly 82.
The bypass body 64 carries an outer O-ring seal 90 below
bypass port 56 for sealingly engaging the bypass sleeve as
is further described below.
In FIG. 3F, the bypass body 64 is seen to have a plura-
lity of outwardly e~tending longitudinal splines 92 for
engagement with the bypass sleeve as is further described
below.
Bypass body 64 is threadedly connected to packer mandrel
66 at 94 with a set screw 96 locking the same and with an 0-
ring seal 98 therebetween.
The packer mandrel 66 is threadedly connected to connec-
tor 68 at thread 100 (see FIG. 3J) with an O-ring seal 102
being provided therebetween. Connector 68 is threadedly
connected to bottom guide 70 at 104 with an 0-ring seal 106
being provided therebetween.
A packer means generally designated by the numeral 108
is disposed on the packer mandrel 66 of packer mandrel
assembly 50 for sealing between the packer mandrel 66 and
the drill pipe bore 28 upon engagement of the packer means
108 with the internal upset 36 of the drill pipe string 16
and subsequent application of upward force to the packer
mandrel assembly 50.
The packer means 108 includes a spring collet 110 (see
~L ~3~
--10--
FIGS. 3G-3H) slidably disposed about packer mandrel 66.
Collet 110 includes a radially inward extending lug 112
received in a J-slot 114 defined in the outer surface of
packer mandrel 66. The lug 112 and J-slot 114 are best
illustrated in the laid out view of FIG. 5. In FIGS. 3G and
5, the lug 112 is illustrated in a first position wherein it
defines an upper position of the collet 110 relative to the
packer mandrel 66. As is best apparent in FIG. 5, downward
movement of the packer mandrel 66 relative to collet 110
with subsequent counterclockwise rotation (as viewed from
above) of packer mandrel 66 followed by picking up of packer
mandrel 66 will move the lug 12 into a longer leg 116 of J-
slot 114 thus allowing the collet 110 to move to a lower
position thereof relative to the packer mandrel 66.
The collet 110 includes a plurality of generally down-
wardly extending arms 118 each having an enlarged head 120
defined on the lower end thereof. The head 120 includes a
downward facing tapered surface 122 which will cam the arms
118 inward to allow the collet 110 to be pulled downward
through reduced diameter portions such as 38 (see FIG. 7) of
the pipe bore 28. The heads 120 each also include upward
facing tapered engagement shoulders 124 for engaging the
internal upset 36 (see FIGS. 1, 2 and 7) of the drill pipe
string 16.
The packer means 108 also includes an annular anchoring
wedge means 126 slidably disposed about the packer mandrel
66 below the collet 110. Anchoring wedge 126 includes an
~ig3~
-
upward facing tapered wedging surface 128 which is engaged
by the inside surface 130 of collet arms 118 when the collet
110 drops to its lower position relative to packer mandrel
66. The engagement of anchoring wedge 126 with the collet
arms 118 prevents radially inward compression of the arms
118 of collet 110 when the collet 110 is in its said lower
position, thus holding the upper engagement means 124 of the
collet arms 118 in a radially expanded position so that it
engages the internal upset 36 of drill pipe string 16 when
pulled upward thereagainst.
The packer means 108 further includes an expandable
sealing element 132 located immediately below anchoring
wedge 126. When the collet 110 is allowed to move downward
relative to packer mandrel 66 so that it engages the anchor-
ing wedge 126, an upward pull applied to the packer mandrel
assembly 50 pulls the engaging shoulders 124 into engagement
with the internal upset 36 of drill pipe string 16, and the
further application of a sufficient upward pull on the work
string 46 and the packer mandrel assembly 50 causes the
anchoring wedge 126 to slide downward relative to packer
mandrel 66 thus compressing the sealing element 132 between
anchoring wedge 126 and the connector 68 of packer mandrel
assembly 50 so that the sealing element 132 is caused to
expand radially outward as schematically illustrated in FIG.
2 thus sealing against the larger diameter portion 40 of
drill pipe bore 28.
The bridge plug apparatus 48 further includes a bypass
sleeve assembly 134 (see FIGS. 3D-3F) slidably disposed
about the packer mandrel assembly 50 and movable longitudi-
nal relative to packer mandrel assembly 50 between an open
position as illustrated in FIGS. 3D-3F wherein the bypass
port 56 is open, and a closed position wherein the sleeve
assembly 134 is moved upward relative to bypass mandrel
assembly 50 to close the bypass port 56.
The bypass sleeve assembly 134 includes a bypass sleeve
mandrel 136 and a bypass sleeve 138. The bypass sleeve
mandrel 136 and bypass sleeve 138 are threadedly connected
at connection 140 which is locked by set screws 142 with an
0-ring seal 144 being provided therebetween.
Bypass sleeve mandrel 136 carries an internal 0-ring
seal 146 near its upper end which slidably sealingly engages
a cylindrical outer surface 148 of upper mandrel 62 of
bypass mandrel assembly 50. The bypass sleeve mandrel 136
has an external threaded surface 150 defined adjacent the
upper end thereof for threaded engagement with a rotating
case assembly further described below for purposes of
causing the bypass sleeve assembly 134 to move upwards and
downwards relative to packer mandrel assembly 50 upon rota-
tion of the rotating case assembly.
The bypass sleeve 138 has a plurality of longitudinally
downwardly extending fingers 151 at its lower end which are
meshed with the splines 92 of bypass body 64 so that the
bypass sleeve assembly 134 is fixed against rotational move-
ment relative to the packer mandrel assembly 50.
~lL~8~
-13-
The bypass sleeve 138 has a sleeve port 152 defined
radially therethrough. When the bypass sleeve assembly 134
is in its open position as illustrated in FIG. 3E, the
sleeve port 152 communicates the bypass port 56 and thus
the mandrel bore 52 of packer mandrel assembly 50 with an
annulus 154 (see FIG. 2) between the packer mandrel assembly
50 and the pipe bore 2& of drill pipe string 16. Thus, the
pipe bore 28 of drill pipe string 16 below the sealing ele-
ment 132 of packer means 108 is communicated with the annu-
lus 154 above the sealing element 132 when the bypass sleeve
assembly 134 is in its open position. It is noted that in
the embodiment of FIGS. 3A-3J, the mandrel bore 52 of packer
mandrel assembly 50 has an open lower end 154 (see FIG. 3J)
in open communication with the pipe bore 28 of drill pipe
string 16 below the sealing element 132 of packer means 108.
When the bypass sleeve assembly 134 is moved upwards
relative to packer mandrel assembly 50, in a manner further
described below, an inner bore 155 of bypass sleeve 138 will
move into sealing engagement with the bypass seal assembly
82 thus closing the bypass port 56.
The bridge plug apparatus 48 also includes a rotating
case assembly generally designated by the numeral 156 (see
FIGS. 3A-3D). The rotating case assembly 156 includes a
retrieving mandrel 158, a case 160, and a threaded mandrel
162.
The retrieving mandrel 158 and case 160 are threadedly
connected at connection 164 which is held by set screws 166
L~3~ ~
-14-
with an 0-ring sea] 168 being provided therebetween. Case
160 is threadedly connected to threaded mandrel 162 at
thread 170 which is locked by set screw 172 with an 0-ring
seal 174 being provided therebetween.
Case 160 has an inner bore 176 within which the 0-ring
seal 61 of differential piston 60 is slidably received.
Threaded mandrel 162 has an inner bore 178 which carries an
0-ring seal 180 through which an exterior cylindrical sur-
face 182 of upper mandrel 62 of packer mandrel assembly 50
is slidably received.
A sealed chamber 184 is thus defined radially between
upper mandrel 62 and case 160 and longitudinally between
differential piston 60 and an upper end 186 of threaded
mandrel 162. Particularly, the sealed chamber 184 is sealed
by 0-ring seals 61, 74, 174 and 180. A pair of filling
ports 188 and 190 are defined through case 160 and allow the
chamber 184 to be filled with a relatively incompressible
liquid such as oil. When the chamber 184 is so filled, it
provides a thrust bearing means generally designated as 185,
an upper end of which is defined by the packer mandrel
assembly 50 and a lower end of which is defined by the
rotating case assembly 156 so that upward forces can be
transferred from the rotating case assembly 156 to the
packer mandrel assembly 50 by compression of the oil con-
tained in the sealed chamber 184.
The use of a sealed oil field chamber to provide the
thrust bearing means 185 is particularly useful in the drill
~193~
pipe bridge plug apparatus 48 which necessarily is a rela-
tively narrow tool since it must be received in the inner
bore of a conventional string of drill pipe. Thus the
radial thickness 192 (see FIG. 3C) of the components which
define the thrust bearing means 184 is relatively small on
the order of 1.063 inch, which is not suitable for typical
mechanical type thrust bearings.
The thrust bearing means 185 will permit rotation of the
rotating case assembly 156 relative to the packer mandrel
assembly 50 while simultaneously applying a sufficient
upward force on the packer mandrel assembly 50 from the
rotating case assembly 156 to maintain the packer means 108
sealed against the drill pipe bore 28.
The threaded mandrel 162 of rotating case assembly 156
includes an elongated internal thread 194 adjacent its lower
end which is threadedly engaged with the external thread 150
of bypass sleeve mandrel 136.
Thus, after the packer means 108 has been set within the
bore 28 of drill pipe strlng 16, the bypass port 56 can be
closed by rotating the rotating case assembly 156 clockwise
(as viewed from above) with the work string 46 so that the
engagement between threads 150 and 194 will pull the bypass
sleeve assembly 134 upward relative to packer mandrel assem-
bly 50 so that the bypass sleeve 138 will close the bypass
port 56. The bypass port 56 can subsequently be reopened by
rotating the rotating case assembly 156 counterclockwise to
move the bypass sleeve assembly 134 back downward to its
3 ~ 3
-16-
open position.
The bridge plug apparatus 48 further includes an
overshot assembly 196 which is releasably connectable to the
retrieving mandrel 158.
Overshot assembly 196 includes an overshot adapter 198
and an overshot 200 which are threadedly connected at con-
nection 202 with a set screw 204 locking the same and with
an O-ring seal 206 therebetween.
The overshot adapter 198 has an internal thread 208
adjacent its upper end for connection thereof to the work
string 46 of FIG. 2.
Overshot 200 includes a radially inward projecting lug
210 which is received in a J-slot 212 defined in the outer
surface of retrieving mandrel 158. The lug 210 and J-slot
212 are best seen in the laid out view of FIG. 4. The J-
slot 212 includes a longer downwardly tapered leg 214 having
an open upper end 216 defined at the upper end 218 of
retrieving mandrel 158. J-slot 212 also includes an
enclosed shorter leg 220.
The overshot assembly 196 and the retrieving mandrel 158
are releasably connected together when the lug 210 is con-
tained in the enclosed shorter leg 220 of J-slot 212 as
shown in FIGS. 3B and 4. After the bridge plug apparatus 48
has been set in place in the drill pipe string 16 as schema-
tically illustrated in FIG. 2, the overshot assembly can be
disconnected therefrom by lowering the work string to move
the lug 210 to the position shown in FIGS. 3B and 4, then
~9~8~
-17-
rotating the work string 46 clockwise (as viewed from above)
and pulling the work string 46 upward to move the lug 210
through the longer leg 214 and out the open upper end 216
thereof.
The packer mandrel assembly 50 having its mandrel bore
52, barrier 54 and bypass port 56 defined therein, along
with the bypass sleeve assembly 134, the rotating case
assembly 156, and the thrust bearing means 185 can collec-
tively be referred to as a selectively positionable bypass
means which can accomplish a multitude of functions within
the bridge plug apparatus 48. First, this selectively posi-
tionable bypass means prevents fillup of the work string 46
as the work string 46 and attached bridge plug apparatus 48
are run into position in the drill pipe string 16. Second,
this selectively positionable bypass means provides a means
for communicating the pipe bore 28 below the packer means
108 with a low pressure zone, e.g., annulus 154, above the
packer means 108 through the mandrel bore 52 prior to
sealing the sealing element 132 of packer means 108 against
the pipe bore 28. Third, this selectively positionable
bypass means provides a means for isolating the pipe bore 28
below the packer means 108 from the low pressure zone 154
above the packer means 108 after the sealing element 132 of
packer means 108 is sealed against the pipe bore 28.
Fourth, this selectively positionable bypass means provides
a means for recommunicating the pipe bore 28 below the
packer means 108 with the low pressure zone 154 above the
~ Lg~8~
-
-18-
packer means 108 through the mandrel bore 52 to balance
pressure across the sealing element 132 of packer means 108
prior to unsetting the packer means 108.
Alternative Embodiment Of FIGS. 6A-6K
In FIGS. 6A-6K, a modified version of the bridge plug
apparatus 48 is shown and generally designated by the
numeral 222. Most of the components of bridge plug appara-
tus 222 are near identical to components of bridge plug
apparatus 48, and those components have been given identical
identifying numbers in the drawings.
The primary difference between bridge plug apparatus 222
of FIGS. 6A-6K and the bridge plug apparatus 48 of FIGS.
3A-3J, is that the alternative bridge plug apparatus 222 is
designed to bypass fluid from below the packer 108 into the
interior of the work string 46, rather than into the annulus
15~.
The bridge plug apparatus 222 has been modified in three
locations as compared to the apparatus 48.
First, the differential piston 60 of FIG. 3C has been
replaced with a modified differential piston 224 in FIG. 6C
having an open bore 226 therethrough so that the longitudi-
nal bore 52 of the packer mandrel assembly 50 of the modi-
fied bridge plug 222 is communicated through a bore 228 of
retrieving mandrel 158 with the interior of the work string
46.
Second, the bypass sleeve 138 of FIG. 3E has been
replaced with a modified bypass sleeve 230 in FIG. 6E. The
~11933;S
--19--
modified bypass sleeve 230 does not have a sleeve port such
as port 152 of FIG. 3E. Instead, the modified bypass sleeve
230 defines an annular bypass passage 232 which commùnicates
with an upper bypass port 234 defined through the wall of
upper mandrel 62 and communicating with an upper portion of
the mandrel bore 52 defined within upper mandrel 62. Thus,
when the bypass sleeve 230 of the modified bridge plug appa-
ratus 222 is in its open position as illustrated in FIG. 6E,
the upper and lower portions of mandrel bore 52 above and
below the barrier 54, respectively, are communicated with
each other through the bypass passage 232 and the upper and
lower bypass ports 234 and 56.
The third modification to the bridge plug apparatus 222
is the addition to the lower portion thereof of a releasable
closure plug means 236 for initially blocking flow of well
fluid up through mandrel bore 52 as the bridge plug appara-
tus 222 is lowered with the work string 46 into the drill
pipe string 16.
The releasable closure plug means 236 includes a closure
plug 238 closely received in a plug housing extension 240 of
packer mandrel assembly 50. An annular seal 239 seals be-
tween closure plug 238 and plug housing extension 240.
A releasable attachment means 242, which is preferably a
shear pin 242, provides a means for initially retaining the
closure plug 238 in place within the mandrel bore 52, and
for subsequently releasing the closure plug 238 so that the
closure plug 238 can be pumped downward to place the mandrel
~ ~ 1933~
-
-20-
bore 52 below barrier 54 in communication with the pipe bore
28 of drill pipe string 16 below the packer means 108.
The modified packer mandrel assembly 50 further includes
a basket means 244 connected to plug housing extension 240
at threaded connection 246. The basket means 244 provides a
means for catching the closure plug 238 when it is pumped
out of engagement with plug housing extension 240.
The basket means 244 has a plurality of radial ports 247
through a wall thereof. When the closure plug 238 drops out
of housing extension 240 it will be caught by a reduced
diameter annular ledge 248 below the ports 247 so that the
bore 28 of drill pipe string 16 is communicated through the
ports 247 and up through the mandrel bore 52 to the lower
bypass port 56.
Manner Of Operation
Methods of utilizing the apparatus 48 and 222 just
described in order to control flow up through the drill pipe
16 of a well 10 that is flowing out of control are as
foll~ws.
The well 10 will initially be in a condition like that
generally described above with regard to FIG. 1. An upper
end 24 of the drill pipe string 16 is damaged, and well
fluids are flowing upwardly therethrough. It is necessary
to remove the damaged portions at the upper end of the drill
pipe string 16 and reconnect new drill pipe segments to the
undamaged portion of the drill pipe string before the well
10 can be brought completely under control.
~i ~ 93~6
-21-
The repair of the damaged drill pipe string is
accomplished in part by lowering the bridge plug apparatus
48 or 222 on the work string 46 through the snubbing unit 44
down into the bore 28 of drill pipe string 16 to a position
where the drill pipe bore 28 is desirably closed, i.e.,
within one of the undamaged joints of drill pipe.
As the bridge plug apparatus 48 or 222 is being lowered
into the pipe bore 28, it is desirable to prevent fluid
which is flowing up through the drill pipe string 16 from
flowing into the work string 46. With the bridge plug appa-
ratus 48, the differential piston 60 provides a barrier
across the bore of the bridge plug apparatus thus preventing
the work string 46 from filling up. With the bridge plug
apparatus 222, the closure plug means 236 prevents fluid
from flowing upward through the bridge plug apparatus 222
and into the work string 46.
Once the bridge plug 48 or 222 is positioned near the
location where it is desired to block the drill pipe bore
28, the bore 28 below packer means 108 should be communi-
cated through mandrel bore 52 with a low pressure zone above
packer means 108 so that the upward flow of fluid does not
interfere with the setting of packer means 108. With bridge
plug 48 this is accomplished by having sleeve 138 in the
open position of FIG. 3E so that well fluid flows into
annulus 154. If the alternative bridge plug apparatus 222
is being utilized, pressure must be applied to the interior
of the work string 46 to pump the closure plug 238 out of
~L9~8~
-22-
sealing engagement with plug housing extension and down into
the basket 244 thus permitting well fluid to flow through
mandrel bore 52 up into work string 46.
Next packer means 108 must be set. The work string is
lowered and rotated counterclockwise (as viewed from above),
then picked back up to manipulate the lug 112 into the
longer leg 116 of J-slot 114 and to allow the collet 110 to
drop down into engagement with the annular anchoring wedge
126. Then, the work string 46 and bridge plug apparatus 48
or 222 is raised so that the engaging shoulders 124 of arms
118 of collet 110 will engage the internal upset 36 of the
drill pipe bore 28 thus preventing any further upward move-
ment of the collet 108 and annular wedge 126. Applying a
continued and increasing upward pull to the work string 46
pulls the packer mandrel 66 upward relative to the anchor
ring 126 thus compressing and expanding radially outward the
packer sealing element 132 so that the same seals against
the larger diameter portion 40 of pipe bore 28 as schemati-
cally illustrated in FIG. 2.
After the bridge plug apparatus 48 or 222 has been set
and sealed against the pipe bore 28, it is then necessary to
isolate the pipe bore 28 below the sealing element 132 from
the low pressure zone thereabove, i.e., either annulus 154
or the interior of work string 46, to thereby stop the flow
of well fluids up through the drill pipe string 16. This is
accomplished by rotating the work string 46 clockwise (as
viewed from above) through a sufficient number of turns to
~9~
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move the sleeve valve assembly 134 upwards along threaded
connection 150, 194 thus closing the bypass port 56.
Sufficient upward pull must be maintained on the packer
means 108 to hold the same set against the internal upset 36
while the bypass port 56 is being closed.
After the bypass port 56 has been closed, the work
string 46 may be disconnected from the bridge plug apparatus
48 or 222 by lowering the work string 46, rotating the same
clockwise (as viewed from above), then lifting the work
string 46 upward to move the lug 210 up through the open
ended longer leg 214 of J-slot 212.
After the work string 46 is disconnected from bridge
plug apparatus 48 or 222, the bridge plug apparatus is main-
tained in engagement with the internal upset 36 and sealed
against the drill pipe bore 28 due to an upward pressure
differential applied to the bridge plug apparatus by the
pressurized well fluids contained in the drill pipe string
16 below the bridge plug apparatus.
After the work string 46 has been removed, the damaged
upper portions of the drill pipe string 16 above the bridge
plug apparatus can be removed without interference from
fluids flowing upward therethrough. Subsequently, new sec-
tions of drill pipe can be added to those remaining in the
well.
Then, the bridge plug apparatus 48 or 222 can be
retrieved by running the work string 46 with the overshot
assembly 196 attached thereto back into the well, re-
~ig~8 ~:3
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engaging the lug 210 within the J-slot 212, then rotating
the work string 46 counterclockwise (as viewed from above)
to move the bypass sleeve assembly 134 back to an open posi-
tion so that the drill pipe bore 28 below packer means 108
is recommunicated with the low pressure zone above the
packer means 108 to relieve the upward pressure differential
acting across the bridge plug apparatus 48 or 222. This is
preferably accomplished with an upward pull being applied to
the work string 46 and the bridge plug apparatus 48 as the
work string 46 is rotated to reopen the bypass port 56.
After pressure has been balanced across to packer means
108 weight is set down on the work string 46 thereby
unseating the packer means 108 from the pipe bore 28. The
work string 46 is manipulated so as to move the collet 108
back to its upper position as illustrated in FIG. 3G. Then,
the bridge plug apparatus 48 or 222 can be retrieved from
the drill pipe string 16 by removing the work string 46 and
the bridge plug apparatus from the pipe string 16.
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 the
invention may be made by those skilled in the art which
changes are encompassed within the scope and spirit of the
present invention as defined by the appended claims.
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This application is a division of Canadian
Patent Application Serial No. 2,043,756 filed June 3,
1991 .
