Wells – Processes – Cementing – plugging or consolidating
Reexamination Certificate
2001-10-01
2004-06-22
Bagnell, David (Department: 3672)
Wells
Processes
Cementing, plugging or consolidating
C166S152000, C166S177400
Reexamination Certificate
active
06752209
ABSTRACT:
BACKGROUND
This invention relates generally to wellbores, and in particular to cementing systems for wellbores.
Referring to
FIG. 1
a
, a conventional system
10
for cementing a wellbore
12
includes a shoe
14
defining a passage
14
a
that is coupled to an end of a tubular member
16
defining a passage
16
a
. The tubular member
16
typically includes one or more tubular members threadably coupled end to end. The other end of the tubular member
16
is coupled to an end of a float collar
18
including a float
18
a
. The other end of the float collar
18
is coupled to an end of a tubular member
20
defining a passage
20
a
. Centralizers
22
a
,
22
b
, and
22
c
are coupled to the exteriors of the tubular members,
16
and
18
. More generally, the system
10
may include any number of centralizers. The other end of the tubular member
20
is coupled to a fluid injection assembly
24
defining a passage
24
a
and radial passages
24
b
,
24
c
, and
24
d
, and including retaining pins
24
e
and
24
f
. The fluid injection head
24
is commonly referred to as a cementing head. A bottom cementing plug
26
and a top cementing plug
28
are retained within the passage
24
a
of the fluid injection assembly
24
by the retaining pins
24
e
and
24
f
. The bottom cementing plug
26
typically includes a longitudinal passage that is sealed off by a frangible diaphragm.
During operation, as illustrated in
FIG. 1
a
, drilling mud
30
is circulated through the wellbore
12
by injecting the drilling mud into the fluid injection assembly
24
through the radial passage
24
b
. The drilling mud
30
then passes through the passages
24
a
,
20
a
,
18
a
, and
14
a
into the annulus between the tubular member
20
, the float collar
18
, the tubular member
16
, and the shoe
14
. As illustrated in
FIG. 1
b
, the bottom cementing plug
26
is then released and a spacer fluid
32
followed by a cement slurry
34
are injected into the injection assembly
24
through the radial passage
24
c
behind and above the bottom cementing plug. As illustrated in
FIG. 1
c
, the top cementing plug
28
is then released and a displacing fluid
36
is injected into the injection assembly
24
through the radial passage
24
d
behind and above the top cementing plug. As illustrated in
FIG. 1
d
, the continued injection of the displacing fluid
36
displaces the bottom cementing plug
26
into contact with the float collar
18
and breaks the frangible membrane of the bottom cementing plug thereby causing the cement slurry
34
to flow into the annulus between the wellbore
12
and the shoe
14
, the tubular member
16
, the float collar
18
, and the tubular member
20
. As illustrated in
FIG. 1
e
, the continued injection of the displacing fluid
36
then displaces the top cementing plug
28
downwardly until the top cementing plug impacts the bottom cementing plug
26
. The float element
18
a
of the float collar
18
prevents back flow of the cement slurry
34
into the tubular member
20
. The cement slurry
34
may then be allowed to cure.
Referring to
FIG. 2
a
, another conventional system
100
for cementing a wellbore
102
having a preexisting wellbore casing
104
includes a float shoe
106
including a float element
106
a
that is coupled to an end of a tubular member
108
defining a passage
108
a
. The other end of the tubular member
108
is coupled to an end of a landing collar
110
defining a passage
110
a
. The other end of the landing collar
110
is coupled to an end of a tubular member
112
defining a passage
112
a
. A liner hanger
114
is coupled to the tubular member
112
for permitting the tubular member to be coupled to and supported by the preexisting wellbore casing
104
. A centralizer
116
is also coupled to the exterior of the tubular member
112
for centrally positioning the tubular member inside the preexisting wellbore casing
104
. An end of a tubular support member
118
defining a passage
118
a
extends into the other end of the tubular member
112
. A releasable coupling
120
is coupled to the tubular support member
118
for releasably coupling the tubular support member to the tubular member
112
. A wiper plug
122
defining a restricted passage
122
a
is coupled to an end of the tubular support member
118
within the other end of the tubular member
112
. A bumper
124
and a cup seal
126
are coupled to the exterior of the end of the tubular support member
118
within the tubular member
112
.
During operation, as illustrated in
FIG. 2
a
, drilling mud
128
is circulated through the wellbore
102
by injecting the drilling mud through the passages
118
a
,
122
a
,
112
a
,
110
a
,
108
a
, and
106
a
into the annulus between the float shoe
106
, the tubular member
108
, the landing collar
110
, and the tubular member
112
. As illustrated in
FIG. 2
b
, a spacer fluid
130
followed by a cement slurry
132
are then injected into the passages
118
a
,
122
a
, and
112
a
behind and above the drilling mud
128
. As illustrated in
FIG. 2
c
, a pump down plug
134
is then injected into the passage
118
a
followed by a displacing fluid
136
. As illustrated in
FIG. 2
d
, the continued injection of the displacing fluid
136
, causes the pump down plug
134
to engage the restricted passage
122
a
of the wiper plug
122
thereby disengaging the wiper plug from the end of the tubular support member
118
. As a result, the wiper plug
122
and the pump down plug
134
are driven downwardly within the tubular member
112
by the continued injection of the displacing fluid
136
which in turn displaces the spacer fluid
130
and the cement slurry
132
into the annulus between the wellbore
102
and the float shoe
106
, the tubular member
108
, the landing collar
110
and the tubular member. As illustrated in
FIG. 2
e
, the continued injection of the displacing fluid
136
causes the wiper plug
122
and the pump down plug
134
to impact the landing collar
110
and engage the passage
110
a
. Furthermore, as illustrated in
FIG. 2
e
, the continued injection of the displacing fluid
136
fills the annulus between the wellbore
102
and the tubular member
112
with the cement slurry
132
. The float element
106
a
of the float shoe
106
prevents back flow of the cement slurry into the tubular member
108
. As illustrated in
FIG. 2
f
, the tubular support member
118
is then decoupled from the tubular member
112
and raised away from the end of the tubular member
112
. The spacer liquid
130
and any excess cement slurry
132
may then be removed by circulating drilling mud
138
through the annulus between the tubular support member
118
and the preexisting wellbore casing
104
. The cement slurry
132
may then be allowed to cure.
Referring to
FIG. 3
a
, yet another conventional system
200
for cementing a wellbore
202
having a preexisting wellbore casing
204
includes a float shoe
206
including a float element
206
a
that is coupled to an end of a tubular member
208
defining a passage
208
a
. The other end of the tubular member
208
is coupled to an end of a landing collar
210
defining a passage
210
a
. The other end of the landing collar
210
is coupled to an end of a tubular member
212
defining a passage
212
a
. A centralizer
214
is coupled to the exterior of the tubular member
212
for centrally positioning the tubular member inside the preexisting wellbore casing
204
. An end of a tubular support member
216
defining a passage
216
a
extends into the other end of the tubular member
212
and the other end of the tubular support member
216
is coupled to a conventional subsea cementing head. A releasable coupling
218
is coupled to the tubular support member
216
for releasably coupling the tubular support member to the tubular member
212
. A wiper plug
220
defining a restricted passage
220
a
is coupled to an end of the tubular support member
216
within the other end of the tubular member
212
. A bumper
222
and a cup seal
224
are coupled to the exterior of the e
Aguilera Carlos H.
Mondelli Juan Carlos
Bagnell David
BJ Services Company
Dougherty Jennifer R.
Locke Liddell & Sapp LLP
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