Grace Robert. Advanced Blowout and Well Control
Подождите немного. Документ загружается.
166
Advanced
Blowout
and
Well
Control
6.
The total pit volume increase with the influx at
the surface. From
part
4, the length
of
the influx
when it reaches the surface is
1,165 feet.
~0ta1
pit gain
=
hOGp
Total pit gain
=
(1
165)(0.0428)
Total
pit gain
=
50
bbls
7.
The surface annulus pressure profile during
displacement using the Driller’s Method.
Example calculation,
from
Part
2
with the top of
the influx at
2,000 feet, the pressure at 2,000 feet
is calculated
to
be
<-dm
=
1480 psi
With the top
of
the influx at 2,000 feet, the
surface annulus pressure is
P,
=
1480-
0.50(2000)
Po
=
480 psi
Special Conditions. Problems
and
Procedures
in
Well Control
167
Table
4.3
Surface
Annulus
Pressures
Driller’s Method
Annular Pressure
The surface
annulus
pressure profile is summarized in
Table
4.3
and illustrated
as
Figure
4.13:
B.
1.
The pressure at the casing
shoe
at
2,000
feet
when the well
is
first shut
in
is
the
same
for both
the Driller’s Method and the Wait and Weight
Method:
168
Advanced
Blowout
and
Well
Conirol
Pzooo
=
1300
psi
2.
For
the Wait
and
Weight
Method,
the
pressure at
the
casing
seat
at
2,000
feet when the
top
of
the
influx reaches that point
is
given
by
Equation
4.25:
Annuluar
Pressure
Profile
Drillefo
Method
Figure
4.13
+
pbpnrlzx~hb Ab
I
P,,=-+
-
[
4
zb&Ax
Bl
-pml(D-
X)-
Bl
=
5200
-
0.52(10000
-
2000)
-
23(
-)
32.80
+
(x)(0.52
-
0.50)
32.80
0.0406
Bl
=
1,087
Special
Conditions,
Problems
and
Pmcededs
in
Well
Control
169
+
1087
2
pz-
=-
1087*
5200(0.52)(0.816)(540)(246)(32.80)
[-a+
620(
1.007)(32.80)
I
em,
=
1418
psi
3.
For
the
Wait
and
Weight
Method
of
displacement,
the
annulus
pressure
when
the
gas
bubble
first
reaches the
surface
may
be
calculated using Equation 4.25
as
follows:
Bl
~5200-0.52(10000-0)-23
-
(E)+
(-)(O.
52
-
0.50)
B,
=48
170
Advanced
Blowout
and
Well
Control
48
2
Po,
=-+
482 5200(0.52)(0.883)(520)(246)(32.80)
[T+
620(1.007)(34.58)
I
P,,
=
706
psi
4.
The height of the gas bubble at the surface can be
determined
using Equation 4.2
1
:
hb
hx
=
pbzx
'b
eZb
Tb
'x
(246)
5200(0.883)(520)(32.80)
'
=
706( 1.007)(620)(34.58)
h,
=
1,264
feet
5.
The pressure at the casing seat when the influx
reaches
the
surface may
be
calculated
by
adding
the annulus pressure to the mud and
influx
hydrostatics
as
follows:
em
=
p,,
+Pf-+pm(2000-h,)
4
A0
Pzoo0
=
706+ 23
-
32-80
+0.50(2000-
1264)
[
34.581
P-
=
1096
psi
Special Conditions, Problems
and
Procedures
in
Well
Control
171
6.
The total pit volume increase with the influx at
the surface. From part
4,
the length
of
the
influx
when it reaches the surface is
1,264
feet.
Total pit gain
=
(1264)(0.0428)
Total pit gain
=
54
bbls
7.
The surface
annulus
pressure profile during
displacement using the Wait and Weight Method.
Example calculation, from Part
2
with the top
of
the dux at
2,000
feet,
the pressure at
2,000
feet
is calculated to be
=
1418
psi
With
the top
of
the influx at
2,000
feet, the
surface
annulus
pressure is given by
Equation
4.19:
P,
=
p,
+p,X
P,
=
1418-O.SO(2000)
Po
=
418
psi
The surface
annulus
pressure profile
is
summarized
in
Table
4.4
and illustrated
as
Figure
4.14:
112
Advanced
Blowout
and
Well Control
Annuluar
Pmswr
Me
Wait
and
Weight
Methcd
800.0
700.0
600.0
-
5
500.0
u
E
400.0
f
2:
100.0
0.0
0.0
lw.o
200.0
300.0
400
.O
500.0
600.0
Volume
Pumpad
(pblr)
Figure
4.14
Table
4.4
700.0
600.0
-
5
500.0
u
E
400.0
f
2:
100.0
0.0
0.0
lw.o
200.0
300.0
400
.O
500.0
600.0
Volume
Pumpad
(pblr)
Figure
4.14
Table
4.4
Special Conditions,
Problems
and Procedures
in
Well
Control
173
8.
The rate
at
which barite must be
mixed
and the
minimum
barite required:
X'
=
350
x
s,,,
(4.27)
Where:
X'
=
Amount
of
barite, Ibs baritebb1 mud
W,
=
Finalmudweight,ppg
4
=
Initialmudweight,ppg
sm
=
Specific gravity
of
the weight
Note:
S,,,
for
barite
=
4.2
material, water
=
1
1
(1
0
-
9.6)
(8.33
x
4.2)
-
10
X'
=
35N4.2)
X'
=
23.5 Ibs baritelbbl
mud
Minimum
volume
of
mud
=
548
bbls
in
the drillpipe and
annulus:
Barite required
=
(23.5)(548)
Barite required
=
12,878 Ibs
of
barite
Rate
at which barite must
be
mixed:
Rate
=
(23.5)(3)
Rate
=
70.5 lbs baritelminute
C
. Compare
the
two
procedures.
Table
4.5
and Figure
4.15
compare the
two
methods:
174
Advanced Blowout and Well Control
surface
Height of the
gas
Table 4.5
Comparison
Of
Driller’s
Method
And
Wait
And
Weight Method
Wait
and
Weight
Method
1300 psi
1165
feet
v
Driller’s Method
seat when well is 1300 psi
Pressure at casing
seat when
influx
1480 psi
759
psi
bubble at the surface
I
Total pit volume
1
increase
50
bbls
~~~
1418 psi
1520 psi
706
psi
1264 feet
54
bbls
Special
Conditions,
Problems and Procedures
in
Well
Control
175
D.
The significance
of
600
feet
of
6-inch
drill
collars
on the annulus pressure profile.
The significance
of
adding
600 feet
of
drill
collars to each example
is
that the initial shut-in
annulus pressure will be higher because the
bubble
is
longer. The new annular capacity due
to the
additional
drill collars,
C,,,,,
is
0.0253
bbls/ft. pursuant
to
Quation
3.7
the new influx
height is:
10
hb
=-
0.0253
4
=
395
feet
The annular pressure
is
given by Equation
4.20:
Pa
=
5200-0.5(10000-395)-0.094(395)
p,
=
360
psi
As
Figures 4.13,
4.14
and
4.15
and Table
4.5
illustrate, the
annulus pressure profile
is
exactly the same for both the Driller’s Method
and the Wait and Weight Method until the weighted mud reaches the bit.
Mer the weighted mud passes the bit
in the Wait and Weight Method, the
annulus pressures are lower
than
those experienced when the Driller’s
Method
is
used.
In
this
example, the Driller’s Method may result
in
an