BAKER HUGHES - Drilling Fluids Reference Manual

HYDRAULICS
6. Calculate the critical flow rate for the annular sections of the open hole.
• Annulus of drill collar and open hole
2n + 1 n
( 3470 – 1370n a )( 100
a a --------------
1
)K a
----------------- 2 – n
3n
a
a
V = -------------------------------------------------------------------------------
c
928ρ( D – D
144
2 1 ) -------------------- 1 – ------------- n a
D – D 2 1
[ 3470 – 1370( 0.5)
]( 100 )( 11.53) ------------------------ 20.5 ( ) + 1 0.5
30.5 ( )
V c
= ---------------------------------------------------------------------------------------------------------------------
144
928( 15.3) ( 9.875 – 7.25)
----------------------------- 1–
0.5
9.875 – 7.25
---------------
1
2–
0.5
=
5.58 ft/sec
Q
2 2
2 2
( 2.45) V [( D ) − ( D ) ] = ( 2.45)( 5.58)( 9.875 −7.25
) 615gal / min
c
=
c 2 1
=
• Annulus of drillpipe and open hole
[ 3470 – 1370( 0.5)
]( 100) ( 11.53) ------------------------ 20.5 ( ) + 1
0.5
30.5 ( )
V c = --------------------------------------------------------------------------------------------------------------------
144
928( 15.3)( 9.875 – 4.5 ) -------------------------- 1 – 0.5
9.875 – 4.5
Q c = ( 2.45) ( 4.40 )( 9.875 2 – 4.5 2 ) = 833 gal/min
--------
1
2 – 0.5
=
4.40ft/sec
7. Calculate the Fanning Friction Factor.
• Drillpipe (Turbulent)
logn g + 3.93
a p + 3.93 lo
= ------------------------------ = --------------------------------------- ( 0.70)
= 0.0755
50
50
1.75 – logn 1.75 – log( 0.7
b = ----------------------------- p
= ----------------------------------- ) = 0.2721
7
7
f
a
p = --------------- = -----------------------
0.0755
= 0.0064
( Re p ) b 8465 0.2721
• Drill collar (Turbulent)
f
0.0755
p = ---------------------------- = 0.0055
15,192 0.2721
• Drill collar-open hole (Laminar)
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 9-33