BAKER HUGHES - Drilling Fluids Reference Manual

HYDRAULICS
24
f a = --------
Re a
=
24
----------- = 0.0185
1300
• Drillpipe-open hole (Laminar)
24
f a = -------- = 0.0290
827
• Drillpipe-casing (Laminar)
24
f a = -------- = 0.0559
429
8. Calculate the Friction-Loss Pressure Gradient.
• Drillpipe
P p
------
L m
2
f p ( V p ) ( ρ )
= ---------------------------- =
25.81D
There is 10,200 ft of drillpipe.
P p
=
9. Find the equivalent circulating density.
(--------------------
0.0064)
------------------------------------ ( 10.45 2 )( 15.3)
= 0.1083 psi/ft
( 25.81) ( 3.826)
( 0.1083 psi/ft )( 10,200 ft ) = 1105 psi
ECD
=
ΣP
-------------------------------- a
+ ρ
(.052)( TVD)
=
14.5 + 10.5 + 49
--------------------------------------- + 15.3 = 15.45 l b
(.052)( 9600
m /gal
)
Bit Hydraulics
1. Calculate total nozzle area.
A t
=
2. Calculate nozzle velocity.
2 2 2
( J 1 ) + ( J 2 ) + (J 3 )
--------------------------------------------------
1303.8
=
12
------------------------------------- 2 + 12 2 + 12 2
= 0 .3 3 1 3 i n . 2
1303.8
V n
Q
= ------------------ =
3.117A t
3. Calculate pressure-drop across bit.
375
--------------------------------------- = 363 ft/sec
( 3.117) ( 0.3313)
P n
=
-----------------------------------------------------------
156( ρ)Q 2
[ J ) 2 2
+ ( J 2 ) + (J 3) 2 2
]
( 1
=
( 156) ( 15.3) ( 375
-------------------------------------------- ) 2
= 1799 psi
( 12 2 + 12 2 + 12 2 ) 2
Note: The standpipe pressure should be equal to all of the friction loses downhole plus the
pressure drop across the bit. In this example, standpipe pressure = 1105 + 130 + 14.5 + 10.5 +
49 + 1799 = 3108 psi
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 9-34