BAKER HUGHES - Drilling Fluids Reference Manual

HYDRAULICS
Exercise: Calculate the jet sizes required for 3 jets and 2 jets for the total nozzle area for
maximum impact force in the above example.
Answer: 3 jets: 12, 12, 13
2 jets: 15, 15
Practice: Calculate the jet sizes for HHP-impact compromise for a PDC bit with five jets.
Answer: 9, 9, 9, 9
Swab and Surge
Exercise: Following the preceding example calculations, calculate the EMW due to running pipe
in the hole after a trip.
Are the gel strengths progressive or fragile?
Cuttings Transport
Laminar Flow in Annulus
Assume:
Particle thickness, T = 3 / 8 in. = 0.375 in.
Particle diameter, D c = ¾ in. = 0.750 in.
1. Find the boundary shear rate.
186
γ b = ------------- = ------------------------ 186
= 63.4 sec – 1
D c ρ 0.75 15.3
2. Find the shear stress developed by the particle.
τ p = 7.9 T( 20.8 – ρ)
= 7.9 ( 0.375) ( 20.8 – 15.3) = 11.35 lb f /100 ft 2
3. Find the shear rate developed by the particle.
γ p
= ⎛ ⎞
n a
= ⎛11.35
------------ ⎞
⎝ ⎠ ⎝11.53⎠
τp
-----
K a
---
1
4. γ p < γ b , slip velocity is determined by,
6. Calculate the transport efficiency.
------
1
0.50
=
γ b = 0.97 sec – 1
⎡γ
p
D ⎤
c
⎡ 0.97 0.75 ⎤
V = 1.22τ
p ⎢ ⎥ = 1.22 11.35 ⎢ ⎥
⎢⎣
ρ ⎥⎦
⎣ 15.3 ⎦
5. Calculate the cuttings transport for casing drillpipe annulus.
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( )( ) ( )( ) = 5.97 6.0 ft / min
V t = V a – V s = ( 1.12 ft/sec × 60 sec/min ) – 6.0 = 61.2 ft/m in
E t =
V t
61.2
----- × 100 = ------------------------- × 100 =
V a ( 1.12) ( 60)
91%
or
⎛ V ⎞
s
⎛ 6.0 ⎞
Et = 1 − ⎜1
− 100 1
100 91%
V
⎟ × = ⎜ − ⎟ × =
⎝ a ⎠ ⎝ ( 1.12)( 60)
⎠
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 9-36
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s
=