Page 170 - Formulas and Calculations for Petroleum Engineering

Drilling engineering formulas and calculations Chapter 2 163

SF: Safety Factor (fraction)
W u : Mud Weight in use (ppg)
H: Depth from Rotary Kelly Bushing to Mudline (ft)
H s : Depth of Seawater (ft)
W s : Seawater Weight (ppg)

Output(s)

YP c : Corrected Internal Yield Pressure (psi)
HP: Hydrostatic Pressure of Mud in Use (psi)
HP sw : Hydrostatic Pressure exerted by sea water (psi)
CBP: Casing Burst Pressure (psi)

Formula(s)

YP ¼ YP SF
c
HP ¼ W 0:052 H
u
HP ¼ H 0:052 W s
sw
s

CBP ¼ YP HP + HP
c sw
Reference: Formulas and Calculations for Drilling, Production and Workover, Second Edition, Lapeyrouse, Page: 146.

2.212 Subsea considerations—Choke line pressure loss

Input(s)
W m : Mud Weight (ppg)
L: Choke Line Length (ft)
R c : Circulation Rate (gpm)
D i : Choke Line ID (in.)

Output(s)

CLPL: Choke Line Pressure Loss (psi)

Formula(s)

1:86
0:000061 W L R c
m
CLPL ¼
D 4:86
i
Reference: Formulas and Calculations for Drilling, Production and Workover, Second Edition, Lapeyrouse, Page: 148.

2.213 Subsea considerations—Maximum allowable mud weight—Subsea
stack from leakoff test

Input(s)

P lo : Leak off test pressure (psi)
H: TVD Rotary Bushing to Casing Shoe (ft)
W u : Mud weight in use (ppg)