Page 166 - Formulas and Calculations for Petroleum Engineering

Drilling engineering formulas and calculations Chapter 2 159

Formula(s)

2
F ¼ Dp 0:7854 P
W ¼ W L BF
dc
W adp ¼ F W

W
adp
L ¼
bp
BF W
dp
L ¼ L + L
ds bp
Reference: Formulas and Calculations for Drilling, Production and Workover, Second Edition, Lapeyrouse, Page: 139.

2.202 Stripping/snubbing calculations—Height gain and casing pressure from
stripping into influx

Input(s)
C dp : Capacity of Drill Pipe or tubing (bbl/ft)
D dp : Displacement of Drill Pipe,Drill Collar or tubing (bbl/ft)
C a : Annular Capacity (bbl/ft)
L: Length of Drill Pipe Stripped (ft)
G: Gradient of Mud (psi/ft)
G i : Gradient of Influx (psi/ft)

Output(s)
H: Height gain from stripping into influx (ft)
P: Casing Pressure increase from stripping into influx (psi)

Formula(s)

C + D dp
dp
H ¼ L
C a
ð
P ¼ H G G Þ
i
Reference: Formulas and Calculations for Drilling, Production and Workover, Second Edition, Lapeyrouse, Page: 140.

2.203 Stripping/snubbing calculations—Maximum Allowable surface pressure
governed by casing burst pressure
Input(s)

W o : Mud Weight behind casing (ppg)
W u : Mud Weight in use (ppg)
H: Casing Shoe TVD (ft)
P bc : Casing Burst Pressure (psi)
S: Safety Factor (e.g., 80% represent 0.8) (dimensionless)