Stripping/snubbing calculations - Breakover point between stripping and snubbing
Input(s)
\(D p\): Pipe or collar OD (in.)
P: Wellbore Pressure (psi)
\(W_{d c}\): Weight of Drill Collar (lb/ft)
L: Drill Collar Length (ft)
BF: Buoyancy Factor (dimensionless)
\(W_{d p}\): Drill Pipe Weight \((\mathrm{lb} / \mathrm{ft})\)
Output(s)
F: Force created by wellbore pressure on Drill collar or pipe (lb)
W: Weight of Drill Collar (lb)
\(W_{a d p}\): Additional weight required from Drill Pipe (lb)
\(L_{b p}\): Length of Drill Pipe required to reach over breakover point (ft)
\(L_{d s}\): Length of Drill string req to reach breakover point (ft)
Formula(s)
\[
\begin{gathered}
F=D p^{2} * 0.7854 * P \\
W=W_{d c} * L * B F \\
W_{a d p}=F-W \\
L_{b p}=\frac{W_{a d p}}{B F * W_{d p}} \\
L_{d s}=L+L_{b p}
\end{gathered}
\]
Reference(s)
Formulas and Calculations for Drilling, Production and Workover, Second Edition, Lapeyrouse, Page: 139.