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.