Stripping/snubbing calculations - Breakover point between stripping and snubbing


\(D p\): 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 \((\mathrm{lb} / \mathrm{ft})\)


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)


\[ \begin{gathered} F=D p^{2} * 0.7854 * P \\ W=W_{d c} * L * B F \\ W_{a d p}=F-W \\ L_{b p}=\frac{W_{a d p}}{B F * W_{d p}} \\ L_{d s}=L+L_{b p} \end{gathered} \]


Formulas and Calculations for Drilling, Production and Workover, Second Edition, Lapeyrouse, Page: 139.

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