Drill string design - Drill pipe length for bottomhole assembly


BF: Buoyancy Factor (dimensionless)

T: Tensile Strength for New Pipe (lb)

f: Safety Factor to Correct New Pipe to No. 2 Pipe Equal to 1-safety Factor of Pipe (fraction)

MOP: Margin of Overpull (lb)

\(\mathrm{W}_{\text {bha }}\): Bha Weight in Air (lb)

\(\mathrm{W}_{\mathrm{dp}}\): Drill Pipe \(\mathrm{Wt}\) in Air including Tool Joint (lb)

\(\mathrm{BHA}_{\mathrm{I}}\): Length of Bore Hole Assembly (dimensionless)


\(\mathrm{L}_{\text {max }}\): Drill Pipe Length for a Specific Bore Hole Assembly (fraction)

Depth: Total Depth That Can be Reached with a Specific Bottomhole Assembly (ft)


\[ \begin{gathered} \mathrm{L}_{\text {max }}=\frac{65.5-\mathrm{MW}}{65.5} \\ \operatorname{Depth}_{\mathrm{t}}=\left[(\mathrm{T} * \mathrm{f})-\mathrm{MOP}-\mathrm{W}_{\mathrm{bha}}\right] *\left(\frac{\mathrm{BF}}{\mathrm{W}_{\mathrm{dp}}}\right) \end{gathered} \]


Lapeyrouse, N. J., 2002, Formulas and Calculations for Drilling, Production and Workover, second edition, Gulf Professional Publishing, Page: 43.

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