# Drill string design - Drill pipe length for bottomhole assembly

## Input(s)

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)

## Output(s)

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

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

## Formula(s)

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

## Reference(s)

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

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