# Annular capacity between casing and multiple tubing strings

## Input(s)

\(\mathrm{D}_{\mathrm{h}}\): Hole Size (in.)

\(\mathrm{T}_{\mathrm{a}}\): Outer Diameter of Tubing No. 1 (in.)

\(\mathrm{T}_{\mathrm{b}}\): Outer Diameter of Tubing No. 2 (in.)

## Output(s)

AC: Annular Capacity (gal/ft)

## Formula(s)

\[
A C=\frac{D_{h}^{2}-\left(T_{a}^{2}+T_{b}^{2}\right)}{1029.4}
\]

## Reference(s)

Lapeyrouse, N. J., 2002, Formulas and Calculations for Drilling, Production and Workover, Second Edition, Gulf Professional Publishing, Page: 14.