# Velocity of fluid in annulus

## Input(s)

\(Q\): Flow rate \((\mathrm{gpm})\)

\(D_{o}\): Open Hole Diameter (in.)

\(D_{p}\): Outside Diameter of Pipe (in.)

## Output(s)

\(v_{a}\): Velocity of Fluid in Annulus (ft/s)

## Formula(s)

\[
v_{a}=\frac{Q}{2.448 *\left(D_{o}^{2}-D_{p}^{2}\right)}
\]

## Reference(s)

Samuel. E Robello. 501 Solved Problems and Calculations for Drilling Operations. Sigma Quadrant. 2015. Houston, Texas, Page: 321.