Calculate annular velocity, capacity, or pump output from flow rate, hole and pipe diameters, strokes per minute, and pump displacement.

Find average fluid speed from flow divided by annular capacity. A barrel (bbl) is 42 US gallons.

Annular Velocity Formula

The following equation is used to calculate the Annular Velocity.

AV = PO / AC
  • Where AV is the annular velocity (ft/min)
  • PO is the pump output (bbl/min)
  • AC is the annular capacity (bbl/ft)

Select Annular velocity and divide pump output by annular capacity. Other solve choices find pump output, capacity from flow or diameters, or output from stroke rate and displacement. Each input has its own unit control; oil barrels are 42 US gallons.

What is an Annular Velocity?

Definition:

Annular velocity is the average linear velocity of a fluid (typically drilling fluid/mud) moving through the annulus—the space between the drill pipe (or casing/tubing) and the borehole (or outer casing).

How to Calculate ?

Example Problem:

The following example outlines the steps and information needed to calculate the Annular Velocity.

First, determine the pump output. In this example, the pump output is found to be 12.5 bbl/min.

Next, determine the annular capacity. In this case, the annular capacity is measured to be 0.25 bbl/ft.

Finally, calculate the Annular Velocity using the formula above:

AV = PO / AC

AV = 12.5 / 0.25

AV = 50 ft/min