Annular Volume in Barrels

Now that we have a good understanding of how to calculate Drill Pipe, Drill Collar, and Drill String volume in bbls, let’s examine how to calculate Annular volume in barrels.

The general formula to calculate Annular Volume in bbls is as follows:

Annular Volume bbls = (Dh^2 – OD^2) / 1029.4 x Length in feet, where Dh is the hole diameter.

So, and given that we can now calculate Annular Volume, let’s complete a few examples given the following data -

Drill Collar Specs – 8 in OD, 3.25 in ID, 600 feet in length

Drill Pipe Specs – 6 in OD, 4.376 ID, 12225 feet in length

Open Hole Specs – 12.25 in diameter

Casing Specs – 13.625 in, ID = 12.615 in. Set depth = 4650 ft

1. Annular Volume for Drill Collar (open hole) – (12.25^2 – 8^2) / 1029.4 x 600 = 50.16 bbls

2. Annular Volume for Drill Pipe (open hole) – (12.25^2 – 6^2) / 1029.4 x 12225 = 1354.59 bbls

3. Annular Volume for Drill Pipe (cased hole) – (12.615^2 – 6^2) / 1029.4 x 4650 = 556.24 bbls

4. Total Annular Volume = 1960.99 bbls