Bottoms Up” or Bit to Surface Strokes

“Bottoms Up” Strokes = Annular Volume bbls / Pump Output in bbls-stk

Step 1 is to calculate Annular Volume -

The first thing we must to do in order to calculate “Bottoms Up” or Bit to Surface” strokes is to find the Annular Volume.

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

Step 2 is to calculate “Bottoms Up” or Bit to Surface strokes-

Now that we know the Annular Volume, and given that Pump Output = 0.148 @ 95%, we have all of the information we need to solve “Bottoms Up” or Bit to Surface strokes.

So,

“Bottoms Up” strokes = 1960.99 bbls / 0.148

“Bottoms Up” strokes = 13249.93 strokes