Petroleum engineering question .. please answer You are drilling 8-1/2\" lateral
ID: 107774 • Letter: P
Question
Petroleum engineering question .. please answer You are drilling 8-1/2" lateral at 21, 500'MD, 7500'TVD, using 5" XH 25.6ppf Grade E drill pipe. Calculate the number of stokes needed to pump a bottoms up, B/U. The mud pumps have a calibrated output of 0.081bbls/stk. The 9-5/8" 40ppf (ID = 8.835") intermediate casing was set at 4250'. If you are pumping 500GPM, how many stokes per minute (spm) are the pumps set at if you have 2 mud pumps? How long in minutes would a B/U take? What is the fluid velocity in the open hole annulus? What is the fluid velocity in the cased annulus?
Explanation / Answer
Bottoms Up” Strokes = Annular Volume bbls / Pump Output in bbls-stk
Step 1 is to calculate Annular Volume is 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 = (Dh2 – OD2) / 1029.4 x Length in feet, where Dh is the hole diameter.
So, and given that we can now calculate Annular Volume, let’s see the following data -
Drill Collar Specs – 8-1/2” in OD, 8.835 in ID, 600 feet in length
Drill Pipe Specs – 6 in OD, 0.081 ID, 21500 feet in length
Open Hole Specs – 12.25 in diameter
Casing Specs – 13.625 in, ID = 12.615 in. Set depth = 4650 ft
-Annular Volume for Drill Pipe (open hole) – (12.25^2 – 6^2) / 1029.4 x 12225 = 1354.59 bbls
-Annular Volume for Drill Pipe (cased hole) – (12.615^2 – 6^2) / 1029.4 x 4650 = 556.24 bbls
-Total Annular Volume = 1910.83 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 = 12911.01 strokes.
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