In order to get the correct value of drill pipe pressure, you need to have the correct floating bumping procedure. In this section, I will show you how to bump the float correctly.
These following procedures will demonstrate you how to bump the float correctly in order to get SDPP.
1. Ensure well is properly shut in. No leak or whatever.
2. Record shut in casing pressure (SICP)
3. Pump as slowly as possible (5-10 stroke per minute) at constant pumping speed down into the drill pipe and keep monitoring the drill pipe pressure and the casing pressure.
4. You will see the drill pipe pressure increase while pumping. At this stage, you need to monitor carefully for a “lull” in the drillpipe pressure, which will occur when the float is opened. The drillpipe pressure showing when the lull is first seen is your shut in drill pipe pressure (SIDPP).
5. You also need to verify that the float has been opened by continuing to pump down the drillpipe slowly until you see an increase in the casing pressure. It should happen very quickly after the lull was seen on the drillpipe gauge.
6. Shut down the pumping operation as soon as increase in casing pressure is detected.
7. Check the shut-in casing pressure again. If there is any excess casing pressure, you may bled-off some pressure in small increments until it equates or a little bit above SCP in steps no 2.
If you see trapped pressure on drill pipe after bumping the float, you can calculate the actual shut in drill pipe pressure with this following formula.
Shut in drill pipe pressure = shut in drill pipe pressure after bumping the float – Shut in casing pressure increase while bumping float
Reference book: Well Control Books