Let’s have one more test in order to remind you about the first circulation of driller’s method.
When you shut the well in, you record these following pressure readings.
Initial Circulating Pressure (ICP) = 1500 psi
Original Shut in Drill Pipe Pressure = 500 psi
After you circulate the 1 st step of driller’s method, you see drill pipe pressure and casing pressure reading like this image below.
What do you think about this well?
Answer: There are 2 possible answers. The first one is that there are still gas in the annulus because the annulus pressure (casing pressure) is not equal to the initial shut in drill pipe pressure.
The second answer is that there is a safety factor applied for this circulation because both pressure readings has the same amount of pressure increment which is 150 psi.
If this situation happens in your real situation, you need to try to shut down and bleed off trapped pressure in the annulus.
How do I check the trapped pressure?
Bleed the casing pressure in small amount as 50 psi.
Observed if the casing pressure increases. If yes, you still have influx in the wellbore.
If not, you have trapped pressure. You must check the drill pipe pressure too. And the drill pipe pressure must decrease the same amount of pressure bleed off.
Please remember that if you bleed pressure off, you should not let casing pressure below 500 psi otherwise influx can enter into the well.
Reference books: Well Control Books