I just got the question regarding kill rate selection while performing the well control operation. Why is the kill rate quite low while circulating influx out of the well?
Typically, most people select the kill rate of 2 – 5 bbl/min because of the following reasons.
More flow you have, more gas will come out. It may cause the flow rate over specification of the mud gas separator. You may end up with blow though of gas into your pit system while circulating kick out of hole.
You will have more time to think and react while circulating. The higher rate you use, the less reaction time you will have.
Most of the rigs are able to pump at this low rate without any hassle.
The most important thing is the ECD (equivalent circulating density). You don’t want to create at lot of frictional pressure because you may break the formation resulting in unbalance U-Tube.
From my experience, the low rate will give more time and I will be more comfortable to see what is going on in slow mode instead of fast. Please do not save the rig time by just only cranking your pump rate up. It will not work very well when you are in the well control situation.
Reference book: Well Control Books