Once you finish weighing up your mud system to required kill mud weight, you need to do the 2 nd circulation of driller’s method. This post will describe how to do the 2nd circulation of driller’s method.
The second circulation of the driller’s method will be started after drilling fluid is weighted-up to required kill weight.
First, when you establish the desired pump rate you must hold casing pressure constant while bringing the pump up to speed, killing rate +/- 2-5 bpm. Please always hold this pump rate constant throughout the killing process.
In order to hole casing pressure constant as the kill mud goes down the drill string, you must manipulate choke.
The casing pressure will be held constant until kill mud goes down to the bit. At this stage, you need to know how many strokes from surface to the bit by calculating the drill pipe capacity.
Once the kill mud reaches the bit, you must hold this drill pipe pressure constant throughout the remainder of the kill operation. Then you still need to continue circulation until the hole is full of kill mud. You can estimate how many strokes and volumes based on the estimated hole size.At this stage, you will see decreasing in casing pressure.
Practically, you must check mud weight out to confirm that you have good kill mud all way around. For example, if you circulate total of hole volume all way around but you don’t get the desired kill weight up completely out of hole, you need to continue circulating until good kill mud all way around prior to shutting down pumps..
Reference book: Well Control Books