Choke drill is one of well control drills that will improve crew competency in driller’s method. The advantages from the choke drill are as follows:
• Get more familiar to practice controlling the pressure via a choke on the rig
• Get more understanding about lag time
• Practice the procedure to obtain the shut-in drill pipe pressure
• Ensure the surface well control equipment as pressure gauges, choke, BOP is ready for work
• Get more practices when attempting to bring the pump up to kill speed, slow the pump down and change the pump rate
Choke Drill Steps are listed below:
1. Trip in hole above top of cement
2. Fill the pipe and circulate seawater or mud around for few minutes
3. Close annular preventer or upper rams preventer
4. Pressure up annulus to 200 psi (the pressure may be different depending on the company policy.)
5. Line up the pump
6. Pump slowly to bump the float and obtain shut in drill pipe pressure
7. Bring the pump to kill rate by holding casing pressure constant – personnel need to adjust the choke
8. Measure lag time for the drill pipe gage after the adjustment of choke is made.
9. Change circulation rate by holding casing pressure constant. Crew needs to adjust choke to achieve this.
10. Shut the pump down by holding casing pressure constant.
11. Bleed off pressure and line up for drilling operation
Reference book: 
Well Control Books
Certainly I will thank drilling formulas team, I dont just find data useful but it keeps me refreshed at all times.
Keep up the good work,
Best Regards,
Paul
Some people say that if you killing a well while applying back-pressure on formation (Choking), you will damage the formation, is this true?
We’re working on gas wells completions, where applying back-pressure (Choking) is a must to kill the well …. but Engineering dept. requested not to apply a back-press. while killing.
I want to know whether applying back-pressure may damage the formation or not?
Back pressure may damage the formation but you need to kill the well before working on the project. It must be scarified at this stage.
good
IF ADJUSTABLE CHOKE FAILED WHILE CONTROLLING
YOU SHOULD SHUT IN AND LINE UP TO SECOND CHOKE
Rebea,
Thanks for sharing.
Regards,
Shyne
what about BOP drill