For the drilling industry especially when we talk about well control, there are 2 types of shut in which are Hard Shut-in and Soft Shut-in. This post will describe both shut in types and I wish I would be helpful for you all 🙂
Hard shut in: It means that while drilling choke line valves (HCR) are in the closed position; it will be opened after the well is shut in. The hard shut-in is the fastest method to shut in the well; therefore, it will minimize volume of kick allowed into wellbore.
Soft Shut In: It means that while drilling, the choke line valves (HCR) are in the opened position. When the well control situation is occurred, you shut in BOP and then close choke valves to shut in the well. The soft shut in procedure allows fluid to flow through the surface choke line before the well will be completely shut in. This is the bad part of the soft shut in procedure because it doesn’t minimize the size of the wellbore influx.
The shut in procedure is the company specific procedure. You need to follow your company policy to shut in the well. Anyway, I personally recommend “HARD SHUT IN PROCEDURE” because it allows me to shut well in as quickly as possible and kick volume entering into a well bore will be minimized. Please also remember that less volume of kick you have in the well bore, the less problem you will see when you attempt to kill the well.
Reference book: Well Control Books