What does "shut-in" mean in the context of well control?

In the context of well control, "shut-in" refers to sealing off the wellbore to prevent any flow of fluids, including gas and liquids. This is a critical operation that is performed during drilling and completion operations to control well pressures and prevent blowouts or other dangerous situations. By isolating the well, operators can manage the well's pressure and ensure that it remains safe, particularly when there are indications of unexpected pressure build-up or influx.

Sealing off the wellbore assists in stabilizing the situation, allowing time for assessment or intervention, such as adjusting the drilling parameters, adding weight to the drilling fluid, or implementing further safety measures. This practice is essential for maintaining control over the well system and ensuring the safety of drilling operations. In contrast, opening the wellbore would increase the risk of uncontrolled flow, while pumping more drilling fluid might be part of a response to a specific situation but doesn't represent the act of shutting in the well. Monitoring surface conditions is a relevant part of well operations but does not directly correlate with the definition of shutting in a well.