What does a "flow check" involve after a well is shut in?

The correct choice focuses on evaluating whether formation fluids are entering the well after it has been shut in. Conducting a flow check is a critical safety procedure in well control as it helps determine if there is any influx of fluids from the formation into the wellbore, commonly referred to as a kick. Detecting the presence of formation fluids is essential to assess the well's stability and to decide on the appropriate response to maintain control of the well.

In the context of well monitoring, a flow check is carried out after a well is secured to ensure that the well is not flowing uncontrolled. If formation fluids are entering the well, it indicates a breach of the well integrity, which must be addressed immediately to prevent a blowout or other dangerous situations. Understanding these dynamics is crucial for anyone involved in drilling operations and well control.

Other options, such as assessing the temperature of the well fluid or measuring the volume of drilling fluid, do not provide direct information on the well's inflow condition. Inspecting blowout preventer functionality is important for overall well safety, but it is a separate procedure not specific to the flow check.