Why should the well be shut in quickly after a kick is detected?

Shutting in the well quickly after a kick is detected is crucial to minimize the influx of formation fluids into the wellbore. When a kick occurs, it indicates that high-pressure formation fluids have breached the barrier created by the drilling mud, leading to potentially dangerous conditions. By promptly shutting in the well, the pressure differential can be restored to prevent further inflow of these fluids, which could lead to a blowout or other catastrophic events. This action is essential for maintaining control over the well and ensures the safety of the drilling operation and personnel involved.

The other options do not directly address the immediate need to control the influx of fluids. Maintaining drilling operations or adjusting mud properties can be part of the subsequent response to the kick, but they do not address the urgent priority of controlling the wellbore pressure and stopping additional fluid from entering the well. Evaluating kick size is important for understanding the situation, but it is secondary to the immediate action required to secure the well and prevent further influx.