Which of the following is a key indicator of a kick during drilling?

Increased mud flow is a key indicator of a kick during drilling because it typically signifies that formation pressure has exceeded the pressure exerted by the column of drilling fluid (mud). When a kick occurs, formation fluids, including gas, oil, or water, can begin to enter the wellbore, which causes an increase in the volume of fluid being returned to the surface. This increase in mud flow is a critical sign that operators should monitor closely as it indicates that the well may be becoming unstable and under pressure.

Conversely, stable pressure readings, decreased mud flow, and normal gas readings do not suggest the occurrence of a kick. Stable pressure readings would indicate that the well is under control at that moment, while decreased mud flow typically points to a lack of sufficient pressure in the system to continuously circulate mud effectively. Normal gas readings would indicate that there are no abnormal hydrocarbon influxes into the well, which is contrary to the situation of a kick. Thus, recognizing increased mud flow as a response to a change in downhole pressure is essential for effective kick detection and management during drilling operations.