Which of the following is a positive kick indicator?

An increase in pit volume is a positive kick indicator because it signifies that there is an influx of formation fluids into the wellbore, which displaces the drilling mud and causes the volume of fluid in the pits to rise. This situation is indicative of a well control problem, often associated with an uncontrolled influx of oil, gas, or water from the geological formations being drilled into. Recognizing this indicator is critical for prompt and effective well control responses, as it allows drilling personnel to take necessary actions before a kick escalates into a blowout.

The other options do not serve as reliable indicators of a kick. For instance, a decrease in pump pressure might occur for various reasons that do not necessarily relate to a kick, such as equipment malfunction or changes in mud properties. A decrease in mud temperature could be influenced by several factors unrelated to well control, like changes in surface conditions or fluid properties during drilling. Lastly, flow from the well with the pumps off can indicate a flow issue, but it does not exclusively confirm that a kick has occurred as it could also result from other well conditions. Understanding these distinctions is crucial for effective well control management.