Abstract: A system is provided for monitoring in the real time the wellbore pit volume to promptly determine the occurrence of a wellbore kick and take corrective action to minimize fluid influx volume and/or drilling fluid losses. A system includes one or more level sensors 22 which output signals to a pit volume totalizer 20 and then to a computer 26. Computer 26 may also receive signals from one or more fluid temperature sensors 40 and one or more fluid compressibility sensors 42. The output from the computer may be displayed in real time in various monitors 28, then also may be output to a permanent record 30. Computer 36 may also automatically activate the conventional alarm 32 to alert the drilling operator to the occurrence of a kick. Substantial savings in drilling time and cost may be realized according to the present invention, along with benefits of reduced environmental contamination and enhanced well safety.