this is the pvt versus time curve whereby time zero is the instant the pumps are shutdown and at this instant the pvt is arbitrarily also set at zero the fluid in the wellbore is contained within a known and controlled space with no possibility of wellbore breathing or a formation fluid influx contributing to the recorded flow back profile this curve becomes the baseline upon which future determinations of a stable wellbore may be based the flow back profile for the baseline rep when drilling the interval if this level is exceeded the well may be determined to be unstable once formation rock is exposed the system of the present invention may be used to establish if either or both of wellbore breathing and formation fluid influx kick are occurring at every flow check connection of drill pipe or drilling fluid pump shut down recorded time may be set at zero as may be the instantaneous pvt level and the flow out of the well may be monitored and recorded in real time using the pvt data the base line most preferably is displayed together with the real time flow back profile should wellbore breathing be identified the volume associated with the breathing may be determined and the pre set alarm levels may be adjusted and the base line thus re set if a kick is indicated or suspected well control procedures may be implemented if the well is stable drilling may commence a flow chart of the software.