Abstract: An apparatus for improved detection of underground well kicks, preferably comprising a first acoustic sensor mounted on the top drive of a drilling rig in acoustic contact with a liquid level within a drill string which is generally located within a wellbore, a second acoustic sensor in a trip tank connected to the wellbore, and a drawworks position indicator. The acoustic sensors detect signals reflected from liquid level interfaces allowing calculation of injected liquid volumes from the trip tank into the wellbore and liquid volume changes within the drill string. The drawworks sensor allows calculation of tubular volumes removed from the wellbore over time. Comparison or totaling of calculated volumes allows early detection of unwanted fluid fluxes between the wellbore and an underground formation.