An apparatus and a process for wellbore characterization are disclosed, including: separating, in a separation vessel, drilling mud from gas produced during drilling of a wellbore; transporting the separated produced gas from the separation vessel to a downstream process; and measuring at least one of a temperature, a pressure, a mass flow rate, and a volumetric flow rate of the separated produced gas during transport using one or more sensors. Properties of the gas separated from the mud may be used to determine characteristics of a wellbore.