An automatic well test system (100) utilizes a two phase vortex separator 104 connected to a pair of Coriolis flowmeters (154, 166) to measure volumetric flow rates in three phase flow. Measurements are performed according to a process (P200) including an iterative convergence technique. Measurements are enhanced by the use of real time density and water-cut measurements from a water-cut meter (172) and a water density meter.