Provided is an estimation apparatus comprising an acquisition unit that acquires state data including intensity data of at least one frequency band related to a detection signal detected by a vortex flow meter for a fluid, a state determination estimation unit that estimates a state of the fluid based on the state data acquired by the acquisition unit, a fluid quality estimation unit that estimates, from the intensity data, at least either of a liquid amount or dryness related to the fluid according to the state of the fluid estimated by the state determination estimation unit, and an output unit that outputs at least either of the liquid amount or the dryness estimated by the fluid quality estimation unit.

A multiphase vortex flowmeter system determines the gas-to-liquid ratio (GLR) and flow rates from a well producing multiphase gas, oil and water by detecting the frequency and amplitude of vortices shed in a vortex flowmeter. In particular, the phase of the flow can be identified by detecting the change in the frequency of the vortices with respect to time, and the amplitude of the vortices. Based on the phase, the flow rates of liquid and gas can be calculated. As a feedback technique, these calculated values can be tuned by comparison with actual GLR and flow rates recorded for the well by a test separator.