The calibration of a multiphase flowmeter is usually
highly dependent on the flow regime of the mixture being
monitored. Since the flow regime present in a pipeline cannot
always reliably be predicted, then online calibration of such instruments
is usually required. As the range and capabilities of
multiphase flowmeters increase, the problems of how to validate
the performance of such instruments online also increases. This
study considers the extent to which simple capacitance-sensing
techniques can be used to validate the multiphase flowmeters’
performance by identifying the carrier, dispersed phase(s), and
flow regime in the flow stream. Finite-element analysis, using the
ANSYS software, was used to predict the ability of a simple capacitance
sensor to identify carrier and phase composition in a range
of oil, water, and gas mixtures. The sensor parameters investigated
included electrode length, electrode separation, pipe material, and
the effect of guards. The results obtained were used to optimize the
sensor geometry for reliable identification of carrier and phase(s).
The results obtained from the simulation were experimentally
verified. It was shown that a capacitance measurement technique
combined with statistical and fuzzy-logic-type methods can form
the basis of a simple and robust validation unit that could be
retrofitted to multiphase flowmeters for online validation. Such a
system could be used as an early warning system for instrument
malfunctions.