Measurement Of Multiphase Flow Water Fraction And Water-cut

Abstract

This paper describes a microwave transmission multiphase flow water‐cut meter that measures the amplitude attenuation and phase shift across a pipe diameter at multiple frequencies using cavity‐backed antennas. The multiphase flow mixture permittivity and conductivity are derived from a unified microwave transmission model for both water‐ and oil‐continuous flows over a wide water‐conductivity range; this is far beyond the capability of microwave‐resonance‐based sensors currently on the market. The water fraction and water cut are derived from a three‐component gas‐oil‐water mixing model using the mixture permittivity or the mixture conductivity and an independently measured mixture density. Water salinity variations caused, for example, by changing formation water or formation/injection water breakthrough can be detected and corrected using an online water‐conductivity tracking technique based on the interpretation of the mixture permittivity and conductivity, simultaneously measured by a single‐modality microwave sensor.