Application of single-probe fiber optic reflectometry on phase discrimination and velocity and size determination in an oil–gas–water three-phase flow

Abstract

This paper presents an experimental study to investigate the applicability and accuracy of phase discrimination and measurements of velocity and size for bubbles and droplets using a single-probe fiber optic reflectometer technique in an oil–gas–water three-phase flow. The technique is capable of identifying dispersed and continuous phases and measuring velocity and size of gas bubbles or oil droplets in two-phase flows. In this study, the technique was expanded to identify water, air bubbles, and oil droplets and quantify velocity and size of bubbles and droplets in an oil–gas–water three-phase flow through processing the acquired signals. By applying Fresnel reflectivity, setting a threshold, and using wavelet transform for phase discrimination, bubbles and droplets were identified with improved accuracy. In the study, 99.9% of the droplets and 98.3% of bubbles were successfully discriminated for the approximately 7000 combined bubble and droplet encounters. Besides, the velocity, size, and phase were correctly measured and identified in 100% of 117 encounters (63% of which are bubbles) for the cases with signals containing the velocity information. Furthermore, a dominant dimensionless parameter was identified to quantify the applicability limit of the probe to bubble and droplet size ratios.