Measurement of gas phase characteristics in bubbly oil-gas-water flows using bi-optical fiber and high-resolution conductance probes

In the present study, experiments are carried out to investigate local gas phase characteristics of bubbly oil-gas-water flows in a vertical upward pipe with small inner diameter (ID). Bi-optical fiber probe signals at different radial positions and leading and rear half-ring conductance sensor fluctuation signals are collected in a 20 mm ID test pipe. Then flow parameters, including local gas volume fraction, gas velocity and bubble size distribution are extracted according to optical probe signals. The results show that the gas phase superficial velocity, mixture superficial velocity of oil and water as well as mixing ratio of oil and water all have significant impacts on the distribution of gas phase flow parameters. Additionally, in order to validate the results obtained from optical probe signals, multi-scale cross entropy (MSCE) algorithm is applied to analyze signals of high-resolution half-ring conductance sensor to uncover the dynamical instability of oil-gas-water bubbly flows under different flow conditions.