Dispersions in three-phase high pressure slug flows based on X-ray measurements

Abstract

An X-ray instrument was used to measure phase fractions for three phases over the pipe cross section in upward inclined three-phase flows at high pressure at $40\mathrm{Hz}$. The fluids used in the experiments were hydrocarbon gas, hydrocarbon liquid and brine at 100 bar and 70 C. A novel analytical approach was developed for analysing the X-ray time series of the local phase fractions over the pipe cross section. The experimental data included a range of water cuts and mixture velocities at 1-degree and 10-degree inclinations in a 3-inch ID pipe. Attention was given to the effects of the fraction of water on the dispersion levels in slugs flows. The X-ray had 30 vertically aligned detectors which allowed the fluid phase fractions to be quantified in each measurement region. To establish which fluid represents the continuous phase at each measurement region, certain phase inversion criteria were needed. These criteria were applied locally for each measurement detector region. The presence of any remaining phases within the region of a given continuous phase allows the quantification of the local dispersed phase fractions. Using this approach, the gas–liquid interface could be identified where the liquid layer may include significant levels of gas dispersion in the liquid. Gamma densitometers were used to corroborate the X-ray measurements for liquid holdup and to establish characteristic velocities for waves and slugs using cross correlations.