Studies in low-liquid loading in gas/oil/water three phase flow in horizontal and near-horizontal pipes

Low liquid loading in gas/oil/water three-phase flow was experimentally studied using representative fluids for horizontal and near-horizontal pipes. The main focus of the study was to investigate the entrainment of oil and water in the gas phase for large diameter pipes. The liquid superficial velocity and gas superficial velocity are varied between 0.005 m/s to 2.5 m/s, 10 m/s to 23 m/s, respectively. Droplet transport was investigated for water cuts of 0, 10, 20, 40 and 100 % at inclinations of −2, 0 and +2° from the horizontal. An Isokinetic sampling system was developed to measure droplet flux at different locations along the vertical axis of the pipe cross-section. A backlit high speed visualization system was developed to measure the size of the entrained drops. Algorithms for analysis of raw images to calculate drop size distribution were investigated and implemented. A new capacitance probe system was developed to study wave characteristics in case of air-oil two phase flow. Signal processing algorithms to obtain wave celerity, wave amplitude and wave frequency from voltage signal were implemented in Matlab.;New correlations for determination of wave celerity, wave frequency and wave amplitude were proposed based on data available in literature. The upper limit lognormal distribution (ULLN) best describes the droplet size distribution. Stratification in droplet sizes was observed with increasing distance from bottom of the pipe. Droplet flux was found to be more sensitive to superficial gas velocity than to superficial liquid velocity and inclination angle. In the case of entrainment in gas/oil/water flow, the flux of entrained water is enhanced due to presence of the continuous oil phase. The distribution of water drops in the gas phase is, however, not affected by the presence of the oil drops and vice versa. Assuming uniform dispersion in the liquid phase, a simple approach based on these observations is proposed for estimation of the amount of water and oil entrained for three-phase stratified-atomization flow conditions.