Onset of Separated Water-Layer in Three-Phase Stratified Flow

Abstract

The onset to separated water-layer in three-phase gas-oil-water stratified flow in horizontal pipes is studied theoretically and experimentally. The objective is to determine the transition boundary between the separated liquid-phase and the dispersed liquid-phase in three-phase stratified flow. An experimental facility was constructed, enabling data acquisition under horizontal three-phase stratified flow. A total of 75 experimental runs were conducted varying the water cut between 5% and 40%. The results are presented in the form of flow pattern maps, including the transition boundary between the two liquid-phase flow configurations. The transition mechanism is the occurrence of large waves at the oil-water interface, which reach the bottom of the pipe, swiping the water layer and dispersing it. A mechanistic model was developed for the prediction of the transition boundary between the separated and dispersed liquid-phase under three-phase stratified flow. The proposed model requires as input the three-phase stratified flow variables, which are determined based on the Taitel et al. (1994) model. The transition boundary is then predicted based on the proposed flow mechanism, utilizing a simple Froude number criterion. The model predictions of the transition boundary between the separated and dispersed liquid-phase flow show a good agreement with the acquired experimental data.