Investigation of three-phase flow in horzontal pipes and its representation in ternary diagrams

The physical understanding of three-phase flow characteristics in horizontal pipes is of importance in the production of hydrocarbons from oil fields since very often oil, water, and natural gas flow together in the transporting pipelines. The work is focused on evaluating the effect of air injection on the pressure drop of a two-phase oil-water flow. Experiments reported are performed at the two-phase thermo-fluid dynamics laboratory of the Politecnico di Milano, using mineral oil and tap water of viscosity ratio about 800 and density ratio 0.9, together with ambient air. For the interpretation of the wide set of experimental data we use newly introduced, easily readable three-phase flow diagrams. In our experiments, the presence of air always has a negative effect on drag when it is injected into an oil-water flow in annular regime. Conversely, in the stratified regime, air supply at moderate flow rates can increase the drag reduction effect of water, but the stratified regime is not well suited for viscous oil transportation