Improved Prediction of the Stratified – Non-stratified Flow Pattern Transition in Gas-Liquid Mixtures

Abstract

Although all of humanity is converging on the path of an energy transition oriented towards the use of energy sources with lower environmental impact and reduction of the carbon footprint as much as possible, the use of hydrocarbons is still essential even for progress toward the most anticipated clean source, hydrogen. As long as the use of oil is necessary, the mission of technicians should be to make the industry more efficient to reduce its impact on the environment as much as possible. Heavy crude oil production, generally of high viscosity, is a necessary activity. In general, its transportation in pipelines includes the handling of several phases. Flow pattern prediction and pressure drop calculation models, which have generally been developed for low-viscosity liquids (close to 1 cP), are used to design the lines correctly. The present work presents a modification to the transition criterion from the stratified flow pattern to non-stratified flow based on the Kelvin-Helmhotz instability, incorporating new expressions to improve the estimation of friction losses. The evaluation of friction factors is proposed with the Churchill and Swamme correlations. The calculated transition lines are compared and validated against the experimental data of Lin, Andritsos, and Hanratty for different diameters and viscosities. With the modifications studied, it can be concluded that they improve the prediction of the stratified non-stratified transition for mixtures with viscosities between 1 and 90 [cP], obtaining better results with the modified criteria when compared with experimental values and the values estimated with the models without Modify.