Stability analysis of stratified oil/water flow in inclined pipelines

A theoretical study was conducted to investigate flow-pattern transitions in slightly inclined pipelines carrying oil/water mixtures. Two criteria obtained in the Linear-stability theory of stratified oil/water flow were used to predict the transition from a stratified- to nonstratified-flow pattern. A comparison of theoretical transition boundaries with published experimental data for horizontal and inclined pipes (+/-1 degrees and +/-5 degrees) was performed. The study revealed that pipe inclination has a significant effect on the stratified-flow region. The results obtained can be useful for the design and operation of crude-oil flowlines and directional wells.