Types of Flow Pattern

Two-Phase Vertical Flow Patterns

The most familiar two-phase flows in petroleum production are gas-water flow and oil-water flow. In our study, we focus on the gas-water vertical flow patterns.

Two-phase flow in vertical pipelines may be categorized into five different flow patterns, as shown in figure 1-2 and listed here: Bubble flow, Slug flow, Churn flow, Froth flow and Annular flow.

This plot is helpful for understanding the phenomena, several flow regimes are identified on the map such as annular flow at very high gas rates and very low liquid rates & bubble flow at very low gas rates. Also note the large zone of intermittent/slug/churn flow in the center of the plot.


            Figure 1-2 Flow regime transition criterion for upward two-phase flow in vertical tube

            Source : http://aghajar.okstate.edu/content/singletwo-phase-heat-transfer-laboratory


                                           Figure 1-3 Slug flow pattern in vertical pipes


In our study, we are interested in the slug flow pattern in vertical pipes and risers, figure 1-3. In vertical flow, the bubble is an axially symmetrical bullet shape that occupies almost the entire cross-sectional area of the tubing. The velocity of the gas bubbles is greater than that of the liquid slug, thereby resulting in a liquid holdup that not only affects well and riser friction losses but also flowing density.