Effect of the down-slope on the structure and the pressure loss of an oil-water stream

The methodology and the results of an experimental campaign aimed at characterizing a two-phase flow of an oil-water-mixture in downward inclined pipes are here described. The goal was to assess the effects of the downslope on an oil-water stream in terms of flow patterns, pressure gradients and phase holdup inside a 40 mm I.D. pipe. The experiments ranged within (0.56 - 1.06 m/s) and (0.66 - 1.33 m/s) oil and water superficial velocities, respectively. The transition from annular to stratified-wavy flow pattern was analyzed and showed to occur at lower oil velocities with respect to the horizontal configuration. The frictional pressure gradients were measured, the results compared to mechanistic and empirical models showed to be in good agreement. The phase holdups were measured by quick-closing valves and compared to horizontal configuration results and literature models. Eventually, the drift-flux model was implemented confirming its applicability and a relationship for the of oil holdup was derived.

Automated summary

The methodology and results of an experimental campaign on characterizing the two-phase flow of an oil-water mixture in downward inclined pipes are described. The goal was to assess the effects of downslope on flow patterns, pressure gradients, and phase holdup. The experiments covered a range of oil and water superficial velocities. The transition from annular to stratified-wavy flow pattern occurred at lower oil velocities compared to the horizontal configuration. The measured frictional pressure gradients and phase holdups were compared to models and showed good agreement. The implementation of the drift-flux model confirmed its applicability and derived a relationship for oil holdup.