The effect of drag reducing agent in multiphase flow pipelines

The effect of drag reducing agents (DRA) on pressure gradient and flow regime has been studied in horizontal and 2 degree inclination. Experiments were conducted for full pipe, stratified, slug, and annular flow in a 10 cm inside diameter, 18 m long plexiglass section and inclinable flow loops from horizontal to vertical. Superficial liquid velocity between 0.06 and 1.5 m/s and superficial gas velocity between 1 and 14 m/s were studied. The DRA effectiveness was examined for DRA concentrations between 0 and 75 ppm. The results indicate that DRA was effective in reducing the pressure gradients in single and multiphase flow. The DRA was more effective for lower superficial liquid velocities and gas velocities for both single phase and multiphase flow. The DRA was effective to reduce pressure gradients up to 42% for full pipe flow, 91% for stratified flow and up to 35% for annular flow in horizontal pipes. Kang, Wilkens and Jepson (1996) showed that the stratified flow disappears entirely and slug flow dominates the flow regime map in inclined upward flow. In 2 degree inclination, the pressure gradient reduction for slug flow with a concentration of 50 ppm DRA is 28% and 38% at superficial gas velocitiesmore » of 2 and 6 m/s respectively. Flow regimes maps with DRA were determined in horizontal pipes. The transition to the slug flow with DRA was observed to occur at a higher superficial liquid due to higher liquid flow rates. There is a conspicuous absence of drag reduction work for multiphase (oil-water-gas) flow in horizontal and inclined pipes.« less