A study of drag reducing agents in multiphase flow in large diameter horizontal pipelines

This study examines the effect of drag reducing agents (DRA) on multiphase flow in a 10 cm acrylic and stainless steel pipeline at ambient temperature and pressure. Two and three phase flow is studied using a 6 cP refined oil, water and gas. The effect of DRA on full pipe, oil/water, stratified, wavy stratified, slug, pseudo slug and annular flow is examined. This study also compares the performance of an oil and water soluble DRA.; The results show that the oil soluble DRA significantly decreases the pressure drop for all flow regimes studied when the water cut is 10% or less, except for annular flow. The annular flow regime shows only shows an effectiveness of 10% and less. At the high water cut of 50%, the oil soluble DRA creates a dispersion at 50 ppm of DRA, causing the pressure drop to increase. The dispersion also creates large shifts in the flow regime map causing slug flow to become the dominant flow regime.; The water soluble DRA generally showed a higher effectiveness than the oil soluble DRA. The water soluble DRA does not create a dispersion at 20 to 75 ppm of DRA at water cuts of 10, 50, and 90%. The water soluble DRA decreases the average pressure drop of full pipe and slug flow.; This study also shows that the DRA changed the flow properties. For example the slug frequency decreased with increasing DRA concentration when a dispersion is not created. There is no significant difference shown in the effectiveness of the acrylic and stainless steel pipeline.; The pressure drop components of slug flow is also calculated to show that the accelerational pressure drop due to the slug front is the major contributor to the total pressure drop. This study also shows that the cause of large decreases in pressure drop is generally the large decrease in the accelerational pressure drop of the slug front, which is contributed to the large decrease in slug frequency. A correlation for slug frequency is also developed for the slug frequency with and without DRA present.