The Use of Flow Improvers to Decrease Pressure Drop in Multiphase Pipelines

Abstract

Experiments were performed in a 10-cm diameter, 44 m long Plexiglas pipes, multiphase flow loop to examine the effect of flow improver in slug flow at inclinations of ±5degrees. Superficial liquid velocities between 0.5 and 1.5 m/s and superficial gas velocities between 2 and 6 m/s were studied. A 2.5 cP oil at 25 °C was used and water cut was 10%. The experiments were undertaken at a pressure of 0.13 MPa and a temperature of 25 °C with carbon dioxide as the gas. The effectiveness of flow improver on pressure drop and slug frequency was examined for concentrations ranging from 0 ppm to 50 ppm. The results showed that the flow improver was effective in reducing the pressure drop significantly at all superficial liquid and gas velocities. The flow improver concentration of 50 ppm was more effective than 25 ppm for all cases. At superficial gas velocities of less than 4 m/s and all liquid velocities with 50 ppm flow improver, the effectiveness of flow improver in upward flow was around 30%. At superficial liquid and gas velocities of 1.0 and 2 m/s with 50 ppm flow improver concentration, the effectiveness of up to 64% was achieved in downward flow. The slug frequency in both upward and downward flows decreased significantly in all cases with addition of flow improver. For example, at superficial liquid and gas velocities of 1.5 and 2 m/s, the slug frequency in downward flow decreased from 43 to 14 slugs/min. when 50 ppm of chemical was added. The flow pattern in downward flow was changed from slug flow to stratified flow at several velocities, which led to a large decrease in the pressure drop.