Effect of Drag-Reducing Agents in Multiphase, Oil/Gas Horizontal Flow

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAn experimental study has been carried out in a 36-m long, 10-cm diameter in horizontal multiphase system. Oil with a viscosity of 2.5 cP was used as the liquid phase and carbon dioxide was the gas phase. The effect of drag reducing agents (DRA) on average pressure drop, maximum pressure drop and slug characteristics for superficial liquid and gas velocities of 0.5 to 1.5 m/s and 2 to 12 m/s, respectively, was studied at DRA concentrations of 0, 20 and 50 ppm. Temperature was kept at 25 o C and pressure was maintained at 0.13 MPa.The DRA was effective in reducing the average pressure drop significantly for all superficial liquid and gas velocities in both slug and annular flow. The average pressure drop reduction of up to 82% for slug flow and 47% for annular flow was achieved. For slug flow, the effectiveness generally decreased with increase in superficial liquid velocity. The maximum pressure drop across the slug also reduced with addition of DRA. The effectiveness for maximum pressure drop was over 28% at a superficial liquid velocity of 1.5 m/s for all gas velocities.At superficial liquid and gas velocities of 0.5 and 2 m/s, the flow pattern changed from slug flow to stratified flow by decreasing the slug frequency to 0 slug/min. when 50 ppm DRA was added. At higher liquid and gas velocities, the slug frequency also decreased significantly. The effective height of the liquid film decreased with addition of DRA.

Drag reduction in horizontal annular two-phase flow

“…In general, the drag reduction increased with increasing U SL and decreased with increasing U SG . This result contradicts the finding of Kang and Jepson (2000) and Sylvester and Brill (1976), but is consistent with the present experiments. In general, the drag reduction was higher in the 2.54 cm pipe (maximum of 63%) than in the 9.53 cm pipe (maximum of 48%).…”

Direct Numerical Simulation of Gas-Liquid Drag-Reducing Cavity Flow by the VOSET Method

“…They obtained a 35% drag reduction rate. Kang and Jepson [16,17] and Daas et al [18] found the drag reduction rate of gas-liquid two-phase flow varied from 30% to 50% for the concentration of the high polymer increasing from 10 ppm to 50 ppm, respectively. For higher superficial gas velocity, the drag reduction rate drops from 50% to 30%.…”

The Performance of Drag Reducing Agent in Three Phase Slug Flow and Annular Flow

“…Recently, Kang and Jepson [3,[5][6][7][8] have published laboratory test results for drag reduction in multiphase flow. They have noted that DRA works not only ftictional pressure drop but also accelerational pressure drop in slug flow regime.…”

“…Effectiveness of DRA depends on a lot of parameters such as types of DRA, temperature, pH, DRA concentration, oil viscosity, pipe diameter, liquid and gas flow rates, pipe roughness, composition oil, and so on [8], Therefore, it is suggested that laboratory test for drag reduction should be performed due to the technical and economic aspects before DRA is used in the field.…”