According to the eccentricity of core oil flow in water-annulus transport of heavy oil

a simulated experiment for heavy oil flow boundary layer under the action of aqueous foam system-2 (AFS-2) (foam quality 50%) was proposed. A corresponding pipe flow simulated device and a system of foam generating

injecting and foam layer generating were designed and built. Flow resistance characteristics of heavy oil simulated by 201 methyl silicone oil under the action of aqueous foam in horizontal pipe were determined experimentally

and the influence of velocities and flow ratios of foam and silicone oil on silicone oil flow patterns and drag reduction was analyzed. Based on the hypothesis on complex boundary layer of upper foam-lower foam drainage film

a model for predicting pressure drop of silicone oil-foam-foam drainage film core-annular flow in horizontal pipe was established. At room temperature 20℃

drag reduction efficiency was above 70% when flow ratios of foam and silicone oil were between 0.2 and 0.5

and its mechanism of drag reduction could be the complex isolating-lubricating layer of upper foam-liquid film between oil and pipe wall. The predicted values were in good agreement with the experimental data

and relative errors were between －17.55% and 9.76%.