Based on visualizable fluid circuit

a lab-scale setup for drag reduction of aerated heavy oil was designed. Two heavy oil models mixed with air were experimentally studied for flow resistance characteristics in horizontal pipe. Photos were taken to capture fluid flow patterns in pipe at various air liquid ratios. The drag reduction effect of air on heavy oil at different conditions was analyzed and a corresponding pressure drop prediction model was established. At gas-liquid ratios ranged from 0 to 15

six flow patterns were observed

i.e.

bubbly flow

plug flow

stratified flow

slug flow

annular flow and spray flow. The drag reduction rate of 220# and 440# model oils reached peak at 48.19% and 33.76% at air liquid ratio of 1.17 and 0.96 respectively. When the ratio was in a range of 0.9 to 1.2

drag reduction rate of both oils could be maintained at 20%. The mechanism of drag reduction was attributed to that air changed interface from oil-oil to oil-gas-oil such that shear stress between layers of mixed phase could be lowered. The Dukler's method is not applicable to gas-liquid two-phase flow of high viscosity oil

however

the established heavy oil-gas two-phase pressure drop model predicts well with measurement which has less than 20% average relative standard error.