Abstract:

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.

Key words: heavy oil, gas-liquid flow, aerated drug reduction, flow patterns, viscosity, vapor liquid ratio, model

摘要：

依托流体可视化环道装置，设计并加工稠油掺气减阻模拟装置，实验研究水平管内两种稠油模拟油掺气流动阻力特性，拍摄不同气液流量比下的管流流型，分析不同实验条件下气相对稠油的减阻效果并建立相应的压降预测模型。结果表明：在气液比0~15范围内，共观察到六种流型，分别是泡状流、弹状流、分层流、段塞流、环状流、雾状流。220^#与440^#模拟油所对应的管路减阻率分别在气液比1.17和0.96时达到最大值48.19%和33.76%，当掺气比为0.9~1.2时，减阻率均可维持在20%以上。其机理可归结为空气使油-油接触转变为油-气-油接触，降低了混合相的层间剪切应力。Dukler法不适用于高黏气液两相流，所建立的稠油-气两相压降模型预测值与实测值吻合良好，平均相对误差在20%以内。

关键词: 稠油, 气液两相流, 掺气减阻, 流型, 黏度, 气液比, 模型