Abstract
Churn flow commonly exists in the pipe of heavy oil, and the characteristics of churn flow should be widely understood. In this paper, we carried out air and viscous oil two-phase flow experiments, and the diameter of the test section is 60 mm. The viscosity range of the oil was 100~480 mPa·s. Based on the measured liquid holdup and pressure drop data of churn flow, it can be concluded that, due to the existence of liquid film backflow, positive and negative frictional pressure drop can be found and the change of frictional pressure drop with the superficial gas velocity is related to superficial liquid velocity. With the increase of viscosity, the change rate of frictional pressure drop increases with the increase of the superficial gas velocity. Combining our previous work and the Taitel model, we proposed a new pressure drop model for viscous oil-air two-phase churn flow in vertical pipes. By comparing the predicted values of existing models with the measured pressure drop data, the proposed model has better performance in predicting the pressure drop.
Highlights
Churn flow commonly exists in the petroleum industry
Wang et al [4] presented a new model of pressure gradient, liquid holdup, and wave behavior in churn flow, and he analyzed the liquid viscosity effects on the pressure gradient, liquid holdup, and wave behavior
In our previous work [23], the uncertainty analysis of data is the basis to ensure the accuracy of experimental data; the uncertainty for total pressure drop, liquid holdup, and the frictional pressure drop has been provided; they are within ±2%, ±5%, and ±5.4%, respectively
Summary
Churn flow commonly exists in the petroleum industry. Heavy oil accounts for more than half of the world’s total oil reserves [1]. Due to the complexity of churn flow, the understanding and model research of gas-liquid two-phase churn flow with different viscosity received little attention. Wang et al [2] and Zhang et al [3] studied drop entrainment in churn flow. Wang et al [2] proposed a new model for drop entrainment in churn flow. Shaahid et al [21] analyzed the effects of different inclination angles on the two-phase frictional pressure drop. Ganat et al [22] proposed a new method of the frictional pressure drop for the oil-water-gas three-phase flow. We carried out the oil-gas two-phase flow experiments, and the churn flow was observed and the data of liquid holdup and the total pressure drop was measured in the experiments. We proposed a combined model for churn flow and gave a comparison of performance with other models
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