The optimal dehydration rate of two cylindrical cyclone separators were compared under the water cut of 95%, 90%, 80% and 70% at the inlet, by changing oil-water mixing flow rate and split ratio. The experimental results show that when the inlet water cut is 95%, 90% and 80%, the optimal dehydration rate of the cylindrical cyclone with orifice vortex finder is 12%~22% higher than the cylindrical cyclone without orifice vortex finder. And the pressure drop between the inlet and the overflow increases 3~52 kPa. When the inlet water cut is 70%, the optimal dehydration rate of the former has little difference with the latter, but the maximum pressure drop between the former and the latter is 68 kPa. Under different experimental conditions, the pressure drop between the inlet and the underflow is not obvious, and the former is slightly higher than the latter. At the same time, when the inlet water cut is constant, the relationship between the optimal split ratio and oil-water mixing flow rate is consistent with the dehydration rate.

The viscosity of heavy oil is high, the pipeline transportation is difficult, and the viscosity decreases greatly after dissolved gas. Thus researching viscosity-reducing properties of dispersion system of heavy oil with dissolved gas is of great significance to the actual pipeline operation. The viscosity-reducing mechanisms, viscosity models and influence factors of heavy oil with dissolved gas are summarized. The research indicates that dilution micelle damage, swelling, molecular force and micro-bubbles effect can reduce the viscosity of dispersion system. Viscosity models are mainly established by Shu, Abivin and so on, and the defects in the model are presented. The property of oil and gas, temperature, pressure, the amount of dissolved gas and micro-bubbles have different effects on the system's viscosity, and the direction of the heavy oil with dissolved gas is proposed.