Multiphase transportation is widely used as the oilfield development moving into deepwater. Temperatures will have a drop when multiphase flow from normal region to cold region in the subsea pipelines or experience Joule-Thomson cooling in choke valves. The unexpected temperature drop can lead to viscosity increase and ice suspensions formation, and even ice blockage. In this study, viscosity variation of ice suspensions formed from water-in-oil emulsions was measured. Viscosity started to increase when ice suspension was forming. The experimental results showed that viscosity increased firstly until a maximum value upon ice formation and then decrease to a stable value in the process of ice suspension formed from w/o emulsion. So the critical viscosity included a maximum value and a stable value. The effects of temperature (subcooling) and shear rates on viscosity variation were investigated. Experimental results indicated that ice suspension viscosity increased faster with lower temperature (larger subcooling) and stronger shear disturbance. Heat transfer was a principle factor that determined viscosity increase in the process of ice suspensions formation. Therefore, good insulation of subsea pipelines is required to avoid ice blockage when emulsion flow from normal region to cold region.

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