Study On The Effect Of Waxy Crude Oil Emulsification On Rheological Properties At Low Temperature And Wax Crystallization Characteristics

During long-distance transportation of oil,the gelation temperature and yield stress are important indexes to measure the low-temperature fluidity of waxy crude oil and its emulsions.The gelation temperature is the maximum temperature at which a crude oil or emulsion loses fluidity under certain conditions and the yield stress is the minimum stress that must be applied to restore the fluidity of the fluid in the pipeline and the value determines the difficulty to restart the oil-water mixture in the pipeline.Due to the current controversy about the structural change of the emulsion in low temperature,four representative waxy crude oils were selected in this paper to study the effects of different water contents on gelation temperature,elastic modulus,yield stress and wax crystallization characteristic.It was ultimately found that when waxy crude oil contains higher level of wax,gel structure of the water-in-oil emulsion is more stable than that of crude oil in the form of higher gelation temperature,larger elastic modulus and yield stress,and conducted mechanism analysis and mathematical fitting.This paper attempts to raise a new perspective why the structural strength of waxy crude oil emulsion becomes larger under low temperature conditions.A possible explanation was asphaltenes’ effect on the combination of wax crystals.Also,the presence of water in the system slows down the cooling rate of the emulsion.Disperse water droplets to provide a core for precipitation of wax crystals.The viscosity of the liquid increases so that the experiment measured "gelation temperature" rise.