Rheological Study About Different Characteristic Temperature Of Waxy Crude Oil

As the temperature dropped in pipeline,wax of waxy crude oil gradually precipitated.Due to the non-uniform cooling rate,the wax precipitation characteristics of waxy crude oils will change.In the previous study researchers exploring the relationship between wax precipitation characteristics and rheological process of waxy crude oil,researchers measure the wax precipitation characteristics by DSC at a cooling rate of 5?/min,while rheological experiments at a cooling rate of 0.5?/min,no agreement with the cooling rate.In this paper,differential scanning calorimeter(DSC)will be used to measure wax precipitation characteristics of waxy crude oil at different cooling rates to find the influence of the cooling rate to the wax precipitation characteristic.And it is found that feature points on the curve increase linearly with cooling rate decreasing.There is a special point on the wax precipitation curve,it is called inflection point.In the experiment it is found that the inflection point is greater about 2?or 3?than solidifying point of three test sample crude oil.And another special point is calculated with the non-isothermal crystallization kinetics,it is called turning point.The turning point equals with the abnormal point of the three test sample crude oil.It provides a convenient method to calculate the abnormal point and solidifying point.Use small amplitude oscillatory shear experiments with RS150 to measure the storage modulus and the maximum stress value within the linear viscoelasticity range of wax crude oil.It is found that structure of the three test sample increases rapidly below the inflection point,which is bad to the shutdown and restart of crude oil.Then compare with the degree of crystallinity measured at cooling rate of 0.5?/min,it can be seen that the storage modulus and the degree of crystallinity respectively agree to a power-low relationship.Within the temperature range of research,feature points divided it into three intervals.Discussing rheological law in the three intervals,the same rule with three test sample oil is found.