The effect of final cooling temperature on the wax deposition of Daqing oil modified with additives

In order to analyze the effect of final cooling temperature on the wax deposition laws of the crude oil modified with additives, keep the same temperature difference of oil wall and control different final cooling temperatures, static wax deposition contrast test and dynamic shear contrast test were carried out on Daqing oil with nano pour point depressant, Daqing oil with EVA pour point depressant and Daqing blank oil using the wax deposition device of agitation tank, rheometer, differential scanning calorimeter and other test instruments. Then, based on the mechanisms of molecular diffusion and gelling, the wax deposition laws of Daqing oil modified with additives under different experimental conditions were investigated. It is shown that when the final cooling temperature is lower, the blank oil is low in the total wax deposition but its wax crystal structure is stronger; while the oil with additives is significantly higher than the blank oil in the total wax deposition, but there is more condensate in the total amount of wax deposition and the wax crystal structure is weaker. With the increase of the final cooling temperature, the wax deposition in the oil with additives and that in the blank oil decrease gradually and tend to be consistent. When the final cooling temperature is lower and the shear peel strength is weaker, the addition of pour point depressant can increase the wax deposition of pipeline transportation. And once the shear is high or the final cooling temperature is increased, the wax deposition of the oil with additives will be reduced significantly and the safety of pipeline transportation will be improved.