Liu Yigang

The aquathermolysis visbreaking behavior of heavy oil under the combined action of initiator

Initiator is used in the aquathermolysis visbreaking of heavy oil combined with catalyst and other additives. The results show that viscosity reduction ratio goes up from 61.4% to 72.7% after adding 0.2 wt% di-tert-butyl peroxide at 220°C. Initiator is an effective addictive and can further enhance the level of thermal cracking, surprisingly leading to a decent viscosity reduction ratio 69.0% under a relatively low reaction temperature of 150°C. Oil samples are analyzed before and after the reaction, with results showing that the contents of saturate and aromatic increased, while the contents of resin and asphaltene decreased. In addition, the average molecular weight value of each component decreased after the reaction. Elemental analysis of both resin and asphaltene shows that hydrogen to carbon atomic ratio increases slightly. The contents of sulfur decreased remarkably, yet the contents of nitrogen decreased slightly. This phenomenon indicates that sulfur plays a remarkably important role during the aquathermolysis. The HAU/CA of both resin and asphaltene increases. The results above imply that with the help of catalyst and hot water, the cracking reaction of heavy oil occurs, and initiator strengthens the process. Asphaltene and resin suffer a deeper level of cracking into lighter fractions, leading to a substantial viscosity reduction and then an improvement of the flow properties of heavy oil, which also contributes to the improvement of the quality of heavy oil.