自由基引发剂强化稠油催化水热裂解降黏行为

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

本文考察了自由基引发剂对胜利油田单56区块稠油样品催化水热裂解反应过程的协同强化作用.在反应温度为220℃,添加0.2 wt%的引发剂——过氧化二叔丁基,使水热裂解后的降黏率由不加引发剂时的61.4%升高到72.7%.此外,在引发剂存在、150℃条件下,降黏率可达到69.0%,表明引发剂的加入可显著提高较低反应温度下的水热裂解效果.对反应前后油样进一步分析发现,反应样品中饱和分、芳香分、胶质和沥青质平均分子量均下降;饱和分、芳香分含量增加,而胶质、沥青质含量下降;胶质、沥青质中氢碳原子比增加,含硫量减少,含氮量变化不大;表明重质组分在水热裂解过程中发生了裂解反应、尤其是含硫官能团在水热裂解中发生了反应;反应样品沥青质及胶质芳香环系的缩合程度降低.实验结果表明,反应过程中稠油重质组分发生了裂解,而且胶质的裂解程度更大,轻质组分含量增加,导致稠油黏度降低、流动性提高,在一定程度上改善了稠油的品质;引发剂可以在较低温度下产生自由基,从而使水热裂解反应在较低反应温度下有效进行.

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℃. 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℃. 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 H_（AU）/C_A 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.