Application of nano-nickel catalyst in the viscosity reduction of Liaohe extra-heavy oil by aqua-thermolysis

Nano-nickel catalyst was prepared in methylcyclohexane-water-n-octanol-AEO9 micro-emulsion system, and used in the viscosity reduction process of Liaohe extra-heavy oil by aqua-thermolysis. It is observed that the nano-nickel can catalyze the aqua-thermolysis reaction of extra-heavy oil at 280 °C. The experimental results demonstrate that compared with the original crude oil sample, the mean molecular weight of the upgraded sample decreases, the content of sulfur changes from 0.45% to 0.23%, the content of resin and asphaltene reduces 15.83% and 15.33%, respectively. Based on the GC-MS analysis results, a reaction pathway is proposed that involves hydrogen transfer from methylcyclohexane to the extra-heavy crude oil resulting in the formation of toluene. During the cooling process after upgrading reaction, the W/O emulsion is formed in the presence of the surfactant AEO9. As a result, with respect to the original crude oil, the viscosity of upgraded sample is changed from 139800 mPa·s to 2400 mPa·s at 50 °C, an approximately 98.90% reduction by the synergetic effects of upgrading, emulsification and diluting.