Abstract:

The South China Sea crude oil has rich reserves; its exploitation has important economic value and strategic significance. Resin and n-heptane asphaltene were separated from the crude oil and their structures were determined. In addition, a nitrogen-containing long-chain polymeric viscosity reducer was synthesized and its effect on viscosity of South China Sea crude oil was studied. The results indicate that South China Sea crude oil has high contents of resin and asphaltene. The high viscosity of South China Sea crude oil is mainly attributed to its associative structure of resin and asphaltene. Moreover, resin and asphaltene molecules contain aromatic sheet with side chain, connecting with alkyl chain and the polar groups which can form hydrogen bonds. Furthermore, the average molecular weights of resin and asphaltene are 760 and 1 129, respectively. The comparison results show that the parameters of average molecular structures of resin and asphaltene are consistent with the characterization values. With an addition of 1 000 of viscosity reducer, the viscosity of South China Sea crude oil at 15 ℃ and 40 ℃ decrease 44.2% and 40.2%, respectively. And the yield stress is reduced from 1 070 Pa to 563 Pa, indicating the remarkable viscosity reduction effect.

Key words: the South China Sea crude oil, resin, asphaltene, structure characterization, viscosity reduction