Abstract: The efficient desalting process for high TAN (Total Acid Number) crude oil has become a key technique for refineries. The main components and emulsification characteristic of three high TAN crude oils, Roncador, Doba and Albacora were studied in the paper. The results show that high TAN crude oils contain a certain amount of naphthenates, in addition to naphthenic acids. It is found that the naphthenic acids and naphthenates, except the alkaline naphthenates, have a limited impact upon the demulsification of the high TAN crude oil. However, the alkaline naphthenates makes the crude poor demulsification because the alkaline naphthenates have comparatively strong surface activity and thus promote the stability of the emulsion formed by high TAN crude oil and water during the desalting process, resulting in emulsion hard being broken.

Key words: crude oil, naphthenic acid, naphthenate, emulsification , demulsification