An analysis of crude oil-acid reaction products by size-exclusion chromatography

The contact of acid with crude oil generates a reaction product known as ac id-sludge which has been interpreted as polymerised asphaltenes due to Frie del-Crafts reactions. A size-exclusion chromatographic analysis of crude oi ls and fractions showed, however, that acid-sludge is composed of small mol ecules. The greatest increase in molecular weight was observed for the nonp olar fractions. The results could be explained by assuming surfactant-like behaviour of protonated basic crude oil components. Aggregate formation, th erefore, explains the higher molecular weights observed. (C) 2000 Elsevier Science Ltd. All rights reserved.