Structural analysis of weathered oil from Kuwait's environment

An average molecular structural analysis was applied to the oils extracted from a sediment at Shuaiba in June 1995, and from soils at Jaidan in November 1993 and November 1994, Sabriya in November 1993 and November 1994, and the heavy fraction (boiling point >340°C) of Kuwait crude oil. Using the results of elemental analysis, average molecular weight measurement, 1H and 13C NMR analyses, an average molecular structure was estimated on the saturate-free fraction of each sample, and the variation of the average molecular structures was discussed. All average molecules of saturate-free fractions included only one fused ring system, 35–42 total carbons, 52–64 hydrogens, 10–14 aromatic carbons, and 1 sulfur atom, which included benzothiophene or dibenzothiophene type structure. The oil samples from the soils included 1–2 oxygen atoms. The oil from Sabriya in November 1994 had more naphthenic rings than any other oils, indicating its further degradation. From the comparison of the average molecular structural parameters, it became clear that oils in soils degraded by condensation, aromatization, cyclization, and oxidation reactions. In contrast with those oils, oil in sediment degraded by the formation of naphthenic rings and the decrease in aliphatic chains, which suggested some effects of microorganisms.