Título: Geochemical study of crude oils in the Machete area, eastern Venezuela basin: Effects of biodegradation

Autor: Tocco, R.; Mendez, M.; Ceccarelli, C.

Fuente: Revista Latinoamericana de Geoquímica Orgánica, Vol. 2, 1997

Año: 1997

Descriptores: Venezuela; Biodegradation; Crude Oils; Machete area; Eastern Venezuela Basin

Tipo de documento: Articulo

Resumen:

Eight extra heavy crude oils samples from the Machete area in the Eastern Venezuela basin were analized to study the distribution of saturate and aromatic biological markers and the effects of biodegradation on these organics compounds. These crude oils have a marine source and were formed in association with their source rocks's main phase of hydrocarbon geneation and expulsion. The biomarkers analyses show how two principal crude oils groups (A and B) according to different biodegradation levels. The group A shows a higher degree of biodegradation than group B. For example, the group A shows depletion in the concentrations of the C27-C29 steranes, presence of dementhlylated hopanes, the monoaromatic hydrocarbons are totally absent, alteration of methyl phenanthrene and methyl dibenzothiophenes compounds. The C27-C29 steranes, methyl phenantrene and methyl dibenzothiophenes distributions are apparently untouched by bacterial alteration in the groups B oils.