Synthesis and identification of biomarkers in oils of the Campos and Potiguar Basin: identification of 3-alkyl-steranes / Sintese e identificação de biomarcadores em oleos da Bacia de Campos e Bacia Potiguar : identificação de 3-alquil-esteranos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

This work reports an investigation using oils from Campos (southem Brazil) and Potiguar (northeastem Brazil) Basins which are the two most important petroleum producer basins in the country. The main focus in this research was the analysís of neutral and acidic biomarkers as indicators of biodegradation. Consequently, we have selected oils samples originated from the same source rock and found reservoirs of distinct depths and geological characteristics in the Campos Basin. The analyses of neutral fractions (Campos oils) revealed the presence of alkyl-sterane biomarkers: 5a(H)-stigmastane, 5b(H)-stigmastane, 3a(methyl)-5b(H)-stigmastane and 3a(methyl)-5b(H)-stigmastane, which structures were confirmed by co-injection with synthetic standards. Previous work on oils from Potiguar Basin Lopes et aI. (1999, 1997) had detected a whole series of alkyl steranes belonging to the stigmastane and ergostane families. Their structures were proposed based on mass spectra data, which required total synthesis of ten 5a(H) and 5b(H)-stigmastane and alkyl-stigmastane standards. These were co-injected with the oil fractions confirming the biomarkers structures. The reanalysis of the Potiguar Basin oils allowed us the identify several aromatic biomarkers used as indicators of source, maturation and biodegradation which confirmed previous analyses (Lopes et al., 1999; Lopes, 1995). Furthermore, GC/MS analysis allowed to the identification of eleven new alkyl-steranes, eight of which, possessing the unusual SP(H) configuration. Finally, a new series of alkyl-steranes: 3-n-propyl-5a(H)-norcolanic acid, 3-propyl-5a(H)norcolestanic acid and 3-propyl-5a(H)-24-methylcolestanic acid, was identified in the acidic fraction of the Campos Basin oils.

ASSUNTO(S)

potiguar basin bacia potiguar 3-alkyl-steranes biomarcador biomarkers 3-alquil-esteranos campos basin bacia de campos

ACESSO AO ARTIGO

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