Resumo

ROMERO HERNANDEZ, Alicia et al. Analytical procedure for chromatographic analysis of samples for geochemical purposes. Rev. CENIC Cienc. Quím. [online]. 2020, vol.51, n.1, pp. 49-61.  Epub 01-Jun-2020. ISSN 2221-2442.

Crude oil is a highly complex natural mixture consisting predominantly of hydrocarbons [alkanes (paraffins), alkenes (olefins) and aromatics] with other elements such as sulfur, nitrogen and oxygen. The geochemistry of the deposits starts from the basic principle that within a deposit where there are no permeability barriers, a compositional homogenization of the crude will occur, so that in any part of the deposit the same composition or "fingerprints" will be presented. For this reason it is necessary to develop a chromatographic method for the analysis of light compounds in samples of crude oil (fraction C15-). Seven light, medium and medium-heavy crude samples were selected. In the geochemical characterization of discontinuities and compartmentalisations in reservoirs, high-resolution gas chromatography is used as a routine technique on total crude oil, the interpretation of the results obtained obtained contributes to reduce the probability of drilling unproductive oil wells, the chromatographic parameters remained invariant in the analysis of the crude oil samples, which facilitated the study of the composition of the molecular species present. The identification of the compounds was based on the retention times and by comparison with reference standards. 100 chromatographic peaks corresponding to the light fraction C15- (cycloparaffins, naphthenes and aromatics) were identified. Of these, 22 were selected and their heights were obtained for each sample. The repeatability and intermediate precision in all cases were less than 3%, which demonstrated the precision of the analytical method developed.

Palavras-chave : Crude oil; deposit; geochemical characterization; chromatography; identification.

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