Estudio comparativo de biomarcadores a partir de crudos provenientes de la Cuenca Austral y del Golfo
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2019
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Abstract
El petróleo o “aceite de roca” es un recurso no renovable que se puede separar en 4 grandes
fracciones (alifáticos, aromáticos, resinas y asfáltenos). Las dos primeras fracciones contienen
moléculas específicas de importancia para la Geoquímica Orgánica conocidas como
“Biomarcadores”. El objetivo de este trabajo fue determinar los perfiles de biomarcadores (isoprenos,
hopanos y esteranos, etc) para dos muestras de crudo pertenecientes a la Cuenca Austral (CA) y
dos a la Cuenca del Golfo (CG). Para tal fin las muestras de crudo fueron sometidas a una
separación de sus fracciones alifáticas y aromáticas por cromatografía en columna de sílica gel y
los extractos obtenidos fueron analizados por separado por cromatografía gaseosa con detección
de masas estudiando los iones característicos para los diferentes compuestos de interés. Con los
datos obtenidos se calcularon diferentes relaciones de diagnóstico como ser Pr/Fi, Pr/n-C17, Fi/n-
C18, Ts/Tm, entre otros. Los resultados mostraron como a partir del estudio de biomarcadores
pueden establecerse diferencias entre las muestras a nivel de una misma cuenca y más aún si se
hace entre cuencas. Las muestras de la CG se caracterizaron por un ambiente deposición más
anóxico, mayores niveles de biodegradación del crudo y un aporte de materia orgánica
predominantemente marino ya que la relación Pr/Fi fue cercano a 1; en el caso de las relaciones
Pr/n-C17 y Fi/n-C18 los valores se ubicaron por encima de 0,5 y en estas muestras se detectó la
presencia de metilesteranos (S30). Como conclusión podemos destacar que el estudio de los
biomarcadores constituye una poderosa herramienta para caracterizar un yacimiento a partir de
muestras obtenidas de él, y que como aspecto secundario esto permite marcar las diferencias
existentes ellas.
Oil or "rock oil" is a non-renewable resource that can be separated into four large fractions (aliphatic, aromatic, resins and asphaltenes). The first two fractions contain specific molecules of importance for the Organic Geochemistry known as "Biomarkers". The objective of this work was to determine the profiles of biomarkers (isoprene, hopanos and esteranos, etc) for two samples of crude oil belonging to the Austral Basin (CA) and two to the Gulf Basin (CG). For this purpose the crude samples were subjected to a separation of their aliphatic and aromatic fractions by silica gel column chromatography and the obtained extracts were analyzed separately by gas chromatography with mass detection studying the characteristic ions for the different compounds of interest. With the obtained data, different diagnostic ratios were calculated such as Pr/Fi, Pr/n-C17, Fi/n-C18, Ts/Tm, among others. The results showed how, from the study of biomarkers, differences can be established between the samples at the level of the same basin and even more if it is done between basins. GC samples were characterized by a more anoxic deposition environment, higher levels of crude biodegradation and a contribution of predominantly marine organic matter since the Pr/Fi ratio was close to one; in the case of the Pr/n-C17 and Fi/n-C18 ratios, the values were located above 0.5 and in these samples the presence of methylterans (S30) was detected. In conclusion, we can highlight that the study of biomarkers is a powerful tool to characterize a site from samples obtained from it, and that as a secondary aspect this allows to mark the existing differences.
Oil or "rock oil" is a non-renewable resource that can be separated into four large fractions (aliphatic, aromatic, resins and asphaltenes). The first two fractions contain specific molecules of importance for the Organic Geochemistry known as "Biomarkers". The objective of this work was to determine the profiles of biomarkers (isoprene, hopanos and esteranos, etc) for two samples of crude oil belonging to the Austral Basin (CA) and two to the Gulf Basin (CG). For this purpose the crude samples were subjected to a separation of their aliphatic and aromatic fractions by silica gel column chromatography and the obtained extracts were analyzed separately by gas chromatography with mass detection studying the characteristic ions for the different compounds of interest. With the obtained data, different diagnostic ratios were calculated such as Pr/Fi, Pr/n-C17, Fi/n-C18, Ts/Tm, among others. The results showed how, from the study of biomarkers, differences can be established between the samples at the level of the same basin and even more if it is done between basins. GC samples were characterized by a more anoxic deposition environment, higher levels of crude biodegradation and a contribution of predominantly marine organic matter since the Pr/Fi ratio was close to one; in the case of the Pr/n-C17 and Fi/n-C18 ratios, the values were located above 0.5 and in these samples the presence of methylterans (S30) was detected. In conclusion, we can highlight that the study of biomarkers is a powerful tool to characterize a site from samples obtained from it, and that as a secondary aspect this allows to mark the existing differences.
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madurez térmica, ambiente de deposición, litologia, materia orgánica
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