Chemometric-enhanced geochemical characterisation of diamondoids in Niger Delta crude oils.

Autor: Faboya, Oluwabamise L., Liao, Zewen, Sonibare, Oluwadayo O., Ajani, Clement K., Faboya, Olubunmi O., Fomba, Khanneh W.
Předmět:
Zdroj: Arabian Journal of Geosciences; Dec2023, Vol. 16 Issue 12, p1-14, 14p
Abstrakt: Information on the possible sources, genetic relationship, and thermal maturity of crude oil samples collected from the northern and central depobelts of the Niger Delta Basin was extracted from diamondoid data using chemometric techniques for a better understanding of the petroleum system of the basin. The occurrence and distribution of diamondoids in crude oil samples were determined using gas chromatography-triple quadrupole mass spectrometry (GC–MS-MS). The absolute concentration of total diamondoids in the crude oils ranged from 684 to 1980 μg/g indicating a difference in the origin and/or thermal maturity of the crude oils. The oil samples from the northern depobelt have lower diamondoid concentrations (av. 772 µg/g) when compared with the oil samples from the central depobelt (av. 1465 µg/g). The results of the combined multivariate discriminant analysis on the concentrations of individual and total diamondoid, their homologues, concentrations, and isomers ratio classified the oils into two distinct groups, consistent with the associated depobelts. The diamondoid concentrations are generally constrained by the source parameters and/or sedimentary redox environment and are also closely related to the thermal maturity parameters in oils from the central depobelt. The observed chemometric grouping was supported by cross-plots of diamondoid isomerisation ratios such as DMAI-1 versus TMAI-1 and DMAI-2 versus TMAI-2 and concentration ratios including DMAs/TMAs versus TMAs/TeMAs and A/1-MA versus 1,3-DMA/1,3,5-TMA, which categorised the oils into their corresponding depobelts. Diamondoid isomerisation ratios (MAI, DMAI-2, DMAI-1, and TMAI-1) showed a general increase with increasing maturity of the crude oils from the central depobelt, suggesting their potential use as maturity indicators of crude oil in the basin. The results of this study indicate that the concentrations and ratios of diamondoid are useful for the geochemical characterisation of crude oil in the Niger Delta Basin. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index