Biomarker-Based Geochemical Characterization and Oil–Oil Correlation of Oredo (Nigeria) and Agadem (Niger Republic) Crude Oils”
DOI:
https://doi.org/10.33003/Keywords:
Biomarkers, Crude oil, GC–MS, Oil–oil correlationAbstract
This study evaluated the geochemical characteristics and possible genetic relationship between Agadem crude oils from the Niger Republic and Oredo crude oils from the Niger Delta, Nigeria, based on thermal maturity, organic matter source characteristics, and depositional conditions. Five crude oil samples were investigated, comprising two samples collected from different oil wells in the Agadem oil field, Niger Republic, and three samples obtained from different oil wells in the Oredo oil field, Niger Delta, Nigeria. The samples were collected in clean glass bottles and analysed using gas chromatography–mass spectrometry (GC–MS) to characterise their hydrocarbon and biomarker compositions. The identified biomarkers included n-alkanes, hopanes, steranes, phenanthrenes, and triaromatic steroids. Molecular maturity and depositional-environment characteristics were assessed using carbon preference index (CPI), odd–even predominance (OEP), diagnostic equivalent weight (DEW), and pristane/phytane (Pr/Ph) ratios. The CPI values obtained were 1.0049 for Agadem1, 0.9524 for Agadem2, 0.9423 for Oredo5, 0.9477 for Oredo8, and 0.9482 for Oredo11, indicating that the oils generally exhibit CPI values close to unity and have undergone substantial thermal alteration. The Pr/Ph ratios ranged from 1.15 in Agadem1 to 0.18 in Oredo5, indicating variations in the redox conditions of the depositional environments. DEW and OEP values also showed variations among the samples, with DEW ranging from 0.94 to 2.34 and OEP from 0.83 to 1.02. The occurrence and distribution of the investigated biomarkers reveal appreciable similarities among the Agadem and Oredo crude oils, suggesting comparable source characteristics and depositional conditions.
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Copyright (c) 2026 Nasiru Abdullahi Sani, Bukar Wakil, Lawan Khalid Khalid, Muhammad, Zuru
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