Geochemical Assessment of Naphthalene Homologues (C₀–C₄) in Niger Delta Crude Oils and Their Mixtures

This study investigates the distribution patterns and diagnostic utility of C₀–C₄ naphthalene homologues in two Niger Delta crude oils and their binary blends, using Gas Chromatography–Mass Spectrometry (GC-MS). Six samples were analyzed: two unblended oils (Samples A and F) and four volumetric blends (Samples B–E). Results revealed that Sample A exhibited a moderate aromatic profile, dominated by dimethylnaphthalene (33.68%) and trimethylnaphthalene (35.13%), while Sample F showed a more alkylated profile with trimethylnaphthalene (35.70%) and a higher tetramethylnaphthalene content (16.36%), indicative of greater thermal maturity. Blending these oils produced varying aromatic signatures, with Sample C (60:40 blend) displaying an unusual enrichment in tetramethylnaphthalene (30.93%), suggesting non-linear behavior during mixing. Biomarker ratios, including M/P, DM/P, aromaticity index (AI), and C₄/C₀, provided insight into maturity and source input, with Sample F consistently showing the highest AI (14.20) and C₄/C₀ (2.43) values. The findings underscore the diagnostic value of naphthalene homologues in assessing source characteristics, thermal maturity, and compositional alterations in mixed petroleum systems, and support their use in oil correlation, refining strategy, and environmental forensics within the Niger Delta region.