Trace Metals Geochemistry of Crude Oils from Umutu/Bomu Fields in South West Niger Delta Nigeria

Seven crude oil samples were collected from two oil fields south Niger Delta Nigeria which had not been previously characterized with trace metals and analyzed using Atomic absorption spectroscopy. The concentration of Fe ranges from 0.38 to 31.53 ppm, Zn ranges from 0.65 to 80.69 ppm, Pb ranges from 1.39 to 25.00 ppm, Cu ranges from 0.26 to 6.43 ppm, Cr ranges 0.60 to 2.94ppm, Cd ranges from 0.09 to 0.33ppm, Ni ranges from 0.63 to 8.93 ppm, Mn ranges from 0.21 to 2.25 ppm, V ranges 0.30 to 0.72 ppm, Co ranges from 0.38 to 0.62 ppm. The divergent ratios calculated from the concentration of the trace metals include V/Ni, V/(V+Ni), Co/ Ni and Fe/V, which varies between 0.36 and 0.67 for V/Ni, between 0.07 and 0.40 for V/(V+Ni), between 0.06 and 0.99 for Co/ Ni and finally between 1.26 and 43.78 for Fe/V. Two genetic groups of crude oils are identified and the organic matter originated from mixed sources deposited in an oxic environment.