Study of the Crude oil Properties of Oily seepages found in South Eastern Nigeria.

Abstract

ASTM D-270 method was applied in obtaining well-head crude oil samples from Awoba 8T (Rivers State), Odidi 23L, and Odidi 46S (Delta State), Eremor 1L (Bayelsa State) and Oily Seepage samples from Ugwueme (Enugu State) and Anam (Anambra State). The0API gravity value of all the samples were 16.190 and 21.470 for Ugwueme seepage and Eremorcrude respectively, 22.470 for Odidi 46s crudeand 44.700, 43.840 and 34.760 for Anam seepage, Awoba 8t and Odidi 23L crudesrespectively, indicating heavy, medium and light crude oils respectively. All the well-head crudes and oily seepage samples studied in this work are onshore samples except Odidi 46s which is an offshore crude sample. The samples were subjected to liquid-liquid extraction using a mixture of n-hexane and dichloromethane (3:1). The extracted fractions were analyzed using GC-FID. The result of the analyses gave polycyclic aromatic hydrocarbons (PAHs) concentrations (mg/kg) of 7106.43 for Awoba 8T crude, 6767.41 for Odidi 23L crude, 5771.20 for Odidi 46S crude, 5191.21 for Eremor crude, 4908.04 for Ugwueme Seepage and 6983.16 for Anam seepage. The predominance of low molecular weight PAHs (LMWPs) over the high molecular weight PAHs (HMWPs) indicate that both the crude oil samples and the oily seepage samples were of Petrogenic Source. However, various ratios were obtained to identify the possible source of PAHs in the crude oil and seepage samples. Mixed sources of pyrogenic and petrogenic PAHs were also discovered with evidence of „pyrolytic‟ input which may suggest some geothermal-mediated processes.