26 Abyssinia Journal of Science and Technology Vol. 3, No. 1, 2018, 13-19 Abyss. J. Eng. Comput. Vol. 1, No. 1, 2021, 26-30 © 2021 Kombolcha Institute of Technology, Wollo University Characterization of Petroleum Oil Seepage Using Modern Spectroscopic Techniques: In Case of Were Ilu-Legeheda, Ethiopia a *Sisay Awoke & b Dessalegn Gezahegn a Department of Chemistry, Wollo University, Ethiopia. b Department of Geology, Wollo University, Ethiopia. ABSTRACT The sedimentary regions of Ethiopia cover a significant portion of the country and comprise five distinct sedimentary basins; namely, Ogaden, Abay, Mekele, Gambela and Southern Rift Basins. The Blue Nile basin is a North West-South East trending branch of the Ogaden intra continental rift basin. The presence of an oil seepage at Were Ilu and Legeheda points to the presence of an active petroleum system. The main aim of this study was to characterize the chemical nature of the seepage oil leaked out from the hard basalt rock of Mechela river. Seepage oil samples were analyzed using ultraviolet (UV), infrared (IR), and nuclear magnetic resonance (NMR) spectroscopic methods. All the chemical analysis obtained from UV, IR and NMR showed that high contents of saturated hydrocarbons were found in the petroleum collected from the stated areas, which is the principal criterion for identification of pure petroleum oil. Key words: Were Ilu; legeheda; petroleum; oil seepage; abay basin INTRODUCTION Ethiopia has five distinct sedimentary basins that cover a significant portion of the country, namely, Ogaden, Abay (Blue Nile), Mekele, Gambela and Southern Rift Basins [1] [2]. The development of most of these basins is related to the extensional tectonic events that have taken place intermittently since the Late Paleozoic and continued up to Tertiary. The former three basins are presumed to be intra continental rift basins formed as a result of extensional stresses induced by the break-up of Gondwana land in Upper Paleozoic [3], [4]. The Abay Basin covers an area of approximately 63,000km2 in the central northwestern plateau of Ethiopia. It consists of Paleozoic and Mesozoic sedimentary succession exceeding 2000 m in thickness [5], [6]. As the basin shares the same geotectonic origin as the Ogaden Basin, the different strati graphic units in the Abay are nearly similar to some of the units encountered in the Ogaden wells [7]-[9]. Beds of marl, shale and mudstone inter bedded with carbonates in the lower part of the thick limestone unit (Antalo) and upper part of the Amaba Aradom Formation (the Upper Sandstone) are potential source rocks in the Abay Basin [1], [2]. A geochemical analysis of an oil seepage from Were-Ilu locality in the northeastern margin of the basin suggests the presence of mature oil source rock of marine origin; possibly marine shale that has generated oil [10]. Oil generated from the Jurassic source rocks in the Abay Basin might be trapped by a combination of stratigraphic and structural traps [4], [8]. Crude oil is naturally occurring material that comprises various hydrocarbons including paraffins, olefins, naphthenes, aromatic and heteroatom containing compounds as well as organometallic compounds of nickel and vanadium (porphyrins) [11]. Crude oil, shale oil, and sand oil are all sources of petroleum and comprise masses of compounds whose components can be grouped into four essential instructions known as SARA: Saturated hydrocarbons (alkanes and cycloparaffins), Aromatics (with alkyl side chains), Resins (aggregates with a large number of building blocks which includes sulfoxides, amides, thiophenes, pyridines, quinolines, and carbazoles), and Asphaltenes (aggregates of prolonged polyaromatics, naphthenic acids, sulfides, polyhydric phenols, fatty acids, and metalloporphyrins) [12]. However, the presence of some compounds like polyaromatics, that are toxic or carcinogenic, sulfur and heavy metals in high concentrations, which have environmental implications and cause huge Abyssinia Journal of Engineering & Computing *Corresponding author: sisay.awoke@wu.edu.et