Fossil fuel energy resources of Ethiopia

Abstract

Inter-Trappean coal and oil shale-bearing sediments are widely distributed in the Delbi-Moye, Lalo-Sapo, Yayu, Sola, Chida, Chilga, Mush Valley, Wuchale and Nejo Basins. Coal and oil shale-bearing sediments were deposited in fluvio-lacustrine and paludal depositional environments. The Ethiopian oil shales reach a maximum thickness of 60 m, and contain mixtures of algal, herbaceous and higher plant taxa. Type II and I kerogen dominated the studied oil shales. Pyrolysis data revealed that the Ethiopian oil shales are good to excellent source rocks types up to 34.5 % TOC values and up to 130 HC g/kg S₂. A total of about 653,000,000 - 1,000,000,000 tones of oil shale reserve registered in the country. The coal and coal-bearing sediments attain a maximum thickness of 4 m and 278 m, respectively. Proximate analysis and calorific value data show that the Ethiopian coals fall under the soft coal series (lignite to bituminous coal), and genetically classified under humic, sapropelic and mixed coals. A total of about 297,000,000 tones of coal reserve registered in the country. The Permian Bokh Shale, Oxfordian-Bathonian Hamanlei Limestones, Kimmeridgian Urandab Shale are potential organic-rich source rocks. The Permian Calub sandstone, Triassic-Liassic Adigrat sandstone and Oxfordian-Bathonian Hamanlei carbonates are reservoirs in the Ogaden and Blue Nile Basins. 2.7 TCF (76 x 10⁹ m³) sulfur-free gas and 1817 x 10⁶ tons condensate reserves are estimated in the Calub field. About 1.3 TCF gas deposit is also encountered in Hilala field. The Blue Nile Basin is one of the potential basins for hydrocarbon exploration. The presence of mature source rocks and oil seepage in the Blue Nile Basin is clue for the generation of hydrocarbon in the basin. The Gambella Basin is the southern extension of the petroliferous Sudan Interior Basins, and could be one of the potential basins for oil and gas deposits.

KEY WORDS: Coal, Energy, Ethiopia, Fossil fuel, Oil shale, Oil and gas

Bull. Chem. Soc. Ethiop. 2008, 22(1), 67-84.