AAPG Annual Convention and Exhibition

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The Deep Water Plays Offshore East Africa: Understanding Their Extent and Potential From Integrated Regional Seismic Interpretation

Abstract

The offshore areas of Tanzania and Mozambique have proven a rich exploration province over the last 5 year with over 130 tcf of gas discovered to date, as well as an emerging liquids potential. However, fundamental questions remain regarding the structural history and the impact that has on reservoir distribution and source maturation. Integrated interpretation of regional, deep seismic data from Kenya in the north to Madagascar in the south, including the most recent data in the Comoros Islands area, has allowed for the development of a regional play based framework to address these questions. Basement architecture and tectonic history began with the development of the Karoo basin system and was followed by continental extension and break-up in the Jurassic. Multiple re-configurations of the Indian Ocean plates continued throughout the Cretaceous including the development of the Davies Fracture Zone. Development of the Ruvuma and Rufiji Delta systems in the Cenozoic was driven and enhanced by uplift of the African Craton. These delta systems distributed sediment thicknesses of over 4km far out into the deepwater Somali Basin; clear evidence shows robust modern channels carrying terrestrial plant material as far as 500km offshore. The interplay of sediment supply and structural development of the delta systems including gravity driven deformation and the development of the Kerimbas Graben system will be discussed. More recent emplacement of the Comoros Volcanic province in the Late Tertiary has redistributed recent sediments and deformed existing sediments with the potential for formation of trapping mechanisms and enhanced heat-flows. The new seismic data in this area demonstrates the potential extensions of the proven deep water plays in Tanzania and Mozambique further out in the basin.