--> Abstract: Tectonic Control from Hydrocarbon Accumulation in the Intra-Continental Albertine Graben of the East African Rift System, by Dozith Abeinomugisha and Robert Kasande; #90082 (2008)

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Tectonic Control from Hydrocarbon Accumulation in the Intra-Continental Albertine Graben of the East African Rift System

Dozith Abeinomugisha and Robert Kasande
Petroleum Exploration and Production, Ministry of Energy and Mineral Development, Kampala, Uganda

The Albertine Graben forms the Northern termination of the Western arm of the East African Rift System (EARS). It stretches from the border between Uganda and Sudan in the north to Lake Edward in the south. It is a Tertiary intra continental rift that developed on the Precambrian orogenic belt of the African Craton. Rifting was initiated during the late Oligocene or Early Miocene.

The tectonic evolution of the Graben is little understood. It does not fit well with traditional models of rifted continental basins, defined by discrete basin bounding faults opposed by a low gradient flexural margin especially over Lake Albert. Almost similar amounts of displacement on the eastern border faults and western border fault produce close to a full graben structure in contrast to half graben structures. The available geological and geophysical data indicate that the Graben has gone through extension and compression episodes resulting into a variety of structures. Deformation and prevalence of flower structures in the shallow sedimentary sections in some basins in the graben indicate that the neo-tectonic processes are compressional.

The Albertine Graben has undergone substantial tectonic movements and thick sediments (6km) have been deposited in fluvial - deltaic and lacustrine environments. It is this sedimentary section that has demonstrated a working petroleum system in the graben. Although hydrocarbon production has not yet started, its hydrocarbon generating potential is no longer in question. To date, twelve successful exploration and appraisal wells have been drilled in the graben. All the wells have been drilled on structural highs which are Positive flower structures and have encountered hydrocarbon shows. This demonstrates the importance of the compression episodes in trap formation in the Albertine Graben.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery