Outcrop Geology of Onshore Kwanza Basin, Angola

Brandao, Mario, Carlos Figueiredo, Murthy Inkollu, Sonangol, Luanda, Angola

Exploration efforts are invigorated during this year after 30 years of lull in Kwanza basin onshore. This classic region is in the salt basin of West Africa that covers nearly 25,000 sq.km area. Within the basin, the surface outcrops represent the entire stratigraphic column that ranges from Early Cretaceous to Recent. During the early exploration phase several reservoirs are found in Aptian, Albian and Miocene age group. These are spread in the north portion of the onshore basin. The current objective is to present outcrop study of the key reservoirs in Aptian and Albian.

Classic outcrop sections of prominent reservoirs in Aptian and Albian are illustrated to show the various lithofacies. Clastic, Shaly and Carbonate facies are discernible in Aptian Binga formation. The different facies thickness is variable from few millimeters to several meters that represents lagoonal to near shore deposition. The Albian is known under sever­al facies. It varies from anhydritic carbonate (Tuenza), lagoonal (Catumbela), sub-tidal (Oölitic Carbonate) and distal depositional (Quissande) facies that vary from few to hun­dreds of meters in thickness.

The petrographic, biostratigraphic and log criteria for Aptian and Albian section further enhance the knowledge on the key reservoir section.

To sum up, the study results of the outcrop section for the key reservoirs in Aptian and Albian will be an important understanding to the strata of the subsurface in exploration work.