Rift basins of interior Sudan: petroleum exploration and discovery

Abstract

The sedimentary basins of interior Sudan are characterized by thick nonmarine clastic sequences of Jurassic(?)-Cretaceous and Tertiary age. Over 13 716m of sediment was deposited in the deepest trough and extensive basinal areas are underlain by more than 6096m of sedimentary rocks. The depositional sequences include thick lacustrine shales and claystones, floodplain claystones, and lacustrine, fluvial, and alluvial sandstones and conglomerates. Those lacustrine claystones deposited in a suboxic environment provide good oil-prone source rocks. Reservoir sandstones have been found in a wide variety of nonmarine sandstone facies. The extensional tectonism that formed these basins began in the Jurassic(?)-Early Cretaceous. Movement along major fault trends continued intermittently into the Miocene. This deformation resulted in a complex structural history that led to the formation of several deep fault-bounded troughs, major interbasinal highs, and complex basin flanks. This tectonism has created a wide variety of structures, many of which have become effective hydrocarbon traps. During the past 8 years, several important oil discoveries have been made. Significant accumulations have been delineated in the Heglig and Unity areas, where estimated recoverable reserves are 250-300 million bbl of oil. -from Author