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The Petroleum Systems (!) of Muglad Basin, Sudan: Evolution, Growth and Entrapment

K.B. Trivedi
ONGC, India
kbtrivedi1234@yahoo.com

The Muglad Basin of southern Sudan owes its origin to rifting and drifting of the African Plate from Gondwanaland, which was synchronous with intra-continental rifting within western and central Africa, during Late Jurassic-Early Cretaceous times. The basin evolved as a consequence of the Sudanese rift, which is a main component of western and central African rift related system. Accommodation created by these rifts resulted in the deposition of continental-fluvial sediments of Cretaceous and Tertiary age, which in the deeper part of basin are estimated to be 15–20 km thick. The application of sequence stratigraphic concepts to understand the facies distribution pattern indicated that the fluvial system was draining to the marine or lacustrine realm. Changes in lake and sea levels and the graded profile of the rivers, affected the channel type, sediments and environment. Hence the sediments can be partitioned into predictable packages as a function of base-level position. These concepts have helped in identifying key surfaces and allocyclic control upon stratal architecture. Cycles up to fourth-orders are being identified and these have helped in understanding and better defining the main source rock (Abugabra Formation) and reservoir (Bentiu Formation). In the acreage under study, 80% of hydrocarbon entrapment is structurally controlled. The major elements are listric normal faults and entrapment is controlled by fault throw, type and juxtaposition of lithology across the fault. Studies of the structural evolution have helped in understanding the plays in the Muglad Basin and has added value for the exploration in hitherto enigmatic and lesser explored basin.

 

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain

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