Seismic study of the Orange Basin, offshore Namibia and its relecance for Hydrocarbon system analysis
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Date
2014
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Publisher
University of Namibia
Abstract
The Orange Basin is located on the South-west African continental margin adjacent to the boundary between South Africa and Namibia. The interpretation of the existing 2D seismic and well data using Petrel software provided a structural and stratigraphic analysis of the Orange Basin. The objective of the study is to identify and characterize the regional petroleum systems and reveal the sequence of depositional events and structural developments which occurred in the Basin. Four major tectonostratigraphic units separated by three major unconformities were identified as Pre-rift (Carboniferous to early Permian), Syn-rift (late Jurassic to Hauveterivian), Early drift (Barremian to Cenomanian) and Late Cretaceous (Turonian to recent). The stratigraphic analysis of seismic data revealed a number of depositional features such as clinoforms, channels and palaeo highs which were used to depict different depositional environments in the Basin.
Onshore analogues such as the aeolian/lava deposits of the Huab Basin, Kalkrand Formation, Ganigobis Shale Member, Whitehill Formation and Orange River Mouth deposits provides an insight into the depositional history of the Orange Basin There is a complete petroleum system in Orange Basin which consists of a lacustrine Synrift section, succeeded by Barremian to early Aptian and Cenomanian-Turonian source rocks. Three potential reservoir intervals have been identified, one in the lacustrine Synrift section, the second in aeolian/lava deposits of the Barremian section and the youngest one in Tertiary sandstones. The Orange Basin exhibits both, stratigraphic and structural traps. Deep marine Cretaceous to Tertiary shales are predicted to act as seals in the Pre-rift, Syn-rift and Drift sequences. Less faulted Cretaceous and Tertiary shales reveal a good quality seal. Faulting augments the migration pathway of hydrocarbons in the Basin. The southern part of the Basin is considered to be more prospective because it attains thick sediment accumulations which augment source rock maturity and contains most of the stratigraphic and structural closures in the Basin.
Description
A thesis submitted in fulfilment of the requirement for the Degree of Master of Science in Geology
Keywords
Orange basin, Hydrocarbon system