Regional tectonostra tigraphic architecture of the Owambo basin and reassessment of its hydrocarbon potential
Loading...
Date
2019
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Namibia
Abstract
The Owambo Basin is one of Namibia’s two main onshore basins and is a significant target area for hydrocarbon exploration. Although exploration activities in the Owambo Basin commenced in the 1950s spanning more than 58 years, no commercial discovery of hydrocarbons has been made in this basin to date. Numerous hydrocarbon occurrences have been reported throughout the basin, and available geophysical data suggests the presence of both structural and stratigraphic signatures that may be associated with petroleum traps. However, the lack of critical understanding of the tectonic and stratigraphic framework in the context of the petroleum system has made it difficult to apply a systematic approach during previous hydrocarbon exploration activities in basin. Analysis and interpretation of recently reprocessed vintage 2D seismic lines makes it possible to characterize the tectonostratigraphic domain of the Owambo basin, therefore allowing proper understanding of the petroleum system’s evolution through time and hence the application of a systematic approach in hydrocarbon exploration. Hydrocarbon trap formation is influenced by three main phases of deformations during the evolution of the Owambo Basin: (1) Rifting phase – rifting of the Rodinia continent that resulted in north-northwest-trending normal faulting in the metamorphic Precambrian basement; (2) Collision phase – Convergence and collision of the Kalahari Congo, and South America cratons that resulted in the Damara Orogeny; (3) Rift Phase - extensional faulting that resulted in the opening of the South Atlantic.
The tectonic events that were accompanied by the deformation in the Owambo basin led to the present tectonostratigraphic architecture of the basin. Three prominent sequences were deposited and are recognized on the seismic data: the Damara (Nosib and Otavi and Mulden groups), Karoo and Kalahari sequences. Potential hydrocarbon significance has been recognized within these sequences such as source rocks (Otavi group – post-glacial deposition carbonates within the Abenab Subgroup and post glacial deposits and restricted intra-platform carbonates of the Tsumeb subgroup; Mulden group – black shales; Karoo supergroup – shales). Reservoirs are associated to the Otavi group carbonates, the Mulden group sandstones as well as the syn-rift sands in the deeper sections within the Nosib group. Migration pathways and trapping structures related to the tectonic events as well as stratigraphic mechanisms have been recognized on the seismic data. Several leads have been mapped from magnetics and gravity data which may be potential trapping structures for hydrocarbon accumulations
Description
A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science in Petroleum Geology
Keywords
Hydrocarbon, Owambo basin, Tectonostra tigraphic architecture