Integrated Hydrocarbon Exploration of the Owambo Basin, Onshore Northern Namibia: Implications for a Modern Frontier Basin
Hydrocarbon potential of ONSHORE Namibian basins has been bypassed during the recent rush to explore offshore areas. Recent analysis of the Owambo Basin in Northern Namibia has identified significant onshore potential. Subsurface data limitations, however, caused by extremely limited drilling activity (one reservoir test in a Texas-sized basin) have required critical reliance on potential field geophysics, 2D seismic, and basin periphery outcrop studies, to predict hydrocarbon occurrence and drilling opportunities. Interpretations were made of approximately 2000 line-km of vintage 2D seismic, a recent high-spatial-resolution magnetic/gravity survey, satellite imagery, and older regional potential field data set. The integration of these data sets allowed us to identify the structural style of the basin, and implications for trap development. The integrated effort confirmed three primary phases of deformation and hydrocarbon trap formation in the region. Rift phase (∼900 Ma): Rifting of the Rodinia continent and the development of NNW-trending horsts and grabens in the metamorphic basement. Some deep grabens may be structural traps. Collision phase (∼580-500 Ma): Damara Orogeny contractional tectonics resulted from complex collision between the Kalahari and Congo cratons. E/W shortening (580-550 Ma) formed N/S trending Kaoko Belt structures overprinted by N/S shortening and E/W trending structures in the Damara Belt (550-500 Ma). NE trending (dextral) and NW trending (sinistral) wrench zones developed in the basement rocks and reactivated some older trends. Some contractional faults and folds may serve as structural traps. Rift Phase (∼132 Ma-present): Initiation of South Atlantic rifting along NNW-trending faults. Extension caused sinistral wrench motion along prominent NNE-trending basement zones, forming local wrench-related structural traps. These late folds are prominent structural features. These three structural trap styles have been further documented by basin margin outcrop studies of source rocks, reservoir facies, and structural features including fractures, faulting, and mesoscale folding. From our basin analysis, further constrained by thermal maturity studies, we have attempted to minimize exploration risk in a modern frontier basin. Future acquisition of 2D and 3D seismic should further minimize exploration risk in an unexplored modern frontier basin with tremendous potential for world-class reserves.
AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014