Hydrocarbon prospectivity of the South Atlantic Orange Basin

The Orange Basin is situated on Southwestern Africa's Atlantic shore, offshore of South Africa and Namibia. Seismic with well-log data, geochemical interpretations, and structural and stratigraphic analyses of the Orange Basin are re-evaluated and presented here. This paper aims to review the regional hydrocarbon potential from its hydrocarbon system and structural development. Tectonostratigraphic events best explain the Orange Basin's source rocks. Three observable source-rock intervals exist within the Orange Basin, and the Cretaceous source rocks are considered fair quality. The limited datasets show that source-rock thickness and quality are increasing basin ward; the study area contains clastic reservoirs with diagenetically reduced porosity and permeability. The Albian–Cenomanian gas reservoirs at Ibhubesi exemplify this. Cenomanian mudstones dominate seal rocks at the Ibhubesi gas field; overall, Cretaceous–Cenozoic marine mudstones provide an extensive sealing mechanism in the Orange Basin. Reservoir rocks are of poor quality and composed of thin, relatively tight heterogeneous sandstones. Generally, the Orange Basin play system comprises Oxfordian to Recent synrift and post-rift turbiditic sandstones as the primary reservoir rocks with varying stratigraphic and structural configurations providing trapping mechanisms. Besides providing an overall understanding of the distribution of petroleum system elements in the Orange Basin, this review also highlights the multifaceted approach suitable for exploration in the frontier South African margin. This was achieved by comparing and discussing regions from around the globe.