Petroleum habitats of the Atlantic margin of South Africa

Petroleum system logic is applied along South Africa’s western margin to improve understanding of the observed petroleum habitats and the evaluation of the area’s potential for hosting profitable hydrocarbons. Three major groups of source rocks are identified and, consequently, the source-centred petroleum systems and complementary exploration plays form three major groups: (1) those sourced from syn-rift, Upper Jurassic-Neocomian, generally lacustrine source rock pods; (2) those sourced from Barremian-lower Aptian, generally marine, transitional succession source pods; (3) those possibly sourced from the Cenomanian-Turonian boundary, generally marine, drift succession source pods. These groups are further subdivided into individual petroleum systems in terms of specific individual source rocks, level of certainty, type of hydrocarbon and extent; and into individual exploration plays in terms of stratigraphic level of the reservoir and trap type. The geographic location of the known and actively generating oil and gas pods, whether in the syn-rift or transitional successions, is the major control on the observed distribution of petroleum habitats. The predominantly gas-bearing areas coincide with the main depocentre of the Orange Basin where the lower Aptian source rocks are in the gas window. More oil-bearing areas are predicted outside the depocentre, in deeper water, where the lower Aptian source rocks may become more oil prone and are possibly located in the oil window. These possibly more oil-prone areas coincide with major syn-sedimentary structures and hypothetical deepwater turbidite sandstones. They represent a new frontier for future exploration.