The Resource Evaluation Department is responsible for evaluating and quantifying the oil and gas potential of the offshore areas around South Africa that can be developed through current exploration and production technology. This department is tasked with the identification of exploration opportunities in the area and for facilitating the entry of new explorers into the South African upstream industry. The department also works very closely with our operators in understanding the geology and prospectivity of areas under exploration. A major responsibility is the upkeep of a quantified and risked inventory of exploration opportunities. While technical team members are involved in projects in all basins around the coast, each also specialises in a particular area and/or field of interest.
Over the last few years, as interest in our offshore has increased and more acreage has been taken up, the department's focus has shifted towards in-depth geological and geophysical studies on a basin-wide scale, with a view to achieving a fuller understanding of the petroleum geology. This approach will allow us to assist and support our explorers in their own geological and geophysical work.
The Resource Evaluation Department is also responsible for the maintenance of the Agency's website as well as for the design and production of promotional material such as technical and exhibition posters, booklets and presentations, through the draughting section.
|Manager:||David van der Spuy||Geochemistry: Conventional Resources Evaluation Department Manager|
|Geologists:||Anthea Davids||South Coast basins and GIS|
|Sean Davids||East Coast basins and resource reporting|
|Jonathan Salomo||West Coast and geophysics|
|Chantell van Bloemenstein||Geologist West Coast|
|Thulisile Buthelezi||Geologist East and South Coasts|
|Draughting:||Shaheed Russon||Draughting and website|
|Zuko Ponco||Draughting, website and branding|
|Admin support:||Nazley Parker||Website, branding and promotional events|
South Africa's offshore basins can be divided into three distinct tectonostratigraphic zones. The western offshore comprises a broad passive margin basin related to the opening of the South Atlantic in the Early Cretaceous. This is known as the Orange Basin which is the largest offshore basin.
The eastern offshore is a narrow passive margin that was formed as a result of the breakup of Africa, Madagascar and Antarctica in the Jurassic.
Very limited deposition has occurred here and only the Durban and Zululand Basins contain an appreciable sedimentary section. The southern offshore region, known as the Outeniqua Basin, shows a history of strong strike slip movement during the Late Jurassic - Early Cretaceous breakup and separation of Gondwana. The Outeniqua Basin consists of a series of en echelon sub-basins (the Bredasdorp, Pletmos, Gamtoos and Algoa basins) each of which comprises a complex of rift half-graben overlain by variable thicknesses of drift sediments. The deepwater extensions of these basins (excluding the Algoa Basin) merge into the Southern Outeniqua Basin.
Subduction on the southwest margin of Gondwana in the Late Carboniferous - Early Permian led to the transformation of an old passive margin into a foreland basin (the Great Karoo Basin). Further convergence in the Permo-Triassic led to the development of the Cape Fold Belt which extends from Australia through Antarctica and South Africa to South America.
Following erosion and peneplanation there was a phase of widespread volcanism in the Early to Middle Jurassic in southern Africa, the Falklands and Antarctica. This provides the first evidence of the impending breakup of Gondwana .
At this time the Falkland Islands lay off the south or southeast coast of South Africa . Breakup started on the eastern margin of Africa with Madagascar and Antarctica beginning to move away in the Middle Jurassic. This initiated the formation of the Durban and Zululand basins.
During the Early to Mid-Cretaceous a complex series of microplates including the Falkland Plateau gradually moved west southwestwards past the southern coast of Africa creating important dextral shearing of the South African margin. This created the Outeniqua sub-basins as a series of oblique rift half-grabens which may be regarded as failed rifts, oldest in the east and youngest in the west.
The rift phase on the south coast ended in the Lower Valanginian , but was followed by at least three phases of inversion related to continued dextral shearing. This ended in the mid-Albian with the final separation of the Falkland Plateau from Africa. This transitional rift-drift phase was followed by development of a true passive margin. The Lower Valanginian drift-onset unconformity on the south coast is contemporaneous with the earliest oceanic crust in the South Atlantic.
The Orange Basin was initiated as a series of isolated and linked north-south trending grabens during the Lower Cretaceous. The drift-onset unconformity here is dated as Hauterivian, somewhat younger than in the Outeniqua Basin. A rift-drift transitional phase in the Orange Basin occurred until the Early Aptian. Later Cretaceous and Tertiary sedimentation took place in a marine passive margin setting.
All these basins are generally clastic in nature and have been explored over the last few decades for both oil and gas. Gas production has been ongoing since the middle 90's from shallow marine sandstones on the flanks of the Bredasdorp Basin, while oil has been produced from mid-Cretaceous aged basin floor fan deposits in the central basin. Interest in exploration has recently increased dramatically and large areas of the South African offshore, including very deep water acreage, are currently being explored.