Investigation of CO2 storage potential of the Durban basin in South Africa

Abstract

Abstract The mitigation of anthropogenic carbon dioxide (CO2) emissions through technologies such as Carbon Capture and Storage (CCS) has been internationally identified as one of the major technical approaches that can be used to combat global climate change in fossil fuel dominated countries. The South African Centre of Carbon Capture and Storage (SACCCS) was established in 2009 to investigate the potential for CCS in the country. Results from a country-scale assessment of CO2 storage potential suggest that South Africa has a theoretical storage capacity of ∼150 Gt, of which 98% occurs offshore in Mesozoic sedimentary basins preserved on the submerged continental shelf. This paper will discuss the progress associated with the ongoing investigation of CO2 storage potential in the 10 000 km2, offshore Durban basin on the east coast of South Africa. With the use of existing data and information the geological development and CO2 storage suitability of the offshore Durban basin is assessed. The basin is structurally complex, hosting a number of horst and graben structures but is dominated by the Tugela Cone, a Tertiary-age, deep-water fan complex that is located seaward of the continental shelf. Although not formally given formation status, sequence stratigraphic correlation can be applied to the Jurassic to Cretaceous succession, separating it into four formations based upon onshore sequences in the Zululand basin to the north. Formations are namely; Syn-Rift, Makatini, Mzinene, St Lucia. Cenozoic sediments range in thickness from ∼1300 m to ∼2000 m comprising a variety of lithologies that cap the sequence. Re-analysis of existing legacy 2D seismic and exploration borehole data has been undertaken in the context of CCS to assess the CO2 prospectivity, geological evolution, and depositional architecture of this portion of the South African continental shelf.