Carbon-Dioxide (CO2) Geological Storage Atlas

Carbon capture and storage (CCS) is one of the recognised mitigation measures for the lowering of greenhouse-gas emissions. Assessment of the potential for CCS in South Africa requires a detailed investigation into locating and characterising potential carbon geological-storage sites. This eighteen-month investigation will start imminently and is sponsored by Sasol, Eskom, PetroSA, Anglo American plc and the South African National Energy Research Institute (SANERI). The CGS, along with the Petroleum Agency of South Africa, has been appointed to compile and publish the resulting CO2 Geological Storage Atlas. This project by the CGS and aforementioned collaborators was announced by the Honourable Minister of Minerals and Energy, Ms Buyelwa Sonjica, at the recently held annual meeting of the International Carbon-Sequestration Leadership Forum in Cape Town.

The atlas, which will be completed by December 2009, will report methodologies and the results of the storage-potential evaluations for all the onshore and offshore basins of South Africa. It will provide ranking of the basins according to risk and tectonic settings, and will discuss storage options. It will also contain illustrated maps showing the geographic distribution of the basins and relevant geological and seismic profiles to support salient findings. Additional data, such as the estimated CO2 storage capacities of basins, the main emission sources, location of industrial complexes and transport issues will also be included.

The production of this atlas constitutes:

* Phase 1: The CO2-storage prospectivity assessment, which will most likely lead to further research, the development of a pilot project and potentially large-scale pilot CO2 storage ventures in South Africa. Provided that potentially suitable deep-storage sites are identified, the following multiphase approach will have to be adopted:

* Phase 2: Carry out confirmatory seismic surveys to investigate likely deep structures inferred from Phase 1 investigations, and synthesise all data with a view to planning the next step of exploration activities (see Phase 3);

* Phase 3: Verify by means of deep drilling the seismic-survey findings of Phase 2, and conduct geotechnical testing on recovered drill core and down-the-hole geophysical soundings and tests; document and synthesise all data with a view to identifying the most promising storage reservoirs;

* Phase 4: Use all available information to model the reservoir capacities of the most suitable reservoirs selected in Phase 3, model CO2 injectivity (how many wells, and at what spacing and depth) and start with small-scale site tests and monitoring;

* Phase 5: If Phase 4 shows promising results, develop an integrated national strategy linking capture, transport and storage options.

Worldwide, storage reservoirs are commonly associated with the sedimentary basins in which oil and gas occur. South Africa unfortunately lacks natural world-class storage reservoirs, but the onshore central basin of the Karoo Supergroup with its substantial sedimentary formations may offer storage opportunities. Offshore sedimentary rocks along the coastline also have some potential for storage.

The CGS is also a cooperative member for a project proposal to the European Commission, which will aim to align the CCS knowledge of South Africa, Brazil, India, Mexico and Colombia with that of Europe. This will include harmonisation of applied methodologies between the listed countries and capacity building in the emerging economies. The initial proposal has passed the first phase of submission and a full proposal will be submitted to the 7th Framework of the European Commission at the end of May 2008.

[via]