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Petroleum System and Exploration Risk Assessment in Deep and Ultra-Deep Waters of Offshore Namibia: Application of High Resolution Geochemistry Technology (HRGT), Satellite Oil Slick Detection and 3d Compositional Petroleum System Modeling

Marcio R. Mello, Nilo C. Azambuja Filho, Andre A. Bender, Frederico R. Mello, Antonio Catto, Sergio Contreras, and Previous HitAlexandreTop Coelho
HRT Petroleum, Rio de Janeiro, Brazil

The high cost of offshore deep and ultra-deep water exploration has made the use of an integrated petroleum system approach a well-accepted risk assessment methodology in offshore frontier basins around the world.

Natural oil slicks, high resolution geochemical analysis and 3D petroleum system modeling have historically provided invaluable information to oil explorers in frontier basins. Furthermore, they indicate the presence of active generative hydrocarbon source rocks without which there can be no hydrocarbon accumulations. Also, they provide clues regarding hydrocarbon origin, type, age and thermal evolution of their putative source rocks. More recently they allow the quantification of oil mixing and extension of oil cracking to gas.

In offshore Namibia the acquisition and interpretation of Radarsat-1 satellite images shows the presence of oil slicks associated with transform fault zones that occur close to the Kudu gas field, Offshore South Namibia. Such data suggest that offshore Namibia can be oil prone in an area considered before as gas prone, therefore reducing exploration risk for liquids in the region. Also, high resolution biomarkers, diamondoids, CSIA-B and CSIA-D data, from the Kudu condensates, not only agree with the oil slick data, but also suggested an origin composed by a mixture of oils from at least three distinct Petroleum Systems: highly cracked condensates (constitutes more than 80% of the sample) possibly derived from Jurassic, Paleozoic or older source rock; and a black oil, at peak stage of generation, sourced from a Mesozoic marine carbonate source rock.

The 3D petroleum system results when integrated with structure maps generated from 2D PSDM seismic data indicate the presence of giant to super giant light oil condensate accumulations in the study area.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery