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Giants in the Rift: Petroleum System Elements of Rift-Basin Hosted Giant Fields

Abstract

Ancient rift basins are found on every continent of the world and account for over 30% of giant fields discovered with over 600,000 MMBOE of estimated recoverable hydrocarbons worldwide. Due to technological advances in deepwater drilling, the petroleum industry has begun to explore beneath salt canopies and penetrate deeper continental margin strata. Recently, new rift plays have been discovered, with the most recent drilling activity focused along the Atlantic margins of Africa and South America. Due to the complex geometries of rift basins, one of the biggest challenges has been understanding how the various components combine to create a working petroleum system and viable play. This is a difficult task because of the dearth of information available from new exploration areas. This study focuses on known rift basins that host giant oil and gas fields and the distribution of different petroleum system elements within them. We focus on the geographic distribution of the basins and their temporal evolution – for example, when and where different rifting events occurred and the different petroleum systems elements were deposited through geologic time. Through the construction of a database of petroliferous rift basins, unique trends in reservoir and seal type as well as the timing of different ancient rifts show that there are certain elements that are unique to identifying successful rift basin petroleum systems. Such successful plays usually have deltaic/near-marine clastic reservoirs, evaporite seals, and a Mesozoic timing for rift initiation. By specifically focusing on rift basins that host giant fields, this study highlights only the most petroliferous rift basins in the world and the petroleum system elements that made them successful. By studying these fields, this study determines keys to success for future exploration success in rift basin plays.