Salient Features of Giant Fields in Marine Carbonates in the World

Abstract

Marine carbonates are one of the main domains for discovery of giant fields. With an update database, this study aims at documenting the main features of giant fields discovered in marine carbonate reservoirs. As end of 2013, 340 giants, had been discovered in the marine carbonates in 37 basins in the world. They contain proved plus probable (2P) reserves of 1524.8 billion barrels of oil equivalent. The top eight basins with rich petroleum reserves are the Arabian, Zagros, North Caspian, Amu-Darya, Gulf of Mexico, Sirte, Volga-Ural, and Permian basins. Together they host 93.5% of the total 2P reserves. The structural trap is the dominant type for marine carbonate giants and this type of trap hosts 84.2% of the total. It is followed by combined (14.8%) and stratigraphic (2.9%) traps. Passive margin and foreland basins are the two most important types. Of the 340 giants, 160 are located in 8 passive margin basins and they account for 72.6% of the total. Of the 37 basins with marine carbonate giants, 14 are foreland basins, which are the most common basin type for discovery of marine carbonate giants. In addition, 128 giants are distributed in foreland basins and their reserves constitute 20.4% of the total. Petroleum reserves are sealed by four types of cap rocks in marine carbonate giants: evaporite, clastics, carbonate and mixed lithology. The evaporites seal 58.2% of the total, indicating the close relationship between the high sealing effectiveness of the evaporites and the giant reserves. The clastics are the most common seal type. They constitute cap rocks in 135 giants and seal 21.2% of the total. Stratigraphically, the more prolific intervals for reservoiring oil and gas in marine giants are the Jurassic (hosting 27.0% of the total), Cretaceous (24.9%), Permian (18.0%), Triassic (9.8%), Neogene (7.0%) and Paleogene (7.0%). On the basis of the location of marine carbonate giants and distribution range of source rocks, a statistical analysis for lateral migration was carried out. The results indicate that lateral migration distance for most of the marine carbonate giants are less than the 5km. Furthermore, both the number of carbonate giants and the reserve sizes of giants decrease with the lateral migration distance. This implies that giants are mainly located in the vicinity of the hydrocarbon source kitchen and adjacent areas.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015