Print this pageThe Super Giant Sub-Salt Hydrocarbon Province of the Greater Campos Basin
In most areas of the ultra deep waters from the Brazilian margin, exploration has just begun with the discovery of four of the biggest oil fields found in the world. The fields encompassing more than 20 Bbbls of oils of reserves are the Tupi, Jupiter, Guará and Iará, oil fields. This paper presents the results of petroleum system modeling that was run on a detailed 3D geological framework built on a 20,000 Km2 of the best 3D PSDM seismic data (CGGVeritas) ever performed in the Santos Basin and on proprietary geological and geochemical data of HRT & Petroleum. With the discovery of the supergiant pre-salt oilfields in the Santos Basin, the meaning of petroleum exploration in Brazil changed completely. The paradigm against the existence of super giant hydrocarbon fields, in the sub-salt sequence in the Greater Campos realm, has been destroyed. New discoveries in the same pre-salt province suggest that the Brazilian reserves are indeed much larger, close to 50 Bbbls. This paper comprises a 3D petroleum system modeling used to assess the interplay among source, reservoirs, seals and trap geometries, thermal evolution of source rocks, hydrocarbon types, charge, timing of migration, accumulation and oil quality and a volumetric quantification of the accumulated petroleum. The main results indicate the presence of an overcharged source rock system reaching almost 90% transformation in the main depocenters of the studied area. Also, low excess pressure and temperature values occur below salt, in the main carbonate reservoirs from the Upper Lagoa Feia Fm, and range from 0.3 to 0.4 MPa and 80o to 100o C, respectively. Such values are critical in preserving the oil prone nature of the whole area. In general the pressure behavior seems to reflect the distribution of the massive halite layer in the basin, indicating normal pressure for most of the area below salt. Also, the salt layer was key in sealing the escape of hydrocarbons upward.The reservoir rocks, composed by stromatolites, coquinas and vulcanoclastics sum more than 300 m in thickness and extend for more than 1500 km to the north, presenting porosities up to 18% and permeability ranging from 50 to 400mD. The supergiant accumulations are trapped below a huge salt layer that acted as the BEST preservation element possible (seal, cushion and temperature drainer). Such ideal conjunction of the elements and processes established one of the most prolific petroleum system of the world.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil