Two main source rock systems have been identified in the Espirito Santo Basin: the Alagoas shales related to an evaporitic environment of Aptian age, and the Jiquia shales of Upper Neocomian age deposited in a continental to lagoonal environment. The open marine Tertiary to Upper Cretaceous slope sediments, previously believed to have source potential, do not actually constitute a source section.

Almost all the studied oils showed some degree of degradation, probably caused by bacteriological attack. Gas chromatography-mass spectrometry was used in order to provide biomarker information which, together with isotopic studies and gas chromatography, provided reliable oil/oil and oil/rock correlations.

Oil is produced in the basin, mainly from Alagoas sands below the Aptian evaporites and from Tertiary-Upper Cretaceous reservoirs. The proposed oil migration geometry from source rocks to the Alagoas reservoirs is relatively simple, since both source and reservoir rocks have close stratigraphic relationships. Entrapment is provided by structures at the level of the Alagoas anhydrite beds that provide the seal. The generative depression where Alagoas source rocks are presently mature lies a few kilometers east of the discovered accumulations (Rio Itaunas, Sao Mateus), implying relatively short distance migration.

In the case of oil accumulations in Tertiary-Upper Cretaceous turbiditic reservoirs (Lagoa Parda, Fazenda Cedro), the mature Jiquia source rooks are exposed by erosion along the bottom of the submarine canyons along which turbidites were deposited. The complex, coalescent, turbiditic sand bodies acted as a hydrocarbon collecting system and pools were formed where structural or stratigraphic closure exists.

The offshore Cacao field is related to a paleogeomorphic closure at the bottom of the submarine canyon. The oil is trapped in Albian reservoirs capped by Upper Cretaceous marine slope shales. It can be explained by a migration geometry including a subcrop of Jiquia mature source rocks below the pre-Alagoas unconformity, and upward migration of the oil through the sandy, permeable Alagoas section, due to the absence of Alagoas anhydrites at this particular location.