Petroleum Habitat in the Prerift and Synrift Sequences in the Brazilian Sedimentary Basins

GUIMARAES, PAULO DE TARSO M., GERSON J. F. FERNANDES, ANTONIO M. F. DE FIGUEIREDO, Petrobras, Rio de Janeko, Brazil

The Late Jurassic and Early Cretaceous strata represent the sedimentary sequences deposited during the prerift and synrift tectonic phases in Brazilian basins. These basins developed by crustal thinning and rupture related to the separation of the African and South American continents.

Since the beginning of oil exploration in Brazil, 139 oil and gas accumulations have been found in prerift and synrift sediments. Most of these accumulations occur in continental sandstones, but a few of them are also present in lacustrine carbonates and basalts. The hydrocarbon-producing basins in these sequences are Campos, Reconcavo, Tucano-Sul, Sergipe-Alagoas, Potiguar, and Ceara; with a volume of 1.46 * 10x9 cubic meters (9.21 * 10x9 bbl) oil equivalent in place and a proved exploitable reserve of 112.5 * 10x6 cubic meters (708 * 10x6 bbl). Their contribution to the oil industry in Brazil amounts to 340 * 10x6 cubic meters (2.14 * 10x9 bbl) of oil equivalent already produced.

In spite of the exploration maturity of the basins, technological advancements will ensure the continuation and refinement of exploration in the Late Jurassic and Early Cretaceous sequences of the producing basins as well as in the potential ones. The volumes of oil and gas already discovered justify additional investigation in these sequences.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)