Petroleum Geology of the Campos Basin Brazil, a Model for a Producing Atlantic Type Basin
L. R. Guardado, L. A. P. Gamboa, C. F. Lucchesi, 1989. "Petroleum Geology of the Campos Basin Brazil, a Model for a Producing Atlantic Type Basin", Divergent/Passive Margin Basins, J. D. Edwards, P. A. Santogrossi
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The Campos basin is currently the most productive offshore Brazilian petroleum-bearing basin. It covers an area of about 100,000 km2along the southeastern Brazil passive margin (Figure 1). The basin extends roughly from 15 km inland to the 3400 m isobath. Geologic studies of the basin started during the 1930s with the mapping of onshore and coastal areas by Lamego (1937, 1940, 1944, 1945). In 1958 PETROBRAS carried out a gravimetric survey of the onshore area and drilled a strati- graphic test at Cape São Tomé. Detailed seismic investigations of offshore areas began in 1968, and the first oil field, the Garoupa field, was discovered in 1974 (Tessari et al., 1978; Meister, 1980; Guardado et al., 1982; Marroquim et al., 1984). To date, more than 30 oil fields have been discovered and the basin is known to contain oil reserves of 1441 million bbl. This estimate does not include potential reserves from deep-water giant oil fields which have been recently discovered and still are not fully appraised. The majority of producing fields in the basin lie along a northeast-southwest trend, seaward of the hingeline. New giant oil fields are still being discovered. These new fields have been drilled in water depths ranging from 400 to 1500 meters. As a consequence there is increasing interest in exploration and exploitation in still greater water depths in the Campos basin.
The purpose of this chapter is to synthesize the geology and exploration history of this basin in order to provide
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All basins in the Divergent Margin class occur along continental margins near a midplate position, where they overlie and straddle rigid continental and oceanic crust. These basins are now essentially aseismic and non-volcanic. All extant divergent margins are post-Traissic and are related to the sequential breakup of Pangea. They represent the opening ocean part of the Wilson cycle of earth history ? as Pangea split, continental plates moved away from the African center. The inboard roots of divergent margin basins lie on attenuated, subsided continental crust beneath the coastal plain, continental shelf, and continental slope. Outboard, they lie on subsided oceanic crust beneath the continental slope and rise. All phases of basin development are dominated by gravity-driven extension tectonics. Hence, they are called passive, pull-apart, Atlantic-type, or divergent continental margins. This publication was initiated by the AAPG Publications Committee in 1985 and contributors were invited to write. AAPG designed their ?World Petroleum Basins? series and sought to publish the definitive volume on each of several basin types. In this volume, “Divergent/Passive Margin Basins,” a detailed overview was written about the Campos Basin (Brazil) as representative of divergent margin basins. The key paper was followed by less detailed reviews of three other selected passive margin basins: 1. Northwest Shelf of Australia 2. Gabon basin and 3. Niger Delta area. Contributors undertook to provide useful geologic information on the regional setting, stratigraphy, structure, tectonics, basin evolution, and oil and gas systems of these four basins. The goal was to develop a better understanding of the basin-forming, basin-filling, and basin-modifying processes that control hydrocarbon plays and resultant oil and gas fields in this class of basin. The volumes in the AAPG Basin Series include: 1. Divergent/Passive Margin Basins (AAPG Memoir 48) 2. Interior/Cratonic Basins (AAPG Memoir 51) 3. Active Margin Basins (AAPG Memoir 52) 4. Foreland Basins and Foldbelts (AAPG Memoir 55) 5. Interior Rift Basins (AAPG Memoir 59).