Portal de Periódicos da CAPES

Artigo Produção Nacional Revisado por pares

BIBTEX RIS

Carbonate cementation patterns and diagenetic reservoir facies in the Campos Basin cretaceous turbidites, offshore eastern Brazil

1995; Elsevier BV; Volume: 12; Issue: 7 Linguagem: Inglês

10.1016/0264-8172(95)93599-y

1873-4073

Marcos V.F. Carvalho, Luiz Fernando De Ros, Newton Souza Gomes,

Hydrocarbon exploration and reservoir analysis

Massive turbidite arkoses contain more than 80% of the oil reserves of the Campos Basin, the main petroleum province of Brazil. The porosity and permeability distribution in the Namorado (Albian-Cenomanian) and Carapebus (Turonian-Santonian) sandstones in controlled by carbonate cementation at shallow depths below the seafloor and by compaction and silicification of mud intraclasts. The carbonate cementation followed two patterns: (1) in the Albian sandstones, concretionary sulphate reduction and fermentation calcite cementation occurred around bioclastic levels with marine microcrystalline cement; (2) in the Upper Cretaceous sandstones, coarse sulphate reduction and fermentation carbonates precipitated along the intercalated shales. The sources of the carbonate cements included sea water, bioclasts, bacterial alteration of organic matter and Albian carbonate rocks. Four diagenetic reservoir facies were characterized: (1) massively cemented facies along bioclastic layers with marine cements and intercalated shales; (2) partially cemented facies bordering massively cemented facies with cements derived from the burial dissolution of early carbonates; (3) porous facies with dominantly primary porosity preserved due to the late subsidence and early oil saturation of the reservoirs; and (4) intraclastic facies in channel/levee deposits with mud intraclasts compacted to pseudo-matrix and silicified.