| Campos Basin | |
|---|---|
| Bacia do Campos | |
  | |
| Coordinates | 22°28′52″S34°50′00″W / 22.48111°S 34.83333°W /-22.48111; -34.83333 |
| Region | Southeast |
| Country |  Brazil |
| State(s) | Rio de Janeiro,Espírito Santo |
| Cities | Campos dos Goytacazes andMacaé |
| Characteristics | |
| On/Offshore | Both, mostly offshore |
| Boundaries | Vitória,Cabo Frio Highs,Serra do Mar |
| Part of | Brazilian Atlantic margin |
| Area | ~115,000 km2 (44,000 sq mi) |
| Hydrology | |
| Sea(s) | South Atlantic |
| Geology | |
| Basin type | Passive margin onrift basin |
| Plate | South American |
| Orogeny | Break-up of Gondwana |
| Age | Neocomian-recent |
| Stratigraphy | Stratigraphy |
| Field(s) | Marlim,Albacora-Leste,Barracuda,Roncador,Cachalote,Badejo |
TheCampos Basin is one of 12 coastal sedimentary basins ofBrazil. It spans both onshore and offshore parts of the South Atlantic with the onshore part located nearRio de Janeiro. The basin originated inNeocomian stage of theCretaceous period 145–130 million years ago during the breakup ofGondwana. It has a total area of about 115,000 square kilometres (44,000 sq mi), with the onshore portion small at only 500 square kilometres (190 sq mi).[1]
The basin is named after the Campos dos Goytacazes city.[citation needed]
The Campos Basin is bound on the south by theCabo Frio High, separating the basin from theSantos Basin and on the north by theVitória High, forming the boundary with theEspírito Santo Basin. Campos Basin contains theParaiba do Sul River delta.[2]
TheSouth Atlantic margin developed on Archean stablecratons consisting of hard and resistant rocks and partly on theNeoproterozoic mobile belts composed of less resistantmetamorphic rocks.[4] ThePrecambrian basement of the Santos Basin is exposed as theAraçuaí Belt along the Brazilian coast, most notably in theinselbergs of Rio de Janeiro, of whichSugarloaf Mountain is the most iconic. The ancient rocks consist of a Neoproterozoic toCambrian high-grade metamorphic core ofgranites andgneisses, formed during the collision of Gondwana in thePan-African-Brasiliano orogeny.[5] Basalts similar to theParaná and Etendeka traps, exposed to the west in theParaná Basin, have been found underlying the Santos Basin.[6] TheTristan da Cunhahotspot, known as theTristan hotspot, is considered the driver behind the formation of theseflood basalts.[7]
During theEarly Cretaceous, the former continentGondwana, as southern part ofPangea, starting to break-up, resulting in a sequence ofrift basins bordering the present-day South Atlantic. The Pelotas-Namibia spreading commenced in theHauterivian, around 133 million years ago and reached the Santos Basin to the north in theBarremian. Seafloor spreading continued northwards to the Campos Basin in theEarly Albian, at approximately 112 Ma.[citation needed]
Five tectonic stages have been identified in the Brazilian basins:[8]
Oil reservoirs include formations deposited during theAptian and pre-Aptian continental rift phase, of post-saltAlbian-Cenomanian shallow-water marine carbonates and deepwatersandstones, and inturbidites of the open marine drift phase ofLate Cretaceous and earlyTertiary ages.[2]
TheNamorado Field "location was selected based on seismic interpretation of a structural high at the top of theMacaé Formation (Albianlimestones)" at a depth of about 3 kilometres (9,800 ft),[2] and the reservoirs are marine turbidite deposits transgressing over the Albian limestone shelf.[2]
The stratigraphy starts withbasalt flows dated at 120 Ma, overlain by theLagoa Feia Group, consisting of the organic-richlacustrine "green shales" followed bylacustrine limestones and continental sandstones andconglomerates, transitioning into marine sediments with evaporites, limestones, and limestone altereddolomites.[2] The shallow marine limestones of the Macaé Formation follow, then theNamorado turbidite sandstones, and finally theCampos Formation, consisting of the turbidite sandstone Carapebus Member and the prograding slope and shelfUbatuba Formation.[2]
The off-shore oil exploration in the Campos Basin began in 1968.[9] The first exploratory well was drilled in 1971. The first field to be discovered wasGaroupa in 1974, at a shallow water depth of 120 metres (390 ft), followed by Namorado in 1975 in 166 metres (545 ft) of water.[2] The first oil production started in 1977 fromEnchova Field, at a water depth of 124 metres (407 ft).[1] The largest fields, listed by their year of discovery year, includeLinguado (1978),Carapeba (1982),Vermelho (1982),Marimba (1984),[10]Albacora (1984),Marlim (1985),Albacora-Leste (1986),Marlim Sul (1987),Marlim Leste (1987),Barracuda (1989),Caratinga (1989),Espadarte (1994),Roncador (1996),Jubarte (2002),Cachalote (2002), andBadejo (2008). The largest Marlim field is located in the northeast of the basin, 110 kilometres (68 mi) offshore in water depths ranging from 650 to 1,050 metres (2,130 to 3,440 ft).[9]
By 2003, 41 oil and gas fields were discovered, which ranging at distances from 50 to 140 kilometres (31 to 87 mi) from the coast and at water depths varying from 80 to 2,400 metres (260 to 7,870 ft). Of these fields, 37 are being developed byPetrobras. By 2003, the oil production from the basin had reached 1.21 millionbarrels per day. The production comes from a variety of reservoirs including siliciclasticturbidites, fracturedbasalts,coquinas,calcarenites (limestones). The total cumulative production from the Campos Basin by 2003 was 3.9 billion barrels of oil with remaining reserves of 8.5 billion barrels.[1]
In February 2010, a new 65 million barrel discovery was made byPetrobras near the Barracuda oil field.[11]
In 2020, the Enchova, Enchova Oeste, Marimbá, Piraúna, Bicudo, Bonito, Pampo, Trilha, Linguado, and Badejo concessions were sold by Petrobras to Trident Energy. These concessions are located in the shallow part of the Campos Basin, offshore Rio de Janeiro state.[12]
Sedimentary basins of Brazil | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Onshore |
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| Offshore | ||||||||||
| Source | Souza Lima, Wagner; Hamsi Junior, Gilvan Pio (2003)."Bacias sedimentares brasileiras".Phoenix.49: 1. Retrieved2017-09-04. | |||||||||
