Description Guaratiba Group

the guaratiba group of santos basin deposited in half-grabens of opening south atlantic



the tupi prospect, later renamed lula field, honouring president of brazil lula, first giant field of many found in pre-salt guaratiba group



piçarras formation

the piçarras formation 990 metres (3,250 ft) thick , consists of clastic , carbonate rocks. formation includes reddish polymictic conglomerates, clasts of basalt , quartz in clay-sandy matrix. includes white, reddish lacustrine coquinas (shelly limestones) , sandstones, siltstones , shales of stevensite composition. age, based on ostracod assemblages, hauterivian aptian.

the conglomerates , sandstones of formation representative of alluvial environment. coquinas represent shallow lacustrine environment. similar atafona formation of campos basin, sandstones, stevensite-bearing siltstones , shales represent alkaline lacustrine environment affected volcanic activity. shales represent deeper lacustrine waters in more distal areas. alternation of 2 facies implies series of alluvial progradation-retractions cretaceous carbonate lakes. low textural , compositional maturity of conglomerates , sandstones implies basin supplied areas close basin margins.

itapema formation

the itapema formation several hundreds of metres thick , consists of calcirudites (limestones) , dark shales. calcirudite limestones consist of fragmented bivalve shells, dolomitized , silicified. in more distal sections, formation consists of dark organic matter rich shales. in 1-rsj-625, formation includes 110 metres (360 ft) of radioactive shales interbedded carbonates. theses facies thought represent lacustrine environment. organic matter-rich shales 1 of main source rocks of santos basin. formation correlative coqueiros formation in campos basin. age of itapema formation barremian aptian.

barra velha formation

the barra velha formation approximately 300 350 metres (980 1,150 ft) thick. in proximal sections, formation comprises limestones of stromatolites , laminated microbialites. in distal sections, composed of shales. interbedded laminated microbialites there limestones packstone , grainstone textures made of algal clasts , bioclasts (fragmented ostracods). carbonates partly or dolomitized. these facies represent transitional continental , shallow marine environment. age of formation has been estimated late barremian aptian. correlative macabu formation in campos basin, both typified laminated microbialites , stromatolites. these limestones 1 of sub-salt reservoirs in santos basin, notably of giant lula , reported supergiant lapa fields.

petroleum geology

the formation hosts important pre-salt reservoir rocks of santos basin.