Page 36: of Marine Technology Magazine (September 2010)

type of exposure only occurs in the northern Sergipe-

Alagoas and Recôncavo Basins in Brazil. These rift and pre-rift exposures do not occur in the southern Brazilian

Basins, such as Santos and Campos. According to Marcio

Rochas Mello in his book ‘Petroleum Systems of the

South Atlantic Margins’, these differences partially reflect a asymmetrical rifting pattern along the two continental margins.

Northeast Brazil was attached to what is now known as the countries of Ivory Coast, Ghana, Togo, Benin,

Nigeria, Cameroon and Gabon. Although Petrobras has not been actively pursuing pre-salt exploration in

Northeast Brazil, Marco Rocha Mello from HRT Oil &

Gas, who as a geologist for Petrobras at the time, partici- pated in the early seismographic studies undertaken along the Brazilian coast in the late seventies and early eighties, claims that there is seismic data that indicates the presence of potential pre-salt hydrocarbon reservoirs all the way up to Recife in the Northeast state of Ceará and that the drilling was not undertaken due to high costs and not hav- ing the necessary technology at the time. If we take into consideration the new pre-salt discoveries in Gabon, the likelihood of pre-salt structures and their hydrocarbon reservoirs being present in Northeast Brazil must be con- sidered high.

One of the reasons for the large discoveries on the

Brazilian side of the South Atlantic Ocean is the very thick continuous layer of salt, which has served to keep much of the hydrocarbon accumulations in place. This means that the potential for large volume reservoirs on the Brazilian side could be higher. This is not the case on the Angolan side, where the salt structures are not as homogeneous and neither are the source rocks underneath them. In Gabon, it appears that the geological systems hold much more similarity to the systems found at the Santos Basin, so the possibility of finding large reservoirs there is higher. There is still much more drilling to be done on both sides of the

Atlantic Ocean, in order to reach the full potential and a 36 MTR September 2010

Seismic ship shooting a 3D marine survey. (Photo cr edit W estern Geophysical)

South Atlantic Basins cross section.

Cr edit Cobalt International Ener gy .