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 BRAZIL
South America
The main sedimentary basins along Brazil’s Atlantic
coastline are, from south to north, Santos, Campos, Espirito Santo,
Reconcavo, Sergipe-Alagoas, Potiguar and Ceará. The Amazon basin is
located inland.
Onshore production began from Bahia State (Reconcavo) in
1940 and had reached 160,000 bbls per day by 1970. However it was when Petrobras started offshore exploration in 1967 and its
first fully offshore oil find (Guaricema in the Sergipe/Alagoas basin) began producing in 1968
that the potential of Brazil was truly recognised.
 Since 1977 all significant production
has been concentrated in the shallow and deep waters of the Campos
basin. The first oil field in Campos, Garoupa, was discovered in 1974
and over 60 fields have been discovered, including many deep water fields.
Deep water production began in 1987. Most other activity occurs in the
neighbouring Santos basin to the south and Espirito Santo Basin to the
north.
Brazil is made up of ancient crystalline rocks of the
Guayana and Brazilian Shields separated by a transcurrent fault, which
follows the Amazon River. This fault extends across the Atlantic to also
form the southern limit of the bulge of Africa. Like the Gulf of Mexico
the evolution of the Brazilian offshore was controlled by events
subsequent to the Mesozoic break-up of South America from Africa
followed by the opening of the South Atlantic Ocean.
It led to rift basins containing rich oil source rocks,
laid down in lakes as rifting began and overlain by unstable salt
deposits derived from shallow seas that intermittently engulfed the land
before evaporating. Above the salt deposits carbonates were deposited in
the open sea, then covered by turbidites when the waters deepened.
These carbonates and, more importantly, individual
turbidite fans over large surface areas, form the main offshore reservoirs.
Turbidites are submarine avalanches consisting of muddy sandstones and
clays. In the Campos Basin longshore
currents have winnowed out the fine-grained material, depositing
dune-like bodies of sand with excellent reservoir characteristics.
Individual offshore basins are separated by fracture
zones and volcanic ridges. Ridges known as the Rio Grande Rise (linked
to the Walvis Ridge in West Africa) near the Uruguayan border, and the
North Brazilian Ridge (linked to fracture zones that disappear beneath
the Niger Delta in West Africa) define the best areas for petroleum
potential. In the deepwater extension of the Campos Basin, many large
gentle structures in communication with the underlying source rocks have
been found to be oil-filled.
The state company Petroleos Brasileiro SA (Petrobras) was
founded in Brazil in 1953. It operated a monopoly in exploration and
production and was also engaged in refining, transportation, import and
export of oil and oil products, natural gas distribution, petrochemicals
and fertilisers. It produced all of Brazil’s oil and gas and exported
refined fuel.
In exploiting the Campos Basin Petrobras and its
contractors pioneered much of the deepwater technology now in existence
in most parts of the world. Having exclusive rights gave Petrobras
considerable benefit but since resources were required for further
deep water development projects the state approved a deregulation bill in
1997 to open the oil sector to private capital.
A National Petroleum Agency (ANP) was created to
encourage investment, represent the state and issue licences. Petrobras
was eventually able to retain around 60% of the Campos basin area but
lost its rights to much of the rest of Brazil’s offshore area. Since
June 1999 numerous Licensing Rounds have been held in which Petrobras
has been active.
The Campos Basin: Oil was discovered in the Campos
Basin in 1974 in the Garoupa field. Over 60 oil fields have been
discovered in shallow and/or deep waters although the distinction
between deep and shallow production is hard to draw owing to the large
field areas and hence range of water depths overlying a single field.
A series of the largest fields located mostly in deep
waters include Roncador, Albacora Leste, Marlim, Marlim Leste and Marlim
Sul, Barracuda, Bijupira, Caratinga, Marimba and Frade. First Campos
production was from the shallow water Enchova field in 1977. The giant
partly deep water Albacora Field was discovered in 1984 and began
production in 1987. In 1985 the then largest field in Brazil, Marlim,
was discovered in water depths ranging from 400 to 1,400m and production
began in 1991 from an early production system. The giant Marlim Sul
field went onstream in 2001 and additional giant fields and numerous
smaller fields have also been discovered in both shallow and deep waters
of which at least 35 are producing.
The giant Roncador field, Brazil’s largest was discovered
in 1996. This field suffered temporary loss of output when its P-36
semi-submersible FPU sank in March 2001 in 1300m of water.
Bijupira-Salema, onstream since August 2003, was the first field to be
produced by a foreign company (Shell) since 1997. The Campos basin also has additional prospects in
ultra-deeper waters and peripheral to the main fields. Petrobras continues to make discoveries
including large heavy oil deposits in the Jubarte and
Cachalote fields in the northern BC-60 block.
The oil fields in the Campos Basin produce some
associated gas but large quantities are flared. Petrobras is working to
reduce flaring volumes with field compression and expanded pipelines.
The Santos Basin: Outside the Campos basin the
geology appeared to be less favourable for large accumulations and Petrobras on its
own had little incentive to explore. However the Santos basin, off Sao
Paulo and Paraná States, south of Campos, is now the most likely to have a
future impact on Brazil’s offshore hydrocarbon industry.
In the Santos basin a number of shallow water oil fields and one
gas field have been producing for many years. The first fields to be
developed were the Caravela oil field and nearby Coral fields in 180m of water
in 1993. In 2007 the Tupi oil field was announced in the Santos Basin.
See
Discovery Review for more information. This was followed by
Jupiter and Carioca all of which are located under the salt layers and
are probably giant fields and will lead to much increased oil output
over the next decade.
The Santos Basin could also dramatically alter Brazil’s gas
market. The Merluza gas field began producing in 1993. Located in 119m
of water it is the only offshore non-associated gas development in
Brazil, producing less than 0.5 Bcm per year but due to rise rapidly. In 2003 Petrobras reported
the discovery and appraisal of over 400 Bcm of gas in four new
discoveries in the basin. The accumulations lie in water depths ranging
from 400 to 1,500m. Situated close to Brazil’s main consumer market, they are
well placed for rapid development and Petrobras has formed joint
ventures with foreign companies, firstly over the Mexilhão field.
Other offshore Brazil: The rest of Brazil has
minor shallow water oil and gas production. The Espírito Santo basin,
north of Campos, produces some oil and gas onshore although one field,
Cacao, produced oil offshore in the 1980s.
Some small developments started up in Espírito Santo
State in 2002 but this may be better designated as coming from the
neighbouring Campos basin which partly lies in the state.
Further north in the Reconcavo basin in Bahia State, the
Dom Joao and Candeias fields lie partly offshore and provided the
first offshore production. A number of fully offshore fields have produced north of
Reconcavo from the Sergipe/Alagoas basin located in two states of the
same name.
On the northeast coast the Potiguar basin, in Rio Grande
do Norte State, produces a few thousand Bbls per day from the offshore Ubarana field and its
neighbours. This area also produces offshore gas. Further west the Amazon delta is
relatively small because the Amazon flowed westward into the Pacific
until its flow was reversed by uplift of the Andes in the later
Tertiary. Some exploration is proceeding in the deep waters.
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