* To scrutinize area home to about 80 pct of Brazil oil
* Probe could look at giant Petrobras offshore oilfields
* Region known for porous, crack-prone rock, natural seeps
By Sabrina Lorenzi
RIO DE JANEIRO, March 30 (Reuters) – A Brazilian federal
prosecutor plans to expand his investigation of a November
offshore oil spill in a field run by Chevron to areas
operated by other companies in the country’s main oil region.
The probe will explore geological conditions and operational
practices in the Campos Basin in an attempt to prevent future
accidents, said Eduardo Santos de Oliveira, federal prosecutor
for Campos, Brazil, the city for which the offshore oil province
is named.
The biggest operator in the Campos Basin is Petrobras
, Brazil’s state-led oil company, which operates 39 of
the 47 producing fields in the region, according to Brazil’s oil
regulator, the ANP.
“Now that the working environment has been created (by the
Chevron spill), let’s promote this debate and use the official
investigation tools to try to understand this situation,
including for preventative reasons,” Santos de Oliveira told
Reuters.
Santos in November launched a 20-billion-real ($10.9
billion) civil-environmental lawsuit against California-based
Chevron and its drilling contractor Transocean. Earlier
this month he filed criminal charges against Chevron, Transocean
and 17 of their employees. The crimes alleged by the criminal
case carry sentences of up to 17 years in prison.
Chevron is the No. 2 U.S. oil producer.
Other companies with exploration or production operations in
the Campos Basin include Anglo-Dutch Shell, Brazil’s
OGX Petroleo, Spain’s Repsol YPF, Denmark’s Maersk Oil
and UK-based BP.
The Frade field, operated and 52 percent owned by Chevron,
is close to some of the largest oilfields in Brazil, including
Marlim Sul, Roncador and Marlim, all 100 percent owned and
operated by Petrobras.
The region is known to contain sub-sea rock that is porous
and prone to cracking. If not covered with a natural seal that
stops oil flow, petroleum can seep through it naturally to the
seabed and then bubble to the surface.
“The Campos Basin is prone to natural seeps that can stain
the ocean,” said Cleveland Jones, a geologist at the National
Oil Institute at the State University of Rio de Janeiro. “That,
in fact, is one of the reasons that geologists knew that there
was a good chance of finding oil there in the first place.”
Such natural seeps are even more common in the Gulf of
Mexico, Jones said. Most natural spills are broken up by wave
and tide action and oil-eating bacteria.
POROUS ROCK
The porous and fragile rock is believed to have been a
contributing factor to the November leak in the Frade field.
Chevron said oil seeped from a crack in the bore of an
exploratory well and worked its way through the rock to the
seabed and then ocean surface.
About 3,000 barrels leaked in the accident, less than 0.1
percent of the 4.9-million-barrel BP spill in the Gulf of Mexico
in 2010. None of it reached shore and an ANP official told
Congress in March that the Frade spill caused no discernable
environmental damage.
Chevron and Transocean say the criminal and civil charges
are excessive, they have committed no crimes and acted according
to accepted industry practice.
Petrobras also has a 30 percent minority stake in Frade,
while a Japanese group led by Inpex and Sojitz
owns 18 percent.
Chevron, with the agreement of its partners, asked for and
received permission to stop production temporarily at Frade
after discovering unexplained leaks in the field in early March.
Oil leaks were also found in 2004 at Petrobras’ Marlim Sul
field. Marlim Sul’s production of 300,000 barrels a day makes it
Brazil’s top-producing field.
Petrobras said studies suggested the Marlim leak probably
resulted from “the existence of natural faults and fractures in
the reservoir where the oil migrated to the sea floor”.
Santos says the Frade accident gives his federal prosecutors
office, known as the Public Ministry, a chance to fulfill its
constitutional role as an independent arbiter of government and
economic activity.
“Whenever you have an accident of this type, it is normal
that public agents concentrate on the accident to make those
responsible take responsibility,” he said. “But the recent
accident is also an opportunity to seek to identify what is
happening with the rest (of the area).”
(Writing and additional reporting by Jeb Blount in Rio de
Janeiro; Editing by Dale Hudson)
