UPDATE 1-BP, Shell among bidders in $800 million Brazilian oil auction

(Updates with Equinor and Chevron no comment)

By Gram Slattery and Marta Nogueira

RIO DE JANEIRO, Oct 10 (Reuters) - BP Plc, Chevron
Corp and Royal Dutch Shell Plc are among the
companies that will compete for exploration and production
rights off the Brazilian coast on Thursday, in the first of
three oil bidding rounds scheduled for coming weeks.

Combined, the minimum signing bonuses for the blocks in the
so-called 16th post-salt oil bidding round in the Latin American
oil powerhouse come to roughly $800 million.

That is significant by historical standards, but pales in
comparison to Brazil's so-called transfer-of-rights bidding
round and 6th pre-salt round, both scheduled for early November.
Those rounds are expected to bring around $25 billion and $2
billion into government coffers, respectively.

The post-salt blocks are less prolific than the pre-salt
blocks, where billions of barrels of oil are trapped under a
thick layer of salt beneath the ocean floor.

Still, there are some prized areas in the 16th round,
particularly in the Campos and Santos Basins off the coast of
Sao Paulo and Rio de Janeiro. One block in particular, the
C-M-541 in the Campos Basin, has a minimum signing bonus of
roughly 1.375 billion reais ($335 million) and directly borders
the pre-salt region.

Seven relatively minor blocks off the northeastern state of
Bahia are the subject of environmental litigation by federal
prosecutors, authorities said on Wednesday, casting judicial
uncertainty over parts of the auction.

Authorities and environmentalists are concerned that the
seven blocks in question, which have a combined signing bonus of
roughly $16 million, are too close to the ecologically
significant Abrolhos archipelago.

Ecopetrol SA, Karoon Energy Ltd, Qatar
Petroleum, Equinor ASA, Total SA, China
National Offshore Oil Corp Ltd, Repsol SA,
Murphy Oil Corp, Petrogal, Petronas and Wintershall Dea
GmbH are also registered to participate in the bidding.

Brazil's Petroleo Brasileiro SA, known as
Petrobras, and Enauta Participacoes SA are eligible
to bid as well.

Karoon, Shell, Enauta, Ecopetrol, Petrobras, Chevron and
Equinor declined to comment on the bidding round. All other
companies did not immediately respond to a request for comment.

(Reporting by Gram Slattery and Marta Nogueira; editing by
Richard Pullin and Steve Orlofsky)