BP Share News (BP.)

By Marta Nogueira and Alexandra Alper

RIO DE JANEIRO, March 29 (Reuters) - Exxon Mobil Corproared into Brazil's prolific offshore oil fields againon Thursday, clinching eight blocks in partnership with otheroil firms eager to lap up the country's choice reserves ahead ofpresidential elections later this year.

Exxon along with Petrobras and Qatar PetroleumIntl shelled out 2.8 billion reais ($844 million) for a block inBrazil's offshore Campos basin as the American oil major seeksto aggressively replace dwindling reserves.

Chevron Corp, Repsol SA, Royal Dutch ShellPlc, BP Plc and Statoil ASA also spenttop dollar to lock down stakes in Brazilian offshore blocks,some of which may be part of the coveted pre-salt play, whereoil is trapped under layers of salt beneath the ocean floor.

"We are more confident in investment in Brazil, without adoubt," said Carla Lacerda, Exxon's top executive in Brazil,after the round. "We have lots of opportunities ahead. We areanalyzing each round. We want a robust portfolio here."

Exxon, which also won a pre-salt block in October last year,will operate six of the eight blocks it won on Thursday.

Exxon took 10 blocks in a September round in Brazil lastyear. Before that, it was among the few oil majors without apresence in the exploration of the vast offshore fieldsdiscovered off the Brazilian coast over the past decade.

Higher oil prices and the need to replace shrinking reserveshave boosted appetite among oil majors for costlier,higher-yield offshore ventures, though some projects are stillseen as too pricey to be viable.

The offshore segment of the concession-style auction was amajor success for Brazil's cash-strapped government, which rakedin more than 8 billion reais by placing 22 blocks, compared withits forecast of 4.6 billion reais from both onshore andoffshore rounds. Blocks in two onshore basins will be auctionedin the afternoon.

Results exceeded expectations despite an unexpected move bya Brazilian court on Wednesday to remove two of the mostattractive blocks in the Santos basin from the round, based onthe argument that they should be auctioned under aproduction-sharing regime to create more value for thegovernment.

The government will seek to auction off those blocks as partof a pre-salt round in June.

The big bids underscore oil majors' urgency to lock instakes in Brazil before a wide-open presidential election inOctober that could bring to power a government seeking to haltor slow private investment in Brazil's oil sector.

Still, there may be more opportunities than previouslythought to take stakes in Brazil's pre-salt this year.

Officials told Reuters the June round could be followed byan auction of top geology pre-salt areas in the Santos basin inthe second half of the year if the government and Petrobras canend a dispute over the area.($1 = 3.32 reais)(Reporting by Alexandra Alper, Marta Nogueira and Rodrigo VigaGaierEditing by Grant McCool and Matthew Lewis)