SAO PAULO, Nov 6 (Reuters) - Brazilian state-run oil company Petroleo Brasileiro SA said on Monday it has made its own estimates of excess volumes of oil in offshore fields under the so-called transfer of rights program that dispute forecasts published by oil regulator ANP.
Petrobras' analysis indicates the upper and lower limits of the excess oil to be found in those areas are below ANP's, it said in a filing referring to the regulator's estimates released on Friday.
Last week, ANP estimated at least 6 billion barrels of oil equivalent of excess reserves in areas covered under the transfer of rights regime that are in the so-called pre-salt area, where hydrocarbons are trapped beneath a thick layer of salt below the ocean floor.
Petrobras also said it will carry out further studies with the help of consultants at DeGolyer and MacNaughton, which should be ready in about 30 days.
Pinning down the amount of excess barrels in the area should help resolve a dispute between Petrobras and the government over a 2010 contract between them, signed as part of a Petrobras share offer.
It gave the company rights to produce 5 billion barrels of oil from pre-salt fields.
The deal, which closed when oil prices stood at $90 a barrel, included an agreement to re-evaluate the transaction. Brent oil rose 0.8 percent to $62.58 on Monday, and Petrobras believes the government owes it a substantial sum due to the massive slump in oil prices.
Reporting by Luciano Costa; Writing by Ana Mano; Editing by Chizu Nomiyama