April 15 (Bloomberg) -- Brazil's offshore Carioca oil field may hold about 10 billion barrels of recoverable reserves, Citigroup Inc. said, an amount that would be worth $1.13 trillion at today's crude prices.

Citigroup calculated the figure using a reserves estimate announced yesterday by Brazilian National Oil Agency Director Haroldo Lima, who said the Carioca field may hold 33 billion barrels of oil. Additional wells must be drilled to develop a ``more conclusive'' forecast, Rio de Janeiro-based Petroleo Brasileiro SA said yesterday in an e-mailed statement.

Lima's estimate is probably a figure for oil-in-place reserves, Citigroup analyst David Thomas said in a research note today. Thomas assumed a recovery rate of about 30 percent to calculate the recoverable reserves, which are ``still massive in any context.''

Brazil, with an estimated 12 billion barrels of crude reserves, has South America's second-largest deposits of oil behind Venezuela, according to London-based BP Plc. Should the 33 billion-barrel estimate for Carioca be confirmed by additional drilling, Brazil's reserves would surpass those of Libya.

Crude oil touched $113.93 a barrel in New York today, the highest since futures began trading in 1983. Oil and gasoline rose as investors purchased commodities because their returns outpaced stocks, bonds and other financial instruments. China said today that diesel imports surged 49 percent in March.

Petrobras Gains

Petroleo Brasileiro, or Petrobras, jumped 5.6 percent in Sao Paolo trading yesterday, following Lima's comments on the Carioca field. Brazil's securities regulator said today that comments by the country's petroleum agency yesterday on the potential size of the Carioca field were ``harmful'' for investors.

The Carioca field is 45 percent-owned by state-controlled Petrobras, while BG Group Plc holds 30 percent and Repsol YPF SA controls 25 percent. The field, also known as BM-S-9, is located beneath a layer of salt in the deepwater Santos basin off Brazil's southeastern coast.

Petrobras said in November the Tupi field, also in the Santos basin, contains as much as 8 billion barrels of recoverable oil and gas. That amounts to three-quarters of the reserves of Kazakhstan's Kashagan field, the largest oil discovery in the last three decades. BG Group owns 25 percent of Tupi and Petrobras is the operator.

Potential new deposits in Tupi alone may raise Brazil's oil reserves from the world's 17th biggest to among the top 10, according to Petrobras. The oil at Tupi is a light grade, more valuable and cheaper to refine than the heavy crude that dominates Brazilian output.

In January, Petrobras said that another gas and oil discovery known as Jupiter may be as big as Tupi.

To contact the reporter on this story: Joao Lima in Lisbon at jlima1@bloomberg.net.

Last Updated: April 15, 2008 11:31 EDT