Pemex's Cantarell offshore oil field, which accounts for about 60 percent of oil production, is forecast to produce 1.9 million barrels a day in 2006, a 6 percent decline from 2.03 million barrels a day so far in 2005, Pemex said in an e-mailed statement.

Pemex forecasts Cantarell will produce 1.68 million barrels per day in 2007 and 1.43 million barrels daily in 2008. The decline in Cantarell's production will be made up with investments in other oil fields, including Ku-Maloob-Zaap, Crudo Ligero Marino and Complejo Bermúdez, Pemex said.

Pemex Chief Executive Officer Luis Ramírez has called on congress to allow the company to form partnerships with foreign oil companies to help drill deepwater oil deposits in the Gulf of Mexico and head off a decline in total oil production.

Former Energy Secretary Fernando Elizondo, who resigned in September to run for senate, said in January Mexico may need to import oil within 12 years unless the country opens its energy industry more to private investment.

Pemex officials announced in March that Cantarell may begin declining in production for the first time this year.

The massive field was discovered in 1976 and began production in 1979, turning Mexico into an oil exporting power. Since 1979, the field has produced 11.49 billion barrels of oil. The proven reserves left in Cantarell were 6.98 billion barrels as of January.

In 1997, Pemex designed a project to inject nitrogen into wells in Cantarell that helped double production to 2.03 million barrels a day this year from 1.08 million barrels daily in 1996.