MEXICO CITY, March 18 (Reuters) - Mexican state energy

company Pemex is in talks with companies owned by billionaire

investor Carlos Slim about an investment in the country's most

important natural gas field, Ixachi, President Claudia Sheinbaum

said on Tuesday.

Reuters revealed last week that officials at Pemex and

Slim's companies were considering a so-called mixed contract for

Ixachi in Veracruz state and a joint operating agreement for the

deepwater Zama field in the Gulf of Mexico.

"We're discussing this with the companies belonging to

Slim," Sheinbaum said during her regular press conference when

asked about further participation.

Sheinbaum added that Grupo Carso, as one of Slim's companies

is known, was already involved in some parts of the operation of

Ixachi. It currently drills wells.

Mixed contracts, which sources told Reuters would likely be

used for Ixachi, are a new form of partnership between Pemex and

private companies.

These allow Pemex to work with private companies,

complementing its own expertise and capital, while retaining

ownership of resources.

Cash-strapped Pemex is struggling to meet the crude oil

production target of 1.8 million barrels per day (bpd) as

fields, especially in the Gulf of Mexico, are being depleted and

new discoveries fail to compensate for it.

Ixachi has been celebrated as the most important find in

more than a quarter of a century for Mexico, which seeks to

become self-sufficient in energy.

Nearly two-thirds of the gas consumed locally is imported,

mostly from its northern neighbor via pipelines.

RBN Energy, a market advisory service, wrote in a recent

note that U.S. imports, mostly from the Permian and the Eagle

Ford, have increased threefold over the past decade.

Mexico's own production has declined rapidly, it noted,

adding that much of it is considered unusable because of the

high nitrogen content.