UPDATE 1-Mexico oil reserves dip again as private firms begin to contribute

By David Alire Garcia

MEXICO CITY, March 23 (Reuters) - Proven oil and gasreserves in Mexico fell again this year as new discoveriesfailed to keep pace with ongoing production, but officialspointed to the first-ever reserves contributed by privatecompanies operating their own blocks as silver lining.

Overall reserves fell by more than 7 percent at the start of2018 compared with a year earlier to total 8.483 billion barrelsof crude oil equivalent (boe), according to data published onFriday by Mexico's National Hydrocarbons Commission (CNH).

The vast majority of Mexico's proven reserves have beencontributed by national oil company Pemex, which enjoyed adecades-long monopoly until a 2013 constitutional reform endedit, paving the way for private producers to enter the sector.

But a relatively small amount of the reserves now reflectdiscoveries made by private and foreign oil companies.

They include some 251 million boe from two shallow waterblocks auctioned in late 2015 to Italy's Eni andArgentina's Hokchi Energy, which is backed by British oil majorBP.

"What we see here is the first certification of reservesthat are being presented by two companies that receivedcontracts at auction," said Juan Carlos Zepeda, head of the CNH,as the new figures were announced.

He said reserves from the two blocks have tripled since thecompanies took them over from Pemex.

Zepeda said another major discovery announced last year by aconsortium comprising U.S. firm Talos Energy, Britain's PremierOil and Mexico's Sierra Oil & Gas, has yet to becertified.

"That will come later," he said.

The so-called Zama find made by the Talos-led consortium isestimated to hold more than 1 billion barrels.

The 2018 reserves also reflect Pemex's onshore Ixachidiscovery announced in late 2017, which added nearly 98 millionboe.

According to CNH data, the total reserves consist of 6.46billion barrels of oil as well as 10.02 trillion cubic feet ofnatural gas.

At the start of last year, proven reserves in LatinAmerica's second-biggest economy totaled 9.16 billion boe.

Over the past decade, reserves have slid more than 40percent as Pemex's exploration activity yielded fewerdiscoveries.

The energy reform was designed in large part to reverseyears of declining crude output by allowing foreign and privateproducers to make their own discoveries.(Reporting by David Alire Garcia;Editing by Dave Graham and Cynthia Osterman)