HOUSTON, Aug 14 (Reuters) - An oil production

breakthrough that producers say can safely tap ultra-high

pressure fields could put up to 5 billion barrels of previously

inaccessible crude into production, analysts said.

Chevron ( CVX ) on Monday disclosed it had pumped first oil from a

field at 20,000 pounds per square inch pressures, a third

greater than any prior well. Its $5.7 billion Anchor project

employs specially designed equipment from NOV, Dril-Quip ( DRQ )

and drillships from Transocean.

The No. 2 U.S. oil firm began pumping from the first Anchor

well on Sunday, with the second already drilled and close to

being ready to turn on, said Bruce Niemeyer, head of Americas

oil exploration and production.

A 2010 blowout at Gulf of Mexico's Macondo prospect killed

11 workers, fouled fisheries and covered area beaches in oil.

Transocean was the operator of the ill-fated Deepwater

Horizon vessel and BP was the owner of the Macondo

project. Both are involved in the new, higher pressure well

developments.

Today, the industry is employing new drillships and

equipment that has been created to cope with the extreme

pressures that are a third greater than encountered in the

Macondo failure.

"The industry has done their bit to safely deliver the

barrels, with the new technology," said Mfon Usoro, a principal

analyst who focuses on Gulf of Mexico operations at research

firm Wood Mackenzie.

The new gear promises Chevron's ( CVX ) Anchor and similar projects

by Beacon Offshore Energy and BP will deliver a combined 300,000

barrels of new oil, and put 2 billion barrels of previously

unavailable U.S. oil within producers' reach, she said.

"These ultra-high pressure fields are going to be a big

driver for production growth in the Gulf of Mexico," Usoro

added.

The Gulf of Mexico has produced below the record 2019

level of 2 million barrels per day, and the additional oil could

help return the region to its peak output.

BP has its own high-pressure technology it hopes can tap 10

billion barrels of known oil. Its first 20k project, Kaskida,

was discovered in 2006 and put aside because of a lack of

high-pressure technology.

Similar high-pressure, high-temperature oil fields that

would benefit from the 20k technology are found off the coasts

of Brazil, Angola and Nigeria, said Aditya Ravi, a Rystad Energy

analyst. The Gulf of Mexico will be the proving ground for the

new gear.

Brazil has major offshore developments that "are prime

candidates for future 20k technology application due to their

complex high pressure, high temperature environments," he said.

Including non-U.S. fields, more than 5 billion barrels of

known oil and gas of known resources globally could benefit from

the technology, Ravi said. Those volumes equate to about 50 days

of current global production.