HAVANA - Cuba is moving fast to try to tap subsea oil wealth, and will start work in "days" with Russia's Zarubezhneft, drilling this country's deepest offshore well yet, state oil firm Cubapet said Saturday.

"Cubapetroleo reports that (Norwegian-owned) semisubmersible platform Songa Mercur has arrived offshore off the north-central coast to continue in a matter of days offshore exploratory well-drilling work," said a statement in Granma, the Communist Party of Cuba's newspaper. The Norwegian-owned machinery run in partnership with the Russian company will tap exploratory well L-01X, down to 6,500 meters (21,325 feet), the deepest drilled to date in Cuba. Work is expected to go on for about six months, the statement added.

Songa Mercur is replacing the Italian-owned Scarabeo 9, which was used but failed to strike usable crude three times. The nearby United States voiced concerns about potential for catastrophic environmental damage in the event of an accident, in Cuba's still untested industry.

Energy is Cuba's Achilles heel, and it relies heavily on close ally Venezuela and its Socialist President Hugo Chavez for its cut-rate supplies. With Chavez, 58, recovering from more cancer surgery here, Cuba has never been in as big a hurry to try to achieve energy independence.

Some studies estimate the 112,000-square-kilometer area has probable reserves of between five and nine billion barrels of crude oil, though Cuban authorities say there could be as many as 20 billion barrels.

Cuba produces oil from wells on land and in shallow water, but they are reaching their capacity limits. It also imports 100,000 barrels of oil a day from Venezuela, which supplies oil to Cuba on easy terms. If it finally accesses its suspected oil assets, Cuba -- which is larger than Portugal and has just 11 million people -- could go from a dirt-poor Communist Cinderella to an oil-rich Caribbean power almost overnight.

A shock loss of Venezuelan support and its economic importance to Cuba could endanger the Americas' only one-party Communist regime.

But sudden oil wealth almost certainly would stabilize and fund the current regime well into the future, much to the chagrin of the United States, which also is missing out on energy and environmental partnerships.

The Cuban report said Cupet experts inspected the Norwegian platform to guarantee environmental safety. It said international firm ModuSpec inspected it to guarantee less than 10 percent of its parts were from the United States due to the more than 50-year-old US trade embargo on Havana.

Cuba's economic zone in the Gulf of Mexico was divided into 59 blocs, 22 of which were put under contract to companies from Angola, India, Malaysia, Norway, Russia, Spain, Venezuela and Vietnam.