Gulf of Mexico's Tahiti is an island of steel

Mar 19, 2007 01:00 AM

by Kristen Hays

Soon there will be more than one Tahiti in ocean waters, but this one won't be a romantic Pacific honeymoon destination with white sand beaches and mesmerizing waterfalls.
Instead, this Tahiti will be Chevron's 100,000-ton island of high-powered steel and iron floating in 4,000 feet of water in the Gulf of Mexico.

The company aims to place Tahiti above its oil field of the same name about 190 miles south of New Orleans this summer and, by mid-2008, begin producing 125,000 barrels of oil each day from more than 20,000 feet below the seabed.
"We have a long way to go, and we have many challenges between us and first oil," Tim Mitchell, facilities manager for Chevron's Tahiti platform, said after a recent tour of its massive decks that are in the final phases of construction.

Tahiti's journey from discovery to production -- like that of platforms run by other companies -- has been a multi-year process. In April 2002, San Ramon, California-based Chevron announced that an exploratory well drilled more than 4 miles below the seabed found oil at its Tahiti prospect. Upon further assessment, the company estimated that up to 500 mm barrels of oil could be recovered.
About one-fourth of the nation's oil comes from the Gulf. So Chevron began awarding contracts to design, engineer and build all the parts for the massive structure with an eye toward turning on all the production switches by next year.

Wall Street is watching. Tahiti is one of several long-term production projects Chevron aims to get on line next year.
"We consider 2008 to be the make or break year for Chevron in terms of the street's perception, given the large number of project start-ups," Merrill Lynch & Co. oil analyst John Herrlin said in a report this month. "Should they become 2009 events, we believe Chevron stock could languish. At this stage, management has been given the benefit of the doubt," Herrlin said.

Tahiti Power and Light
Like other platforms, Tahiti will be a mini-city that doesn't sleep. One of its five main levels will house three gas turbine generators with enough juice to power 30,000 homes, which Mitchell jokingly called "Tahiti Power and Light."
Its living quarters will be able to house up to 100 people. It also will have oil and gas processing equipment, but no onboard drilling rig. Travelling rigs or drillships will handle any of those needs. Altogether, Tahiti's price tag will reach $ 3.5 bn, with Chevron at the wheel and partners Total of France and Norway's Statoil along for the ride.

But much remains to be done before Tahiti begins production. The decks, dubbed "topsides" with a combined area of about three acres, are in Gulf Marine Fabricators' massive construction yard in Ingleside, about 200 miles southwest of Houston.
The spar hull, a 555-foot-long single steel cylinder and truss equivalent in height to the Washington Monument, is under construction by Paris-based Technip in Pori, Finland.

More contractors
More contractors are building other critical parts, including the steel flowlines that carry oil and gas from the seabed to the platform; a series of manifolds, or huge boxlike structures that sit on the seafloor and control the flow of oil and natural gas from multiple wells; and umbilicals, or hydraulic hoses used to control subsea structures like manifolds from the platform.
Standing next to one of the deck modules at Ingleside, Tahiti topsides construction manager Martin Jackson pointed at a near-empty "workshop" that looks like a gigantic aircraft hangar. In the beginning, construction took place there, under a roof. Now construction is outside, rain or shine.
"We're 85 % complete on the job, so the work has migrated. There's very little work left to be done in the workshop," Jackson said.

Still, sounds of welding and pounding on pipes resonate as visitors walk up and down the stairs of the decks. The living quarters have yet to be delivered and placed on the top deck. And jutting into the sky like missiles are two bright yellow "king posts," on which platform cranes will be placed to eventually move food and other cargoes from boats to the platform and back.
The hull and topsides will be towed separately on barges to the Gulf this summer -- preferably in early summer, Mitchell said. The hull will be unloaded first so its 13 mooring lines can be tethered to steel piles driven into the seafloor.

Then the topsides will be lifted and placed onto the top of the hull by Netherlands-based Heerema's Thialf heavy lift vessel, essentially a floating supercrane more than capable of lifting Tahiti's heaviest component -- its 9,200-ton production module.
Tahiti itself cannot accommodate all the people needed for the ensuing months-long offshore installation and hook-up. So a floating hotel -- in offshore lingo, a "flo-tel" -- will house more up to 400 people at a time -- two-thirds of Tahiti's anticipated offshore workforce at the peak of preparations. Shell brought in a similar structure to house hundreds of workersneeded to repair its Mars oil platform from damage wrought by Hurricane Katrina in 2005.

Rigorous tests
Before, during and after installation in the Gulf, Tahiti's components must ace rigorous tests to ensure problem-free operation of all systems, from oil and gas flowlines to turbines to computer-run controls. But problems can erupt. London-based BP's Thunder Horse platform has endured repeated delays since being placed in the Gulf about 150 miles southeast of New Orleans in 2004.
Thunder Horse originally was slated to start producing up to 250,000 bpd in 2005. Hurricane damage in 2005 and failure of a manifold during testing last year pushed start-up to 2008. So far everything is on schedule for Tahiti, but Mitchell said some bumps are always expected -- particularly when dealing with such intricate systems in the harsh, high-pressure deepwater environment.

Never enough
“We have spent literally years preparing for what is coming next, but in our business it's never enough. Weplan and prepare, we develop contingencies and we react to day-to-day obstacles or problems," Mitchell said.
"Our success will lie in our ability to execute our plans and in how we respond to adversity," he said.

Source / Houston Chronicle
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