INGLESIDE — Of the towering oil platforms under construction along the Texas coast, one stands out because it can’t yet stand.
It’s a 23,000-ton cylindrical column the length of two football fields, and it must remain on its side at a noisy construction yard here until it is towed into place in the deep waters of the Gulf of Mexico and hoisted upright. The steel hull is too big to handle any other way.
On a recent weekday, workers welded finishing touches to the 605-foot, 110-foot-diameter structure, a critical component to one of the several new platforms being completed in Ingleside to reach oil reserves in ever deeper and more challenging locations.
The Lucius truss spar is the culmination of a multibillion-dollar project by The Woodlands-based Anadarko Petroleum Corp. to pump up to 80,000 barrels of oil per day from a set of Gulf wells under about 7,100 feet of water.
The project would have seemed unreasonable a decade ago.
But as recent advances in imaging technology allowed geologists to more clearly scan rock layers beneath the seafloor, oil companies have been able to find extensive reserves in obscure locations. They’ve engineered advanced platforms to extract these reserves and engaged thousands of workers across multiple continents to get the projects done.
At Ingleside, one of those solutions is approaching completion. With sparks flying and saws screeching, crews there assembled the layers of decks that will sit atop the Lucius spar.
Once all pieces of the spar platform are completed, Anadarko will ship the hull into position about 274 miles southeast of Galveston, then flood its steel tanks with water to flip it vertically, a process that takes 24 hours because of the sheer size of the equipment.
Enormous seagoing cranes will hoist the topside decks and lower them onto the spar, finishing the assembly of a floating island that will be able to withstand hurricanes and 90-foot waves while staying attached to oil wells under more than a mile of water.
“We have a lot of people who have done this over and over, so they have learned from the experience,” said Darrell Hollek, senior vice president of Gulf of Mexico operations for Anadarko, which pioneered spar technology and has six spars in operation.
(Photos by Houston Chronicle photographer Melissa Phillip and courtesy of Anadarko Petroleum)
Atop a steel column
The company plans to add the Lucius spar and one called Heidelberg to its fleet of platforms by 2016, bringing two of its most advanced facilities into the deep Gulf.
Unlike most offshore production facilities, spar platforms float on singular steel columns, rather than atop an assortment of floating pontoons or on large ships.
The technology has helped oil companies produce in some of the deepest and most challenging offshore locations.
The world’s deepest producing offshore well, for example, is managed by Royal Dutch Shell’s Perdido spar platform. The Perdido spar is fixed like a floating island in about 8,000 feet of water and taps into a well 9,596 feet below the surface of the Gulf of Mexico.
“We really like the spar,” said Don Vardeman, vice president of worldwide projects for Anadarko, which expects to have eight spars operating by 2016. Murphy Oil Corp. has the next most, with three spars in operation.
When Shell chose a spar for Perdido, engineers felt the platform type would give it more stability. That was especially important because Shell wanted the ability to drill wells from the same platform it was using to extract oil, said Martijn Dekker, who helped plan the Perdido spar and is the business opportunity manager for Shell’s planned ultra-deepwater Stones project.
“If you want to drill from a platform, that’s got to be pretty stable,” Dekker said.
Anadarko’s Lucius is equipped with a truss section that includes a set of heave plates that help hold the vessel in place. Those plates work to align the vessel with more calm currents underwater, even as surface currents begin crashing high against the hull, Vardeman said.
Spiralling finlike strakes wrapped around the spar hull also help to reduce movement, said Jenifer Tule, project manager for the Lucius spar.
“When you have a current coming across the facility, it breaks the direction, breaks the flow of the water and disperses it around the facility, thus dampening the effects of vortex-induced motions or vibrations,” Tule said.
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The improved stability helps equipment and personnel operate more efficiently, Vardeman said. For example, machinery that separates natural gas from oil can work faster when the movement of a platform isn’t stirring up the material.
Spars can overcome that challenge because they have relatively low amounts of vertical motion, Vardeman said.
The cost factor
Anadarko’s spar preference also has to do with costs. The more the company uses spars, engaging the same stream of contractors and refining similar designs, the lower its costs become.
“We really understand these structures very well,” Vardeman said.
While tension-leg platforms have provided stability and boosted production capacity to other companies, they are not suited for waters more than a mile deep. That’s because they maintain their positioning and minimize movement by using legs that extend to the seafloor and pull down against the vessel’s buoyancy.
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Those legs become too expensive when producing from the deepest oil fields in the Gulf of Mexico.
Nor is the spar the best solution for all ultradeep-water offshore wells. Even Anadarko has turned to other solutions in waters more than a mile deep. The company’s
Independence Hub semisubmersible is the world’s deepest operating platform of that kind, working in 7,920 feet of water.
When making a decision on a platform, oil companies weigh the advantages of different options based on the availability of mooring points on the seafloor, the regional ocean characteristics, well development plans and the types of resources being pursued, among other concerns.
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