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'Top Hat' Should Be In Place This Week

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Deepwater Horizon Gulf of Mexico Oil Spill

A smaller version of the containment dome should be operational by the end of the week, BP executives predicted Monday during afternoon press conference at the company's Houston offices and at a Unified Command center north of New Orleans.

All In One Rather Than Piece-By-Piece

"We will bring it in operationally," said Kent Wells, BP's Senior Vice President of Exploration and Production, of the so-called top hat structure that will be lowered over the primary leak source. Speaking to reporters from Houston, Wells explained that the dome will be deployed already connected to the riser system.

Measuring four feet in diameter and five feet tall, the smaller "top hat" will be lowered over the primary leak point by the drillship one pipe at a time. In contrast, the large cofferdam that became clogged with hydrates over the past weekend was lowered by crane from another vessel.

Doug Suttles, BP's Chief Operating Officer based at the Louisiana site, said that the top hat -- like the larger containment dome -- is designed to channel the flow of crude oil up through the riser system to the drillship Discoverer Enterprise. Unlike the larger dome, however, the smaller dome will have much less space for seawater to enter and facilitate hydrate formation -- at least that is BP's rationale.

Suttles added that the injection of methanol, along with sending heated water down through the risers from the drillship, should aid in keeping the slushy crystals at bay. The smaller dome is undergoing modifications at Port Fourchon, La., before deployment later this week.

The top hat technique is intended to serve as a temporary solution because it would control oil flow and not actually stop it. The "junk shot," or "top kill," technique is meant to accomplish the latter task.

Wells said the junk shot method has been applied worldwide -- most notably in Kuwait following the first Gulf War  -- but never at 5,000 feet below sea level. It will involve shooting ground up golf balls, tires, and other materials into the choke and kill line of the blowout preventer and then inserting heavy fluids and cement; the idea is to push the oil back into the reservoir. Top kill operations are expected to begin in the next two to three weeks.

A 'Small Army'

 Wells pointed that the top hat and top kill/junk shot approaches, along with other strategies such as injecting two relief wells to intersect and plug up the original wellbore above the oil reservoir, are meant to complement each other. He said that an international "small army" of technical and operational experts from across industry and government has been assembled at BP's Houston office to collaborate on ideas to control the flow and stop the leakage.

"We want to have multiple options coming out simultaneously," Wells said. "We're designing for every option to be successful and we're planning for failure."

BP Chief Executive Tony Hayward, who was present for a portion of the Houston press conference, added that the initial failure of the cofferdam approach has provided a better idea of the amount of natural gas present in the crude oil. In addition, he expects that the massive response to the industry's first-ever blowout at such a great water depth will have lasting effects on areas such as well intervention and redundancy.

"There is a lot of real-time learning going on," Hayward concluded.

More info on the Deepwater Horizon Gulf of Mexico Oil Spill


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