BP robots hit snag while sawing pipe

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BP Plc has hit a snag in its attempt to saw through a riser pipe in a risky operation to funnel leaking oil from a blown-out well to the surface, the top U.S. official overseeing the effort said on Wednesday.BP's undersea robots in the Gulf of Mexico succeeded in making a shear cut to the pipe, but the robot's diamond-tipped saw blade became stuck inside the pipe while attempting a second cut, said Coast Guard Admiral Thad Allen, speaking to reporters in Schriever, Louisiana."They're working to move the riser pipe to set it free," Allen said. "The goal is later on today to finish that cut, and to be able to put a containment device over the top of the wellhead."The operation is BP's latest attempt to contain the leak, estimated by U.S. scientists to be up to 19,000 barrels (800,000 gallons or 3 million litres) a day. BP's "top kill" attempt to plug the well failed on Saturday, and the London-based energy giant is also drilling two relief wells that won't be completed until August.Late Tuesday, underwater robots used massive shears to slice a pipe, known as a riser, at the top of a lower marine riser package, or LMRP.If the saw is freed and finishes the job, BP aims to place a containment cap with a rubber seal over the gushing opening to funnel most of the oil. A pipe attached to the top of the cap would transport captured oil and gas to a drillship on the water's surface, a mile (1.6 km) up.An underwater camera feed showed huge clamps trying to jiggle the riser and free the saw.BP must make two cuts to the riser pipe, with the second key to ensuring that BP gets a clean seal between the pipe and the containment dome."The cleaner the cut, the tighter the seal we can make on it," Allen said, enabling BP to capture more oil and funnel it to the surface. A jagged surface could foil the seal and allow more oil to escape, he said.In that instance, BP can use a larger box-shaped containment dome already at the seabed known as a "top hat." BP spokesman Robert Wine told Reuters that other containment domes of various sizes and different types of seals are being constructed -- or shipped to the site if already built -- as backups."We've got various designs of cap to put down depending on how clean the cut is," Wine said. "There are various options to get the best fit and capture."Allen said if the saw can't be freed, BP may have to deploy a second saw to finish the job. "They're looking at that as we speak," he said mid-morning.Allen said BP is spraying dispersants at the leak site to try to break up the oil leaking.Allen said U.S. officials don't anticipate the leak's flow to increase until the second cut is finished. (Additional reporting by Chris Baltimore, editing by Philip Barbara)
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