BP is preparing to launch a procedure as early as Sunday to clog the flow of oil and gas from the month-old Deepwater Horizon spill in the Gulf of Mexico. But the proposed “top kill” method is untested at the 5,000-foot depth of the spill, and could easily join the growing list of fixes thwarted by the spill’s punishingly remote environment. It is also the most invasive maneuver attempted to date, and could rupture the leaking well and actually accelerate the flow of crude.
The potential environmental impact of the spewing oil picked up gravity this week when observers saw the first evidence of oil entering the loop-flow current that washes out of the Gulf and up the eastern side of the Florida panhandle. The oil threatens to foul Florida’s sensitive coral reefs and its tourism economy by the end of May.
Oil containment operations simultaneously gained ground last week as BP installed a tube in the crippled mile-long riser that once linked the Deepwater Horizon rig to its seafloor wellhead. By Wednesday, the ad-hoc Riser Insertion Tube Tool was sucking 3,000 barrels of oil per day into the holding tank of a drilling vessel, cutting releases to the sea by roughly half; the vessel is also flaring off about 14 million cubic feet of captured natural gas per day.
BP’s riser insertion operation marks its first real technology success after a string of high-profile failures. One early effort to suck up spilling crude–a 100-ton steel box lowered over the wellhead–jammed within hours with a frozen slurry of natural gas and seawater. This fiasco followed weeks of fruitless attempts to stimulate the blowout preventer, or BOP, that sits atop BP’s crippled wellhead. Ongoing Congressional investigations last week highlighted design limitations and potential maintenance lapses involving the equipment, which the offshore industry hitherto regarded as a “fail-safe” defense against deepwater spills.
The BOP’s possible design flaws may help explain why it could not stop the flow of oil and gas and save the rig after it lost control of its 18,000-foot well on April 20. Steve Newman, president and CEO of Transocean, Deepwater Horizon’s owner-operator, told a Senate hearing Tuesday that the BOP’s “dead man” mechanisms failed to trigger its rams to pinch off or sheer the drill pipe because the automatic activation mechanisms respond to separation of the BOP from the riser or rig–only the latter occurred, and not until two days after the accident.
Maintenance issues, meanwhile, may also explain the failure of the BOP. A loose fitting on a hydraulic line may have limited the force of the BOP’s rams and crimpers. And shipboard testing of a control panel recovered from the BOP revealed a low battery.
The top kill procedure, if it works, will stanch the flow of oil and ultimately allow workers to cap off the well with two relief wells-but these caps won’t be ready for several months. It will use the BOP’s three-inch-diameter choke and kill lines, which open into the space between the well’s casing and the drill pipe that runs up the riser. The lines are being cut and spliced into hoses connected to the Q4000, a vessel on the surface, whose 30,000-horsepower pumps will drive a dense mix of clay and other substances called kill mud into the lines. If the mud cannot stop the flow of oil, BP says it will be ready with a “junk shot,” in which a mix of materials from shredded rubber to golf balls are pushed into the lines to further gum up the flow paths through the BOP.