Another Chance to Stop the Gulf Leak
But BP’s “top kill” method to stanch the spill could also break it wide open.
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.
Federal officials acknowledge that the top kill carries a risk of breaking open the well or the BOP and exacerbating the spill. “We’re carefully looking at all the pressures involved–what the BOP can handle, what the down-hole [pipe] can handle,” says Lars Herbst, director of field operations in the Gulf for the U.S. Minerals Management Service (MMS), the federal regulator that both sells offshore oil and gas leases and regulates the resulting drilling.
Paul Bommer, a senior lecturer in petroleum engineering at the University of Texas at Austin, says he believes the junk shot will prove necessary. But he also sees it as a gamble–the junk shot could fail to block the BOP and further damage and open up the riser. “The bent riser is the weak link. The riser probably does not have the pressure rating of the BOPs and possibly could rupture,” says Bommer.
Members of Congress called for tighter regulation of offshore drilling this week, and President Obama’s interior secretary, Ken Salazar, announced plans to split the MMS’s offshore oil promotion and permitting functions. Oil and gas drillers, meanwhile, are already adopting more and better technology in a bid to ensure that a current moratorium on issuing drilling permits does not turn into permanent restrictions.
Newman told senators that acoustic triggers should be added to BOPs to enable remote activation. BP documents released by Congressional investigators show that it has initiated subsea testing of the emergency mechanisms on BOPs, hitherto subject to testing only prior to installation on the seabed.
Shell, which is currently drilling seven wells in the Gulf, revealed extra precautions last week for an exploratory drilling program it intends to launch in the Arctic in July. These include doubling the deep-sea safety inspections of their BOP and prebuilding a “coffer dam” to cap blowouts.
Environmental activists are increasing pressure on the Obama administration to require tough environmental assessments before further drilling is authorized. For instance, the Tucson-based Center for Biological Diversity and a former environmental contractor for BP filed a notice of intent to sue the MMS, accusing it of violating federal law by issuing drilling permits for the Gulf without taking account of impacts to endangered species and marine mammals such as sperm whales, bottlenose dolphin, and the Florida manatee.
Center for Biological Diversity senior attorney Myoko Sakashita says the threats are even greater in the Arctic, dismissing as “meaningless” Shell’s promised technology upgrades there: “In the Gulf, the waters are relatively calm and response is nearby. There are no measures that can be taken that would make drilling in the remote, frozen Arctic safe.”