The unabated flow of crude oil from a well off the Louisiana coast speaks to “the tyranny of distance and the tyranny of depth,” according to Coast Guard Admiral Thad Allen, named by President Obama last week to be national incidence commander to take control of the response effort from BP.
Allen has expanded already extensive efforts to disperse, skim, and block the oil that is surfacing from the well blowout that destroyed the Deepwater Horizon drill rig last month. But he told a media briefing this weekend that his top job is stopping the flow of new oil into the sea–a complex and risky process at the one-mile depths where Deepwater Horizon drilled.
The oil leak also reveals an overreliance on one piece of equipment that academic and industry experts have warned of for close to a decade: The blowout preventers, or BOPs, that are the industry’s primary line of defense against deepwater oil spills.
Industry experts say BOPs will be front and center in a review of offshore drilling technology ordered by Obama last week, to be completed this month, prior to authorizing any further drilling. “A thorough review and technology change is likely coming now,” says Paul Bommer, a senior lecturer in petroleum engineering at the University of Texas at Austin.
The Deepwater Horizon’s BOP is a 450-ton set of hydraulic rams that straddles the wellhead, just above the seabed. When the well blew out last month, sending oil and natural gas up the well, signaling from the rig operators or loss of communication with the surface should have automatically released pneumatic pressure stored in the BOP’s tanks, driving it to mechanically crimp or shear off the well pipe and close off the well.
BP has been using remotely operated vehicles in a hitherto vain effort to activate Deepwater Horizon BOP’s control system’s valves. Some experts say that the Deepwater Horizon BOP’s lack of a signaling device called an acoustic trigger, which enables remote control of some rigs’ BOPs, probably had no impact in this case. Bommer says an acoustic trigger would simply have sent the same signal that the remotely operated vehicles are now delivering, albeit several days earlier.
A second rig has been positioned at the leak site to commence the industry’s only proven fallback measure once an undersea well has blown out: bypassing the BOP by drilling a new well or wells to intersect with and then block the leaking well. Unfortunately drilling a relief well will take two to three months.
The delay does not stem from the need for high-precision. Intersecting a seven-inch-wide pipe from several miles away is well within the telemetry capabilities of offshore drill rigs. Rather, the well will take months because of its depth: BP is planning to drill through 18,000 feet of rock to reach down close to the bottom of the leaking well.
Andy Radford, a petroleum engineer and senior policy advisor for offshore issues at the American Petroleum Institute, a Washington trade group, says BP needs to drill deep to create a relief well with sufficient mass to counteract the force of flowing oil. “You have pressure coming up the well from the producing formation. It’s thousands of pounds per square inch coming up the hole. You need to be able to overcome that pressure with the kill fluids. The deeper you intersect, the less pump pressure you need to overcome the pressure of the well coming up,” says Radford.
In a worst-case scenario, the force of one relief wells will prove insufficient, requiring drilling of a second, adding further delay.