The technology behind the Gulf oil spill disaster

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.

Fairley notes that 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, D.C.-based 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 well will prove insufficient, requiring drilling of a second, adding further delay.

Meanwhile, BP and its industry partners are hatching an array of alternative efforts that have never been tested in ultra-deepwater conditions (1,500 meters or more of water depth). These include:

• placing a funnel-like structure over the leaks and sucking it to a ship on the surface
• pumping chemical dispersants to the leak to break up the oil and keep it from reaching the surface
• crimping the broken riser pipe coming up from the wellhead

Allen says that all of these ideas have promise, but the latter is the more risky since it could interfere with existing crimps in the pipe and actually increase the flow of oil several fold. The flow is very roughly estimated at 5,000 barrels per day currently (although our calculations, based on the amount of oil released so far, show that this figure is conservative. The more likely number is 10,000 or so released into the water each day).

Why were these alternative methods not validated prior to this accident? “It’s something I’m sure we’ll look at,” says Radford.

Fairley writes that while the Deepwater Horizon leaks’ depth is unprecedented, it was not unanticipated. A report by engineering consulting firm URS Corp. in 2002 concluded that “Technologies used in shallow waters are no longer adequate for water depths over 1,000 meters. As a result, the environmental consequences of some of the newer deepwater technologies are not well understood.”

In 2005 petroleum engineering researchers from Texas A&M University suggested that drilling in the “dangerous and unknown” ultra-deep environment required new blowout control measures: “While drilling as a whole may be advancing to keep up with these environments, some parts lag behind. An area that has seen this stagnation and resulting call for change has been blowout control.”

An analysis of incidents in the Gulf of Mexico by the Texas A&M researchers showed that offshore blowouts had continued at “a fairly stable rate” since 1960 despite the use of BOPs. Regulators require inspection of BOPs every fourteen days. BP says it inspected the Deepwater Horizon’s ten days before last month’s blowout.