Now he had to cope with a wild, seemingly unstoppable gusher in conditions that had no precedent. The pressure readings the technician was calling out stopped dropping at roughly 6,000 psi, meaning that the flowing oil was successfully pushing back against the pump engine's 30,000 horsepower. The pressure readings just wouldn't drop—even when BP tried again with denser mud.
By May 27, it had become clear to even its main supporters like Tony Hayward that the top-kill attempt had failed. And by the end of the weekend, BP had new overseers. Chu killed top kill on May 28, worried that BP's efforts would cause a subsurface blowout and make the gusher impossible to control.
By mid-June, Chu wrote an e-mail to his team, including physicist Richard Garwin, who had helped invent the hydrogen bomb as well as cap burning oil wells after the Persian Gulf War, and Tom Hunter, former director of Sandia National Laboratories in New Mexico. Quoting Gregory Peck in The Guns of Navarone, Chu wrote: "Your bystanding days are over! You're in it now, up to your neck! They told me that you're a genius with explosives. Start proving it!" Of course, Chu quickly noted that explosives—despite calls for the U.S. Navy to bomb the well shut, with nukes if necessary—were not likely to be useful "on this mission…the rest rings true."
What finally worked
Despite Chu's oversight, BP remained in charge of critical information flowing from the deep-sea blowout. Chu's team had to know what to ask for and request it specifically in order to get their hands on data. The government scientists got enough information to give their blessing to BP's "top hat" approach, which—taking a lesson from the failed cofferdam—boasted circulating methanol to prevent methane-filled ice from forming. By June 3, the top hat was capturing roughly 15,000 barrels a day—or three times early estimates, and the upper threshold after which BP's Tooms had calculated "top kill" would fail—with no discernible impact on the flow of oil into the ocean.
Even when BP began pumping oil and gas through a line from the blowout preventer to the Q4000 well-servicing ship—at Garwin's suggestion—the flow of oil into the sea remained undiminished. The Q4000, which had pumped the mud for top kill, had specially designed flares for oil and gas that enabled BP to burn off as much as 10,000 barrels a day—bringing the total amount of oil prevented from flowing into the sea to as much as 25,000 barrels a day at times. Because this containment still failed to show any visible improvement in the amount of oil flowing from the wellhead, Secretary Chu's back-of-the-e-mail math suggested that at least 40,000 barrels a day must be gushing from the well.
What finally worked on July 12 was a smaller blowout preventer installed atop the failed blowout preventer at the well's head on the seafloor, replacing the top hat. This "capping stack" had risks, however, such as creating the kind of subsurface blowout that would end up draining all the estimated 110 million barrels of oil in the entire formation. But government scientists calculated the flow would have to be 100,000 barrels per day—or nearly twice as much as it actually was (roughly 50,000 barrels per day)—for that risk to be realized.