This story is by David Hammer and Mark Schleifstein
Powerful puffs of natural gas, called kicks, are a normal occurrence in many deep-ocean drilling operations.
But one intense kick of natural gas caused the Deepwater Horizon drilling rig to be shut down because of the fear of an explosion just weeks before a similar release succeeded in destroying and sinking the platform and sent millions of gallons of oil on a collision course with Louisiana and the rest of the northern coast of the Gulf of Mexico.
Shortly before the accident, engineers argued about whether to remove heavy drilling mud that acted as a last defense against such catastrophic kicks, and the decision to replace the mud with much lighter seawater won out.
Those are some of the new details gathered by Robert Bea, a University of California at Berkeley engineering professor better known in New Orleans as co-leader of an independent team of scientists that conducted a forensic investigation of the causes for the failure of levees and floodwalls during Hurricane Katrina.
In an effort to piece together the cause of the region's most recent calamity, Bea has been gathering statements, transcripts and other communications from about 50 people since the accident, including workers on the rig, engineers who worked with the rig from onshore locations, and engineers and oilfield workers who have been active in drilling for decades.
"As the job unfolded, ... the workers did have intermittent trouble with pockets of natural gas," said one statement sent to Bea. "Highly flammable, the gas was forcing its way up the drill pipes. This was something BP had not foreseen as a serious problem, declaring a year earlier that gas was likely to pose only a 'negligible' risk. The government warned the company that gas buildup was a real concern and that BP should 'exercise caution'".
A second statement said, "At one point during the previous several weeks, so much of it came belching up to the surface that a loudspeaker announcement called for a halt to all 'hot work', meaning any smoking, welding, cooking or any other use of fire. Smaller belches, or 'kicks,' had stalled work as the job was winding down" in the days before the accident. Bea said he could not name the people who gave the statements or reveal their positions.
Chilling image of explosion, chaos on rig
The material paints a chilling image of the violent force of the rig explosions and the chaos that ensued as rig workers tried to escape spewing mud, seawater and methyl hydrates in the form of icy slush. That same type of frozen natural gas blocked BP's attempts during the weekend to control the well leak with a huge box lowered 5,000 feet to the sea floor.
Back on April 20, the slush forced its way to the rig, shot 240 feet in the air and heated into a gas that quickly ignited into fireballs, Bea's witness accounts say. Among those tossed asunder by the explosions were BP officials who were on the rig to celebrate a seven-year spotless safety record.
Bea also said the statements he has gathered back up a report last week by The Times-Picayune about the questionable choice made by oil giant BP, rig owner Transocean and others to remove heavy drilling mud that was supposed to help tamp down destructive gas kicks.
The witness statements add to the story's clarity just as the Coast Guard and Minerals Management Service begin hearings Tuesday at a Kenner hotel to try to determine what went wrong. The civil courts may provide another vector for understanding the accident, as lawyers continue to file suits against BP, Transocean and other companies connected with the Deepwater Horizon. Among the defendants in those suits: Halliburton, a contractor responsible for installing key cement barriers that were supposed to keep gas out of the well in the first place, and Cameron International, the manufacturer of the blowout preventer valves that were supposed to be a last-ditch way to shut off the well, but failed.
Risk assessment questions raised
Bea believes the narrative he is creating raises serious questions about the risk assessments used by BP and the Minerals Management Service, the federal agency charged with determining whether the drilling plans were adequate.
They failed to address what's called "residual risk," those things that planners don't think will fail. And in doing so, they underestimated the risk in ways very similar to the engineers who designed New Orleans' levee system, Bea said.
"BP fell into the same damn trap, and they were not engineering; they were 'imagineering,'" he said. "Risk analysis continues to mislead us because we're only looking at part of the risk.
"The same trail of tears led to Katrina, to the Massey Big Branch (coal) mine disaster, and it's showing up here again," Bea said.
"For me, the tragedy of Katrina was floating bodies and the homes and businesses that were destroyed," he said. "This time, it's different. Certainly the people on the rig were killed and the pieces of equipment were destroyed, but like Katrina, there's another non-voting population getting hurt this time and it is those marine animals that are our equivalents."
Frequent gas kicks reported
Bea said he has spent more than 200 hours reviewing first-hand reports of the Deepwater Horizon's operations. A constant theme was that gas kicks were more frequent in this oilfield than others the crew had worked on, and members were concerned.
The situation was particularly tense a few weeks before the accident, when the exploratory drill had made it down the 5,000-foot riser pipe from the rig to the sea floor and penetrated more than halfway down to the oil that awaited some 18,000 feet below that.
"One gas kick that occurred as they got toward the bottom of the hole, approximately 10,000 feet below the sea floor, was such a large gas kick that they had to shut down operations," Bea said. "They were concerned about spark sources (on the rig at the surface) so they had to shut it down, because there was so much gas coming out of the rig and they were afraid of the explosion."
Deposits of oil are not in underground caverns; they ooze in the pores of a sponge-like layer of rock, along with natural gas in both gaseous and the crystallized hydrate forms. But the hydrates also exist throughout the drilled rock formations, and like the oil below, they exert upward pressure when a drilling operation opens a path to the surface.
In the incident that forced Deepwater Horizon to shut down drilling temporarily, workers in the rig's drilling mudroom stabilized the situation by putting a heavier form of "mud," actually a mixture of clay and chemicals, into the drill-pipe as a counter-balance, pushing down against the upward pressure of the gas, Bea said.
A transcript Bea collected from a witness says the companies were confident enough they had a lucrative oil source that they decided to convert from an exploratory well to a more permanent production well, a process that requires them to apply a metal and cement casing to the well hole. They chose casing 7 inches in diameter, Bea said, and that was further sealed with cement pumped in by Halliburton. Bea said his sources reported that Halliburton was using a "new" kind of cement for the seal, something the scientist said made him say, "Uh oh."
"The cement is infused with chemicals and nitrogen, and those chemicals and nitrogen form a frothy cement that is like shaving soap sprayed from a can," Bea said. "It was put in there because of the concern about damage or destruction of the seals by methane hydrates."
The crew on the Deepwater Horizon waited 20 hours for the cement job to cure before opening a key valve at the wellhead so they could place a final cement plug about 5,000 feet down the well. Bea gives Halliburton credit for writing "many excellent papers" in the past two years about the challenge of setting cement seals in the presence of large amounts of methane hydrates, which the Deepwater Horizon crew encountered in spades.
"Because of the chemicals they've added, they think the cement can cure rapidly," Bea said.
But Halliburton's awareness of cementing's challenges did not stop the cement from failing in the Deepwater Horizon's well. The chemicals they added for the curing process also create a lot of heat, which can thaw the methane hydrate into the gas that causes dangerous kicks, Bea said.
"I call that 'Uh oh' again," he said.
A heated debate described
One of Bea's witness transcripts describes in detail a heated debate among BP, Halliburton and Transocean officials as they are about to add the final cement plug to the well, 5,000 below the wellhead and 10,000 feet below the rig. They argued about whether to set the plug with drilling mud still in the well and riser, or if they should do it with lighter sea water there instead.
As The Times-Picayune reported last week, Bea's witness claims the decision was made to displace the heavy mud barrier with water before the final plug was set in order to finish the job more quickly.. The crew was planning to temporarily abandon the well, and before leaving, they would need to remove the riser and the blowout preventer, a massive stack of valves and slicing rams that are supposed to shut off the well in case of an emergency, and some time later another operation would re-tap the well to extract its riches.
The mud in the riser would have to be replaced with salt water before the crew could take the final step of removing the blowout preventer, or else polluting mud and chemicals would spill into the sea, angering environmental regulators. But based on Bea's witness, who describes the debate on board the rig and with officials in Houston, there was still a question about whether to replace the mud before the final plug was set.
"The debate comes back that it's been pressure-tested, the coast is clear, so they will displace the upper 10,000 feet of heavy mud and replace it with salt water," Bea said. "This is a crucial step, and the reason it's crucial is if the seal at the bottom is fine, it's OK, but if it's not OK, we're screwed. We don't have enough pressure (from mud) in the column anymore to fight the reservoir (gas and liquid) pressure."
Bea says it's unclear how far down the well the crew managed to get the final cement plug before the destructive blowout. But he said it's clear the process was under way because an important valve in the blowout preventer stack, called the annular valve, was open to allow the plug assembly pipes through. Once the well's lining or bottom plug was breached, the gas had a 10,000-foot path clear of both mud and shut-off valves all the way to the water's surface.
'A geyser of water'
Three witness reports gathered by Bea describe what happened next. "A geyser of water" shot 240 feet into the air, he said, followed by "gas that spills out in the moon pool area, onto the drill deck and begins spreading. They can smell it, they can see it, but in this stage it does not ignite. It looks like ice slush, and they can see the gas emanating from it."
The next thing workers on the drill floor saw was mud, the three accounts say. The workers know there's trouble because the mud can only be coming from 10,000 feet down, not from the riser where it can block a gas kick, Bea said.
"At this point, calls come from the rig asking for more mud," Bea said the transcripts show. "I'm certain these radio calls will ultimately be traced and produced. This is at 7 p.m."
The reason nothing ignited initially is that the 21-by-93-foot moon pool, a well in the center of the drill ship, is carefully designed to remove any sources of sparks. But in the mud room and the galley and elsewhere, there are pumps with exposed metal parts. Soon, the gas did ignite when it came in contact with those, Bea said, and the descriptions in the transcripts are dramatic.
Bea said that the first explosion occurred in the mud pit room, a room where drilling mud is mixed and stored in big bins. The two engineers responding to requests for more mud in an attempt to control the runaway well were killed instantly, he said.
That explosion also blew out the wall leading to the galley, where a party was being held.
"The party is to celebrate the Transocean Deepwater Horizon going for seven years without an accident," Bea said. Present were several BP engineers or executives, who traveled to the rig for the celebration, he said.
'Here's where I broke down ...'
"The explosion hurls them against the other wall" of the galley, Bea said. "Here's where I broke down when I read it.... It describes bodies being broken, necks gashed and people bleeding, and now everybody's in the dark. People are screaming for help. People are busy helping their comrades get to two lifeboats.
"People in the lifeboats are screaming, 'We've got to get out of here!' but the lifeboats aren't full," Bea said. "The doors slam and they drop the (lifeboats), and as they do, they can see some of their colleagues jumping into the sea. They can see their outlines because the rig is burning behind them.
"Back on the drill floor, all hell has broken loose. Explosions are propagating from the mud pit room back toward them," Bea said. "At that point, one transcript that's obviously been an observer heading toward the lifeboats says the drill floor disappears in a ball of flame. And at that point, the three on-board transcripts stop."
Bea said the concluding paragraph from one of those observing the explosion summed up the depth of the failure.
"In order for a disaster of this magnitude to happen, more than one thing has to go wrong, or fail. First, a shitty cement job. The wellhead packoff/seal assembly (the equipment directly below the blowout preventer that connects the lower pipe casing to the preventer) while designed to hold the pressure, is just a backup. And finally, the ability to close the well in with the BOP somehow went away," the witness said.
David Hammer can be reached at firstname.lastname@example.org or 504.826.3322.
Mark Schleifstein can be reached at email@example.com or 504.826.3327.