Undersea robots tried to thread a small tube into the jagged pipe that is pouring oil into the Gulf of Mexico on Friday in BP's latest attempt to cut down on the spill from a blown-out well that has pumped out more than 4 million gallons of crude.
Company engineers were trying to move the 6-inch tube into the leaking 21-inch pipe, known as the riser. The smaller tube will be surrounded by a stopper to keep oil from leaking into the sea. BP said it hopes to know by Friday evening if the tube succeeds in siphoning the oil to a tanker at the surface.
Since an April 20 drilling rig explosion set off the catastrophic spill, BP PLC has tried several ideas to plug the leak that is spewing at least 210,000 gallons of oil into the Gulf a day. The size of the undulating spill was about 3,650 square miles, or the size of Delaware and Rhode Island combined, said Hans Graber, director of the University of Miami's Center for Southeastern Tropical Advanced Remote Sensing.
In the fateful hours before the Deepwater Horizon exploded about 50 miles off the Louisiana shore, a safety test was supposedly performed to detect if explosive gas was leaking from the mile-deep well.
While some data were being transmitted to shore for safekeeping right up until the blast, officials from Transocean, the rig owner, told Congress that the last seven hours of its information are missing and that all written logs were lost in the explosion. Earlier tests that suggested explosive gas was leaking were preserved.
The gap poses a mystery for investigators: What decisions were made -- and what warnings might have been ignored?
"There is some delay in the replication of our data, so our operational data, our sequence of events ends at 3 o'clock in the afternoon on the 20th," Steven Newman, president and CEO of Transocean Ltd, told a Senate panel. The rig blew up at 10 p.m., killing 11 workers and unleashing the gusher.
Houston attorney Tony Buzbee, who represents several rig workers involved in the accident, questioned whether what he called "the phantom test" was even performed.
"I can just tell you that the Halliburton hands were scratching their heads," said Buzbee, whose clients include one of the Halliburton crew members responsible for cementing the well to prepare for moving the drilling rig to another site.
Details of a likely blowout scenario emerged this week for the first time from congressional and administrative hearings. They suggest there were both crew mistakes and equipment breakdowns at key points the day of the explosion.
Buzbee said that when Halliburton showed BP PLC and Transocean officials the results of the pressure tests that suggested gas was leaking, the rig workers were put on "standby." BP is the rig operator and leaseholder.
Buzbee said one of his clients told him the "Transocean and BP company people got their heads together," and 40 minutes later gave the green light.
The attorney said the Halliburton crew members were not shown any new test results.
"They said they did their own tests, and they came out OK," he said. "But with the phantom test that Transocean and BP allegedly did, there was no real record or real-time recordation of that test."
None of the three companies would comment Thursday on whether any data or test results were purposely not sent to shore, or on who made the final decision to continue operations that day.
Five thousand feet under the sea, the effort to thread the smaller tube into the larger pipe began overnight. But the crushing depth requires engineers to work slowly and carefully, BP spokesman John Crabtree said Friday.
Crews overseeing the effort hope to have a better grasp Friday evening on whether this latest method is going to work, Crabtree said.
If the tube doesn't work, BP could try a second containment box, which would be placed over the well and also would siphon the oil to the surface.
BP also could wind up trying a "junk shot" -- shooting different sized golf balls, bits of tires, knotted rope and other carefully selected debris into the blowout preventer, the machinery allowing some oil to escape. The hope is the junk will fill the appropriate holes and allow BP to seal off the well.
BP also has sprayed chemicals on the oil to break it up into smaller droplets, with about 4 million gallons of oily water recovered.
The size of the spill, as measured from satellites, seems to have grown about 50 percent from May 10 to late Thursday, said Graber from the University of Miami.
"There's a hell of a lot coming out," Graber said of the oil.
The estimate of 210,000 gallons daily from the leak comes from the National Oceanic and Atmospheric Administration and has frequently been cited by BP and the Coast Guard. Some scientists have said based on an analysis of BP's video of the leak that the flow rate is much higher, while others have concluded the video is too grainy to draw any such conclusions.
BP is sticking with the NOAA estimate, company spokesman Mark Proegler said Thursday. He said BP hasn't sent down equipment that might be able to more accurately measure the oil because "our focus is on stopping the leak, not measuring it."
As for the missing data, rigs like Deepwater Horizon keep a daily drilling report. It is the version of that report given to Congress that cuts off at 3 p.m.
The log confirms that three pressure tests, conducted from the morning to the early afternoon of April 20, indicated unseen underground leakage into the well. But there is no mention of a fourth test that BP and Transocean say was conducted and that they say indicated it was safe to proceed.
In the hours leading up to the explosion, workers finished pumping cement into the exploratory well to bolster and seal it against leaks until a later production phase. After the tests that indicated leakage, workers debated the next step and eventually decided to resume work, for reasons that remain unclear.
At the same time, heavy drilling fluid -- or mud -- was being pumped out of a pipe rising to the surface from the wellhead, further whittling the well's defenses. It was replaced with lighter seawater in preparation for dropping a final blob of cement into the well as a temporary plug for the pipe.
When underground gas surged up uncontrollably through the well, desperate rig workers tried to cap it with a set of supersized emergency cutoff valves known as a blowout preventer. However, the device was leaking hydraulic fluid and missing at least one battery, and one of its valves had been swapped with a useless testing part.
Rep. Bruce Braley, D-Iowa, said the lack of offsite data storage is something he intends to look into further.
"I'm sure we'll be taking action to follow up with those requirements," he said. "Because it's critical information that would give rise to understanding of what happened and why more wasn't done to shut off the flow of oil and prevent this from happening."