KENNER, Louisiana (Reuters) - For the captain of the Damon B. Bankston, a ship anchored alongside the Deepwater Horizon drilling rig when it exploded, the first sign of trouble was a flood of mud that poured off the rig’s drill deck like black rain.
In testimony on Tuesday before a federal government panel investigating the explosion on the night of April 20 that claimed 11 lives, Alwin Landry also recalled a green flash that preceded the first explosion and a desperate effort to pull 115 survivors from the water.
It was a routine evening on the deep waters of the Gulf of Mexico, about 42 miles off the Louisiana coast. The Damon Bankston was pumping heavy drilling mud from a three-mile deep well drilled by the rig through a hose. Landry was on the bridge catching up on paperwork.
Shortly after 9 p.m. CDT, “my mate advised there was mud coming off the rig. It looked like it was a black rain coming down,” Landry said.
Swiss-based Transocean Ltd’s Deepwater Horizon rig, under contract with BP, exploded and caught fire on April 20 while it was putting the finishing touches on a well about a mile beneath the ocean surface. It sank two days later.
The accident has triggered a huge oil spill that is threatening an environmental and economic disaster along the U.S. Gulf Coast.
Drilling mud is poured down the drill pipe to control the powerful pressures within the underground hydrocarbon reservoir and prevent a “kick” of methane gas and oil from rushing up the drillpipe. It was unusual for the mud to be pouring out the well in an uncontrolled flood.
“I was advised they were having trouble with the well,” Landry said, and workers on board advised him to disconnect the hose and move his vessel away. Landry said he registered concern in the rig worker’s voice.
Landry said he heard something else that concerned him: the loud hiss of a high-pressure release of air and gas that lasted for 30 seconds or more.
According to accounts from rig workers reviewed by Robert Bea, a University of California Berkeley engineering professor, this was the sound of a surge of methane rushing up the drill pipe which engulfed the rig’s deck in highly-flammable gas.
According to Landry, the explosion came at 9:53 p.m.
“I saw the green flash on the main deck of the Horizon to the aft of the derrick.” About 10 minutes later, a distress call went out from the rig’s radio — “Mayday! Mayday! Mayday! The rig’s on fire. Abandon ship,” Landry said.
The fire enveloped the rig as workers scrambled to reach life boats and some plunged into the dark waters, he said.
The rig’s two lifeboats made it clear of the burning rig but a smaller life raft was hung by a rope and couldn’t get free as fire spread beneath the rig.
The Damon Bankston’s rescue boat pulled alongside the hung-up life raft and passed its crew a knife, which they used to hack themselves free, Landry said.
According to Landry, the rig’s captain, Curt Kuchta, said his crew had slammed a “kill switch” on the drill deck meant to activate an underwater blowout preventer that is designed as a fail-safe method of shutting off the well.
“He said they pressed the kill switch,” Landry said. “They didn’t know if it worked.”
At about 11:05 p.m. CDT the Coast Guard issued its first alert. “Coast Guard has received a report of the ... Deepwater Horizon on fire,” according to the radio alert, read by a Coast Guard official at the hearing. “All mariners are requested to maintain a sharp lookout, assist if possible.”
Writing by Chris Baltimore; editing by David Storey