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Who, why, what still not clear Congressional hearings reveal the likelihood of several causes behind the April 20 Gulf of Mexico well blowout The Associated Press Edited by Petroleum News
Bad wiring and a leak in what’s supposed to be a “blowout preventer.” Sealing problems that may have allowed a methane eruption. Even a dead battery, of all things. New disclosures at recent congressional hearings revealed a complex cascade of deep-sea equipment failures and procedural problems that appear to have contributed to the April 20 oil rig explosion and spill in the Gulf of Mexico.
As the day of the catastrophe that killed 11 people got under way on the drilling platform 48 miles off Louisiana, workers were stabilizing the mile-deep exploratory well to mothball until production.
Shortly after midnight, nearly 22 hours before the explosion, contractor Halliburton finished pumping cement into the well. Heavy cement is used to fill gaps around the drill piping and block any surge of natural gas or oil.
As part of the planned routine, the workers next capped the drill pipe with the first of multiple cement plugs. The plugs are meant to stop any upsurge of gas or oil inside the piping.
The cement and metal casing along well walls were then checked. Positive pressure tests indicated they were sound.
But there are no federal standards for the makeup of the crucial cement filler, MMS spokesman David Smith said May 12. Government and industry have been working to publish new guidelines later this year, but they will be recommendations, not mandates.
Also May 12, a group of Louisiana crab fishermen claimed in a lawsuit that Halliburton — with permission of well owner BP and rig owner Transocean — used a new quick-curing cement mix with nitrogen. It supposedly generates more heat than other recipes and could allow dangerous bursts of methane gas to escape up the well.
According to the testimony and other evidence that has emerged at the May 11 and 12 congressional hearings, the first sign of trouble came shortly before dawn. Workers pumped out heavy drilling fluid for a negative pressure test to make sure underground gas couldn’t seep into the well. That test failed: it meant the well might be leaking. Another test was run. It too failed.
Workers debated what to do next. They eventually decided to resume work.
Further reducing protection from a blowout, heavy drilling fluid was pumped out of a pipe rising to the surface from the wellhead. It was replaced with lighter seawater in preparation for placing the last cement plug.
Whatever the main cause — cement or something else — the last plug was still missing just before 10 p.m. on the 20th, when drilling fluid pushed by underground gas started kicking up uncontrollably through the well.
Leaking hydraulic fluid Rig workers tried to activate a set of hydraulic cutoff valves known as a blowout preventer to squeeze off the surge. However, hydraulic fluid was leaking from a loose fitting in the preventer’s emergency system, making it harder to activate powerful shear rams to cut the piping and cap the blowout. Also, a battery had gone dead in at least one of two control pods meant to automatically switch on the preventer in an emergency.
The preventer “was to be the fail-safe in case of an accident,” Lamar McKay, the president of BP America, said at the House hearing.
Yet industry officials acknowledged a fistful of regulatory and operational gaps: There is no government standard for design or installation of blowout preventers. The federal government doesn’t routinely inspect them before they are installed. Their emergency systems usually go untested once they are set on the seafloor at the mouth of the well.
As gas pushed upward on the Deepwater Horizon, it suddenly ignited from an unknown source, and turned the rig floor into an enormous fireball. Eleven people were killed.
In the days that followed, workers kept trying to force the blowout preventer to close — without success. Maddeningly, they lost a day trying to close a ram without realizing it had been replaced by a useless test part.
Sometimes finger pointing at each other, officials from several of the companies involved said at May 12’s hearings that it’s not yet clear what precisely triggered the accident.
At the close of the day, BP was still considering two ways to stem the leak. One was a pipe linked to the end of the gushing tubing. The other was a box to cover the leak and siphon the oil to a ship.
As a backstop, a relief well is being drilled, but its completion is months away.
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