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Gulf Tragedy Update
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Based on the interviews, Bea believes that the workers set and then tested a cement seal at the bottom of the well. Then they reduced the pressure in the drill column and attempted to set a second seal below the sea floor. A chemical reaction caused by the setting cement created heat and a gas bubble which destroyed the seal.
Deep beneath the seafloor, methane is in a slushy, crystalline form. Deep sea oil drillers often encounter pockets of methane crystals as they dig into the earth.
As the bubble rose up the drill column from the high-pressure environs of the deep to the less pressurized shallows, it intensified and grew, breaking through various safety barriers, Bea said.
"A small bubble becomes a really big bubble," Bea said. "So the expanding bubble becomes like a cannon shooting the gas into your face."
Up on the rig, the first thing workers noticed was the sea water in the drill column suddenly shooting back at them, rocketing 240 feet in the air, he said. Then, gas surfaced. Then oil.
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Rig Workers: Bubble Of Methane Triggered Rig Blast
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As bad as the oil spill looks on the surface, it may be only half the problem, said University of California Berkeley engineering professor Robert Bea, who serves on a National Academy of Engineering panel on oil pipeline safety.
"There's an equal amount that could be subsurface too," said Bea. And that oil below the surface "is damn near impossible to track."
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US Gulf Coast dreads oil spill creep toward shores
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Professor Robert Bea
http://coe.berkeley.edu/labnotes/0105/bea.html
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