by David Hammer and Mark Schleifstein

Petty Officer 2nd Class Scott Lloyd / U.S. Coast Guard

A Coast Guard rescue helicopter crew documents the fire aboard the offshore drilling rig Deepwater Horizon while searching for survivors April 21.

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.

Times-Picayune archive

Robert Bea, center, a University of California at Berkeley engineering professor, is better known in New Orleans as co-leader of a team of scientists that investigated 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.

http://www.nola.com/news/gulf-oil-spill/index.ssf/2010/05/gas_surge_shut_well_just_weeks.html

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