By David Hammer, The Times-Picayune
May 19, 2010, 10:30PM
Michael DeMocker, The Times-Picayune archiveA few minutes before 10 p.m. on April 20, a belch of natural gas shot out of the Deepwater Horizon well, up a riser pipe to the rig above, igniting massive explosions, killing 11 crewmembers and sending millions of gallons of crude oil into the Gulf. Efforts to extinguish the fire were photographed on April 21.
BP hired a top oilfield service company to test the strength of cement linings on the Deepwater Horizon's well, but sent the firm's workers home 11 hours before the rig exploded April 20 without performing a final check that a top cementing company executive called "the only test that can really determine the actual effectiveness" of the well's seal.
A spokesman for the testing firm, Schlumberger, said BP had a Schlumberger team and equipment for sending acoustic testing lines down the well "on standby" from April 18 to April 20. But BP never asked the Schlumberger crew to perform the acoustic test and sent its members back to Louisiana on a regularly scheduled helicopter flight at 11 a.m., Schlumberger spokesman Stephen T. Harris said.
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Gregory McCormack, director of the Petroleum Extension Service at the University of Texas, called the cement bond log the "gold standard" of cement tests. It records detailed, 360-degree representations of the well and can show where the cement isn't adhering fully to the casing and where there may be paths for gas or oil to get into the hole.
Schlumberger's Harris said the contractor was ready to do any such wireline tests, but was never directed to do so. The team had finished doing tests on the subsea layers of earth being drilled five days earlier and hadn't done any work since, Harris said.
In fact, Harris said there was no time to get the company's wireline testing equipment off the rig before it exploded.
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No O-ring seal depicted
McCormack, the University of Texas professor, isn't so sure that the blowout went through the annulus, rather than breaching the center of the well and blowing out the top. But either way, he was baffled by the diagram Halliburton gave to Congress. He was so surprised by the lack of an O-ring seal that he wondered if it was an error.
"There's a free path all the way to the top of the well bore. Normally you wouldn't do that," he said. "If the well was completed as designed, I think that would be an issue the way it's shown there."
McFarland said a cement bond log is costly and takes time, but it would have told the crew right away whether the annulus was exposed to hydrocarbons. He and McCormack said that if the log showed problems, the crew would have done what's called a "perf and squeeze," perforating the weak spots in the liner and squeezing more cement in to defend the well against the gas pressure of the earth formation around it.
BP spokesmen did not respond to repeated requests for comment on the decision to send Schlumberger home without conducting a cement bond log or on the cementing schematic Probert gave the Senate committee. And Halliburton didn't respond to questions about the accuracy of Probert's diagram.
http://www.nola.com/news/gulf-oil-spill/index.ssf/2010/05/costly_time-consuming_test_of.html
You'd think that after the Challenger Shuttle disaster, people would pay attention to the damn O-rings.