http://savethegulf.gulflive.com/savethegulf/db_101513/contentdetail.htm?contentguid=SIcmc4BM
BOP investigator admits to fault in model used in forensic examination
David Hammer, The Times-Picayune
Posted:04/04/2011 12:01 PM
The maker of the blowout preventer that failed to shut in BP’s blown-out Gulf oil well last year took aim at aforensic examination of its equipment, raising significant concerns about the models used by the inspectors.
The inspectors at Det Norske Veritas (DNV) used computer models to determine that the massive blowout preventer failed to stop the blowout because it couldn’t cut drill pipe that had shifted to the side.
The implication was that the BOP never had a chance and wasn’t designed to handle the intense pressures of a deepwater blowout.
But a lawyer for Cameron International, the BOP’s manufacturer, blasted the project manager for the Norwegian company hired to perform the autopsy during testimony in the Deepwater Horizon Joint Investigation hearings that reconvened in Metairie Monday.
The lawyer, David Jones, showed that a model used by examiners at DNV depicted an impossibility: In running the computer models of how a key set of slicers and seals would have malfunctioned, it placed the drill pipe where oil was flowing in a place where it couldn’t have been.
The model showed the drill pipe inside a wall of the BOP, and Neil Thompson, the project manager for DNV, was forced to admit it was an error in the model placement.
That, combined with Thompson’s acknowledgement that he’d “never laid eyes on a blowout preventer” before he began this examination, called into doubt some of the most critical findings of the report.
Thompson also admitted that his team never conducted tests to determine flow pressures or figure out what forces caused the pipe to deflect inside the BOP and muck up the works.
Some BOP experts have questioned why a set of pipe that was stuck in the BOP for two days after the accident would have shot up above the machinery after the rig sank. Thompson stumbled when Jones asked him repeatedly about how Det Norske Veritas determined a valve called the “upper annular” was closed. Testimony from surviving rig workers stated a different valve was the one closed.
Joining Jones in his skepticism of the forensic report was BP lawyer Richard Godfrey. He wanted to know whether there was any physical evidence that the 5.5-inch, heavy-duty drill pipe bowed in the middle, knocking it off-center. That’s a key hypothesis of the inspectors’ report.
Thompson said there was no physical evidence of the elastic bowing of the pipe. He said it was recovered as a straight, 28-foot piece because it would have straightened out after it was cut, about two days after the accident. Godfrey suggested that nobody in the industry had ever seen such “elastic buckling” of a drill pipe before. But Thompson said it’s a commonly understood concept of physics.