What was BP thinking when they chose the unconventional single long pipe design into the reservoir?
From the WSJ article
The cement job was especially important on this well because of a BP design choice that some petroleum engineers call unusual. BP ran a single long pipe, made up of sections screwed together, all the way from the sea floor to the oil reservoir.
Companies often use two pipes, one inside another, sealed together, with the smaller one sticking into the oil reservoir. With this system, if gas tries to get up the outside of the pipe, it has to break through not just cement but also the seal connecting the pipes. So the more typical design provides an extra level of protection, but also requires another long, expensive piece of pipe.
“I couldn’t understand why they would run a long string,” meaning a single pipe, said David Pursell, a petroleum engineer and managing director of Tudor, Pickering, Holt & Co., an energy-focused investment bank. Oil major Royal Dutch Shell PLC, in a letter to the MMS, said it “generally does not” use a single pipe.
By the time the well began shooting mud out of the derrick, it was too late. This was no ordinary gas kick. It was far more ferocious. The curse of Macondo lived on.
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