"Flaws in a cement encasement intended to seal BP's well were most likely the root of last month's deadly explosion on the Deepwater Horizon drilling rig, according to interviews, government officials, congressional hearing testimony, drilling reports and other company documents.
The April 20 accident, which has resulted in millions of gallons of oil being spewed into the Gulf of Mexico, is the subject of multiple investigations that promise to be long and complex. Hearings in the last two weeks offered multiple lines of inquiry into what one engineer calls "a confluence of unfortunate events."
But at least a dozen experts with intimate knowledge of offshore drilling, including one who has seen investigation documents, agreed that, deep in the well, cement, or pipes encased by cement, had to have failed first.
Several have specifically fingered BP's design for that cement job, which used relatively little cement and relied on an unusual configuration that made it harder to test for imperfections, they said."