Cement could unglue Halliburton’s BP spill defense

New criticism of Halliburton Co.’s work on BP P.L.C.’s blown-out Gulf of Mexico well could make it harder for the world’s second-largest oilfield services company to escape significant responsibility for the disaster. Lawyers for the government and spill victims gained ammunition after the National Commission on the BP Deepwater Horizon Oil Spill said Halliburton knew of, but did not address, flaws in the cement used in the doomed well before the April 20 disaster.