DMandPenfold writes "Advanced modeling software analyzed the cementing conditions for BP's Deepwater Horizon oil well as unstable, days before the blast that killed 11 oil rig workers and let millions of barrels of oil spill into the Gulf of Mexico. Halliburton, the company that carried out the cement job, used its own modeling software called OptiCem, to support arguments that more stability was needed for the piping and cement. ... An OptiCem test on 15 April, five days before the blast, stipulated that from Halliburton’s point of view, 21 ‘centralizers’ needed to be added to the well bore. The centralizers are used to provide space around the oil pipe casing within the well, as cement is poured around it, and are a vital part of safe drilling. BP initially adhered to the OptiCem software test and ordered 15 extra centralizers. But when technicians on the rig received the extra centralizers they mistakenly decided the new centralizers were the incorrect type. At this point BP proceeded with the drilling anyway, with the six centralizers, deciding another known technique of injecting cement in other places would work."