Harry Thierens, executive vice president for drilling and completions at the oil major, told a panel of federal investigators that crucial hours after the 20 April explosion were wasted after it became apparent that Transocean had made the changes.
The Texas-based panel heard from Thierens, who had a personal role in trying to stop the leak, yesterday that it took between 12 and 24 hours to locate drawings of the changes.
His testimony is part of a joint investigation by the US Coast Guard and the Interior Department into the causes of the Deepwater Horizon explosion, which killed 11 people and led to one of the worst oil spills in history.
Thierens testified alongside Billy Stringfellow a subsea superintendent for Transocean and Halliburton’s Vincent Tabler.
On Tuesday, Jesse Gagliano, a Halliburton technical adviser told the panel that BP had ignored his concerns that a cement seal inside its Macondo well might fail.
He also alleged that the oil major had argued with him when he suggested that more devices used to plug the well were needed.
However, BP’s lawyers disputed his allegations after producing email evidence that Gagliano had said that he was happy with the procedure.
BP hired Halliburton to perform and design the cement jobs on the Macondo well.
The oil giant is currently attempting to retrieve the damaged blow out preventer from the floor of the Gulf.
Meanwhile, BP confirmed yesterday that it has withdrawn its application for an exploration licence in Greenland, currently the centre of a new oil rush.