The plea deal with BP does not preclude further criminal charges against individuals, and the Justice Department has said the criminal investigation is not closed. The department would not comment on the assertion by the attorneys for Vidrine and Kaluza that their clients were being scapegoated.
The grand jury has also charged one BP executive, David Rainey, with obstruction of Congress for allegedly misleading a congressional subcommittee about the well’s flow rate. He also faces arraignment Wednesday and will plead not guilty, his attorneys have said.
The manslaughter charges against Kaluza and Vidrine — and BP’s agreement to plead guilty to manslaughter — hinge entirely on a single procedure that occurred on the day of the disaster. It was called “the negative test.”
The well had supposedly been plugged at the bottom with a modest quantity of cement, 60 barrels. The negative test essentially tempted oil and gas to invade the well. The drill team removed much of the heavy drilling mud that normally choked the well, to see whether that would cause pressure to build up on the drill pipe. If the cement had effectively plugged the bottom of the well, there should not have been any pressure.
But the initial result was troubling, according to testimony at the government inquiry conducted by the Coast Guard and what was then called the Minerals Management Service. When the drill pipe was opened at the top, fluid surged up onto the rig. When crewmen closed the drill pipe, pressure rose again.
People on the rig that day testified that one of the Transocean employees, tool pusher Jason Anderson, suggested that the troubling pressure reading was due to what he called the “bladder effect.” This has remained a fuzzy element of the disaster narrative. The testimony indicated that Anderson believed that heavy mud still in the well could have been creating the pressure seen on the drill pipe and that the pressure was not caused by oil and gas invading the well bore.
Anderson never had a chance to testify, because he was killed in the subsequent explosion as he and his co-workers desperately tried to seal the blown-out well.
BP’s well site leaders, Kaluza and Vidrine, were part of the discussions during the negative test and had ultimate authority to decide how to proceed. According to testimony and BP internal investigatory notes, Vidrine decided to conduct another negative test, this time looking for pressure on a flexible line that was connected to the bottom of the well.