The spill investigations so far…

We wrote this week about how federal prosecutors have picked up the pace of their criminal investigation into the BP oil spill.

Here are some of the key conclusions of investigations into the deadly blowout of BP’s Macondo well that have been completed as of the one-year anniversary:

Internal investigation led by BP safety chief Mark Bly — Sept. 8, 2010

Source:, follow links “Gulf of Mexico restoration” and “investigating the accident.”

  • The blowout was largely the fault of BP contractors including Deepwater Horizon rig owner Transocean and cement contractor Halliburton, and of BP’s own rig-based workers.
  • Cement around the well bore most likely failed because of poor quality, allowing oil and gas to escape.
  • Rig crews misread a procedure called a negative pressure test designed to determine the integrity of the well.
  • When crews realized oil and gas had breached the well and blowout preventer, they diverted the material to a device on the rig instead of sending it overboard, and the hydrocarbons exploded.

Presidential Spill Commission Final Report — Jan. 11, 2011


  • “Failure of management” and individual mistakes by workers for BP, Halliburton and Transocean directly caused the accident, but it also revealed “systemic failures” in the oil industry and its government regulators.
  • Companies placed undue reliance on timely intervention and human judgment but didn’t provide workers with necessary information, tools and training.
  • Regulators must acquire more technical expertise to improve oversight.
  • Industry must take unilateral steps to improve safety, including creating a new safety institute.

Presidential Spill Commission’s Chief Counsel Report — Feb. 17, 2011


  • BP had reported concerns with Halliburton cement work on previous jobs and on the Macondo project, and should have monitored the cement job more closely.
  • Halliburton did not fully review its own cement foam stability test two days before the blowout.
  • Halliburton did not cooperate with investigators.

Blowout Preventer Forensics Report done for BOEMRE— March 23, 2011

Source: DNV report on blowout preventer used at BP well

  • A section of drill pipe buckled and moved off-center between the blowout preventer’s shear rams, preventing them from fully cutting and closing the pipe as oil and gas surged out of it.

Continuing investigations:

• U.S. Coast Guard-Bureau of Offshore Energy Management, Regulation and Enforcement

• U.S. Chemical Safety and Hazard Investigation Board

• National Academy of Engineering-National Research Council

• Department of Justice criminal investigation