‘The Deepwater Horizon spill that took place on April 20, 2010 in the Macondo Prospect oil field has been described as “one of the largest environmental disasters in U.S. history.” The explosion and subsequent spill took the lives of 11 workers, seriously injured 17, and leaked a reported 5 million barrels of oil into the Gulf of Mexico. But what caused this catastrophe? The U.S. Chemical Safety and Hazard Investigation Board (CSB) seeks to answer this question in its recently released investigative report on the disaster, “Explosion and Fire at the Macondo Well.”  Ultimately, the Board determined that the spill was caused by an “unrecognized pipe buckling phenomenon” that stopped the blowout preventer (BOP) from sealing the well and blocking a flow of high-pressure oil and gas from escaping. This investigative report is divided into three parts: the Overview, Volume 1, and Volume 2. The Overview provides a synopsis of the incident and a description of the scope, organization, challenges, and conduct of the Board’s investigation. Volume 1 focuses on “Macondo-specific incident events” including “relevant background on deepwater drilling and temporary abandonment.”  Volume 2 provides the Board’s “technical findings on the Deepwater Horizon blowout preventer […] with an emphasis on the effective management of safety critical elements.” In conjunction with this report, the CSB also created and released an animation of the blowout that visually explains the cause of the disaster.

A few of the key findings of the investigation are the following:

• “The pipe buckling likely occurred during the first minutes of the blowout, as crews desperately sought to regain control of oil and gas surging up from the Macondo well.”
• “The BOP’s blind shear ram […] likely did activate on the night of the accident, days earlier than other investigations found. However, the pipe buckling that likely occurred on the night of April 20 prevented the blind shear ram from functioning properly.”
• “There were two instances of miswiring and two backup battery failures affecting the electronic and hydraulic controls for the BOP’s blind shear ram.”
• “The April 2010 blowout […] occurred during operations to ‘temporarily abandon’ the Macondo oil well.”
• “The blowout followed a failure of the cementing job to temporarily seal the well, while a series of pressure tests were misinterpreted to indicate that the well was in fact properly sealed.”
• “While Deepwater Horizon personnel performed regular tests and inspections of those BOP components that were necessary for day-to-day drilling operations, neither Transocean nor BP had performed regular inspections or testing to identify latent failures of the BOP’s emergency systems.”

A full summary of the Board’s key findings can be found in the report’s press release on the U.S. Chemical Safety Board website.”