Despite numerous past warnings of potential failures of BOP systems, both industry and regulators had a “misplaced trust” in the ability of BOP systems to act as fail-safe mechanisms in the event of a well blowout, according to a new report from the National Academy of Engineering and the National Research Council.
The report -- Macondo Well-Deepwater Horizon Blowout: Lessons For Improving Offshore Drilling Safety -- recommended the redesign and rigorous testing of BOP systems in the dynamic conditions that occur during a blowout.
The study, which was sponsored by the U.S. Department of the Interior, pointed to multiple contributors to the accident. The lack of effective safety management among the companies involved in the disaster is evident in the multiple flawed decisions that led to the blowout and explosion. Regulators also failed to exercise effective oversight.
Despite the challenging geological conditions, there were alternative techniques and processes that were available that could have been used to prepare the exploratory well safely for temporary abandonment, the report stated.
Several signs of an impending blowout were missed by management and crew, resulting in a failure to take action in a timely manner, the report emphasized.
Regarding the BOPs, the report noted that the equipment was invented by Cameron Iron Works in 1922. The pre-publication copy of the report said, “The BOP used with the Deepwater Horizon was part of its TL series, based on the ram-type BOP design, which has matured and evolved over the years. In the absence of regulatory demand, the evolution of this expensive and long-lived piece of equipment appears to have been limited.
“However, advances in well-drilling technology, which allowed operation at greater water depths, presented a substantial challenge to the reliability of this basic BOP design. As other technological aspects of deepwater drilling continue to move forward, there is a need to improve BOP reliability,” the report continued.
For example, it is almost impossible for conventional blind-shear rams to sever tool joints, yet 5% to 8% of the drillstring consists of tool joints.
The report provides a detailed forensic analysis of the BOP. One finding was that when the blind-shear ram was activated, it was unable to center the drill pipe in its blades, which were a combination of straight and “V” blades. This combination has been shown to be inferior to the double-V blade geometry. Because the blind-shear rams did not fully span