I kept close watch on the earlier reports, so here adding the link to the final report from 16th September 2011. Herewith [almost] the entire summary:
The Events
At approximately 9:50 p.m. on the evening of April 20, 2010, while the crew of the Deepwater Horizon rig was finishing work after drilling the Macondo exploratory well, an undetected influx of hydrocarbons (commonly referred to as a “kick”) escalated to a blowout. Shortly after the blowout, hydrocarbons that had flowed onto the rig floor through a mud‐gas vent line ignited in two separate explosions. Flowing hydrocarbons fueled a fire on the rig that continued to burn until the rig sank on April 22. Eleven men died on the Deepwater Horizon that evening. Over the next 87 days, almost five million barrels of oil were discharged from the Macondo well into the Gulf of Mexico.
The Findings
The Panel found that a central cause of the blowout was failure of a cement barrier in the production casing string, a high‐strength steel pipe set in a well to ensure well integrity and to allow future production. The failure of the cement barrier allowed hydrocarbons to flow up the wellbore, through the riser and onto the rig, resulting in the blowout.
The precise reasons for the failure of the production casing cement job are not known. The Panel concluded that the failure was likely due to:
(1) swapping of cement and drilling mud (referred to as “fluid inversion”) in the shoe track (the section of casing near the bottom of the well);
(2) contamination of the shoe track cement; or
(3) pumping the cement past the target location in the well, leaving the shoe track with little or no cement (referred to as “over‐displacement”).
[Nothing about the Halliburton cement job being at the limits of good design, testing and implementation ? Difficult conditions and decisions mentioned later, and one reason why the critical test failure later should have been on everyone’s radar, not just the guys at the workfront.]
The loss of life at the Macondo site on April 20, 2010, and the subsequent pollution of the Gulf of Mexico through the summer of 2010 were the result of poor risk management, last‐minute changes to plans, failure to observe and respond to critical indicators, inadequate well control response, and insufficient emergency bridge response training by companies and individuals responsible for drilling at the Macondo well and for the operation of the Deepwater Horizon.
BP, as the designated operator under BOEMRE regulations, was ultimately responsible for conducting operations at Macondo in a way that ensured the safety and protection of personnel, equipment, natural resources, and the environment. Transocean, the owner of the Deepwater Horizon, was responsible for conducting safe operations and for protecting personnel onboard. Halliburton, as a contractor to BP, was responsible for conducting the cement job, and, through its subsidiary (Sperry Sun), had certain responsibilities for monitoring the well. Cameron was responsible for the design of the Deepwater Horizon blowout preventer (“BOP”) stack.
At the time of the blowout, the rig crew was engaged in “temporary abandonment” activities to secure the well after drilling was completed and before the Deepwater Horizon left the site. In the days leading up to April 20, BP made a series of decisions that complicated cementing operations, added incremental risk, and may have contributed to the ultimate failure of the cement job.
These decisions included:
- The use of only one cement barrier. BP did not set any additional cement or mechanical barriers in the well, even though various well conditions created difficulties for the production casing cement job.
- The location of the production casing. BP decided to set production casing in a location in the well that created additional risk of hydrocarbon influx.
- The decision to install a lock‐down sleeve. BP’s decision to include the setting of a lock‐down sleeve (a piece of equipment that connects and holds the production casing to the wellhead during production) as part of the temporary abandonment procedure at Macondo increased the risks associated with subsequent operations, including the displacement of mud, the negative test sequence and the setting of the surface plug.
- The production casing cement job. BP failed to perform the production casing cement job in accordance with industry‐accepted recommendations.
The Panel concluded that BP failed to communicate these decisions and the increasing operational risks to Transocean. As a result, BP and Transocean personnel onboard the Deepwater Horizon on the evening of April 20, 2010, did not fully identify and evaluate the risks inherent in the operations that were being conducted at Macondo.
On April 20, BP and Transocean personnel onboard the Deepwater Horizon missed the opportunity to remedy the cement problems when they misinterpreted anomalies encountered during a critical test of cement barriers called a negative test, which seeks to simulate what will occur at the well after it is temporarily abandoned and to show whether cement barrier(s) will hold against hydrocarbon flow.
[As it says, the “critical test” misinterpreted. The critical point in earlier reports too. Snipped-out more description of the various processes and actions – but nothing new here, except the report of a near identical near miss on the same rig just weeks earlier, with many of the same crew & management, from which they hadn’t learned fast enough.]
Scheduling conflicts and cost overruns.
At the time of the blowout, operations at Macondo were significantly behind schedule. BP had initially planned for the Deepwater Horizon to move to BP’s Nile well by March 8, 2010. In large part as a result of this delay, as of April 20, BP’s Macondo operations were more than $58 million over budget.
Personnel changes and conflicts.
BP experienced a number of problems involving personnel with responsibility for operations at Macondo. A reorganization that took place in March and April 2010 changed the roles and responsibilities of at least nine individuals with some responsibility for Macondo operations. In addition, the Panel found evidence of a conflict between the BP drilling and completions operations manager and the BP wells team leader and evidence of a failure to adequately delineate roles and responsibilities for key decisions.
At the time of the blowout, both BP and Transocean had extensive procedures in place regarding safe drilling operations. BP required that its drilling and completions personnel follow a “documented and auditable risk management process.” The Panel found no evidence that the BP Macondo team fully evaluated ongoing operational risks, nor did it find evidence that BP communicated with the Transocean rig crew about such risks.
Procedures & Regulations
Transocean had a number of documented safety programs in place at the time of the blowout. Nonetheless, the Panel found evidence that Transocean personnel questioned whether the Deepwater Horizon crew was adequately prepared to independently identify hazards associated with drilling and other operations. Everyone on board the Deepwater Horizon was obligated to follow the Transocean “stop work” policy that was in place on April 20, which provided that “each employee has the obligation to interrupt an operation to prevent an incident from occurring.”
Despite the fact that the Panel identified a number of reasons that the rig crew could have invoked stop work authority, no individual on the Deepwater Horizon did so on April 20.
The Panel found evidence that BP and, in some instances, its contractors violated [the following] federal regulations:
[snip]
Although the Panel found no evidence that MMS regulations in effect on April 20, 2010 were a cause of the blowout, the Panel concluded that stronger and more comprehensive federal regulations might have reduced the likelihood of the Macondo blowout.
Might. The critical failure was not recognizing how critical this particular cement job and testing were. Basic stuff. (Ironic, as I noted before, that much of my own experience of criticality procedures arose from BP projects in the 70’s and 80’s.)