BOEMRE: BP, Transocean, Halliburton at Fault in Macondo Oil Spill

Deepwater Horizon Gulf of Mexico Oil Spill

The Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) and U.S. Coast Guard concluded that BP, Transocean and Halliburton all share blame in the April 20, 2010 Macondo oil spill in the U.S. Gulf of Mexico through a combination of well design, approach to well control and missed steps.

The final investigative report, conducted by a joint investigative team led by BOEMRE and the Coast Guard, found that the Macondo blowout was the result of a series of decisions that increased risk and a number of actions that failed to fully consider or mitigate those risks.

"While it is not possible to discern which precise combination of these decisions and actions set the blowout in motion, it is clear that increased vigilance and awareness by BP, Transocean and Halliburton personnel at critical junctures during operations at the Macondo well would have reduced the likelihood of the blowout occurring," BOEMRE said in the report.

Report Findings

Operator BP was ultimately responsible for conducting operations at Macondo that would ensure the safety and protection of personnel, equipment, natural resources and the environment. Transocean was responsible for conducting safe operations and protecting personnel on board the rig, and Halliburton, as a BP contractor, was responsible for conducting the cement job, and its subsidiary Sperry Sun had certain responsibilities monitoring the well.

The panel conducting the investigation found that BP well designers set the casing in a location that created additional risks of hydrocarbon influx. "Even knowing this, BP did not set additional cement or mechanical barriers in the well."

BP also made two additional decisions that further increased risks: the decision to have the Deepwater Horizon crew install a lock-down sleeve as part of the temporary abandonment procedure, and BP's decision to use a lost circulation material as spacer, which risked clogging lines used for well integrity tests, the panel noted.

Personnel from both BP and drilling contractor Transocean failed to conduct an accurate negative test to assess the integrity of the production casing cement job, the report said. The crew performed temporary abandonment procedures while unaware of the failed cement job below. "Unfortunately, the rig crew then limited its kick detection abilities by deciding to bypass the Sperry Sun flow meter when displacing fluid from the well overboard."

The failure of the rig crew to stop work on the Deepwater Horizon after encountering multiple hazards and warnings also was a contributing cause of the Macondo blowout. "The Deepwater Horizon rig crew missed signs of a kick and thus was delayed in reacting to the well control situation," the panel found.

"Once the flow reached the rig floor, the crew closed the upper annular and upper variable bore ram and diverted the flow to the mud gas separator. The mud gas separator could not handle the volume of the blowout and explosions followed. Forensic analysis suggests the explosions had damaged the rig's multiplex cable and hydraulic lines, which were rendered inoperable by the blowout preventer stack's blind shear rams, by the time a crew member on the bridge had activated the emergency disconnect system.

The blowout's force, and possibly the force from drill pipe in the riser, buckled the drill pipe, putting it in a position where it could not be completely sheared by the blind shear ram blades. As a result, the blind shear ram, when activated on April 20 or 22, could not shear the drill pipe and seal the wellbore.


The panel made a number of recommendations, such as implementing regulations that require the negative pressure testing of wells where the wellbore will be exposed to negative pressure conditions, such as when the BOP and riser are disconnected from the wellhead during permanent or temporary abandonment procedures. "Had the Deepwater Horizon crew interpreted the negative test properly, the blowout may have been averted," the report said.

At least two barriers, including one mechanical and one cement barrier, should be required for wells undergoing temporary abandonment procedures. "Having a cement plug and an additional mechanical barrier would added an increased safety factor," the panel found. "While the Macondo well did have dual float valves, the Panel does not believe that float valves should be considered a mechanical barrier."

Other recommendations include the incorporation into the Code of Federal Regulation parts of the American Petroleum Institute's Recommended Practice Parts 1 and 2, that would require a minimum hole diameter of 3.0 inches greater than the casing outer diameter; rathole mud density greater than cement; and mud conditioning volume greater than one annular volume. The definition of safe drilling margins should also be expanded to encompass pore pressure, fracture gradient and mud weight.

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Generated by readers, the comments included herein do not reflect the views and opinions of Rigzone. All comments are subject to editorial review. Off-topic, inappropriate or insulting comments will be removed.
henry sheil | Sep. 19, 2011
I havent yet read the report, but the report actually means they recommend incorporation into the CFRs of API RP 65 (that bit was missing) Parts 1 and 2, and note there is a credible submission from Shell E&P Corporation that this is NOT appropriate, see You cant have non-experts making up rules as knee jerk reactions to disasters, we need to act smarter than that. I think the oil and gas biz lags way behind aviation in areas such as this.

MT Oil | Sep. 19, 2011
Everyone is so focused on the BP problem that they totally miss the big picture. Everyone wants oil so companies do everything they can to sell as much as possible. This creates a shortage in skilled workers. As someone that has worked in many different oilfields, i have seen the "job getting done" by many operators, it is not just BP that has issues. There are people that get killed everyday in the oilfield, and there is oil spilled everyday in the oilfields. How many of these spills are big enough to hear about? Only one. Does anyone talk about BPs record up on the slope? One incident has marked them as a tyrant. They are better than a majority of operators. Only one thing separates them from the rest, the first big deep water incident happened to them. Who is going to be next, if not off-shore US, somewhere around the world, it will happen again. Let us look at this as a learning experience for everyone, and try to do a better job at making sure we police our own industry, and set a standard of excellence in the process.

James Drouin | Sep. 18, 2011
A badly flawed report, from the very first paragraph of the Executive Summary all the way through to the Conclusion and Recommendation. The report does nothing more than demonstrate the authors fundamental lack of understanding of failure mechanisms in general, and the specific failures on the DWH. For example, it identifies the cement job as failing but fails to identify the double-valve float collar failure (mentioned in passing only on pages 40 and 41), one of the several barriers that were breached. Additionally, they further identify the use of a foamed cement as a risk (which it is) without understanding its absolute and unavoidable requirement for that formations rheology characteristics. Certainly none of their Recommendations will do anything to avert a future occurrence, should an identical sequence of events occur.

Robert Mackenzie | Sep. 16, 2011
I read an interim report a couple of months ago with evidence that suggested the 7" casing may have parted before the cement job was initiated. Maybe BOERME cannot interpret data correctly. I believe there was more serious problems with that casing string and therefore the well as a whole than meets the eye.

David Cole | Sep. 16, 2011
I've read the report, watched the 60 Min. segment and watched in detail the follow up and clean up procedures since the spill. The sad fact is that BP and perhaps others paid little attention as they neared the finish work on the well. Their drilling experience and the expectations of deep well technology should have alerted them the very high pressures likely to come to a head during completion of such as well. Blowout preventors and other safety precautions were ignored. Major Oil Companies are not simply to blame because BP became so reckless with their success. The 20 billion fund set aside for damage to the gulf area industries is also a classic example of getting the job done right but wrong. A trip to Washington, involving the President to bless a settlement is shameless window dressing. BP paid little or no attention to Echosphere and other companies that brought equipment to the Gulf to remove the oil and replace it with pure water of seawater quality even and the bottom of the Gulf. Shell, Exon and the many other majors are sitting on their hands waiting for permits to put Americans back to work while regulators sit on their brains and fail to offer qualified supervision. Regulators lacked the simple enforcement procedures that routine inspections could have possibly slowed the finishing of the well and saved the production of 43,000 barrels per day of a valuable resource from being lost, not to mention the jobs that it would have saved. To revert of my experience from the farm, "Again we are locking the barn door after the horse is gone!"

Jay | Sep. 16, 2011
The Transocean BOP never tested at 100%, they always had leaks and problems and covered them up to keep from pulling the stack and going on down time. That is a fact. If the kick had been identified on the negative test this would not have happened, the company rep should have been on the rig floor. The drilling foreman was to busy entertaining the BP and Transocean guys from the office and not worried about the well.

willy | Sep. 16, 2011
I don't see MMS listed as one of the groups at fault. If they had followed through with their own procedures/ regs which were produced from years of drilling and completion activity lessons learned, I don't believe BP would have been able to continue in such a negligent fashion. I would put more stock in the report if the government who has all of the control offshore had been listed as well they should be(#1)

Oddbjørn Skilbrei | Sep. 16, 2011
I find these reports somewhat short of basic well engineering principles: 1. Every competent well design engineer should know that a cement job must be considered a failure until proven otherwise. So the well safety should not have to rely on good cement, and a poor cement job should not cause a blow out if the casing design is correct. Ergo the blame should go to the design, not the cement. I have not seen this spelled out.  2. When there is HC ingress into the (liquid) cement, it will percolate up into the (in this case 16" x 9 5/8") annulus. This has a high likelihood, and the conclusion HC/gas flowed down around and into the shoetrack would make the annulus upward percolation even more likely. After the HC influx had finished replacing the 16" x 9 5/8" annulus mud content, overpressure acting in top of a gas/fluid column could perhaps reach 10,000 psi. Was the 16" casing burst rated for this? Without a seal lockdown, the 13,000+ of freehanging 9 5/8" casing would be lifted out of the housing and easily extruded up into the BOP. Once this happened, no BOP shear ram in the world could be expected to cut through a 9 5/8 casing head. And this would also be a major blow out path; up the annulus, around outside the 9 5/8" hanger, and into the riser. As soon as the inflow was stopped, the 9 5/8" casing would slip down into the 16" hanger below the BOP again, making the event undetectable at post incident investigation. But the point is; this was all predictable at the time of designing the casing, and had as high a likelihood as a failed cement job. I.e., pretty high! The possibility of the annulus blow out path was dismissed (in the previous investigations) because it was concluded there was a path down around the shoe track. No explanation given, why? Did I miss anything here? Glad to hear comments. 

Bill | Sep. 16, 2011
This is a classic example of drift into failure as outlined in the book by Sidney Dekker "Drift into Failure", it so easy to look back in hindsight and say what should or should not have happened. However, during the event the people involved were doing what they thought was the right thing to do. "When we are standing amid the rubble and looking back. Then it is easy to marvel at how misguided or misinformed people must have been. But why was it that the conditions conducive to an accident were never acknowledged or acted on by those on the inside the system-those whose job it was not to have such accidents happen?"

John Doe | Sep. 16, 2011
Bringing up an ill-conceived rule of thumb of an API RP that would require a completely arbitrary hole diameter to casing OD pegged at 3 despite best practices consideration of the flowrates to achieve successful displacement is sad. Reminds me of a famous Einstein quote, "Make things as simple as possible and absolutely no simpler". Seems that if that gets in the way of a dictate then they opt for simpler still. Pathetic, arbitrary oversimplification along the same lines as the moratorium. Formalized process management is the answer for deepwater management and mind numbing regulatory hurdles based on oversimplifications and checkpoints isn't exactly a genius vision of formalized process management. The good news is that companies now will adopt computerized, formal process management systems. The bad news is the work load of dumbing down numbers to meet oversimplified regulatory supervision checkpoints will complicate and confuse things.

BILL CARTER | Sep. 15, 2011
I would like to see the full report. However, the basic findings seem fair and balanced. It is never easy to isolate a single event that lead to the uncontrolled well flow and consequential results. It highlights the inter-dependance of each Company involved in the well development and the need for team working between professionals. Happy to see no finger pointing but hope the new regs make a mention of the lost lives which can never but rebuilt.

Boss | Sep. 15, 2011
How about not cutting corners to save a dime next time B.P? There is blood on the hands of those that made the decisions that were so out of line with established and proven drilling/cementing procedures.

Lorne | Sep. 15, 2011
This is a prime example of what happens when a company such as BP is left to its own devices as far as internal safety procedures are concerned. Complacency sets in and over time the pressure to reduce overall costs on a per well basis by the drilling managers and superintendents supersedes safety and environmental concerns. Do not for one second believe that this is not the case. At no time can a companies responsibilities or actual practice be allowed to fall behind what they and the industry know is required to ensure this type of disaster does not take place again.

Jeff | Sep. 15, 2011
I don't know everything that happened out there, because I have not read the whole report. I work on a land rig for a sub-contractor, for a major oil and gas company, and I know that every decision that is made is done by the on-site company representative or from the drilling engineer or superintendent. We give them our recommendations, but they are the ones who make the final decision. I feel this incident all goes back on BP.

John Mitchell | Sep. 15, 2011
It all comes down to weak supervision. Better training of rig site supervisors could have prevented this disaster. The industry chooses to manage the perception that they already have strong supervisors rather than to ensure they actually do have strong supervisors. I call it "Better living through denial" Weak and insecure rig site supervision is the number one problem in this industry!

John Doe | Sep. 14, 2011
I think the Panel needs to review how a multiplex system with a deadman system installed actually works before mains statements I just read. I am sorry Bill TO personnel on the rig gets a copy of the plan and has the right to comment and discuss. Stop sticking up for a company that cares nothing about their people!

Robert Gaston | Sep. 14, 2011
I think BOERME didn't know what they were looking at, so they just blamed everyone involved!

Bill | Sep. 14, 2011
I realize that this is an extensive document that you are trying to summarize but I think you failed to mention one key element from the report "...BP failed to communicate these decisions and the increasing operational risks to Transocean." These decisions related to one cement barrier, location of production casing, installation of lock-down sleeve, and the decision to perform a production casing cement job that was outside the norms of industry standards all added risks that BP did not convey to its contractors according to the BOEMRE.


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