It was the float collar

The long-delayed final report on the Macondo disaster from the joint BOEMRE/USCG investigation team chose not to pinpoint a fundamental cause. However, veteran offshore oil & gas consultant and occasional expert witness Ian Fitzsimmons has no such qualm. In his latest opinion piece for OE he concludes:

More forensic and detailed than January's National Commission report to President Obama (OE March), September's final, multi-volume federal investigation report into the causes of the Macondo disaster reads like a horror story. It lays bare a farrago of incompetence and blind obduracy that resulted in the loss of the Deepwater Horizon rig and 11 crew members and led to the worst offshore oil spill in US history.

I lost count of the number of 'possible contributing causes' and 'contributing causes' listed in the investigation panel's conclusions, which start on page 194. But they refrained from identifying any fundamental cause for the disaster.

In my experience, disasters are usually triggered by a fundamental flaw, which exacerbates any contributing cause(s). History offers plenty of examples.

  • The Titanic's watertight bulkheads did not cover the full depth of the hull. Had they done so, the vessel would not have sunk.
  • The Challenger employed O-ring neoprene seals to join its solid fuel rocket booster segments. Had the seals been metallic, the space shuttle would not have disintegrated soon after take-off.
  • The Apollo 1 command module fell victim to the use of pure oxygen. Oxygen accounts for just 21% of the air we breathe- if it were any higher, carbon-based life would be subject to spontaneous ignition.

Looking back, we wonder how such obvious flaws could have gone unnoticed. They did, and with the loss of many lives.

Yet in its 'Report Regarding the Causes of the April 20, 2010 Macondo Well Blowout,' an investigation panel jointly constituted by the now-defunct Bureau of Ocean Energy Management, Regulation & Enforcement and the US Coast Guard either could not, or chose not, to identify a fundamental flaw that could have initiated the disaster. Perhaps this is unfair criticism of the investigators. With upcoming civil court cases set to apportion blame, it may not have wanted to sensationalise a single event, preferring instead that all the 'possible' and 'contributing' causes be examined in equal measure.

But for my part, I am happy to nail my colours to the mast. I have no doubt that the fundamental flaw that caused the Macondo disaster was the float collar in the shoe track. The blame for the selection and use of that particular piece of equipment lies fairly and squarely with operator BP and nobody else.

In my view anyone with a grain of common sense would have to search long and hard to find a more ridiculous piece of equipment. Comprising an 'auto fill tube' and two 'flapper valves', it was run more than 23,000ft into a well full of mud and debris and expected to perform by the crude expedient of pumping cement grout through the ensemble.

Why was this particular piece of equipment, or conglomeration of pieces, ever chosen in the first place? The answer is simple – it was not chosen for its precision engineering – it was chosen because it saved a wireline trip that would have been required by a more conventional approach.

Tripping is an expensive activity in deepwater. The long string well design and its infamous float collar saved BP many days' tripping at about $1 million a day, but the associated risks do not seem to have been considered. How do you monitor if conversion has taken place successfully, and how do you confirm the fact? Can the evidence for conversion be misinterpreted?

Well, yes it can – and it was; hardly surprising given the well operational/circulation activities on the day of the disaster.

Closer reading of the report reveals that the investigators had severe misgivings about the shoe track float collar and its role in the disaster. On page 53 they concluded that the float collar did not convert, and the evidence for that statement is incontrovertible. But ‘the Panel did not find sufficient evidence to determine what caused the blockage that affected the float collar'. It takes very little imagination to realise there were numerous sources of debris in the well that were able to cause such a blockage.

On page 195 is the following:

‘The Panel concluded that hydrocarbon flow during the blowout occurred through the 97/8 x 7in production casing from the shoe track as a result of the float collar and shoe track failure.'

I leave it to the reader to judge if the foregoing points to the fundamental flaw that caused this disaster. But the investigation team did not stop there. In their recommendations, the following can be found on page 203 paragraph 5:

‘The agency should consider revising 30 CFR Section 250.420(b)(3), which is included in the Interim Final Rule, to clarify that a float collar/valve is not to be considered to be a "mechanical barrier". Float collars are designed to prevent the cement from u-tubing back into the workstring; they are not designed to keep the formation pressures from coming up the wellbore. A dual float [flapper – my parentheses] valve was used in the Macondo well. Clarifying the limitations of the float collar would prevent operators from relying on a device not designed specifically for pressure containment.'

Based on all the foregoing, I would say that the fundamental flaw that caused this disaster has been clearly identified as the shoe track float collar. A reminder of its configuration is attached here. Some may classify it as innovative. I say it is a folly and obviously so. I would not specify it for use if it was only five feet underground, let alone 23,000ft deep and submerged in sludge and well debris.

On a more positive note, I found the report's recommendation that an independent control system be used to activate BOPs very encouraging. But I wonder why the panel did not specify the need for a second set of blind shear rams to be included in the BOP configuration (OE July). It seems like commonsense to me.

So where lies the future? BOEMRE was last month disbanded and has been replaced by three separate agencies. There is much work to be done if the industry is to avoid another Macondo disaster. It is to be hoped that none of the ‘contributing causes' and the ‘possible contributing causes' slip between the contiguous boundaries of these new agencies. OE ©


Ian Fitzsimmons, a regular contributor to OE, is an independent consultant with more than 30 years' offshore industry experience. He has worked for major operators around the world and major subsea hardware/ drilling equipment contractors, and has extensive due diligence and expert witness experience. He was chief engineer for RJ Brown & Associates in London. The views expressed in this article are the author's own and do not necessarily reflect OE's position.

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