Lots of blame over BP well blowout, panel reports

Crews responsible for drilling BP’s Macondo well in the Gulf of Mexico, this past spring, missed plenty of signs that a catastrophic accident was looming, according to a November 17 interim report by the National Academy of Engineering and National Research Council.

If heeded, those warnings should have afforded crews ample opportunity to head off an explosion aboard the floating Deepwater Horizon drilling platform, says Donald Winter, who chaired the panel that wrote the report. Winter, a former Secretary of the Navy, now teaches engineering practice at the University of Michigan’s department of naval architecture and marine engineering.

The team of experts that he headed uncovered errors in the tactics employed to complete the exploration phase of drilling.

Ordinarily, crews tap a well, check its potential to supply reliable quantities of oil, then put a temporary cap on it for a period that the industry refers to as “temporary abandonment.” Hibernation might be a more apt term

Explains Winter, the time between a well’s exploratory and production phases can run months. And with costs of leasing a drilling platform running perhaps $1 million a day, companies have an incentive to put a well to sleep until it can begin delivering crude.

It was during the final stages of preparation for this temporary abandonment that the April 20 explosion occurred, he notes. Minutes after displacing mud at the bottom of the well with seawater, crude oil began inappropriately climbing up the bore hole. For the next 50 minutes, this appeared to go unnoticed. Once crew members aboard the Deepwater Horizon did realize what was going on, Winter says, they tried to stop it. But their actions “were incremental; they were not very aggressive in terms of their attempts to control the flow.”

Once it reached the surface, the oil and gas ignited — killing 11 workers and destroying the drilling rig. The blowout would go on to massively foul the Gulf with more than 5 million barrels (more than 200 million gallons) of oil.

The new report found evidence that failures occurred during the cementing of the well that may have caused fractures — and an inability to seal the well from oil in the reservoir. Although there were apparently signs that something had gone wrong, workers either ignored or misinterpreted them, the report finds.

Not only was cement that was sent into the well casing not displacing an equivalent amount of drilling mud — thereby pointing to a potential leak — but there also were anomalous conditions present during cementing operations, which constituted additional hints that the cement might not be making the desired seal.

Winter’s panel also turned up evidence of poor training of crews — and/or their distraction during pivotal decisionmaking steps in the days and hours leading up to the accident.

For instance, the new report notes that several activities were underway as oil had begun snaking its way up from the reservoir, about five miles below the sea’s surface. The report charges that focusing on these activities  — such as transferring drilling fluids to a nearby vessel — might explain why crews missed that intrusion of explosive hydrocarbons.

Cost cutting may have played a role
At a briefing on the new report, Winter and some of his coauthors were asked whether they had turned up evidence of a rush to that “abandonment” phase in order to trim drilling costs. The simple answer: Yes.

The panel focused on key decisions made aboard the Deepwater Horizon as preparation for the Macondo well’s abandonment was underway. “We’ve identified a number of these that we believe potentially contributed to the blowout,” Winter said at the briefing.

And in reviewing those actions, he said, it appeared that the crew failed to adequately appreciate the potential risks associated with the steps they were taking.

Moreover, Winter observed, “all of these decisions appeared to be made in a direction which provides a reduced schedule — and therefore a reduced cost — of completing the well.” This prompted his team “to question the overall risk management approach” in developing the well, he says, and “the adequacy of the checks and balances to weigh costs and schedule versus risk and safety.”

Indeed, he says, “we did not see any evidence that there was an appropriate process in place to provide that check and balance.”

Pretty strong words.

Misinterpreting ‘negative-test’ data
Much attention focused on the drilling crew’s attempt to measure the integrity of the cement that had been used to create a seal within the well casing that stretched from the seabed down — several miles down — to the oil reservoir.

There were a series of three “negative-pressure” tests to investigate the cement’s integrity. And it was following the completion of these tests “when the game changed — not totally out of control, but headed that way,” according to panel member Paul Bommer, a consulting petroleum engineer who also teaches at the University of Texas at Austin. Each time the crews attempted to displace drilling mud with sea water, as part of this test, the well pressure suddenly rose within the casing.

That’s not a good sign.

When those data were “accepted as being okay,” Bommer said, and the drilling crews moved on to “displace mud in preparation for temporary abandonment, their options greatly narrowed.”

This disregard of the test data, he says, appears to signal “a chain of command issue” — a failure to tell higher ups what’s happening on the ground (or in this case, under the seafloor). “It appears that in the negative-test case,” Bommer says, “the chain of command stopped at the derrick floor.”

Geophysicist Mark Zoback of Stanford University, another panel member, agrees that “disregarding the negative-pressure test and proceeding to temporary abandonment was the precipitating decision that led to the blowout. But compounding that decision,” he told me, “was the fact that as hydrocarbons started to come into the well, the well became underbalanced (because seawater was being used to displace drilling mud, and the pressure inside the pipe was decreasing).” That went on for 50 minutes leading up to the accident.

Systems on board the Deepwater Horizon, when used properly, “should have detected that [intrusion of oil],” he notes. Had crews paid attention to such monitoring systems, he said, they could have taken quick action to reduce the severity of the accident or at least warned their crewmates that something was quickly going seriously wrong.

So the situation was that there was no intact barrier to prevent the flow of oil up from the reservoir. “The negative test demonstrated that,” he says, “although that was disregarded.” And then a lack of monitoring failed to signal the approach of up-gushing oil “until literally it was too late.”

This isn’t the last word on the subject of what triggered the BP well’s blowout or at least exaggerated the likelihood it would occur. The NAE/NRC panel plans to interview additional people — ones who initially declined requests to brief the team about the accident. In addition, the blowout preventer — a device that failed to stem the flow of upcoming oil — was recently recovered from the Gulf seafloor and is now undergoing forensic analysis at a Coast Guard facility in Louisiana.

A final report by Winter’s group is due out in the summer of 2011.