Friday, 28 May 2010

Deepwater Horizon and the Unlearned Lessons of Piper Alpha

The Piper Alpha oil and gas platform disaster in the North Sea, which killed 167 men, was largely the product of two things:
1/Badly-planned maintenance, so that two components of the safety chain were being worked on at the same time. (You don't necessarily make things safer by doing lots of maintenance: the Royal Navy Icebreaker, HMS Endurance, was nearly sunk by a sea valve being improperly refitted after unnecessary "maintenance". You make things safer by careful and intelligent planning of maintenance, so that necessary things get done in a safe sequence, by people with the right expertise and the correct tools.)

2/ Mid-life modification of a simple, albeit large, oil production platform, into a mixed oil and gas production platform also acting as collector for other fields. This is what turned a small fire into a sequence of explosions leading to the total destruction of the platform (and a fast rescue boat launched by a standby ship).

This is where lessons were learned in the North Sea, but, surprisingly, given that the disaster cost an American company more than a billion pounds, those lessons seem not to have been even heard of outside British jurisdiction.

As first built, the Piper Alpha rig was as safe for its intended purpose as the technology of 1976 (when it was floated) allowed. There were four modules, with the most dangerous activities happening in the module furthest from the "populated" module which contained crew quarters, and the control room. There were also firewalls in all the right places, but these were intended to contain oil fires, and were not blast walls, which are needed where gas explosions are likely.

The modifications, to allow for gas production and the gathering of gas from other rigs for onwards transfer, brought pipes and control valves next to the rig's control room. The first relatively small fire and explosion effectively took out the control room, which meant that the only damage-control action taken was to activate the emergency stop. This shut off, for a while, most of the flow of gas and oil from its various sources (and this was complicated as there were lots of sources coming onto the one rig) but emptying the pipes near the fire would have required a complex series of actions, and an authorizing intelligence to command them. The control room had already gone. Fairly quickly, the fire burst these various full pipes, releasing more fuel to the fire and causing further bursts and explosions, one compared by witnesses to a tactical nuclear explosion. All of which was happening immediately next to the populated module. Although described as a "blowout" by the media, the sequence was the reverse of this, with an accidental leak on the rig leading to a chain of damage that eventually took the cap off the well as the rig sank.

It isn't known for certain what happened on the Deepwater Horizon, but whatever happened, the President of the United States has been from the outset adamant that BP are completely and solely responsible for it. BP did not own the rig and were not, therefore, in complete control of its configuration and equipment. Most of the permanent equipment being installed from and for the rig, including the blowout preventer, were supplied by the rig's owners, the Swiss company Transocean. Unlike Piper Alpha, this was an exploration rig, intended to be used at many different sites, to set up for a production rig to follow. This is why it was owned by a subcontractor and not an oil company.

Even a company as big as BP, does not have enough work to occupy such a rig full time for its useful life, and there would be competition concerns if BP owned and had control of, an asset also used by its competitors. To a large extent, BP using a rig it didn't own and didn't fully control, was the product of America's cherished anti-cartel laws, (copied in Europe) which were originally designed to curb the power of Standard Oil, Standard Bank and the Rockefeller family.

It is still possible that the truth of the "blowout" and catastrophic oil leak on Deepwater Horizon, is that the pipeline between the rig and the blowout preventer on the sea bed, was damaged when the rig sank, as with Piper Alpha. The big and frightening oil leak, is probably the consequence of the accident and not its cause. The cause was most probably something smaller; a surge of high pressure gas in the drillpipe, which burst into the air and made the same sort of initial explosion, in the same sort of place, as that on Piper Alpha.

The cause of the gas release is different, but the scale probably wasn't all that different at all, and Transocean had nearly a quarter of a century to read the Cullen report on Piper Alpha and ensure that their rig wouldn't succumb to a similar chain of cascading failures. Which is precisely what it did do.

There's no way that anyone can build a rig to withstand the sort of near-nuclear event that finally destroyed the Piper Alpha platform. But that was the biggest of a cascading sequence of fires and explosions, that could have been contained nearer the beginning. It is possible to build rigs that preserve the control room equipment and staff for long enough to fight back (which is why the control rooms in nuclear power stations are well protected). It is possible to design rigs where the personnel are not concentrated near the area of greatest risk. It is basic common sense to concentrate thought and investment on containing failures as near to the start of the chain as possible.

In this instance, BP didn't do any of this, because it was quite literally not their business. It was Transocean's business, as a rig designer, owner and operator. But in his zeal to punish BP to the utmost, the President of the United States is effectively absolving Transocean of all liability and all blame. Which means that Deepwater Horizon won't be the last rig to re-enact the Piper Alhpa disaster, because he's removing the incentive to do something about it, from the people who have the capability and the opportunity to provide safer rigs, and transferring it to their customers.

One of the lessons learned a quarter of a century ago in the North Sea, was to transfer responsibility for safety issues in the industry from the Department of Energy to the Health and Safety Executive. A screamingly obvious move, which has just been half-copied by the US President, a quarter of a century late, largely as an exercise in lining up the existing safety authorities as alternative scapegoats in case attempts to pin it all on BP should fail.

It is baffling and worrying, to British observers, to see all the rage and anger about the Deepwater Horizon accident, centre on the oil spill and not the thirteen men who died.
Thirteen dead is a disaster, one hundred and sixty-seven dead is a catastrophe.

Medawar would also like to debunk one particular bit of hype about the Deepwater Horizon accident: it is not the worst ecological disaster in American history, not by miles:
the Oklahoma dust bowl was the worst ecological disaster in American history, and it was caused by US government policy to encourage farmers to convert permanent pasture into arable cropland. (Wheat is better for speculating with than beef and dairy products!) There is now pressure from so-called "environmentalists" to revive this policy, supposedly because cows cause climate change. The University of Cranfield has recently published a study showing that pasture is one of the most important carbon sinks in agriculture, and the UN has determined that species protection is more important than fighting climate change. But the real argument against any systematic conversion of pasture to cropland, is contained in the Woody Guthrie song about the dustbowl, genuinely America's worst ecological disaster of all time:

"So Long, it's been good to know yer".

Update, September 2016.
There is a book, "Fire in the Night" available as an E-book, which gives an accurate and honest full account of the Piper Alpha disaster. Medawar isn't aware of anything quite like it for the Deepwater Horizon disaster. Now that Hollywood has done its usual thing, the odds are against the full unbiased truth ever getting established in the public's mind. "Fire in the Night" by Stephen McGinty.



Anonymous said...

Most rigs these days are lab glass and will do fine with heat.
Within reason of course. If you go heating one specific spot
over and over again, it’s gonna crack because that’s just how
physics works.

Medawar said...

The firewalls on Piper Alpha were just that: firewalls, as it had been built in the seventies as an oil-only platform. When it was converted to carry out gas-recovery as well, these needed to become BLAST walls and they didn't.

The control room on Deepwater Horizon was lost in the first explosion (ie: BLAST rather than heat) partly because the blastproof shutters on the ventilation system were left open and the alarms that would have triggered them left off "because they kept on sounding." This couldn't be blamed on BP rather than the rig owners, so it was ignored.

Medawar said...
This comment has been removed by the author.
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screen or an enail.

Anonymous said...

u learn something everyday....never heard of this