Close call for Shell Canada: Pipes dumped in stormy seas almost struck oil well


Published September 28, 2016 - 8:32pm

HALIFAX — When heaving waters in the North Atlantic wrenched a string of massive steel pipes from a drilling ship off Nova Scotia’s coast, one of the 20-tonne sections of the plummeting coil struck the seabed just 12 metres from the top of an undersea oil exploration well.

The distance is one of several details in a Shell Canada accident report received through access to information legislation, prompting critics to say the entire incident was too close for comfort in an area near one of Atlantic Canada’s richest fishing grounds of the Scotian shelf.

A summary report by the regulator issued earlier this year had said a heavier portion of the drilling system fell 22 metres from the wellhead, but didn’t mention the closer distance of pipes that are coiled and criss crossed through an area of seabed the size of three football fields in length and breadth.

The Shell project, about 250 kilometres off Nova Scotia, is the first of two offshore wells to be drilled in almost a decade, and the company recently announced it has moved off the well where the accident occurred and shifted exploration to a deep-water well about 120 kilometres away.

“It’s much too close to a worst-case scenario happening,” said Mark Butler, a critic of the project and director of the Ecology Action Centre in Halifax of the accident. “We’re not happy about them drilling in those depths.”

Shell spokesman Cameron Yost says “multiple, independent barriers” on the wellhead would have “provided assurance that the well would have remained secure,” if a pipe had landed on the blowout preventer and well.

He also says the blowout preventer that sits on the well had systems to keep the well closed, and “these two separate systems provide redundancy in our safety systems.”

Still, the Shell Canada report into the accident of March 5 describes a harsh operating environment for the Stena IceMax drill ship in the winter months leading up to the day of the costly loss.

The report says on 10 prior occasions weather reports called for seas that would heave up to three storeys high or for gales to deliver dangerous wind levels —prompting the ship to remove the drilling fluids from pipes and replace the potential pollutants with seawater.

On Feb. 6 through Feb. 10, a winter storm moved through the area 250 kilometres offshore, sending seas heaving “between eight metres and 8.9 metres in 30 minutes” as the ship remained attached to the well.

The document says on March 5, weather forecasts again called for heaves beyond the eight metre operating limits of the drilling ship, and the ship again prepared to move off the site.

It decided to stay put when weather wasn’t as rough as predicted.

Then, a massive 9.25 metre high heave was registered, prompting the decision to unlatch from the well, says the report.

The operators decided to retract six “tensioners” — which resemble giant shock absorbers that move with the heaving drilling pipes — in the area of the ship where the pipes are attached.

This was to create added space between the top of the well at the bottom of the ocean and the drilling pipe system.

At 3:15 p.m., the ship started towing the pipe, but with the absorption system retracted and a special recoil system reset, the pipe system rose up above a metal ring holding it and then slammed down.

Within minutes the ring split open, allowing the pipes to plummet to the sea floor.

[In my opinion, this article - and all material from Shell and CNSOPB since the event - have underplayed the degree to which this shows Shell is out of their depth on this drilling project (literally), and how close we were to a complete catastrophe for the Canada-U.S. Atlantic fishery. A colleague of mine wrote a bit on this, and I'm extracting / paraphrasing here:

2 kilometres of drill pipe, weighing several tonnes was dropped. Pipe is very streamlined and has no buoyancy (like a sinking ship) so was likely travelling at over 100 km/hr when it hit bottom. If it had hit the well head and blow-out preventer (BOP) - which it missed by metres - they would have been obliterated. Due to the nature of the mechanical connection to the drill ship and the wave, the vessel was also at risk, and lucky not to have been struck. If Shell had found oil at that site, we would have had a massive sub-sea oil leak like at BP's Macondo, only in much deeper water and a more hostile marine environment. It took Shell about 10 months to drill this well. Presumably a relief well will take about as long, which means the oil leak could have lasted 3 times as long as Macondo. There is no capping stack closer than Norway (one month travel time - typical conditions), and none which has ever been tested at this depth. The one tested in Alaska for Shell in 2012 folded like a beer can in several metres of water (, not at a depth of kilometres.]

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