This story was originally published in The West Australian on 8 April 2017 with the headline "The day disaster struck Gorgon." © Peter Milne.
Twenty-six million dollars is real purchasing power. But what does spending $26 million every day for 7½ years get you?
For Chevron and its partners Shell and ExxonMobil, it bought the Gorgon project on Barrow Island. Three vast processing units, known as trains, that can process and freeze 15.6 million tonnes a year of LNG — the energy which keeps the lights on from Tokyo to Shanghai.
For the Gorgon project team in January last year, that $26 million a day bought pressure.
A lot of pressure.
As if they weren’t under enough already. The project they were in charge of was one of the biggest industrial initiatives anywhere in the world.
The challenge had been to tap the gas strapped in porous rocks 4000m below the seabed off WA’s rugged North West coast and transport it to a sprawling processing complex on tiny Barrow Island — an area so environmentally sensitive the company was allowed to disturb just one per cent of the land.
On Barrow, the gas would be cooled to liquid form and pumped onto gigantic freighters bound for Asia .
To do this, Chevron installed 230,000 tonnes, equal to three aircraft carriers, of structure on the seabed. It designed sections of subsea pipe strong enough to be unsupported for lengths of up to 270m — 95m longer than the oval at the new Perth Stadium.
On Barrow, the giant processing plant required more steel than four Sydney Harbour Bridges. The three LNG trains comprised 51 modules, one weighing 6600 tonnes, which had floated across rolling seas to Australia from engineering yards in Asia.
The 2.1km jetty jutting out from the island rested on 56 concrete caissons built in Henderson and weighing an average of 2500 tonnes each.
The LNG carriers docking at that jetty each held enough energy to power about 80,000 Japanese homes for an entire year.
The enormity of the engineering challenge was surpassed only by the financial test.
When construction started in September 2009, LNG was to be produced in 2014. By January last year it was more than a year late. An already eye-wateringly expensive project was becoming dearer by the day as 8000 workers — equal to the combined populations of Kalbarri, Carnarvon and Exmouth and so numerous Chevron brought in a 1200-bed floating hotel, the Europa, to house the overflow — put their shoulders to the wheel.
In doing so they chewed through an astonishing $40 billion worth of Australian goods and services.
The initial $US37 billion cost soon blew out by more than 45 per cent to $US54 billion ($71 billion). The extra cash that the Gorgon partners had to cough up was enough to run the WA Government for nine months.
To add insult to injury, revenue projections were plummeting. When the project was approved in 2009, oil cost $US70 a barrel and demand for LNG was strong. Early last year, a barrel of oil could be bought for $US30 and the industry was talking about an LNG glut which would last for years.
Investors were fretting and Chevron desperately needed some good news.
Against that backdrop, Chevron chief executive John Watson told investors in October 2015 that “Gorgon will see first cargo in the first quarter”.
Chief executives do not make commitments to Wall Street lightly. The thousands of workers at Gorgon had just been given a deadline to get the first load of LNG onto a ship by March 31 last year.
For a project team that measured progress in years and months, the most complex start-up phase would be counted in weeks and days.
By January 1 last year, the Chevron LNG carrier Asia Excellence was at Barrow Island, laden with LNG to cool the plant to ready it for producing its own LNG.
The project team must have felt relieved when a few weeks later, on March 7, train 1 produced its first batch of LNG. There was still three weeks to produce sufficient LNG to load the Asia Excellence and ship the first cargo — meeting the chief executive’s ambitious deadline.
To produce that first LNG, untreated feed gas travelled from the Jansz-Io gas field wellheads, 1350m below sea level off the edge of the continental shelf, to Barrow Island, 130km away.
At the plant, a 210m long slug catcher removed condensate — a type of hydrocarbon coveted by industry. Then, successively, carbon dioxide, water and finally mercury were extracted from the feed gas to ready it for cooling and the creation of the final product: almost 600 tonnes an hour of LNG at minus 162C.
The propane refrigeration system provided the first cooling. A compressor circulated 2300 tonnes an hour of propane — the fuel in barbecue LPG bottles — through a propane cooler.
The feed gas ran through that cooler on a separate circuit. The propane pressure reduced in four stages — each time some of it boiled quickly, which was known as a flash. The flash cooled the feed gas like evaporating sweat cools the body. Because each flash was at a lower pressure, the propane had a lower boiling point, chilling the feed gas in stages to minus 40C.
The propane gas from each flash flowed back to the compressor through a knockout drum to repeat the cycle. The knockout drum removed any remnant propane liquid that could damage the compressor.
Eighteen days after first LNG production — and with the eyes of the world on the project — the fourth knockout drum failed.
It was a major catastrophe. The compressor was damaged and production at Gorgon ground to an expensive halt for more than three months.
Day of disaster
What happened that day is sourced from documents at the Department of Mines and Petroleum, the safety regulator for the LNG plant, obtained through freedom of information.
Compared with much of the Gorgon plant a knockout drum is a straightforward piece of equipment. Liquid propane settles to the bottom to drain away and the gas flows out the top to the compressor. For a knockout drum to work the liquid level cannot rise too high.
On the second day of LNG production, March 8, there was a high level of liquid in the fourth knockout drum and vibration in the propane compressor. It was a sign of the trouble to come.
On March 20, train 1 was shut down because of problems with a gas turbine generator.
The next day, Chevron’s LNG carrier Asia Excellence sailed from Barrow Island escorted by tugs spraying their fire hoses. Amid the media attention there was no mention that LNG production had stopped. According to an industry source, very little of the LNG the Asia Excellence carried that day had been produced by the Gorgon plant.
The plant was restarted on March 25. Things again went wrong, this time at the propane refrigeration circuit.
The propane compressor vibrated so much it tripped — an automatic shutdown to protect the equipment. Again, liquid levels in the fourth knockout drum were high, and liquid propane surged into the compressor. The knockout drum was significantly damaged.
DMP described it as a “catastrophic breakdown of the propane refrigeration circuit.” Chevron made no statement and the incident was first revealed by WestBusiness on April 1.
The Gorgon operator’s description was more subdued than the regulator. Chevron said in a statement on April 7: “Based on initial findings, the repair work is of a routine nature and all the necessary equipment and material is available on site.”
As part of the apparently routine work, the propane compressor was flown out of Perth for repairs aboard the world’s biggest plane, the Antonov AN-225, on May 17. The necessary material was on site because Chevron was scavenging parts from trains 2 and 3 to repair train 1.
In early July, more than three months after the incident, Gorgon’s second cargo of LNG left on the Marib Spirit. In that time Chevron had not reported the incident to the DMP.
The regulator and operator of the LNG plant met on August 8 to discuss the propane refrigerant circuit incident.
As recorded by DMP in a file note, Chevron laid out “what didn’t work” leading up to the incident. It was a lengthy list.
Perhaps the most serious was the failure of the stop-work authority that gives any worker the responsibility and authority to stop a task they believe is unsafe.
Another problem was the hazard and operability review, or HAZOP, where engineers and operating personnel brainstorm to identify possible hazards that are then addressed with changes to design or procedures. DMP in the file note of its meeting with Chevron stated: “Start-ups and shutdowns poses significant risk to a process plant and ... HAZOP of this stage is very important”.
The HAZOP for the propane refrigeration circuit did not cover the start-up of the equipment. Had it done so it may have identified a further issue.
The procedures for operating the propane cooler required the operator to know the pressure at the inlet of the propane compressor, but no such indication existed.
Other issues Chevron identified included workers starting up the plant having an “unclear line of management oversight” and “inadequate technical resources to back up operations”.
When contacted by WestBusiness for comment on the incident, DMP director of dangerous goods and petroleum safety Ross Stidolph said the department was satisfied that Chevron had identified the root causes, completed remedial actions and implemented additional controls to minimise future risk.
A Chevron spokeswoman said Chevron had notified the regulator as required, measures were taken to ensure the safety of personnel and the company had applied lessons learnt to the start-ups of trains 2 and 3.
Gorgon started producing LNG from its third and final train two weeks ago.
Main image: Three Gorgon LNG trains on Barrow Island. Source: Chevron Australia Pty Ltd.