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Total reveals Elgin leak rate

Total has estimated that gas is leaking from its Elgin field at the rate of about 2 kilogrammes per second as concern mounts over the North Sea crisis.

The company is mobilising the nearby jack-up Rowan Gorilla V for the possibility of drilling a relief well as the French oil giant considers options to kill the ongoing release, an operation that could take months.

(Click here to read all Upstream articles on the Elgin gas leak crisis.)

David Hainsworth, health, safety and environment manager for Total E&P UK, said there was a “large range of uncertainty” in the leak rate estimate.

“We clearly have got a visual indication of a gas cloud. What we have been trying to do is model that and work backwards and try to estimate that as a leak rate,” Hainsworth told Upstream on Tuesday.

“One figure we have calculated is around 2 kilogrammes per second but there is a large range of uncertainty in that.”

The executive admitted that a relief well on Elgin, if required, would typically take about six months to complete.

Jake Molloy, of offshore union RMT-OILC, said the incident is potentially the most serious for the UK North Sea since the Piper Alpha disaster in 1988.

Molloy said: “Total acted very swiftly in getting everyone off, but the potential still exists for catastrophic devastation.

“If  the gas cloud somehow finds an ignition source we could be looking at complete destruction."

He continued: “This is an unprecedented situation and we really are in the realms of the unknown, but the urgent need now is to find a way of stopping the flow of gas.”

The Unite union has meanwhile called for the full evacuation of all oil and gas platforms within a five-mile radius of the leaking Elgin platform amid fears for the safety of workers.

Wullie Wallace, regional officer for the union which represents thousands of members offshore, welcomed the establishment of an exclusion zone around Elgin but called for greater precautions at nearby facilities.

Wallace said: “The risk may be low but our concern is that if the drifting gas was to hit any of the neighbouring installations the results could be catastrophic.”

Flights by spotter planes have estimated that a sheen on the surface of the sea, thought to contain condensate, measures up to 24 tonnes.

Workers on nearby installations several miles away have reported seeing a gas cloud enveloping Elgin.

Total initiated a full evacuation of Elgin and the Rowan Viking drilling rig, which had been working alongside, after the leak was detected on Sunday afternoon UK time.

All workers were airlifted to nearby installations and back to Aberdeen. Nobody was injured.

On Monday Shell began flying workers off its Shearwater platform and the Hans Deul drilling rig, both about four nautical miles from Elgin, as a precaution.

Hainsworth said the problems had occurred during operations to plug and abandon the field’s G4 well.

“On Sunday there was quite a sudden rise in pressure and they were finding it difficult to bleed off this rise in pressure,” he said.

“That initiated what followed. Witnesses who were working on the well saw a release of what we expect is mud from just below the wellhead at the top of the casing followed by gas.”

Hainsworth said that gas is being released on the Elgin wellhead platform at low pressure – about five bar - and that it is coming from a non-producing reservoir above the Elgin formation.

Earlier unconfirmed reports based on eyewitnesses who said the sea appeared to “boiling” incorrectly suggested the leak was subsea.

A two nautical-mile exclusion zone has been set up around Elgin to shipping and a no-fly zone imposed overhead.

“Clearly there is a chance of ignition,” Hainsworth said.

He added that Total specialists from around the world are being scrambled to Scotland to lend support to the company’s Aberdeen staff to evaluate options for stopping the leak.

Geoscientists are also working to establish the volumes of gas within the reservoir.

“We are evaluating the options,” Hainsworth said. “There is a range of options.”

These include drilling a relief well. Hainsworth said the release may also die down on its own.

“If the gas release diminishes there may be an option to go back onto the platform to use equipment there to continue the kill operation," he said.

Industry well intervention specialists have also been drafted in to help Total assess what can be done.

The Gorilla V has been drilling development wells for Total on its nearby West Franklin project, which is under construction.

“If we take the Rowan Gorilla V off the development drilling to drill a relief well, then there would be a delay in the drilling programme. But it is a multi-well development, so it just means there would be a delay in some of the production later on," he said.

The high-pressure, high-temperature Elgin-Franklin development in the Central Craben area of the North Sea’s UK sector is about 240 kilometres east of Aberdeen.

Average production before the incident was about 230,000 barrels of oil equivalent per day.

Industry body Oil & Gas UK said it is monitoring the situation.

Robert Paterson, the group’s health, safety and employment issues director, said: “Total reacted with commendable speed to ensure the safety of the people on the installation with a swift and successful evacuation.

He said “While it would be wrong to speculate on the incident, Oil & Gas UK will play its role in ensuring any lessons from this are shared across the industry.”

Total yesterday met with the UK Secretary of State’s Representative (SOSREP) and representatives from the Health & Safety Executive, the Department of Energy & Climate Change.