Offshore giant Total has sent two emergency firefighting vessels to its Elgin platform in the North Sea amid fears the gas leaking from it could ignite.
Air and sea exclusions zones have been set up around the installation 150 miles east of Aberdeen which is spewing highly-flammable hydrocarbon methane at the rate of more than seven tonnes an hour.
Total admitted that the leak could take six months to plug, and as the company’s share price dropped by nearly 7% there were union calls for all platforms within a five-mile radius of the incident to be powered down.
More than 200 workers on the installation were evacuated at the weekend after gas started escaping from a “dead well”.
Built in 1999, the Sea Bear is a multi purpose offshore vessel which has left Aberdeen harbour to stand-by the Elgin platform in case of an explosion.
Guarding the installation along side it is the Skandi Saigon which was built last year.
The Skandi Saigon is a new generation of high powered anchor handling vessel designed for field installation operations across a wide range of depths and conditions.
Firefighting vessels are essential both for fighting fires on ships and for aiding in shore-based firefighting operations.
They are able to draw sea or river water and pump it out through directional nozzles to a fire, or through pipes to units on the shore.
The Sea Bear and the Skandi Saigon have now left Aberdeen to head for the platform.
It was estimated that by about midnight last night, more than 430 tonnes of highly-flammable hydrocarbon methane had escaped from the installation’s G4 well.
The leak started during work to seal and abandon the well.
The incident has led to a full-scale emergency and last night Shell announced it had halted production on its nearby Shearwater platform as a result of a drifting gas cloud coming from the Elgin.
As a precaution, a three-mile air exclusion zone has been declared and boats are forbidden from getting within two miles of the abandoned installation.
Total’s health, safety and environment manager David Hainsworth said they were considering how best to tackle the leak, but warned they had to be aware of the risk of an explosion.
He said: “The greatest risk we face is that the gas cloud could ignite. We have taken every precaution to stop this from happening.
“When we left the platform everything was powered down but we have to consider if we send people on it there is a risk this could happen.
“We have now sent two firefighting vessels to the area as a precaution.”
It is understood the cost of having the two boats on the scene could be around £70,000 a day.
Mr Hainsworth said the best possible scenario would be if the leak stopped on its own.
The company is preparing for the possibility of having to drill a relief well, which could take up to six months.
But Mr Hainsworth said they had not ruled out sending men onboard.
He said: “One scenario is it will stop on its own.
“The second is that we will go back to the platform with specialist well-control operators and kill the well which is leaking.
“There is gas on the platform, however we will assess the risks. The specialist well operators are used to dealing with this type of situation.”
The company’s options are restricted because of the exclusion zone around the platform but Mr Hainsworth said they were considering asking to be allowed to cross the safety boundaries to begin carrying out work.
He added: “These options will take several days to develop and we may even progress one of the options parallel to another.
“So, for example, we could start drilling the relief well while we have a team on the platform trying to kill the well.”
Despite the emergency, Total said it was pleased it had managed to evacuate everyone from the rigs without any injuries or fatalities.
The company has now moved people from its offices around the world to Aberdeen and has flown in experts used by BP to battle its Gulf of Mexico spill two years ago.
The Elgin/Franklin hub started producing in March 2001 and, before the leak, delivered 7% of oil and gas in the UK.
It is estimated to have another 20 years of field life and is the largest “high pressure-high temperature” development in the world.
The two adjacent gas fields are located in the Central Graben Area of the North Sea, 150 miles east of Aberdeen.