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Total has warned Royal Dutch Shell that its nearby Shearwater field may be at risk as a corrosive drilling fluid that caused the North Sea’s worst gas leak in 20 years is expected to threaten similar deep-sea wells.

The fluids, such as calcium bromide, implicated in the leak at the company’s Elgin field are said to be commonly used in deep-sea wells.

According to Total, the leakage at the Elgin field in 2012 happened due to a corrosive reaction that took place between calcium bromide, which is used to complete the well, and grease in the pipework, which cracked the piping under high pressure.

Experts are concerned about a similar incident occuring, as gas field operators are under pressure to tide over declining output from conventional reservoirs by venturing into deeper, hotter and higher pressure fields.

"Fluids, such as calcium bromide, implicated in the leak at the company’s Elgin field are said to be commonly used in deep-sea wells."

Due to the incident in the Elgin field, Total reportedly plans to close at least ten other wells in the complex, as well as the one that leaked, which is expected to cost more than $2.34bn to replace.

Total UK chairman, Patrice de Vivies, told Reuters that when sharing information on the causes of the leak, he had cooperated with Royal Dutch Shell.

"With Shell we have shared even more as they have a neighbouring field, Shearwater, meaning they potentially have, perhaps, not identical, but similar problems," de Vivies added.

Elgin, which restarted in 2013, and Shearwater account for more than a tenth of British gas production.

The field resumed output in March, but Total’s investigation into the causes of the leak are said to remain incomplete.

"We hope that the laboratory will be in a position by the end of the year to reproduce the phenomenon," de Vivies concluded.

The Elgin field’s G4 well, which leaked for a month and a half, created a huge cloud of flammable gas above the platform about 150 miles east of Aberdeen in Scotland.

Due to this gas prices increased and UK supply declined by seven percent.

Total chief executive, Christophe de Margerie, said: "The final conclusion hasn’t yet been released because it is not yet over, and there are talks to understand everything that happened and everything that could happen in the future."

Image: Elgin-Franklin gas fields in the Central Graben Area of the North Sea. Photo courtesy of NordNordWest.