UPDATE 2-"Unique" corrosion, compaction caused Elgin gas leak
LONDON, Feb 14 (Reuters) - Last year's leak from the Elgin gas platform tapping one of the world's most highly pressurised fields was caused by a "unique" interaction of rock compaction and pipe corrosion, according to the field's operator.
French oil company Total said the leak, which was discovered in March and took over seven weeks to plug, happened when the compaction caused unusual pressures higher up, eventually breaking pipework weakened by corrosion. The field has been shut ever since.
Patrice de Vivies, Chairman of Total Holdings UK, put the corrosion down to a chemical reaction between bromide in the drilling fluid used to complete the well and grease in the pipework.
De Vivies said what happened was "a unique event", but added: "We will be much more conservative in future in the pressures we can meet from the well."
Total plans a full report on the causes of the incident.
Vallourec, which makes the pipes used at Elgin and other fields around the world, also called the corrosion "unique" and said the incident "does not question the quality of our pipes".
De Vivies was speaking at a post-results news conference in London on Thursday at which Total chief executive Christophe de Margerie said he expected to receive a letter "in the next days" from Britain's Health and Safety Executive (HSE) that will allow it to restart Elgin soon.
"HSE has received the safety case (from Total) and is considering its response," a spokesman for Britain's Health and Safety Executive said.
De Vivies said that the company expected the Elgin-Franklin oil and gas field to produce 140,000 barrels of oil equivalent by 2015, and raise output to 150,000 barrels by 2016.