* Statoil needs several days to assess damage
* Corrosion found in another gas tank
OSLO Nov 16 (Reuters) - Norway's Statoil has found further corrosion in gas tanks at its Troll C platform in the North Sea and will keep the facility offline for several more days while it investigates.
Troll C produces about 120,000 barrels of oil a day, or 8 percent of Norway's output, while its gas output is 10.5 million cubic metres a day, about 3 percent of the country's output.
"Work is now being done to qualify the repair method and scope of work on the tanks. In a few days we will be able to give more information about the expected duration of the production stop," the company said in a statement.
Statoil said the corrosion does not present a safety risk to Troll C.
The company initially discovered corrosion in a tank in an auxiliary system for gas treatment and shut the facility to investigate a similar tank in a parallel system.
"Corrosion under insulation is a well-known problem which is handled in scheduled inspection programmes. The corrosion on the Troll C tanks was discovered during such inspection," Statoil added.
The Troll field's shareholders include state holding company Petoro (56.0 pct), Statoil (30.6 pct), Shell (8.1 pct), Total (3.69 pct) and ConocoPhillips (1.62 pct).