PSA authorizes Visund wells, outlines findings on Statfjord leak

Petroleum Safety Authority (PSA) Norway has authorized use of the semisubmersible COSL Pioneer to drill and complete wells 34/8-C-2 H and 34/8-C-2 AH at Visund Nord in the northern Norwegian North Sea.

Offshore staff

OSLO, Norway – Petroleum Safety Authority (PSA) Norway has authorized use of the semisubmersible COSL Pioneer to drill and complete wells 34/8-C-2 H and 34/8-C-2 AH at Visund Nord in the northern Norwegian North Sea.

The oil field is east of the Snorre field in a water depth of 335 m (1,099 ft). OperatorStatoil expects activity to begin this month and to last around 120 days.

PSA also has issued results of its investigation into a hydrocarbon leak last January on Statoil’sStatfjord C platform in the North Sea. The incident occurred while stabilized oil was being transferred from Statfjord A to Statfjord C.

Preparations were under way for maintenance on a loading pump. An isolation valve for the pump sprang a leak, causing the pump house to fill with oil which drained to the sump tank at the base of the shaft via an open drain valve.

When the level in the sump tank reached 70%, the pump for transferring liquid from the sump tank to the oily water tank under the cellar deck started up. However, the valve controlling the level in the oily water tank failed to open, and oil escaped via fire seals on the cellar deck.

Statoil estimated that up to 42 cu m (264 bbl) of stabilized oil may have escaped in a period of 37 minutes, at a rate of 20.8 kg/sec, with 40 cu m (1,412 cu ft) spilt to the sea and 2 cu m (70 cu ft) dispersed over the installation. No injuries were reported to any of the 270 personnel onboard at the time; production was shut down for almost four days for investigations.

In the event of ignition a spray fire or combustion of oil drops/flowing oil could have resulted, PSA claims, and there was a strong likelihood of similar leaks after the incident.

PSA’s review revealed six nonconformities, related to the original design solution for the drainage system; the modified design solution for the drainage system; consequence classification of the open drainage system; preparations for maintenance; management of simultaneous activities; and qualification and follow-up of contractor expertise. It has identified four improvement/action points, which Statoil must respond to by Oct. 1.

08/12/2014

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