StatoilHydro admits to Statfjord failings

In the report of an internal investigation into the oil spill during the loading of the shuttle tanker Navion Britannia this past December 12, StatoilHydro says it has identified weaknesses both of a technical and organisational nature. These weaknesses have been "immediately addressed", according to Tore Torvund, executive vice-president, exploration and production, Norway.

The incident occurred when a hose ruptured during the loading of the tanker from the Statfjord A platform. Some 4,400 m3 crude oil was spilt to the sea. An investigation ordered by StatoilHydro management identified the immediate cause as a rupture in a hydraulic hose on Navion Britannia; this caused the vessel's coupler valve to close more quickly than expected, generating a strong pressure surge in the loading hose. The loading hose did not meet the specification of the original Coflexip hoses used on the tanker and it could not cope with this pressure surge, resulting in its failure.

The investigation identified the root cause of the hose rupture as inadequate use of process and risk analysis in connection with modifications and change of loading hose. In addition, personnel involved in the operation were unaware of the consequences of the rupture in the hydraulic hose. Further, the failure to notice the oil spill until so much oil had been lost was due to inadequate flow measurement aboard the tanker. A review of other incidents revealed that a similar event at a single-point loading system on the Gullfaks field in 2004 had not been properly followed up.

"StatoilHydro has already implemented several technical and operational actions in order to ensure safe operation of our single-point loading systems," says Torvund. "We will immediately initiate work to address the organisational and managerial weaknesses identified in the report."

StatoilHydro has also been working with Teekay, which operates 18 shuttle tankers in the North Sea. Upgrades have been ordered and in many cases already completed, involving the replacement of hydraulic hoses. The two companies are evaluating the feasibility of installing flowmeters and reducing the rate of flow in the lines. "It is important the cut-off systems work as designed," a Teekay spokesman told Lloyd's List. "We will make these systems more robust and will train crew on these systems."