OSLO, Norway – Petroleum Safety Authority Norway (PSA) has notified BP Norge of an order, following investigation of a hydrocarbon leak last September at the Ula production complex in the southern Norwegian North Sea.
The leak occurred on the production installation that caused 125 bbl of oil and some gas to escape.
PSA’s investigation revealed that the leak was caused by fracturing of the bolts holding together a valve in a separator outlet. Seepage in the valve exposed the bolts to produced water with a high chloride content and a temperature of around 120°C (248°F) – this led to chloride stress corrosion cracking, which weakened the bolts until they fractured.
Production at Ula had to be shut down for 67 days as a result of the leak.
The investigation uncovered various breaches of regulations, in part connected with BP’s management system for activities on the Norwegian continental shelf (NCS).
Following PSA’s earlier review after a fire on the Valhall PCP platform in 2011, operator BP was served with orders that included reassessment of the company’s systems for maintenance management on aging installations. The company was also tasked with ensuring that its maintenance program was tailored to the age and condition of the installations and equipment.
PSA says its investigation of the Ula incident shows that deficiencies still exist in the maintenance system.
BP has been ordered to review its management system for the NCS with a view to assess whether it is adequate for identifying and managing risk, and to analyze why the system has proven inadequate for Ula.
Further, BP must assess whether measures implemented after the fire on Valhall in 2011 and other improvements are valid, following the nonconformities identified following the leak on Ula. In both cases, the deadline to complete the requested reviews is Sept. 1, with identified measured to be implemented by Dec. 31.