A new risk-based goal-setting regulatory framework has replaced the previous prescriptive certificate of fitness regime under which most installations being operated in the UK sector of the North Sea were designed and originally operated. This has resulted in a significant change in approach to the demonstration of life cycle integrity with far-reaching implications for design, fabrication, operation and decommissioning. These fundamental changes have required the approach to the assurance of the structural integrity of older structures installed prior to the implementation of the more recent regulations to be reconsidered using a risk-based methodology. This approach may be constrained by the original design and operational history and, unlike new installations, the opportunity for any further risk control is limited mainly to improved operational procedures. The reassessment of older structures is implicitly required not only as a result of the introduction of the new regulations but also as a result of significant changes to codes and standards and for life extension. In the light of the relatively recent introduction of the new regulations, the approach to life cycle integrity management is still evolving and this paper highlights relevant key issues.
Most North Sea oil and gas-production in the North Sea takes place from over 150 fixed platforms and over 70% of the total offshore work force are employed on them. Fixed installations depend on adequate structural integrity for their continued existence and about half of them are over 20 years old, exceeding their original design life. Manning levels range from occasional visits to normally unmanned installations (NUIs) to platforms accommodating over 250 people. Further life extension of these larger platforms and an increase in technical duty is likely to be required as more tie-ins to other new fields are planned in the future.
