Quantitative risk assessment applied to offshore process installations. Challenges after the piper alpha disaster

Abstract

The Piper Alpha disaster in 1988 has led to widespread adoption of quantitative risk assessment (QRA) in decision-support within the North Sea oil and gas industry. This has presented a challenge to practitioners in QRA, both with respect to the reality and detail which their predictions can represent and in terms of the speed and traceability of their work. This paper uses examples to illustrate the extensive advances which have been required in offshore QRA during the past five years. It traces the growth of time-dependent consequence modelling for leaks from risers and process equipment, and the adoption of linked spreadsheets to speed up the analysis of escalation risks for a full range of such events across a large platform. The quality assurance challenges relating to such complex spreadsheets prompted the development of the multi-sponsored Offshore Hazard and Risk Analysis (OHRA) Toolkit as an industry standard for QRA applied to offshore installations.