Offshore release data – Trends in underlying causes

Risk analysis for hydrocarbon hazards in the offshore oil & gas industry depends on data relating to loss of containment events. The UK HSE Hydrocarbon Release Database (HCRD) is one of the main sources of that information. Recent examination of the HCRD shows a decrease in the annual number of releases.

This raises the question whether the decrease is due to specific causes, because this would affect whether the latest release rates would be applicable to all installations or only to certain categories e.g. newly built installations. To this aim, a study was carried out to determine whether significant trends are apparent when categorizing releases by specific cause.

The data in the HCRD was processed in order to distinguish between the main causal factors: “Equipment”, “Design” and “Procedure”. It was necessary to set up clear schemes to translate the recorded data on causes into the above three categories in an unambiguous way. The assessment looked at relative trends, i.e. it was investigated whether the relative contribution of some causes as compared to all releases, had changed over time.

This avoided the necessity to consider changes in e.g. population data (number of installations and components) and generally provide more robust conclusions. The main conclusion is that the relative contribution of “Procedures” as a cause for release has significantly decreased. “Design” seems to lead to a reduction in releases too, despite appearing to be improving at a slower rate than the procedures.

Finally, “Equipment” was improving at the slowest rate, if at all, until 2003. Since then, it has been improving at a noticeable rate. Sensitivity assessments support that these findings are significant and robust. The conclusions suggest that, when considered over the period for which data was available, improvements in offshore safety have been mainly driven by improvements in management, covering elements like procedures, competence and compliance.