One of the major accident hazards to which offshore installations are exposed is ship collision. Two of the top 20 largest property damage losses in the hydrocarbon industry worldwide between 1974 and 2013 have been caused by vessel collisions (Ekofisk in 2009, $840m; Mumbai High North in 2005, $480m). The latter also resulted in 22 fatalities due to escalation.

Anatec has significant experience in this field and works for most offshore operators in the assessment of collision risk, both in the UK and internationally. The scope of our services includes assessment of the risks associated with:

  • Visiting (infield) vessels (ERRV, Supply, DSV & ROVSV, Flotel, W2W, etc.)
  • Passing merchant traffic (cargo, tanker, ferry, etc.)
  • Fishing vessels
  • Offtake shuttle tankers (e.g., tandem loading)

The nature of the analysis differs depending on the type of vessel being assessed. For example, for passing ships both powered collisions due to watchkeeper failure, and drifting collisions due to engine failure, are assessed. For DP shuttle tankers, the risks of a drive-off or drift-off incident towards the FPSO are considered. In all cases, the consequences are evaluated in terms of risk to the physical structure (energy of impact based on the displacement tonnage and speed of the colliding vessel) and to the personnel onboard (PLL and IRPA).

The assessment work is carried out using Anatec’s COLLRISK software, which is cited as best-practice by the International Oil and Gas Producers Association (IOGP) in the Risk Assessment Data Directory report for Ship/Installation Collisions under “Best practice collision risk modelling for passing vessels”.

In terms of risk management for this hazard, Anatec personnel have worked on a number of HSE research projects, the results of which have been used to update the methodology and models we use to ensure they continue to meet the requirements and best-practice of the regulator. This includes the use of AIS as well as radar for traffic monitoring.

The models are calibrated for the area of interest using the most up-to-date historical accident data available, and take into account a clear trend of improving safety due to lessons learned through joint industry projects, etc.