RIASSUNTO
ABSTRACT
During the spring and summer 2003 Aalesund University College (AUC) completed a unique simulation of navigational problems related to the cessation of the Frigg Field in the North Sea, which will take place in the period from 2004 to 2012. At the final stage in 2012 it is planned to equip the three concrete substructures that remain in place with adequate navigation marks to reduce risk for future collisions. This is the first time shiphandling simulators have been used to evaluate future navigation systems for decommissioned offshore structures.
INTRODUCTION
After shutdown of the production at the Frigg Field in the North Sea, the operator, Total a/s, evaluated different strategies for navigational aiding, such as navigation lights and radar beacons (RACON), to be used during and after the decommissioning and cessation of the field. Together with a traffic study the simulations are believed to be important elements in the future risk assessment. The main purpose of the simulations is consequently to design and evaluate the optimal navigational aids with regard to safety and cost efficiency. Today (2003) the Frigg Field consists of six platform structures (Fig. 1), but will at the final stage only consist of the concrete substructures of platforms CDP1, TCP2 and TP1. The main objective of the simulation was to visualize the different navigational conditions during decommissioning and cessation, as well as provide operator and authorities with a professional nautical approach to the issue. Main focus of the simulation was on the final situation when the steel jackets and topsides are removed, approximately from 2011/ 2012. To meet this objective the following tasks were performed: • Review of different cessation documentation. • Review of different International Authorities of Lighthouse Authorities (IALA) and International Maritime Organisation (IMO) regulations and standards.