Polar Restriction Diagrams for Dynamically Positioned Units

摘要

This work describes the development and applications of PolarrnRestriction Diagrams, which incorporate criteria to determine minimumrn“safe” distances between dynamically positioned (DP) units and anyrnobstacle such as floating production systems. These diagrams arerncentered in the DP unit; the restriction area, where no obstacle can bernpresent, is determined by calculating “safe” distances for a series ofrndirections of the environmental forces. The calculations are based onrnprobabilistic methods that rely on statistical meteo-oceanographic data,rnand follow a pre-defined target probability for the event of a collision.rnOther parameters are also considered, including the hydrodynamicrncharacteristics of the DP unit, and the records of previous DP failuresrnstored by Petrobras describing the mean time between failures, and thernaverage duration of a blackout.