Prelude FLNG Position Keeping Analysis

Location: Browse Basin, Western Australia


Keen to tap into our extensive FPSO position keeping experience, the client engaged our team to provide consulting support to the installation contractor for the position keeping of the Prelude FLNG located in the Browse Basin, Australia – the largest floating facility ever built. Due to the location of the Browse Basin, the FLNG is battered from all directions, with the current changing direction throughout the day and a long period swell hitting the FLNG at a conflicting direction to the wind and short period wind seas.



Before we undertook the position keeping analysis, a basis of design was developed rationalising the metocean loadcases required hook-up. This allowed the analysis to follow a loadcase plan, reducing the analytical time and focusing on the most onerous scenarios. We identified the critical number of tugs using static analysis, as well as the limiting environments, before undertaking a restricted dynamic analysis approach.

The dynamic analysis was used as an understanding tool for the position keeping procedure, understanding vessel drift off etc during operations. As part of the approach, we focused on the validation of the limiting environments using simulator outcomes – little could be gained from dynamic analysis due to the complex nature of the scenarios.

Outcomes and benefits

Our team developed a basis of design by rationalising the metocean report and developing critical load cases for position keeping, reducing the amount of analysis undertaken. This philosophy also reduced the dynamic analysis scope.

Our work led to a robust, functional solution for the client, ensuring downtime was minimised and hook-up operations were safe. The validated environment limitations were implemented into the offshore procedure for use by the project team.

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