North West Shelf Metocean Review

Background

With the increased size of metocean datasets a revised metocean criteria was determined by Woodside for their NWS assets. As a consequence it was deemed that there was a gap between the original designs and the updated metocean resulting in an unquantified change in the assets risk profile.

The scope of work included both rigid pipelines and rigid risers.

Work Performed by Atteris

Gaps within the current assessment matrix were identified, additionally historical reassessments provided by the client were reviewed in relation to the revised metocean conditions. Where gaps existed within the current assessment matrix a reassessment was performed by Atteris. These assessments included stability, fatigue and extreme loading conditions for each of the asset components. When undertaking reassessments Atteris noted any synergies between previous assessments, this allowed Atteris to eliminate the requirement for additional detailed finite element analysis.

As a consequence the overall delivery schedule was shortened considerably resulting in a reduced overall cost to the client.

Benefits

The benefits of the work performed by Atteris to this client were to confirm that the residual risk profile of each asset under the revised metocean conditions was the same as the original design.

To establish the change in risk profile a comparison of the original design metocean criteria with the revised metocean criteria was undertaken and a gap analysis performed. Atteris completed the engineering assessments determined within the gap assessment and reviewed previously undertaken engineering assessments. Based on the engineering assessments Atteris, in conjunction with the client, determined the revised level of risk associated with each of the NWS assets.