Abstract

Global analysis is required when installing flexibles, umbilicals and rigid lines in order to plan the operation and establish safe working environmental limits. Recent advances in modelling software and computing power mean that it is now feasible to model these operations in significantly more detail than has been previously considered. This paper provides an overview of the level of detail which can now be achieved, highlighting various operations which can be modelled and demonstrating how this can reduce risks as well as optimising operability during installation.

The paper focuses on the following areas: modelling techniques, modelling of offshore deck handling operations, and modelling the installation of a Pipeline End Termination (PLET). These case studies are used to highlight the benefits of detailed modelling in reducing risks for the actual operation offshore, in particular by studying the dynamic response as the equipment is installed, and how this relates to the accurate definition of a safe sea state limit. In the past, due to the high level of complexity, these operations have been engineered through the use of standardised calculations or through simplification of the modelling. Comparisons between the simplified and detailed analysis are made, highlighting the differences and the increased accuracy of results which may be obtained, showing areas where offshore installation may be executed more safely. Models are also be compared against the reality of the offshore installation to confirm the validity of the techniques described.

This provides an overview of the level of detail which can now be achieved with the following benefits:

  • Capturing critical motions which may have been previously missed due to over-simplification

  • Modelling new stages of the operation which could not previously be covered

This will ultimately help to reduce risks as well as optimise operability during installation.

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