Origin Energy had previously had an unsuccessful lift attempt, aborted due to unexpectedly large pendulation of the 496te Compressor module they were wanting to install onto the Yolla Platform in Bass Strait, resulting in the failure of a restraining tugger wire.

AMOG were therefore engaged to conduct the lift reengineering, analysing the prevailing metocean conditions at the Yolla site, the hydrodynamic response of the vessel used, and the unacceptable pendulation response of the suspended compressor module as a result of the vessel motions. The lift engineering study, conducted across a comprehensive range of stages of the lift using OrcaFlex, evaluated the behaviour of the module, the tugger lines and support hoist lines against a range of safety and operation criteria stipulated by Origin Energy.

With the original ship unavailable due to unrelated operational conditions in-field, the lift was postponed and AMOG supported Origin Energy in the technical review of four heavy lift vessels operating in South East Asia to identify potential vessels likely to have the greatest operability in the prevailing metocean environment and be able to undertake the lift. AMOG's appraisal included:

  • RAO and phase determination of selected vessels using hull meshes modelled in ANSYS AQWA
  • Analysis of lifting configurations and vessel approaches, considering lifts from the East and West sides of the platform, as well as a lift and skid operation
  • Calculation of natural period based on predicted pendulation length for each configuration
  • Investigation into alternative tugger arrangements including the use of constant tension winches
  • Derivation and analysis of appropriate crane tip heave criteria
  • Operability assessment and determination of predicted monthly lift windows based on 31 years of hindcast data at the Yolla site

Following Origin Energy's selection of the SapuraAcergy heavy lift vessel Sapura 3000, AMOG supported Origin to achieve the successful safe installation of the compressor and condensate modules (496Te and 50Te respectively) in December 2014. As part of this work, AMOG provided:

  • Independent verification of SapuraAcergy's installation engineering, including:
    • Independent derivation of the RAOs of the Sapura 3000
    • Development of a detailed OrcaFlex models including lift rigging equipment, constant tension winches and bumper guides
    • Transient analysis of module bumper engagement and set down lift stages against respective impact force and snatch load criteria
    • Liaison with DNV GL in their review and acceptance of the advanced installation engineering performed
  • Structural FEA of platform bumpers
  • Verification of module pendulation damping using on-board instrumentation during module load out
  • Module and platform motion monitoring using accelerometers during lifting operations


A peer reviewed paper, co-authored by AMOG Consulting, Origin Energy and SapuraAcergy, was published in the 2016 APPEA Journal and a poster presentation made at the 2016 APPEA Conference in Brisbane Australia.