Atteris’ assessment of installation feasibility in the early stages of the project identified a number of potential impacts on the pipeline design which might affect installation requirements. Understanding these impacts and constraints on the trunkline design enabled an optimised wall thickness design and reduced CAPEX.
Woodside’s Browse trunkline, if installed, will be the largest diameter pipeline installed in water depths up to 500m. As the pipeline is optimised for the in-place condition, the wall thickness is minimised. The effects of collapse pressure on the reduced wall thickness, combined with bending in the sagbend during installation required investigation. It is important to assess the installation feasibility in the early stages of project definition to identify any impacts the pipeline design might have on the installation requirements. Pipeline installation has a significant impact on CAPEX as vessel production rates, pipelay tensions and the contractor’s risk profiles are altered.