The Wheatstone Project, a major development by Chevron Australia, involved one of the world’s largest integrated LNG developments.
The offshore facilities included a 35,000-tonne Steel Gravity Structure (SGS) supporting a 37,000-tonne topside for production, processing, and living quarters. The SGS was fabricated and partially assembled onshore before offshore installation.
The scope encompassed detailed structural design, installation engineering, and construction support for the SGS and topside integration.
Poseidon Offshore Energy engineering team provided detailed design and offshore installation engineering, including:
The engineering scope commenced with a comprehensive detailed design of the Steel Gravity Structure (SGS) and topside, developed through advanced finite element (FE) modelling in ANSYS. The FE model captured all critical structural components, including leg cans, skirts, topside support framing, and internal stiffening members, enabling the team to assess both global and local load-carrying behavior under construction, transportation, and in-place conditions.
Nonlinear contact simulations were performed to replicate the load transfer mechanism between the SGS base and the skidways during the loadout phase. These analyses accounted for barge deck flexibility, frictional interface characteristics, and uneven skidway elevations, ensuring that contact pressures remained within allowable limits throughout the operation. The model incorporated geometric and material nonlinearities to accurately represent the interaction between the high-stiffness SGS and the comparatively flexible transport barge.
To verify stability and ballasting performance, hydrostatic analyses were conducted using Maxsurf and Hydromax, allowing for precise prediction of barge draft, trim, and heel during both loadout and lowering operations. This included assessment of intact and damaged stability conditions as well as time-dependent ballast transfer sequences to maintain structural alignment and safe clearance margins during float-off.
Seafastening and rigging systems were designed to meet GL Noble Denton and AISC requirements, ensuring sufficient strength and redundancy under combined dynamic and inertial load effects. The engineering deliverables also included grillage and support framing design, verified through local FE models to confirm stress distribution and to avoid overstressing of primary members.
A series of detailed method statements were developed, supported by analytical verification packages, defining every operational step — from barge ballasting and load transfer to controlled lowering and mating operations. This integrated analytical approach provided a fully validated engineering solution, guaranteeing safety, structural integrity, and compliance with international offshore lifting and installation standards.
This project highlights Poseidon’s advanced structural design and offshore installation capabilities, ensuring reliable performance and safe operations for large-scale substructures. The Wheatstone Project demonstrates the engineering expertise of Poseidon’s team in managing large-scale offshore structures through advanced FE modelling and precise installation planning.
ANSYS, SACS, MathCAD, AutoCAD, Maxsurf and Hydromax
Detailed Design Reports, Design Drawings, Loadout & Lowering Analysis Report, Rigging Design, Barge Stability Assessment, Grillage Drawings.
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