Dermot O’Brien’s, JP Kenny
In an area 130-200 km (81-124 mi) off the west coast of Western Australia, JP Kenny is applying state-of-the-art technologies to the design of the seabed pipeline and its route mapping as well as a proposed carbon dioxide sequestration project.
In addition to pipeline length, other critical issues affecting design are the maximum sea bed depth of 1,350 m (4,429 ft), the gas temperature of 130° C (266°F), and relatively high pressure at 360 bar (5,076 psi).
Scarp crossing super span model simplified from Abaqus integration of Fledermaus 3D view.
Finite element analysis (FEA) technology was added to the computer aided design suite to minimize the design time for components, to minimize the number of prototypes that have to be fabricated, and to provide a virtual test facility to measure several criteria at once. FEA technology is important in making the project economical at this time.
Key project elements are:
- Construction of a network of seabed manifolds and pipelines from the gas fields to an offshore island
- Large subsea structures that require specialized installation technology
- Gas processing on the island
- Gas sequestration in deep formations
- LNG facilities to transport products to international markets.
To study alternative designs, JP Kenny is using Abaqus, a suite of FEA software from Dassault Systèmes SIMULIA. Abaqus has been used to optimize designs through virtual testing. It provides solutions for modeling and visualizing a design’s structural integrity behavior when subjected to loads and contact.
The company is pioneering the use of the Abaqus software in seabed pipeline development. JP Kenny is using Abaqus to evaluate conceptual designs, front-end engineering design studies, and detailed pipeline design because the software capabilities are applied to deepwater and seabed movements and pressures and the high-pressure/high-temperature gas product.
System integration
The pipelay team integrated the Fledermaus interactive 3D visualization system with the software to map the escarpment. At the scarp crossing is a potential pipeline span of 200 m (656 ft) to 300 m (984 ft), so it is crucial for the pipeline to have the structural integrity to span the escarpment. In addition to the usual lay tension, pressure, temperature, submerged pressure and axial spring tensions to be calculated, there were additional elements defining the local geo hazards, including mudflows on the scarp face.
FEA analysis is under way for a range of conditions, including empty pipeline, pipeline with operating contents, and pipeline with flushing media. The sensitivity cases being considered are different pipe outer diameters, wall thicknesses, addition of concrete coating, and residual lay tension.
Results from the span analysis reveal bending moment distribution, longitudinal strain profile, and spanning pipeline profile along the route, plus modal shapes and frequencies. The JP Kenny team also is exploring deepwater trenching to reduce this span.
To make the undersea infrastructure more secure, the team uses the software to plan for major event scenarios, including the impact of cyclones on pipeline dynamics. The software reduces simulation times and improves the efficiency and accuracy of pipeline design and route mapping. This is an improvement over using ANSYS as the standard FEA tool.
The state-of-the-art technologies being applied to the design and development of these gas fields are helping make these huge energy assets commercially viable. In addition to helping to identify the potential to reduce the pipeline length by 40 km (25 miles), the software also helps to make this asset safer and more environmentally responsible as it supplies vital energy and earns valuable export income for Australia.
