Safer, cheaper offshore pipelines for oil and gas production
UWA researchers have developed cheaper and safer offshore pipelines to reduce the cost of building and maintenance in oil and gas infrastructure. This has been achieved via the delivery of new design paradigms that have been adopted by operators and verifiers worldwide, and which now feature in international standards for pipeline design.
Impact Case Study:
Australia’s offshore oil and gas industry is worth approximately $25 billion annually and is critical in supplying the country’s energy needs. With new projects in Australia and worldwide moving into deeper waters and operating with higher well temperatures, offshore structures are facing a number of challenges. During the extraction phase, the hydrocarbons pass from the wellhead through pipelines to the processing and export facilities. These pipelines are susceptible to buckling and progressive axial movement (‘walking’) in response to the operating temperature cycles and can be destabilised by waves and currents, particularly during cyclones. Buckling, walking and onbottom stability must be predicted and controlled to ensure the safe and reliable operation of the pipeline.
Building a pipeline system to link an offshore oil and gas field to the mainland represents a huge capital investment. The cost per kilometre of recent and future pipeline projects, including Gorgon (65-140km), Scarborough (280km), Pluto (180km) and Browse (up to 900km) is typically $4 million per kilometre. With multiple pipelines on each route, over 3000km of pipelines are involved with a capital expenditure of >$10 billion.
The UWA pipeline engineering research program is made up of two major Joint Industry Projects (JIPs), SAFEBUCK and STABLEPIPE. It has been a 10 year collaboration between UWA and the Australian and international oil and gas industry. The research emerging from the STABLEPIPE and SAFEBUCK JIPs is radical and often revamps conventional thinking. Conventionally, pipelines have been anchored and reinforced to provide extra stability and reduced thermal expansion. This design creates increased rigidity and resistance to natural movement, as well as increased costs associated with the physical anchors and reinforcement. The central design principal underlying STABLEPIPE is that the seabed is less stable than the pipeline. As the sea bed shifts with normal wave action, sand transport, and extreme weather events the pipe will generally become buried through scour and sediment transport and thus ‘self-stabilises’. Meanwhile, the SAFEBUCK JIP has promoted a radical solution to the thermal expansions of pipelines, in which the pipe is permitted to buckle and displace across the seabed to relieve, rather than resist the loading. During this work, it was also shown the friction between pipelines and the seabed rises over the operating life, validated by physical modelling and numerical studies undertaken at UWA. The results are more cost-effective designs with a reduced requirement for anchoring and ancillary structures. This success is reflected in the range of industry awards given for the research including: Australasian Industrial Research Group Medal 2014; Subsea Energy Australia Research & Innovation Award 2012; and Engineers Australia WA-Innovation & Development Excellence Award 2012.
This research has transformed how the seabed is characterised and how pipeline-seabed interactions are assessed, ultimately leading to new design methods that have been adopted by a number of industry end-users globally. The new design methods have led to increased efficiency and also to significant cost savings. Woodside Senior Vice President of Health, Safety, Environment & Technology, Shaun Gregory, said by working together the STABLEPIPE project partners had been able to significantly improve the future design of offshore oil and gas pipelines and demonstrated how embracing technology can achieve real cost savings for the industry.
Oil and gas companies have sponsored the research, steered the activities, reviewed the outputs and adopted the outcomes (design methods, calculation approaches, software etc) in their business practices to reduce the cost of pipeline design and improve business performance. The most recent phase of the SAFEBUCK JIP involved 20 participants, including eight major oil and gas operators and a significant number of offshore engineering contractors and resulted in the UWA authorship of the SAFEBUCK Guideline design code. These Guidelines are now the defacto global industry standard for the design of High Pressure High Temperature (HPHT) offshore pipelines and have been used by the JIP industry partners Woodside, Chevron, Det Norske Veritas (DNV) and Wood Group Kenny, and their contractors, on their Australian offshore projects.
The research has been rapidly distributed throughout the local firms; Advanced Geomechanics (part of the Fugro Group), Wood Group Kenny and Atteris. It has been adopted by every major recent Australian offshore project, providing more accurate estimates of pipeline behaviour through an improved understanding of the oceanpipeline-seabed interaction. This reduction in uncertainty leads to more efficient pipeline design, often with major cost savings due to the reduction of mitigation measures such as anchoring. A recent Woodside investor briefing quoted a 10:1 return on investment in this research.
This UWA research is also becoming further embedded in international design practice. Both the SAFEBUCK Guideline (completed in 2015) and STABLEPIPE JIP Guidelines (completed in 2016) have been converted to using DNV guidelines set by UWA researchers. These new guidelines replace the prior recommended practices for pipeline buckling and stability design. UWA researchers have also authored new sections of the relevant ISO/API design codes, to incorporate the research into global standards.
In summary, the design of virtually every offshore pipeline constructed in Australia over the past decade, and many others worldwide, has relied on UWA research. The research is leading to more accurate, reliable and costeffective design of pipelines worldwide, providing safer and more secure energy supply in Australia and overseas. It is also strengthening Perth as a hub of offshore engineering excellence, with Australian firms supporting pipeline engineering designs worldwide.
The research from the SAFEBUCK and STABLEPIPE JIPs encompass new methods to characterise seabed conditions, understand the mechanisms by which pipelines, waves and currents deform and disturb the seabed, and predict the resulting pipe-seabed interaction forces and pipeline behaviour. In offshore Australia, this behaviour is made more complicated by the severe ocean environment and the unusual mechanical behaviour of our carbonate soils.
The UWA pipeline research includes three parallel streams:
- Centrifuge, 0-tube and numerical modelling have revealed the mechanisms by which pipelines and ocean waves deform the seabed, quantifying the resulting interaction forces. This work used UWA’s unique experimental facilities and began in 2007 when David White joined UWA.
- New calculation methods and computational software for pipe-seabed and ocean-seabed interaction have been devised and disseminated through academic publications, and also Guidelines and Recommended Practices written by the UWA researchers for the SAFEBUCK and STABLEPIPE sponsors.
- In a spin-off from the SAFEBUCK and STABLEPIPE JIPs, new tools to characterise the seabed and provide input parameters for assessing pipe-seabed interaction have been devised by UWA, including the piezoball and toroidal penetrometers. This has been supported by UWA-Ied industry collaborations such as the Remote Intelligent Geotechnical Seabed Surveys JIP (2013-present) and the ARC CoE for Geotechnical Science and Engineering.