Baker Hughes’ Materials Engineering Manager, Nick Clark gave The Welding Institute’s South-Western Branch an overview of the logistics of designing, manufacturing and installing equipment for the Gorgon Project off Western Australia. The talk, which took place at the offices of BHGE in Bristol on 7th December, was concerned with subsea production systems for the Oil and Gas industry – with particular note given to ‘Christmas Trees’; the colloquial name given to the collection of valves and pipe work which locates on the wellhead to regulate the flow of oil and gas.
The talk began with Nick describing a historic example of a weld structure failure, before offering some 2016 industry statistics to demonstrate the continuing importance of the oil and gas industry.
Nick noted how 75% of UK primary energy demand is met by this sector, with an estimated 20 billion barrels of oil and gas in UK offshore areas. The industry currently provides over 300,000 jobs with 36,000km of pipelines. Yet, despite the high number of employees, this sector has one of the lowest rates of personal injury, with regulations and directives also in place to protect the environment.
Baker Hughes, being a majority-owned part of the GE Empire, has manufacturing facilities across Europe, the United States and the Far East, where they produce products for the oil and gas industry, including key elements of subsea production systems. These include ‘Christmas Trees’ – the name given to surface well control stacks which control the flow of oil and gas. This name was given as the original stacks were said to resemble Christmas trees – and the name stuck.
These days, these ‘Christmas Trees’ generally weigh 40-100 tonnes, but larger manifold structures can be as much as 1000 tonnes in weight, creating evident challenges for transportation and location on the seabed. Furthermore, all alignment and connections for these subsea structures are done remotely with ROV since the depth at which these units operate often exceeds 1000 metres.
It is important to maintain the properties of these structures in such hostile environments, and so good material selection is paramount, both for the internal (CO2 and H2S) and external (seawater) surfaces. This is addressed through a combination of material property control, Cathodic Protection, and Coatings and Corrosion management strategies. With an operational lifespan of 50 years for most of the structures and some components planned for refurbishment after 25 years, quality assurance is important. As expected, international standards, such as ASME IX, ISO 15614, AWS D1.1, ISO21457 and NORSOK M-601, are used to ensure welds and structures are fit for purpose. These standards are often supplemented by customer specific requirements further adding to the execution complexity.
Nick’s informative talk ended with questions and an exchange of information, while there is a strong possibility for further talks on the subject in the future.
For more information, please Contact Us.