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WA Branch Technical Meeting - 12 July 2021 Asset integrity in Subsea Oil and Gas Source: Dr Alex Ham, Team Lead, Subsea Integrity Management, Wood Dr Alex Ham, holds a PhD in Materials Engineering and has extensive experience in asset management in the water supply industry, mining and in subsea oil and gas. He summarised the principle of asset management as “the coordinated activity of an organisation to realise value from assets". The guiding standard for risk-based asset management is ISO 55000, with the subsea industry also using DNV and API standards. Ultimately, a balance is needed between risk, consequences, and mitigating actions. Dr Ham summarised his role as helping ensure that “nothing exciting happens”, though this raises a challenge in demonstrating value when the outcome is the absence of failures. He remarked that, if anything exciting (or even catastrophic) were to happen, ideally applied risk-based asset management should be able to justify the response that “we wouldn’t have done anything differently”. There are, however, many potential pitfalls, as he went on to explain. Asset management considers both capital expenditure (CAPEX) and total lifecycle expenditure (TOTEX). It therefore requires the integration of asset data and financial data, covering the full asset life cycle: acquisition, operation, maintenance, and ultimately, disposal. In the oil & gas industry, the major opportunities to reduce total life cycle cost are often ‘up-front’ in the design stage.
L to R: Schree Chandran (Branch President) and Dr Alex Ham.
The continuing cycle of asset management comprises four steps:
In general, the goal of maintenance is to ensure a specified level of availability. For surface installations, this might be achieved by ensuring easy maintainability, with only fair reliability. However, in subsea operations, high reliability is essential because maintenance is very expensive.
1. Risk assessment – leading to inspection and monitoring planning 2. Inspection, monitoring and testing – incorporated in maintenance planning 3. Integrity assessment – leading to corrective action 4. Mitigation of risk, intervention and repair – leading management of change and then to revised risk assessment Understanding failure mechanisms is a key part of risk assessment, incorporated in Failure Mode, Effects and Criticality Analysis (FMECA). This involves understanding the equipment in the scope, and understanding the failure scenarios, and describing the failure mechanisms. This is followed by determination of valid inspection, measuring and monitoring responses, and then determining the intervals for these responses. Dr Ham pointed out that the management of subsea assets into different groups raised a particular risk issue: managing the interfaces between the groups to ensure that nothing is missed. Dr Ham referred to shared information on 108 ‘significant issues’ in five subsea fields, reported by three operators. More than 50 per cent involved subsea controls (typically carrying electric currents to operate valves), and only 1 per cent involved risers. However, those few involving risers had potentially much more sever consequences for safety, the environment and production. Dr Ham then spoke about some pitfalls in asset management, starting with the consequence of not effectively managing the people who participate in risk management meetings! The next pitfall is failure to document decisions effectively. 8 | SEPTEMBER 2021
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If the response to a risk is inspection, then an identifiable precursor to failure must be identified, along with an allowable timescale for inspection, and pass-fail criteria. He illustrated the principles involved by giving an example of dealing with the risk of scouring under a seabed pipeline.
The highly engaged audience had many questions. In response to to one question regarding the issue of the people in the risk management workshop, Dr Ham noted that some people tend to derail the methodology: some do not cope with the lack of precision, and the need for balance in ‘suspending disbelief’ when considering options. He also pointed out the need to understand the industry’s (or company’s) appetite for risk, and remarked on the differences between the oil and gas, mining and the water industries, and in the latter, between different jurisdictions. Asked about innovation, he remarked that for subsea oil and gas, saving vessel-days is the big driver. This is leading to a shift from inspection to monitoring, although it has proved difficult to ‘marinise’ monitoring equipment for subsea use. One issue with inspection, is that because it is difficult to mobilise for inspection there is a tendency to over-inspect, just to be sure. Dr Ham highlighted the application of very high resolution underwater cameras. These allow a specified inspection resolution from a greater distance, leading to much more rapid surveillance. He forsees this application being combined with artificial intelligence techniques. As a final comment, Dr Ham likened the inspection task to understanding the complete jigsaw picture, while looking at as few of the pieces as possible. WWW.MATERIALSAUSTRALIA.COM.AU
