Abstract
Middle East offshore platforms installations started in the early 60's and continue today. Managing asset integrity and demonstrating compliance is increasingly challenging due to frequent brownfield modifications, increased safety factors with the introduction of international standards, changes in metocean data and age deterioration. From work with North Sea, Gulf Region and Asia Pacific operators, an approach was developed to manage ageing assets using real-time structural risk assessments and operational procedures that ensures consistent risk levels of life safety and environmental for all assets and is applicable to all regions.
Utilising the improved accuracy of modern weather forecasts, in combination with structural reliability, a methodology has been developed to determine the forecasted risk level for any critical element. This is updated live, with each new weather forecast, to provide proactive notifications and alerts so operators have more up to date knowledge to make decisions on their assets. A live web-based system can be utilised to display this information.
The approach splits the three risks of life safety, environmental and structural damage into separate requirements and calculates the probability of failure, which will lead to each of the three consequences, for the critical component or the overall structure. The risk is evaluated and compared with the industry standard and the operators own acceptance criteria to determine if operational procedures need to be enacted to reduce the consequence. It has been found that the acceptable risk levels for the ‘in a forecasted storm’ risk are governing over the traditional design ‘annual’ risk levels.
If at any point in time the probability of a wave height approaching the field exceeds the maximum allowable for a structure, the system issues timely alerts and warnings to the relevant stakeholder for their actions. The operator then has the option of de-manning or shutting down operations to maintain the risk levels for life safety and environmental at ALARP (as low as reasonably practicable) levels. The system also provides information for post-storm structural damage likelihood.
A combination of online monitoring, inspection and/or asset loading history, which can be incorporated using Bayesian updating methods, and advanced assessment have been used to reduce the occurrence of enacting operational procedures for structures that are non-code compliant to greater than every 10 years while also reducing the annual risks.
An additional advanced feature can be utilised by connecting installed accelerometers to the structure for continuous live streaming of the structural response which can issue alerts if any damage is suspected.
