DNV GL, Bluewater pilot test hybrid digital twin for FPSOs

Classification society DNV GL and FPSO specialist Bluewater have teamed up on a pilot project to use hybrid digital twin technology to predict and analyse fatigue on an FPSO hull.

DNV GL said that the project would quantify the benefits of creating a virtual replica of the FPSO to optimize the structural safety of the vessel and enhance risk-based inspection (RBI), a decision-making methodology for optimizing inspection regimes.

Bluewater’s Aoka Mizu FPSO, currently in operation in the Lancaster field, west of Shetland in the North Sea, will be used. According to the classification society, the pilot test has shown encouraging results.

The technology enables the monitoring of the asset’s hull structure during operation without dependence on costly routine inspection regimes. Termed ‘Nerves of Steel’, the underlying concept permits the use of various data sets combined with digital models of the asset, to develop a hybrid replica model of the vessel’s structure.

This can be used in real-time to monitor the asset’s condition, identify and monitor high-risk locations, and plan targeted and cost-efficient maintenance and inspection activities. 

Hybrid twin technology uses a combination of numerical design models and data from actively recorded strain gauge sensors onboard the FPSO. These sensors allow for a full understanding of the accumulative loading and current state of the FPSO structure.

Koheila Molazemi of DNV GL – Oil & Gas said: “By informing and enhancing the RBI process, operators can reduce operational costs and time, providing significant safety improvements, thereby extending the lifespan and integrity of assets.

“With fluctuating oil price and the impact of Covid-19 on travel, delivering a mirror image of an asset from the safety of shore needs to be trusted and of value.”  

DNV GL’s visual dashboard presents data to Bluewater on stresses in the hull’s structure, alongside information that can be used to identify areas with relative higher risk of cracks or deformities to occur.

The trial will expand on traditional FPSO integrity management strategies, which are based on software-based assumptions made at the design stage as well as the current inspection record to enhance RBI decision-making.

This is DNV GL’s third pilot project evaluating the performance of hybrid digital twin technology. The first involved defining a repair procedure for an FPSO flare tower while the second, still ongoing, is being performed on a fixed offshore platform.  

Francois-Xavier Sireta, technical lead for naval architecture at DNV GL – Oil & Gas, added: “[…] the hybrid digital twin can potentially save millions by avoiding the costly and possibly catastrophic repercussions of ill-informed integrity management by pre-empting and preventing detrimental damage.

“For an asset operating in a harsh environment, where the loads play an important part in the possible degradations of the asset, using data from the site as a basis for optimized inspection planning, alarms for extreme events and asset suitability for life extension is crucial”.

Peter van Sloten of Bluewater said: “[Bluewater] decided to extend our digital twin programme to include our FPSO Aoka Mizu. We are therefore pleased to team up with DNV GL to develop a tool to monitor the structural integrity of this most versatile FPSO, designed and proven to operate in harsh environments with high uptimes and a maintained, strict regulatory and safety regime. This will enhance safety and enables an optimized inspection regime”.