Objectives/Scope: During decommissioning of an offshore platform jacket the removal of the structurewill entail cutting and recovery of the piles driven into the seabed. Uncertainty on the effectiveness of thecutting process can lead to non-productive time and increase in operating cost. The scope of this paper isto present work undertaken to identify a suitable technology that provides near real time cut performancemonitoring of single wall piles and conductors. Methods, Procedures, Process: Abrasive Water Jet cutting is commonly used during pile cutting andremote monitoring of parameters gives valuable information of the cutting process. However, the decisionto pull the pile is often based on the know-how or skill of the cutting operators to interpret what the gaugesare showing them. Uncertainty leads to increased risk and project costs and can result in disputes betweenheavy lift vessel contractors and cutting service providers. Several techniques are claimed to be effective inverifying cutting performance but there are none that provide near real-time mapping of cut performanceat the cut location. Results, Observations, Conclusions: Two optical technologies namely laser scanning and photogrammetrywere identified as having potential and extensively tested to detect cuts in representative mock-up conditionson varying pile wall thicknesses from 30mm up to 90mm. This paper will present the results of the testingand how each technique performed when asked to identify partial circumferential cuts and incompletethrough-wall cuts. The results are compared with physical measurements and evaluated to meet therequirements set out by the project objectives. Field application of each technique was assessed and howthe optical method can be integrated into existing equipment is described. Seawater turbidity in the pilewhich would render optical techniques ineffective has been considered and novel techniques are proposedto overcome this. Limitations and application of each technique in the real world are presented and the paperprovides description on how the technique selected may be implemented into existing pile cutting tools. Novel/Additive Information: This paper will be of benefit to those planning decommissioning of platformjackets and wind turbine piles due to the provision of new techniques resulting in reduction of projectuncertainty and cost when employing heavy lift vessels.
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