On-Board Monitoring, Analysis and Decision Support During Offshore Pipe Lay Operation

For pipe lay operations parameters like heading and position of the lay vessel are available from the GPS system on the vessel. In some cases the current profile may also be monitored. Provided that a fast and robust numerical tool is available and can be integrated with the on-board system, the above parameters and a measure of tension in the pipe will be sufficient to simulate the appurtenant static configuration of the catenary and visualize it online during the lay operation. Such a system will provide valuable additional information such as: catenary shape including stresses in the pipe, lay tension, development of free spans, and lateral stability during installation. In the period April-August 2009 two field tests of the developed system were performed. Both field tests were related to Acergy installation campaigns for the Ormen Lange Phase II development in the North Sea; 1) ∼13 km infield MEG (IMEGDA) installation by Acergy Falcon, and 2) ∼13km infield umbilical (IUMB-DA) installation by Acergy Eagle (both at ∼860m water depth). In this paper the experiences from the field tests are discussed. This includes assessment of on-board data collection and storage of key parameters during installation, real-time online 3D finite element (FE) analysis and satellite link to shore for support during installation. The accuracy of the results obtained in the on-board monitoring system is assessed by comparison to available as-laid survey information.