MoniMoor

Floating production systems and floating wind turbines are designed to remain on station for a prolonged period of
time. To ensure station keeping, these floaters are equipped with mooring systems which must be able to withstand harsh weather loadings. Deterioration of the mooring lines over time will result in a lower resistance against breakage. Therefore, early diagnostics of mooring line damage plays a key role in ensuring a safe performance of floaters. Several technologies and methods exists to monitor the integrity of the moorings.

The MoniMoor project aims to improve the understanding of the fatigue mooring loads from floating production systems and floating wind turbines by in depth analyses of a wide variety of existing in-service measurements by an integrated mooring integrity management platform. The latter platform uses MONITAS and aNySIM Onboard integrity monitoring tools.

MONITAS
MONITAS is the monitoring system which manages the fatigue integrity of hulls and moorings of floating production systems. It helps the owner to understand the real age of the vessel by monitoring fatigue loading and coupling it back to the design tools. MONITAS not only measures the fatigue by sensors on hull or moorings but also explains why the measured fatigue deviates from design predictions. The MONITAS system has already been successfully implemented onboard of seven production units: the Glas Dowr FPSO (Bluewater), the USAN FPSO (ExxonMobil), the CLOV FPSO (TOTAL), the Ichthys FPSO (INPEX), the Moho Nord FPU (TOTAL), the Bonga FPSO (SHELL) and the Aoka Mizu FPSO (Bluewater).

aNySIM Onboard
The aNySIM Onboard system is based on MARIN’s aNySIM XMF simulation software. With a detailed numerical model of the mooring system, the mooring line tensions are calculated with the time domain simulation software, using the measured wave frequency motions and the measured horizontal GPS positions in the field as input. Using the measured response of the floater avoids the uncertainty resulting from a prediction of the hydrodynamic response.

Objectives

The first objective is to improve mooring design and reduce the likelihood of failures through increased knowledge and understanding of fatigue mooring loads. For this purpose, the various integrity management tools developed in recent years within Joint Industry Projects for the oil & gas industry (such as MONITAS and aNySIM onboard) are integrated into a framework for dedicated in-depth analyses. The key concept is to combine different types of information, including various sources of in-site data such as wave data, wind data, motion response and mooring loads, with design data such as numerical models to address mooring load challenges.

By combining multiple data sources and the knowledge of an experienced JIP consortium, a more reliable assessment of the load history and the condition of the moorings can be made. This information can then be used in the decision-making process of the mooring integrity management plan.

The second objective regards the development of a floating wind specific, low-cost mooring tension monitoring system. This system runs in the cloud and uses motion and position measurements coupled to numerical models to infer mooring tension in (near) real-time. The goal is to enable large-scale mooring monitoring without the need to install expensive and often unreliable mooring load cells.

Organisation

MARIN takes the lead in this project as JIP manager. MoniMoor, will be carried out in cooperation with representatives from the floating wind and oil & gas industry including owners, operators, suppliers and classification societies.

BUDGET & PLANNING

The participation fee for oil companies, energy companies and contractors for the three years project equals 15 kEuro/year. The yearly participation fee for classification societies, authorities and small sized companies equals 7,5 kEuro.

Project meetings take place every six months during the FPSO JIP Week. Monimoor started in 2022 and will have a duration of three years.