Wave Measurements for the Monitas System

Hanson, Jeffrey L.; Lübben, Andrea; Aalberts, Pieter; Kaminski, M.L.

doi:10.2523/20869-ms

Cited by 6 publications

(3 citation statements)

References 11 publications

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“…In order to validate the projected simulations, fatigue damage based on buoy-measurement was calculated for comparison. The sea state data in the Sable field were measured by buoys from July 2007 to June 2008 [25]. The fatigue damage in these 12 months was calculated as a reference value (Table 10).…”

Section: Fatigue Calculationsmentioning

confidence: 99%

Projection and Detection Procedures for Long-Term Wave Climate Change Impact on Fatigue Damage of Offshore Floating Structures

Zou¹,

Kaminski²,

Li³

et al. 2021

Preprint

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Fatigue damage is a cumulative process. The fatigue design of offshore structures requires long term wave data to calculate fatigue damage. However, the climate change may affect the long-term wave statistics and consequently affect the cumulative fatigue damage. This paper aims to project the trend of annual fatigue damage of offshore floating structures and to detect the climate change impact on the future fatigue damage by coupling a conventional fatigue design method with climate and wave models. Firstly, climate scenarios are selected to project the global radiative forcing level over decadal or century time scales. Secondly, climate models are used to simulate global or regional atmosphere circulations and to obtain the wind field data. Thirdly, wave conditions are simulated by coupling wind driven wave models to climate models. Fourthly, stress analysis and fatigue assessments are conducted to project the annual fatigue damage. At last, control simulations are carried out in order to identify the range of natural variability and to detect the human-induced change. A case study is presented for a Floating Production Storage and Offloading (FPSO) unit operating in the Sable field offshore South Africa. The results indicate that, in the Sable field, the significant wave height is considerably influenced by the human-induced climate change. However, when detecting its effect on the annual fatigue damage, this change induced by human activities is still partially masked by the dominant natural variability. In addition, both the significant wave height and the annual fatigue damage increase over century time-scales.

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Section: Fatigue Calculationsmentioning

confidence: 99%

Projection and Detection Procedures for Long-Term Wave Climate Change Impact on Fatigue Damage of Offshore Floating Structures

Zou¹,

Kaminski²,

Li³

et al. 2021

Preprint

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“…The demonstrator case for the Glas Dowr FPSO was carried out using the Monitas software that required a lot of "know how" and data processing by a user. The exeWaves is the XWaves software described in Hanson et al, (2010). After successful completion of the demonstrator an industrial version of the Monitas system had to be developed.…”

Section: The Monitas Softwarementioning

confidence: 99%

SS: FPSOs and Floating Production Systems: Overview of the Monitas JIP

2010

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This paper provides an overview of the Monitas project, aspects of which are further detailed in accompanied OTC 2010 papers. The Monitas project is a Joint Industry Project that was presented to the offshore industry in 2005 and now the project is close to its completion. The Monitas project has developed the Advisory Monitoring System (AMS) that presents, explains and advises on the fatigue lifetime consumption of FPSO's hulls. The advice is based on comparisons between the design and the actual fatigue lifetimes predicted by replacing the design factors like operational settings, environmental conditions and hydro-structural response by the measured ones. The name Monitas stands for Monitoring Advisory System.The project has demonstrated that the Monitas system installed on board an FPSO enhances the safety of the crew, the asset and the environment by controlling the lifetime consumption of the hull. Deviations from the design conditions can be timely identified and actions can be undertaken to secure sufficient lifetime in case it is being consumed too fast. The beauty of the system lies in the fact that the system identifies which factor contributes mostly to faster lifetime consumption. The project recommends including the requirement for such a system in the contract specification. This allows for a proper documentation of the fatigue lifetime calculations and cost-effective implementation of the system without expensive change orders.The project results are applicable directly to all FPSOs and with some modifications to all floating structures. The Monitas system, when installed, can give justification for lifetime extension. The paper ends with plans for improving the system.

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“…The partitioning scheme of buoy measured data is presented by Hanson and Phillips (2001). A further introduction can be found in Hanson et al (2010). WaveWatch-III also uses the same scheme.…”

mentioning

confidence: 99%

Applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures

Zou

Kaminski

2016

Ocean Dynamics

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In design and operation of floating offshore structures, one has to avoid fatigue failures caused by action of ocean waves. The aim of this paper is to investigate the applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures. The applicability was investigated for Bluewaters' FPSO (Floating Production, Storage and Offloading) which had been turret moored at Sable field for half a decade. The waves were predicted as sea-state time series consisting of one wind sea and one swell. The predicted waves were compared with wave data obtained from ERAinterim and buoy measurements. Furthermore, the fatigue calculations were also carried out for main deck and side shell locations. It has been concluded that predicted fatigue damages of main deck using WaveWatch-III are in a very good agreement regardless of differences in predicted wind waves and swells caused by differences in wave system partitioning. When compared to buoy measurements, the model underestimates fatigue damages of side shell by approximately 30 %. The reason for that has been found in wider directional spreading of actual waves. The WaveWatch-III wave model has been found suitable for the fatigue assessment. However, more attention should be paid on relative wave directionality, wave system partitioning and uncertainty analysis in further development.

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Wave Measurements for the Monitas System

Cited by 6 publications

References 11 publications

Projection and Detection Procedures for Long-Term Wave Climate Change Impact on Fatigue Damage of Offshore Floating Structures

Projection and Detection Procedures for Long-Term Wave Climate Change Impact on Fatigue Damage of Offshore Floating Structures

SS: FPSOs and Floating Production Systems: Overview of the Monitas JIP

Applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures

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