Sensitivity studies of SCR fatigue damage in the touchdown zone using an efficient simplified framework for stress range evaluation

2021

JMSE

Recent design challenges in ocean observations, energy storage, offloading/discharging, and loading operations in both the offshore-renewable industry have led to advances in the application of catenary anchor leg moorings (CALM) buoys. Due to different seabed profiles, soil stiffness and environmental conditions, there is the need for numerical assessment to investigate the behaviour of the submarine hoses, based on the structural and hydrodynamic behaviour. In this study, experimental and numerical investigations are carried out on the dynamic behaviour of the submarine hoses attached to a CALM buoy in Lazy-S configuration. Six mooring lines are attached to the CALM buoy with a water depth of 100 m in the numerical model. A hydrodynamic model utilising ANSYS AQWA was developed then coupled unto the dynamic model in Orcina’s Orcaflex. The studies were carried out to study the effect of flow angles, wave height, soil stiffness and hydrodynamic loads on the structural behaviour of the submarine hoses. Waves at different angles to the submarine hose affected the effective tension more where the hose bends due to the floats attached. Parametric studies were carried out on both linear and nonlinear seabed models, and recommendations were made from the investigations on the submarine hose models.

Section: Discussionmentioning

confidence: 99%

“…The application of nonlinear seabed profiles has been considered on other offshore structures [54,55]. Examples include nonlinear seabed studies on steel catenary risers (SCR) [56][57][58]. However, it is crucial to investigate the effect of nonlinear seabed models on CALM buoy systems and on submarine hoses, as this has not been studied.…”

Section: Introductionmentioning

confidence: 99%

Numerical Assessment on the Dynamic Behaviour of Submarine Hoses Attached to CALM Buoy Configured as Lazy-S under Water Waves

2021

JMSE

“…Based on the given problem, the mathematical formulation of the hose model was developed with some simplifications, based on the experimental findings of the author and some experiences reported in offshore engineering practice. These applications can be seen on moored WECs [231], steel catenary risers [232][233][234][235][236][237][238], flexible risers [239,240] and pipelaying operations [241][242][243][244][245]. The seabed considered is a horizontal and a rigid plane, and the material for the hose is isotropic and in an elastic state.…”

Section: Mathematical Formulation Of Hose Modelmentioning

confidence: 99%

Mathematical Modelling of Bonded Marine Hoses for Single Point Mooring (SPM) Systems, with Catenary Anchor Leg Mooring (CALM) Buoy Application—A Review

2021

JMSE

The application of mathematical analysis has been an essential tool applied on Catenary Anchor Leg Mooring (CALM) buoys, Wave Energy Converters (WEC), point absorber buoys, and various single point mooring (SPM) systems. This enables having mathematical models for bonded marine hoses on SPM systems with application with CALM buoys, which are obviously a requisite for the techno-economic design and operation of these floating structures. Hose models (HM) and mooring models (MM) are utilized on a variety of applications such as SPARs, Semisubmersibles, WECs and CALM buoys. CALM buoys are an application of SPM systems. The goal of this review is to address the subject of marine hoses from mathematical modeling and operational views. To correctly reproduce the behavior of bonded marine hoses, including nonlinear dynamics, and to study their performance, accurate mathematical models are required. The paper gives an overview of the statics and dynamics of offshore/marine hoses. The reviews on marine hose behavior are conducted based on theoretical, numerical, and experimental investigations. The review also covers challenges encountered in hose installation, connection, and hang-off operations. State-of-the-art, developments and recent innovations in mooring applications for SURP (subsea umbilicals, risers, and pipelines) are presented. Finally, this study details the relevant materials that are utilized in hoses and mooring implementations. Some conclusions and recommendations are presented based on this review.

“…In the study by Yang & Li [121], the sensitivity analysis on the fatigue life of Steel Lazy Wave Catenary Risers (SLWR) conducted was motivated by the major consideration encountered while evaluating the practicality of using SLWR on large motion vessels like semi-submersibles and floating production storage and offloading (FPSOs) structures. There are other sensitivities reported in catenary sections and their impact along the touchdown zone [122,123]. Quéau et al [123] presented some sensitivity investigations on fatigue damage of SCR dynamic loads in the touchdown zone by utilising a simple stress range evaluation framework.…”

Section: Introductionmentioning

confidence: 99%

“…There are other sensitivities reported in catenary sections and their impact along the touchdown zone [122,123]. Quéau et al [123] presented some sensitivity investigations on fatigue damage of SCR dynamic loads in the touchdown zone by utilising a simple stress range evaluation framework. To improve the certainty on the design of SCR attached to deep-water FPSOs, a sensitivity analysis is also conducted by Yoo & Joo [124] under 1,400 m water depth for deep water environment in West Africa.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Hydrodynamic Characteristics, Wave–Current Interaction and Sensitivity Analysis of Submarine Hoses Attached to a CALM Buoy

2022

JMSE

There is an increase in the utilization of the floating offshore structure (FOS) called Catenary Anchor Leg Mooring (CALM) buoys and the attached marine hoses due to the increasing demand for oil and gas products. These hoses are flexible and easier to use but have a short service life of about 25 years. They are adaptable in ocean locations of shallow, intermediate and deep waters. In this research, a numerical model was developed using a coupling method modeled by utilizing ANSYS AQWA and Orcaflex (Orcina Ltd., Ulverston, UK) dynamic models of the CALM buoy hoses. Two cases were comparatively studied: Lazy-S and Chinese-lantern configurations, under ocean waves and current. Comparisons were also made between coupled and uncoupled models. This research presents the hydrodynamic characteristics with a sensitivity analysis on the influence of waves, current attack angle, soil gradient, soil stiffness and environmental conditions that influence the performance of marine hoses. The study comparatively looked at the configurations from dynamic amplification factors (DAF) on marine hoses. The results show that marine hoses can be easily configured to suit the designer’s need, seabed soil type, seabed topography and the profiles that are useful for manufacturers. The sensitivity analysis also shows the effect of hose parameters on its hydrodynamic behavior from the wave–current interaction (WCI).