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Deep-water or open sea area developments bring technology challenges to offshore pipeline installation safeties. With low oil price, offshore contractors endure considerable pressure and struggle to provide cost-effective services. To achieve safe operations with higher efficiencies, it is essential to acquire better understanding of pipeline conditions in-process, which benefits operation planning and decision making. Offshore operational window and pipeline fatigue damage significantly depends on vessel motions. Current engineering practices generally predict motions through metocean and hydrodynamics based numerical simulations. This approach is useful but naturally leads itself to prediction uncertainties, which are most likely conservatism. With deep-water and open sea application, the uncertainties may become underestimations of key parameters due to possibly insufficient metocean data and inapplicable hydrodynamic methods. Subsequently, a real-time offshore pipeline installation monitoring system has been developed to predict realistic pipeline behavior by adoption of real-time operation parameters including vessel motions. A sea-trial for the system has been conducted on a pipelay project in 2016. As an alternative treatment to pipeline installation planning and decision making, the system has been proven capable of accurate simulations and additional functions such as touch point monitoring and fatigue tracking. [ABSTRACT FROM AUTHOR]

Column stabilized semisubmersible is one of the most commonly used hull systems for the design and development of drilling and production platforms used for offshore deep water operations. Recent reconfiguration and design alterations have improved its hydrodynamic behaviour in rough weather conditions and, thus, its application and functionality in ocean engineering. Semisubmersible dry-trees applications and large wind turbine foundation systems in ultra-deep waters require high payload integration for reduced motion responses in all degrees of freedom. This paper presents a review of recent industrial and academic contributions to the development of column stabilized semisubmersible hulls used for deep water operations. It also provides an overview of the motion and structural attachments of semisubmersibles. The type and formation of dry-trees semisubmersibles are discussed. The dynamic behaviour and comparative advantages of them are also explained. [ABSTRACT FROM AUTHOR]

The application of marine bonded hoses has increased in recent times, due to the need for more flexible conduits and flexible applications in the offshore industry. These marine structures include Catenary Anchor Leg Moorings (CALM) buoys and ocean monitoring buoys. Their attachments include floating hoses, submarine hoses and submarine cables. However, the structural performance challenges of a CALM buoy system from its hydrodynamics water waves and other global loadings, have led to the need for this investigation. In this study, a detailed presentation on the motion characterisation of the CALM buoy hose system is presented. The CALM buoy is a structure with six degrees of freedom (6DoF). A well-detailed experimental presentation on the CALM buoy hose model conducted in Lancaster University Wave Tank is presented using three novel techniques, which are: a digital image captured using Imetrum systems, using an Akaso 4K underwater camera, using wave gauges arranged in a unique pattern and using underwater Bluetooth sensors. The buoy model was also found to respond uniquely for each motion investigated under water waves. The results showed that the higher the profile, the higher the response of the buoy. Thus, this study confirms the existence of flow patterns of the CALM buoy while floating on the water body. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The advances observed in the offshore-renewable industry include the recent development of a deep draft paired column semisubmersible platform developed for application on dry trees in Gulf of Mexico (GoM). These developments led to the recent innovation of the Paired Column Semisubmersible by Jun Zou of Houston Offshore Engineering. This paper presents a detailed investigation on the mooring line analysis for two different configurations on the hull of a Paired Column Semisubmersible (PCSemi). The numerical research of the PCSemi platform coupled with mooring lines was conducted, and the model was validated. Two different mooring configurations were investigated: Chain-Polyester-Chain (CPC) and Polyester-Polyester (PP) configurations, with dynamic coupling in frequency domain (FD) and time domain (TD) using ANSYS AQWA and Orcaflex. A comparative study of the mooring lines is also investigated in 2,438 m water depth at GoM, using 16 mooring lines with catenary mooring design. Results of this study gives the natural period of floating PCSemi's heave motion ranged from 21s to 22s. Also, the effect of a damaged mooring line increased the tension in other mooring lines. Lastly, the CPC configuration has a smaller amplitude for wave-frequency platform motions compared to the PP mooring configuration from the depicted PCSemi global performance. [Display omitted] • Mooring design of a paired-column semi-submersible (PCSemi) was investigated under catenary designs. • Two configurations were investigated: Chain-Polyester-Chain (CPC) and Polyester-Polyester (PP) configurations. • Modelling technique adopted for the mooring analysis is well presented. • Mooring lines attached to the fairleads of the PCSemi are presented for different design configurations. • Hydrodynamic loading effects on the PCSemi were conducted for low frequency and wave frequency motions. [ABSTRACT FROM AUTHOR]