bluuebunny/crossref_metadata_2025_split huggingface dataset:
Volumetric Design for Hydrodynamic Response of Modularized Lightweight TLP Structures Under Irregular Waves
Authors: Abbasnia Arash , Kosleck Sascha , Buhr Eric , Lutz Marco , Adam Frank 
Published: August 2024

Abstract
The increasing demand for developing offshore renewable power plants sparks a search for designing floating units that can effectively support energy conversion systems in terms of power storage and transfer, whilst being located far from the shore. The modularized floating structures initiative is highly valued for its ability to easily adjust its operational range to match the capacity of variable energy systems by adding or removing structural members. The circular cross-section’s superior resilience against fatigue and hydrodynamic pressure, as compared to other cross-sections, has prompted an investigation of a tension leg platform modularized by cylindrical members as presented in this paper. The study focuses on a hydrodynamic assessment under various wave conditions. Consequently, a range of centre of buoyancy and volume moments of inertia is triggered by different module sizes and arrangements for a constant displacement. Amongst the numerous possible variations, three module arrangements are subjected to JONSWAP wave spectra. The mooring system assumes linear stiffness with four single-string tendons in the perpendicular configuration. The study employs a linear potential model to calculate the structure’s hydrodynamic responses. The comparison of results illustrates the significant impact of volumetric characteristics on the structure’s operation. Hydrodynamic coefficients, kinematics of the structure and tension loads are scrutinized and comprehensively compared.
A Survey of Control Systems for Offshore Well Service Pumps: State-of-the-Art, Challenges and Future Perspectives
Authors: Klis Pawel , Xing Yihan , Abd Abdalla H. , Ren Chao 
Published: August 2024

Abstract
Safety has become the most important value for many companies. This value is especially important in the offshore industry. Lately, there has been a trend to limit the number of people on a deck of platforms, production boats and other maintenance vessels. On the other hand, experts, operators, and technicians must be present during all offshore operations. Therefore, offshore companies are looking for a balance between safety and the number of personnel on decks. One of the solutions for that problem is a well-designed control system that allows one or more production units to operate remotely. The wireless connection between the machine and the operator’s computer located onshore gives an excellent opportunity to run the production device without physical presence. This solution enables the elimination of people from dangerous places. Furthermore, it will positively impact the environment because the transport of employees will be significantly reduced.
The main goal of this paper is to provide a general overview of the control systems used to operate offshore production units. The operation aspects of the control system are explained using the example of a topside Well Service Pump with a power of 725 HP. Firstly, the article provides the description, challenges and possibilities of the control system used to operate the pump unit. Next, the remote control using Human Machine Interface (HMI) and Supervisory Control and Data Acquisition (SCADA) are explained. Finally, the paper explores the artificial intelligence techniques, such as machine learning, and predictive maintenance. The study concludes with a summary of the findings.
Inspection Planning Optimisation for Offshore Energy Structures Using Digital Twin
Authors: Li Shen , Brennan Feargal 
Published: August 2024

Abstract
Inspection and maintenance are integral elements within the structural integrity management of offshore energy structures. This allows the identification and remediation of progressive structural degradation such as fatigue cracks, ensuring fitness-for-service of critical offshore assets throughout their service lifetime. In view of optimising the offshore retrieval/intervention and eventually reducing the life-cycle costs, risk-based inspection and maintenance planning is highly relevant. However, conducting a comprehensive risk assessment requires gaining a thorough knowledge of the as-built design and actual operational profile whereby accurately predicting its performance. Although design specifications and assumptions can serve as guidelines, a high degree of uncertainty may arise due to the disparity between the actual operational profile and the design assumptions. This paper studies the application of digital twin approach whose virtual monitoring feature coupled with fatigue load updating algorithm enables the derivation of more realistic loading spectrum. Probabilistic fracture mechanics-based model is utilised to simulate the fatigue crack growth. An optimisation of future inspections is performed with an objective to minimise the life cycle expected total cost due to fatigue failure, inspection and repair. For demonstration purpose, a case study using an offshore wind support structure is presented to illustrate this digital twin-enabled proposal. Furthermore, areas open future research in this field are discussed.
Estimation of Maximum Run-Up Heights on a Cylinder for Focused Waves Formed With Different Mechanisms
Authors: Zhang Huidong , Wang Tong , Xu Sheng , Zhou Xueqian 
Published: August 2024

Abstract
To evaluate the maximum run-up height on a fixed vertical column under the action of focused waves formed with different physical mechanisms, a 3D two-phase numerical wave tank is developed in this study. The influences of wave nonlinearity, column radius and water depth on the run-up heights are investigated in a series of tests. For focused waves with identical crest height and trough-to-trough period, the maximum run-up height is always larger in linear focused wave than in nonlinear focused one, due to their different hydrodynamic characteristics. The discrepancies become greater with the increased wave nonlinearity. Moreover, the maximum run-up height, less affected by water depth, is more sensitive to the variation of column radius in linear focused wave. Nevertheless, for both types of focused waves, their maximum run-up heights can be estimated reasonably well by the modified empirical function with the same parameters but different coefficients.
Oil-Based Vs Water-Based Fluids Behavior With Experimental Cuttings-Bed Erosion in Horizontal Wells
Authors: Pedrosa Camilo , Lund Bjørnar , Saasen Arild 
Published: August 2024

Abstract
Efficient removal of deposited cuttings-bed is a necessity during drilling operations. Nevertheless, it is a big challenge specially in horizontal wellbores as larger beds are formed and gravity tends to consolidate the formed beds. Poor cuttings cleaning might cause several problems such as, drill-pipe sticking, increased torque and drag, lower Rate of Penetration (ROP), excessive Equivalent Circulating Density (ECD), among others. Removal of the drilled cuttings is done by the drilling fluid flow thru the annulus and out to the surface.
This paper presents results from bench-top laboratory erosion tests as well as corresponding CFD simulations. The tests were conducted with two different oil fluids; a low-viscosity oil and an oil-based drilling fluids and compared against 2 fluids from previous work; pure water and water-based drilling fluid, flowing over a quartz sand particle bed wetted by different oil-based fluids. A bedload transport model was used to describe and analyze the motion forces imparted by the oil-based fluids into the sand grains from a consolidated cuttings-bed.
The results have shown that a cuttings-bed eroded with oil-based drilling fluid provide higher motion force than a cuttings-bed eroded with base oil fluid. But even with that higher energy to move the particles, to know the cohesive forces that cause agglomeration of particles in the bed may be important in order to design a fluid which can effectively erode a deposited bed.
Development of the Environmental Contour for Ice Drift Speed and Wind Speed
Authors: Sinsabvarodom Chana , Leira Bernt J. , Høyland Knut V. , Chai Wei , Jitpairod Kittikun , Nuntiyakul Waraporn , Seripienlert Achara 
Published: August 2024

Abstract
The purpose of this study is to develop environmental contours for ice drift speed and wind speed. The drift of sea ice is naturally influenced by various external forces, including wind stress at the air-ice boundary, water stress at the water-ice boundary, the Coriolis force, pressure gradients caused by sea surface tilting, and internal stress within the sea ice itself. Typically, sea ice drifts at a rate of approximately 2–3% of the wind speed (as measured at a height of 10 meters above the ocean surface) in the Arctic region. The Nansen number, which relates to the magnitude of the wind speed, can be used to estimate ice drift speed. This research investigates the relationship between wind speed and ice drift speed and applies it to generate environmental contours. Ice drift data for this study are collected through local subsurface measurements using acoustic Doppler current profilers (ADCP) in the Beaufort Sea. The distributions of wind speed and ice drift speed are studied, and the effects of the correlation between them are investigated. Subsequently, the environmental contours demonstrate the relationship between wind speed and ice drift speed. This provides valuable insights into the probabilistic nature of the relationship between wind speed and ice drift speed. The simultaneous values of the wind speed and ice drift speeds to be applied for design purposes can be obtained from the corresponding short term environmental condition along the derived environmental contour.
Digital Twin of Autonomous Surface Vessels for Safe Maritime Navigation Enabled Through Predictive Modeling and Reinforcement Learning
Authors: Menges Daniel , Von Brandis Andreas , Rasheed Adil 
Published: August 2024

Abstract
Autonomous surface vessels (ASVs) play an increasingly important role in the safety and sustainability of open sea operations. Since most maritime accidents are related to human failure, intelligent algorithms for autonomous collision avoidance and path following can drastically reduce the risk in the maritime sector. A DT is a virtual representative of a real physical system and can enhance the situational awareness (SITAW) of such an ASV to generate optimal decisions. This work builds on an existing DT framework for ASVs and demonstrates foundations for enabling predictive, prescriptive, and autonomous capabilities. In this context, sophisticated target tracking approaches are crucial for estimating and predicting the position and motion of other dynamic objects. The applied tracking method is enabled by real-time automatic identification system (AIS) data and synthetic light detection and ranging (LiDAR) measurements. To guarantee safety during autonomous operations, we applied a predictive safety filter to correct inputs from a reinforcement learning-based controller. The approaches are implemented into a DT built with the Unity game engine. As a result, this work demonstrates the potential of a DT capable of making predictions, playing through various what-if scenarios, and providing optimal control decisions according to its enhanced SITAW.
Assessing Hydrate Formation Risk in Infill CCS Wells
Authors: Skogestad Jan Ole , Feneuil Blandine , N'Gouamba Elie , Linga Harald , Aasen Ailo , Skår Gjertrud , Roggeband Serge M. , Nedrum Jack , Helgeland Stig 
Published: August 2024

Abstract
Carbon capture and storage (CCS) has been identified as a part of the solution to the climate crisis, but to play a major role, a massive scale-up is required. This will inevitably lead to a need for drilling wells into existing CO2 storage formations, and with that comes the risk of well control incidents where the influx from the formation into the well is dominated by CO2. A major concern regarding such incidents is the potential formation of hydrates caused by Joule-Thomson cooling when the CO2 loaded drilling fluid is forced through flow restrictions while being circulated out of the wellbore or when flowing through topside valves.
Software tools incorporating mathematical models for hydraulics and flow in the well play an important role in risk assessment related to drilling operations. To evaluate the risk of hydrate formation and subsequent plugging of valves and flow restrictions, a tool that sufficiently well captures the relevant thermodynamics and flow physics may be of crucial importance. By combining existing hydraulic flow models for drilling and well control operations developed for petroleum wells with new sub-models describing Joule-Thomson cooling and hydrate formation risk in the presence of CO2, such a tool can be built. To achieve accurate models, laboratory experiments of hydrate formation in drilling muds loaded with CO2 are required.
In order to enable a software tool for evaluating and handling risks related to hydrate formation during CO2 well control incidents, researchers and industry actors here work together to close knowledge gaps and provide the understanding of the physics involved that is required. We present experimental methods and lab results on hydrate formation in drilling fluids loaded with CO2 along with considerations on modelling aspects. This includes thermodynamical sub-models, integrated hydraulic models and the development of a software tool for use in operations planning and execution. Finally, the impact from such a tool for contributing to reducing the risk for hydrate formation related to drilling of CO2 infill wells is discussed.
Understanding the Role of Buoyancy on Jet Flows Within Viscoplastic Medium: Insights for Plug and Abandonment of Wells
Authors: Hafezi Mohammad , Hassanzadeh Hossein , Akbari Soheil , Faramarzi Mohsen , Taghavi Seyed Mohammad 
Published: August 2024

Abstract
Plug and abandonment (P&A) operation refers to the final stage of the oil and gas well’s operational life-cycle. The successful implementation of a P&A operation ensures the secure sealing of the well to prevent fluid movement and eliminate leakage between different layers. The key steps of a P&A operation entail three processes: (1) accessing the annulus section, (2) cleaning the target area (i.e., inside and outside the casing), and (3) installing cement plug barriers. The proper cleaning helps to enhance the cement-casing bonding while mitigating the risk of cement contamination. Jet cleaning, known as an efficient technique in the second step of P&A operations, displaces undesirable fluids and materials by injecting a cleaning fluid into the target area. Fluid properties, including density difference between injected and ambient fluids and the fluids’ rheological parameters, stand as key variables that directly influence the cleaning efficiency. Hence, a comprehensive understanding of how these parameters affect the jet flow is crucial for optimizing efficiency in well-cleaning procedures. In this study, we experimentally examine the miscible jet flow dynamics for two distinct scenarios: positively buoyant jets, where momentum and buoyancy act in the same direction, and negatively buoyant jets, where they act in opposite directions. The jet flow is formed by introducing a Newtonian fluid vertically downward, through a circular nozzle, into a transparent tank containing a viscoplastic fluid. We assume a “free jet” condition in our experiments, as the large tank dimensions render the wall effect negligible on the jet behavior. We use high-speed imaging to study the effects of the injection velocity, the density difference, and the rheological parameters (in particular, the yield stress) on the jet flow dynamics. The penetration length (indicating the evolution of the jet length over time) is the primary jet feature addressed in this study, which is investigated in both positively and negatively buoyant jets. Our findings show that the yield stress of the ambient fluid resists the jet evolution, leading to a decrease in the jet penetration length.
Study on Practical Control Force Decision to Improve Facility Utilization of PA-WEC
Authors: Murai Motohiko , Kakimoto Shinnosuke , Kawagishi Tatsuki , Han Jialin 
Published: August 2024

Abstract
The Japanese government has set a goal of increasing the share of renewable energy to 36–38% by 2030. Wave energy is one of the sources of renewable energy from the ocean. In this study, we focused on a floating point-absorber wave energy converter (PA-WEC), which has a simple structure like a traditional buoy can be farmed relatively easily to ensure safety. The PA-WEC generates energy by utilizing the heave motion of the floating part. We analytically obtain the control force that maximizes the average power output of the PA-WEC in understood irregular waves, which are defined as the superposition of regular waves.
If the float’s range of motion were infinite, the maximum power generation possible based on linear theory can be achieved. However, increasing the range of motion would result in higher construction and operation costs, while reducing the range would limit the operable wave conditions and decrease facility utilization.
Therefore, it is very important to improve equipment utilization while keeping the range of motion small. This study proposes a practical control strategy with the objective of enhancing the facility utilization of the PA-WEC while ensuring that the heave motion remains within physical constraints. The effectiveness of the control strategy in suppressing the range of float motion and consequently improving facility utilization without being care about the optimal solution in linear theory is discussed.
Experimental Investigation on Vortex Induced Vibration of a Rigidly Coupled Twin-Tube Model
Authors: Shen Jiawei , Fu Shixiao , Zhang Mengmeng , Niu Zhibo , Hua Yilong , Xu Yuwang , Chu Yaopeng , Bin Song 
Published: August 2024

Abstract
The objective of this experimental study is to reveal the features of vortex-induced vibration (VIV) for a tandem rigidly coupled twin-tube model. A series of self-oscillation model tests were carried out under uniform flow with a range of reduced velocity from 3 to 20, and Reynolds numbers from 2 × 103 to 1.5 × 104. The spacing ratio, defined as the center-to-center distance divided by the cylinder’s diameter, varied within a range of 1.5–5. The cross-flow VIV response amplitudes and frequencies of the twin-tube model were studied under different spacing ratio compared with a single-tube model. The results reveal that the VIV response amplitude of the twin-tube structure follows a different trend from that of conventional single-tube structures or two free cylinders. The response characteristic of the twin-tube model shows a separated VIV-galloping at the spacing of 1.5D. The most suitable spacing ratio for a submerged floating tunnel (SFT) is 1.5, as it exhibits the lowest response amplitude. The spacing ratio has a significant influence on the response amplitude and frequency, 3D is a transition spacing of the vortex shedding modes, an amplitude modulation phenomenon is observed at the spacing ratio of 3. When the spacing ratio is larger than 4, the response tends to be similar.
Symbolic Regression Equations to Predict the Maximum Stress Concentration Factors in Flexible Pipes With Damaged Tensile Armors
Authors: Mendes de Sousa José Renato , Cunha dos Santos Anderson 
Published: August 2024

Abstract
Flexible pipes are fundamental in various offshore oil and gas exploration applications, such as production, gas injection, gas lift, or water injection lines. However, such structures can be damaged infield, reducing their structural capacity and leading to costs associated with replacements, production loss, or oil leakage. Among the various failure modes of flexible pipes, the rupture of the tensile armors is critical, as these armors withstand the axial loads imposed on the pipe. In this context, this work aims to contribute to evaluating the structural integrity of damaged flexible pipes subjected to tensile loads. Given the limitations of analytical models and the high computational cost of models based on the finite element (FE) method in assessing the structural behavior of damaged flexible pipelines, this work proposes an empirical-analytical equation obtained through Symbolic Regression (SR) as an expedited alternative for determining the maximum stresses in the tensile armors of damaged flexible pipes. Firstly, several flexible pipes were analyzed using a previously proposed FE model. Several tensile armors in their outer layers were considered broken in these analyses. The maximum stress concentration factors (SCF) in the remaining tensile armors were calculated and, together with nondimensional parameters selected to represent the pipe’s mechanical response adequately, formed a dataset analyzed with an SR tool. Finally, a closed-form equation (SR equation) was obtained to analyze other damaged flexible pipes. The proposed equation was verified against FE model results and experimental tests, and good agreement was shown.
Modeling Emissions of Shipping Operations in Sea Ice
Authors: Veber Joshua , Brown Jeffrey , Wang Jungyong , Browne Thomas , Veitch Brian , Molyneux David 
Published: August 2024

Abstract
The marine industry is a large contributor to overall global emissions and must mitigate its environmental impacts through innovation. These improvements can be achieved through combinations of design fundamentals, such as more efficient hull forms, technical innovations, such as wind-assisted propulsion, and operational transformations, such as switching to alternative fuels. Adopting various decarbonization measures will be expensive and must be informed by a detailed understanding of ship performance. In this paper, a method to predict carbon emissions is presented and applied to the case of a medium icebreaker. The emissions predictions are based on a model of ship resistance and propulsion in ice and open water, and they constitute an essential part of a general ship performance model. Route optimization can be informed by such ship performance models in combination with routing algorithms and rewards functions. Our goal is to incorporate a detailed emissions prediction method in a route optimization framework explicitly aimed at transits involving sea ice. The paper includes a description of a full-scale field trial through which we evaluate the accuracy of the predictions and develop a profile of emissions for tactical maneuvers to broaden the prediction capabilities. The results of the trials will be presented at the OMAE conference in Singapore.