bluuebunny/crossref_metadata_2025_split huggingface dataset:
Position Specific Monopile Fatigue Load in the Frequency Domain
Authors: Dahl Niels Christian , Larsen Richard Thyssen Nørby , Høgsberg Jan , Bjerre Nielsen Martin 
Published: October 2022

Abstract
This article presents a method for frequency domain calculations of fatigue loads for offshore wind turbines from wave loading on the monopile foundation. The method is used to estimate position-specific loads to lower the inherent conservatism to optimise the monopile design compared to the conventional approach where a conservative load envelope is applied for the whole or selected parts of the wind farm. The loads are calculated by transforming a wave spectrum into a stress spectrum, used for frequency domain rainflow counting. The remaining fatigue load is then determined by comparing the wave-only fatigue loads to the loads from an integrated loads analysis including all aero-dynamics associated with the turbine. The remaining contributions to fatigue loading are demonstrated to be nearly constant between positions and can thus be used to calibrate the wave-only load, estimated by frequency domain analysis, which subsequently enables the calculation of position-specific loads. When applying the method on site specific data, load reductions up to 12.5% are obtained on individual positions, while a 1–2% saving is achieved on the overall monopile mass.
Experimental Investigation of Flow Velocity Dispersion in Annuli
Authors: Lund Bjørnar , Ytrehus Jan David , Taghipour Ali , Saasen Arild 
Published: October 2022

Abstract
Deviated well sections are common in modern well construction. In mature areas like the North Sea region, practically all producers or injector wells will have highly deviated sections. These wells must be completed in an optimal manner including annular barrier integrity. This is important for zonal isolation through all stages of the well’s life cycle. Since all wells must be permanently plugged before abandonment it is important to ensure that annular barriers are designed with a long term perspective and not only to minimize construction time and cost. Controlled laboratory environments with various fluid compositions and flow parameters are important to develop, validate and improve models and practices. Cement displacement is normally the objective for such studies. Due to selection of fluids, data for casing cleaning operations are in reality derived.
Fundamental flow properties are investigated qualitatively. Water with and without viscosifiers is used to displace similar fluids from the annular section. The effects of inner pipe rotation are included. It is shown how this gives fundamental data providing a relevant background for understanding displacement processes.
The experiments have been performed in a flow loop that consists of a 10 meters long test section with 5″ OD transparent pipe inside a 6,5″ transparent pipe. Experiments were performed with concentric and eccentric horizontal annulus and both with rotating and non-rotating inner pipe. The applied flow loop dimensions are designed so that the results should be relevant for highly inclined sections in field operation.
Numerical Simulation Research About the Influence of Nozzle Parameters on the Quality of Ice-Core in Hot-Water Ice-Drilling
Authors: Liu An , Shan Zhigang , Shi Ting , Ni Weida 
Published: October 2022

Abstract
Ice sheets in the Arctic contain well-ordered accumulations of ancient ice that fell as snow years to millions of years ago. Ice-core data have become central to our understanding of climate change in the past, and to assessments of possible future climate change. Hot-water ice-coring drills are often used to recover ice-core samples from a desirable depth in conjunction with a full-scaled hot-water drilling systems. However, the recovered cores had the varying quality. In hot-water ice-coring drilling, many small nozzles are used to spray water out and melt out a cylindrical ice. Parameters of the nozzle, which mainly includes angle, diameter and quantity, are the most critical part of the drilling system. To improve the ice-core quality in hot-water ice-coring drilling, the influence mechanism of annular hot-water jets formed by nozzle with different parameters on ice-core quality was studied. Heat transfer law of annular jet on the ice-core was studied using the numerical simulation. Totally nine kinds of nozzle with different parameters were designed by using the orthogonal design method and the corresponding calculation domain model of ice was established. The ANSYS FLUENT software was used to analyze the heat flow field, variation trend of heat transfer to the ice-core with different nozzle parameters was researched. The result indicated that the heat transfer of hot water to ice core increased with the larger nozzle diameter while decreasing with the increase of nozzle quantity and nozzle angle. The result can help to give a reference for the design of hot-water ice-coring drill head used in the polar regions.
Research on Fatigue Load Analysis and Fatigue Strength Assessment of Stern Shaft Bracket of Large Ship
Authors: Xianyin Chen , Gaoxiang Wang , Qingchun Zhu 
Published: October 2022

Abstract
At present, the research on the fatigue strength characteristic of stern shaft bracket is almost in worldwide blank. Taking a large ship (displacement over 10000 tons) as an example, the fatigue loads and structural fatigue strength of the shaft bracket were studied. This paper studied the fatigue damage of shaft bracket separately under the action of high-frequency load (propeller excitation force) or low-frequency load (wave load and local fatigue hydrodynamic force). Based on the linear cumulative damage theory, the fatigue damage under the combined action of the three kinds of fatigue loads was calculated. According to the research results, this paper presented an effective calculation method for fatigue assessment of stern shaft bracket.
Development of Fire Integrity Matrix in Order to Achieve Type Approval for FRP Handrails Offshore
Authors: Eves Simon , Filho David , Jarreta Claudio , Byrne Tom 
Published: October 2022

Abstract
The objective of this project was to develop guidance for a Type Approval for FRP handrails in fire integrity applications offshore. BP, MODEC, PETROBRAS, ABS and NOV Fiber Glass Systems came together to form an FRP Industry Group which developed a Fire Integrity Matrix intended to be used as the basis for a Fire Integrity Type Approval for FRP handrails.
The notation R0, R3, R2 and R1 performance levels for FRP Handrails were adopted with the aim to correlate these levels as far as possible to already existing Service and Location definitions set out in the PFM 2-98 for FRP Grating. Heat flux and duration requirements for the R0, R3, R2 and R1 performance levels were proposed, based on industry practice and HSE guidance regarding heat flux levels.
An industry FRP handrail product (MARRS Offshore) was subsequently subjected to the Fire Integrity Matrix tests by Southwest Research Institute in Texas and found to meet all the test requirements. The data was subsequently assessed by ABS and the product was awarded a new Type Approval allowing, for the first time, use in fire integrity applications offshore.
Design and Demonstration of Autonomous Directional Drilling With a Miniature Scale Rig
Authors: Steinstø Magnus , Hånsnar Gaute , Gjersdal Benedicte , Skretting Trygve Mikal Viga , Pavlov Alexey , Florence Fred 
Published: October 2022

Abstract
Drillbotics, an international student competition hosted by SPE/DSATS, directed the 2020/2021 competitors to design, build and implement a 1.5″ (3.8cm) hole size, fully autonomous drilling rig capable of intersecting multiple pre-set targets within a rock sample with up to 30-degree inclination and 15-degree azimuth adjustments from the KOP. The Norwegian University of Science and Technology (NTNU) won the competition using a fixed bent Bottom Hole Assembly (BHA) and a simulated mud-motor stator with a rod inside the drillpipe transferring rotational torque from a top drive. The team designed and created a custom drill bit, bi-directional hydraulic swivel, and BHA. Trajectory control was achieved by changing the BHA bend orientation over time, rotating the drillpipe with inputs from a nonlinear Model Predictive Controller (nMPC) following a pre-planned Bezier-curve well path. Capabilities of the rig were demonstrated by drilling a 37-degree inclination well path in 6 minutes in a 60 cm sandstone replica.
On the Effect of Free-Surface Linearization on the Predicted Hydrodynamic Response of Underwater Vehicles Travelling Near the Free-Surface
Authors: Lambert William , Brizzolara Stefano , Woolsey Craig 
Published: October 2022

Abstract
This study presents a comparison of the hydrodynamic responses generated by a boundary element method with linear free-surface boundary conditions and a volume of fluid RANSE CFD method with nonlinear surface capturing for a shallowly submerged prolate spheroid travelling with constant forward velocity. Observing the effects of free-surface proximity and forward velocity on the hydrodynamic forces and wave disturbance between the two numerical methods reveals the influence and importance of considering a nonlinear free-surface. The forces and moments acting on the spheroid using the nonlinear method are generally larger than the linear method showing that nonlinear effects are important in the calculation of wave making resistance. The difference between the linear and nonlinear methods grows as submergence decreases or wave making increases. An additional phenomenon is shown where the difference between the methods displays a trend with respect to Froude number and depth that is similar to the values being compared. The physical response of these nonlinear effects is seen in the steepening of surface waves near the body, which breaks some of the assumptions made in the linear boundary element method.
Fatigue Assessment of Wind Assisted Propulsion Systems
Authors: Storhaug Gaute , Borzacchiello Guilherme R. , Hoffmeister Hasso 
Published: October 2022

Abstract
With the increasing focus on decarbonization, IMO has introduced a regime for rating ship emissions. Ship owners must adapt and utilize different strategies to reduce the fuel consumption to stay in compliance with regulations, but also to stay competitive. One solution is to utilize wind and set sails.
The new rapidly emerging technologies are not conventional sails, but wind assisted propulsion systems particularly developed for large vessels operating in harsh environments and designed for a long operational lifetime. They may be automatically adjusted by a sensor-based control system to achieve optimum performance. Associated safety risks may be high and one of the damage modes of concern is structural fatigue.
Fatigue accumulation may be driven by ship motions and wind gusts. The paper describes the process of how a pragmatic design formula has been derived to find a gust factor that is useful for combination with ship motions to predict fatigue damage in design. This factor depends on wind speed and ship roll or pitch period. Since fatigue assessment may result in requirements to increased strength, the new formula offers a less conservative design than gust factors used for extreme design, thereby saving material resources and installation costs.
Numerical and Empirical Based Fatigue Life Analyses of Submarine Cables Under Hydrodynamic Loads
Authors: Schütt Clemens , Otto Christoph , Kosleck Sascha 
Published: October 2022

Abstract
In order to perform meaningful fatigue life analyses and estimate the state of fatigue of existing submarine cables, detailed knowledge of the fluid-structure interaction for a variety of load cases as well as reliable data on the fatigue behaviour of the complex overall cable is required. To protect the conductor, submarine export cables consist of several layers. Here, a lead sheathing ensures complete radial water tightness. Regarding transient loads, due to the low fatigue resistance of lead this layer turnes out to be the weak point of the cable geometry. Accordingly, experimental investigations on full-scale cables are carried out in order to proof the cable’s stress-cycle curve.
Fully flexible, nonlinear time domain simulations are then used to determine transient stress distributions within the cable for defined load cases. Here, a non-linear model based on reduced finite element structures was developed and implemented. Finally, based on the fatigue data previously determined during the experiments, a damage analysis is carried out using rainflow-counting.
Geohazard Study of Mudslide Event at a Subsea Escarpment and Structural Response of Crossing Flowlines: Part II – CFD and FSI Analysis
Authors: Jang Hyunchul , Lai Lawrence S. H. , Hayes Kevin , Musto Anthony 
Published: October 2022

Abstract
Mudslides can occur on the seafloor due to subsea earthquakes. These extreme events have a significant impact on the structural integrity of subsea flowlines and equipment. A numerical geohazard study was performed on a subsea mudslide event occurring at an escarpment. The study objective was to determine the structural response of two flowlines and one umbilical crossing an escarpment area subject to the extreme mudslide event and to assess requirement for additional stabilization ancillaries.
The study utilized several numerical methodologies such as Computational-Fluid-Dynamics (CFD), Finite-Element-Analysis (FEA), and Fluid-Structure-Interaction (FSI). Different levels of CFD models were first considered (without flowlines) to show the effect of including additional physics with the final CFD model considering a viscous seawater column, viscoplastic multi-layered soil and high-mobility mud phases. The mudslide velocity field from this CFD simulation is extracted at every 1 s and applied to the Abaqus FEA simulation approach. This is presented in a separate paper [1].
The current paper utilized a FSI simulation approach where the evolution of mudflow debris is directly coupled with the FEA flowline model. This allows the FEA model to continuously update loading created by the mudslide motion. The flowline structural responses were monitored and assessed in terms of displaced shapes and structural loading. This methodology reduces conservatism over conventional approaches by considering viscous effects of the seawater, multi-layer soil and mud layers.
Key findings from the study is that the mudslide event did not significantly displace flowlines over the escarpment. The two flowline responses were within structural design limits. It was also found anchoring did not significantly affect structural responses. The umbilical line, however, exceeded compression limits by four times the design limit. This is due to the high velocity mud-front interacting with an initially stationary umbilical and pushing it into compression during the initial stages of the mudslide event. The solution proposed was line rerouting which helped reduce compression levels to within design limits. This analysis assisted the project in CAPEX and installation cost reduction with no requirement of further umbilical compression mitigation components, and the omission of the pre-planned anchors.
The Impact of the Spectral Tail on the Kurtosis of Random Seas
Authors: Barratt Dylan , van den Bremer Ton S. , Adcock Thomas A. A. 
Published: October 2022

Abstract
We perform Modified Nonlinear Schrödinger (MNLS) simulations of random seas based on narrow-banded JONSWAP spectra (γ = 6) with directional spreading. Our wavefields are homogeneous in space and non-stationary in time, initialised with Gaussian statistics. We truncate the spectral tail for the initial conditions at different cut-off wavenumbers to assess the impact of the spectral tail on the kurtosis and spectral evolution. We consider two distinct cases based on truncation of the wavenumber tail at |k|/kp = 2.4 and |k|/kp = 6, where kp is the wavenumber of the spectral peak. A comparison of our results with previous experiments and simulations yields good agreement, supporting the findings of our study. Our simulations indicate that the peak kurtosis value increases if the tail is truncated at |k|/kp = 2.4 rather than |k|/kp = 6. For the case with a wavenumber cut-off at |k|/kp = 2.4, augmented kurtosis is accompanied by comparatively more aggressive spectral changes including redevelopment of the spectral tail, rapid broadening of the spectrum and downshifting of the spectral peak. Similar trends are observed for the case with a wavenumber cut-off at |k|/kp = 6, but the spectral changes are less rapid and less substantial. Thus, the spectral tail appears to play an important role in a form of spectral equilibrium that reduces spectral changes and decreases the peak kurtosis value. Our findings suggest that care should be taken when truncating the spectral tail for the purpose of simulations/experiments. We also find that the kurtosis evolution equation of Fedele (2015, J. Fluid Mech., vol. 782, pp. 25–36) provides an excellent estimate of the peak kurtosis value. However, the selected bandwidth parameter must account for the spectral tail to provide accurate estimates of the peak kurtosis.
A More Accurate Approach for the Design of Subsea Chemical Storage Systems Regarding Volume Requirements of Valve Leakage Tests
Authors: Sevillano Lucas Cantinelli , Sangesland Sigbjørn , Gjersvik Tor Berge , Faanes Audun 
Published: October 2022

Abstract
Subsea production systems require different chemicals to be injected into the wells, Xmas trees, manifolds, or flowlines to prevent or mitigate flow assurance issues, such as hydrate formation. Moving the chemical injection system subsea is one of the initiatives of the oil and gas industry to reduce field development costs and debottleneck topside facilities. Different studies present the potential benefits of adopting this technology, and the technological readiness level of the different concepts.
One premise for successfully adopting a subsea chemical storage and injection system is to have sufficient storage capacity and an efficient re-filling strategy. To achieve that, it is essential to have an accurate estimate of the required volume of injected chemicals during the service life of a well. One of the procedures which demands most of the injected volume of chemicals is the equalizing of pressures across a valve after a leak test has been performed. One single tree can easily have more than a dozen valves needed to be tested periodically.
The modelling of fluid behavior when equalizing the pressure across the valve to estimate the required volume of injected chemicals may be simplified, for instance, by employing an ideal gas law approach. However, a more sophisticated approach employing equations of state capable of determining properties based on fluid composition might be needed to properly simulate the behavior of reservoir fluids with changing composition and under different pressure and temperature conditions.
For the gas-producer wells modelled in the study cases of this paper, the results obtained indicate a clear difference in estimated chemical injection volumes when using the proposed equations of state approach instead of the simplified ideal gas approach. This equation of state method may be used to design more accurately the volume capacity of a subsea chemical storage and injection system, in particularly as the subsea production system’s demands evolve with time.
A Numerical Study on the Thrust and Interaction of a Three-Sail Wind-Assisted Propulsion System
Authors: Chen Zhengqiao , Cai Wei , Zeng Qingsong 
Published: October 2022

Abstract
Wind-assisted propulsion is deemed to be a potential way to effectively reduce CO2 emissions in ship navigation. Some studies are discussing the characteristics of different sail types and their thrust performance, but a systematic investigation on the features of a multiple-sail system is insufficient, especially the effects of sail geometry and position on lift and drag. In this study, three arc-shaped sails are selected, and the geometric and spacing parameters are chosen as variables. The Computational Fluid Dynamics (CFD) method is applied to perform the simulations. The 2D overset mesh technique is applied to allow convenient mesh rotations. One sail alone is first investigated to find the best attack angle, and three sails with consistent attack angles and even mast distance are studied afterward. Finally, the Design of Experiment (DOE) is implemented to evaluate the significance level of the variables. Based on the results, it shows that the sails interaction can provide both positive and negative effects on the thrust performance. The distance between Sail 1 and Sail 2, the attack angle of Sail 1 and Sail 2 are significant factors impacting the thrust of the three-sail propulsion system. The mechanism of the interaction effects on the lift is also addressed. This study helps to find the predominant parameters affecting sail thrust performance and contributes to an intelligent manipulation of a multiple-sail propulsion system.
Feasibility of Riser Emergency Disconnections During Drilling MPD Operations With Surface Back Pressure
Authors: Richa Luan , Venero Germain , Carvalho Roberto 
Published: October 2022

Abstract
Managed-Pressure Drilling (MPD) techniques are used by operators to reduce the non-productive time associated with kicks, losses and well-control events. There are different MPD techniques applied to work reservoirs where fluid loss are common, or where the fracture gradient and the pore pressure are close [1].
MPD techniques on deep water drilling operations can lead to extreme scenarios for the riser integrity, with low effective tension scenarios for Floating Mud Cap Drilling (FMCD) up to high effective tension for Pressurized Mud Cap Drilling (PMCD) and Surface Back Pressure (SBP). Feasibility of drilling operations using MPD techniques will depend, among other factors, on the feasibility of the riser disconnection on an emergency scenario, which present restrictions due to the distribution of effective tension and axial forces along the riser. Recoil analysis is required to define safe windows for emergency disconnection during MPD operations.
The critical parameters during emergency disconnection of a riser with MPD have been studied based on recoil analyses, which were performed for ultra-deep water for a range of SBP scenarios and for a non-pressurized operation with equivalent bottomhole pressure. Numerical simulations are applied for solving the transient problem of the riser disconnection in the time domain, considering the mud outflow, the riser dynamics, the vessel response and detailed tensioning system model to properly capture the system behaviour during the disconnection.
Individual and comparative results are presented, and conclusions describes the influence of the SBP usage for the riser integrity during an emergence disconnection.