bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Dynamic Optimization of Lower Completion Configurations Based on the Liquid/Gas Flow Streamline in a Middle East Oilfield
Authors: Shi Shuzhe , Wu Bohong , Nie Zhen , Li Yong , Li Xin , Zhang Lufeng 
Published: September 2023

Abstract
Barefoot horizontal completion is the main technology that applied in the N oilfield Middle East, and several production problems have occurred at the barefoot horizontal wells in the past few years, for example, the water coning, the gas breakthrough, and the uneven production profile, which could be resulted from the edge-bottom water, gas cap or the adjoining injection wells. These production problems will result in a low sweep efficiency and low final oil recovery. In the meantime, poor design of lower completion configuration would not only lead to a lower final oil recovery but also cost a lot in the installation and operation.
Therefore, the fit-for-purpose lower completion technologies and well-designed lower completion configuration need to be studied for the purpose of high sweep efficiency and high net profit value. In this work, the production wells were classified into several categories according to the seriousness and reasons of the production problem. Then, the detailed factor analysis of water coning and gas breakthrough is carried out from the numerical simulations based on the liquid/gas flow streamline, which can find out the water coning issue and the gas breakthrough issue whether are caused by the injection wells or the edge-bottom water. At last, the well-designed lower completion configuration study for the production well and injection well is conducted in the dynamic model simulations. By applying the optimized lower completion configurations and deploying the tools accurately based on reservoir property and production performance, the highest oil recovery and net profit values can be achieved in the oilfield development.
This work can give guidance to the problem classification of production wells, and establish a more accurate optimization method of designing the lower completion to better develop the oilfield.
Hydroelastic Response of Submersible Open Net Fish Pens Under Wave Action
Authors: Chu Yun Il , Wang Chien Ming , Zhang Xinyu , Zhang Hong , Savage Leigh 
Published: September 2023

Abstract
Submersible fish pens are a cost-effective solution for storm proofing fish pens at offshore sites against strong surface waves and winds. This paper examines the hydroelastic responses of submersible open net fish pens and the mooring forces under wave action for various submergence depths. For the hydroelastic analysis, a single cylindrical open net fish pen and mooring system were considered. A regular wave reflecting the worst wave condition observed in an exposed farm site in Tasmania’s Storm Bay, Australia was used for the analysis. A numerical software package AquaSim was adopted for the hydroelastic analysis of the fish pen and mooring system. The analysis results show that the vertical displacement of submerged pen and mooring force are reduced significantly when compared to the corresponding results of the fish pen floating on the water surface. It is shown herein that after a particular submerged depth, the hydroelastic results do not decrease significantly with deeper depths. A future study will investigate the relationship between the optimal submerged depth, fish pen dimensions and wave conditions with the view to save ballasting costs and time to re-float the fish pens.
On Wear Thickness of Rust Layers of Steel Structure due to Ice Impact Load
Authors: Takeuchi Takahiro , Kioka Shinji , Miyazaki Hitoshi 
Published: September 2023

Abstract
Rust layers on the surface of corroded steel are removed due to sea ice action in ice-infested sea, subsequently leading to increased wear due to further corrosion. Damage to coastal structures and training levees comprising steel sheet pile seawalls on the Sea of Okhotsk occurred sooner than expected, since large wear rates had not been considered in their design. This paper investigates the degradation mechanism of steel structures through indoor tests focusing on sea ice impact. The effect of wear thickness is examined based on parameters such as sea ice temperature, sea ice impulse, sea ice momentum, ice impact load, sand inclusion in sea ice, angle of ice impact load, and real contact area of ice impact load. It is shown that wear thickness can be estimated from maximum ice impact pressure on the real contact area between sea ice and rust layer. This implies that the uni-axial compressive strength of sea ice, which relates to maximum ice impact pressure, plays an important role in the estimation of wear thickness. These results also lead to the estimation of thickness of sacrificial (additional) steel walls in addition to the original steel structure as a countermeasure against wear.
Study on the Axial Tension Reduction of a Dual-Bore Vertical Riser System for Deep Sea Mining
Authors: Yamamoto Marcio , Yamamoto Joji , Masanobu Sotaro 
Published: September 2023

Abstract
Exploiting polymetallic nodules in the Clarion-Clipperton Zone shall require a vertical riser with two separate lines. First, the ore-lift line shall convey the slurry composed of seawater and nodules from the seafloor up to the floating platform. The second line is the water-return line that shall bring this seawater to be discharged on the seafloor. One issue of this mining riser is that its top end has the highest axial tension, which may overcome the material’s yield strength resulting in structural failure.
For instance, the drilling riser used in the Petroleum Industry must have buoys attached along its length to address the same issue. The problem with the attached buoy is the hydrodynamic loads increase linearly with the buoy diameter. Thus, we aim to reduce axial tension without attached buoys and keep the internal diameter as constant as possible to avoid flow assurance issues. Our approach is to assemble the mining riser using riser joints with the same external diameter but different wall thicknesses. The pipe’s outer diameter and wall thicknesses assumed in our analyses are defined in the standards API Spec 5CT. Next, we proposed four different optimized configurations for the mining riser. Then, we carried out numerical simulations in the time domain, assuming a 4,000 m riser system. As external loads, we adopted a current profile and irregular waves typical for the Clarion-Clipperton Zone. Our reference is a riser composed of all joints with the same diameter and thickness.
Our results show that the riser with the best-optimized structure had an axial tension reduction of 15% compared to the reference. However, this riser has the highest risk of structural failure criteria defined as Method 1 of API ST 2RD in case of worse external loads.
ASSIST Observations 2017–2021: Uncertainty, Comparison With Sea Ice Charts, and Ice Concentration From Deep Learning Model
Authors: Panchi Nabil , Kim Ekaterina , Skjetne Roger , Hughes Nick 
Published: September 2023

Abstract
The Arctic Ocean is undergoing significant changes, leading to a surge in research and commercial activity in the region. As a result, the number of manual observations of ice conditions, known as ASSIST observations, has dramatically increased in recent years. These observations provide valuable information on the state of the Arctic ice cover and have been used as a source of ‘ground truth’ for other satellite products. However, their manual nature raises concerns about the associated uncertainty. To address these concerns, the present study evaluates the uncertainty of total ice concentrations, partial ice concentrations, ice types, and ice thicknesses reported in ASSIST observations. First, the study compares ASSIST observations from 2017 to 2021 against sea ice charts from the Norwegian Meteorological Institute, the US National Ice Center, and the Arctic and Antarctic Research Institute. Second, as a test case, the study evaluates simulated ASSIST observations conducted on optical images by an ice expert, three non-experts, and a deep learning model. Results from the comparisons indicate a good agreement between ASSIST observations and the sea ice charts, with ∼80% of comparisons resulting in a difference of less than ±10% in total ice concentration. Analysis of the remaining 20% reveals high underestimation in summer and overestimation in winter compared to sea ice charts. Groupwise comparison of ice types reveals an accuracy of ∼50% and a good match between the ice thickness reported by ASSIST observations and ice thickness associated with ice types reported by the ice charts, with ∼70% of comparisons resulting in a difference of ±10 cm. Results from the inter-comparison of simulated ASSIST observation point to an agreement between experts and novices in simple scenes with a single type of ice and disagreement in the case of complex scenes.
Towards Developing a Code of Practice for Offshore Aquaculture Vessels
Authors: Mohajernasab Saeed , Abdussamie Nagi , Harris Andrew , Shearer Chris , Tighe Nick , Bhaskar Prashant , Chin Chris , Islam Rabiul , Binns Jonathan , Enshaei Hossein 
Published: September 2023

Abstract
In recent years, fish farming facilities and the aquaculture industry are gradually moving towards more offshore (or exposed) locations, bringing new opportunities to increase their value creation through better production conditions regarding the aquatic environment due to space availability and water quality which can be extremely beneficial, resulting in more stable farming conditions. This study is focused on the demand for a code of practice for the design, operation, and survey of aquaculture vessels, particularly in offshore regions.
However, offshore aquaculture requires the vessels to operate in more severe sea states, which require the farming structure, station-keeping systems, and vessel-farming site interaction to be more robust. On the other hand, the specific operations demanded from a fish farm vessel, such as net handling, anchoring, mooring, towing, delousing, feeding and live fish transporting, require specific guidelines that can cover the vessel and system design as well as their safe operation.
Relevant rules and regulations from national and international guides and standards, including the Australian National Standard for Commercial Vessels (NSCV), and rules and guidelines of classification societies, are reviewed. Furthermore, the study discusses the current research studies centred around aquaculture vessel design and operations, including crew transfer vessels for fish farms, bunkering and alternative fuel sources. Finally, this paper aims to identify the current gaps and similar guidelines and research concepts towards developing a code of practice for aquaculture vessels. A framework for developing such a novel code of practice for offshore aquaculture service vessels in line with the other current efforts on the safety of aquaculture operations will be discussed.
Evaluation of Seakeeping Model Tests in Open Waters Using Two Submarine Hull Forms
Authors: Büsken Wiebke , Krüger Stefan 
Published: September 2023

Abstract
In this paper, the experimental procedure of seakeeping model tests in open waters with two free-running, remotely-controlled submarine hull forms as realized on Eckernförde Bay from October 2021 to April 2022 is presented. The objective of performing such model tests with surfaced submarines at various conditions of stability, speeds and encounter angles in natural seaway is explained. A summary of the qualitative observations concerning the different identified phenomena, which lead to large motion amplitudes, is given in this paper along with a quantitative evaluation of the model tests by statistical analysis of selected test runs. As part of the results, different heeling moments, which were observed to attack the surfaced submarine during these model tests, are discussed, especially in regard to their inclusion in the recently developed new stability standard for the intact surface stability of submarines of the German Navy.
A Joint Probability Distribution Model for Multivariate Wind and Wave Conditions
Authors: Vanem Erik , Fekhari Elias , Dimitrov Nikolay , Kelly Mark , Cousin Alexis , Guiton Martin 
Published: September 2023

Abstract
This paper presents a joint statistical model that has been fitted to data of wind and wave conditions for an offshore location at South Brittany. The data are from a numerical model and contain hourly values for several wind and wave variables over a period of 32 years. The joint distribution presented in this paper considers the variables wind direction, mean wind speed, significant wave height, wave direction and peak period. A conditional model for turbulence given wind speed is introduced to yield an additional variable for the joint model. The joint model is constructed as a product of marginal and conditional models for the various variables. Additionally, the fitted models will be used to construct environmental contours for some of the variables. For significant wave height, various models are used to obtain different extreme value estimates, illustrating the uncertainties involved in extrapolating statistical models beyond the support of the data, and a discussion on the use of non-parametric copulas for the joint distribution is presented. Such joint distribution models are important input for design of offshore structures, and in particular for offshore wind turbines and the influence of the joint model in design is illustrated by a simple case study.
Numerical Simulation of a Ship Advancing in Pack Ice Area Based on CFD-DEM Method
Authors: Zou Ming , Tang Xiang-Jie , Zou Lu , Zou Zao-Jian , Zhang Xin-Shu 
Published: September 2023

Abstract
The greenhouse effect has caused significant changes in polar ice conditions, and the pack ice condition is expected to become the most common environment of the future polar transportation. Study of the ship-ice interaction in the pack ice area is of great significance for ensuring the safety of polar transportation. In this paper, the numerical simulation models of a ship advancing in pack ice area are established by using the Hertz-Mindlin contact model and Linear Spring contact model, respectively. Taking the KCS ship as study object, the CFD-DEM (Computational Fluid Dynamics - Discrete Element Method) method is used to conduct numerical simulations, and the reliability of the simulation models is verified by comparing the simulation results with those of empirical formula and experimental measurements. On this basis, the effects of the two contact models on the simulated phenomena, ship-ice contact force, mean ice resistance and peak ice resistance are studied. This study provides a reference for the selection of contact model in numerical simulation.
A Simulation-Based Approach for Evaluating Merchant Fleet Decarbonization Strategies
Authors: Bergström Martin , Gosala Vaidehi , Depken Jorgen , Fitz Annika , Euskirchen Frederik , Ehlers Sören 
Published: September 2023

Abstract
The International Maritime Organization (IMO) aims to reduce the annual greenhouse gas emissions from international shipping by at least 50 % by 2050, compared to 2008. To this end, the organization has adopted a set of regulations, including the Energy Efficiency Design Index (EEDI), the Energy Efficiency eXisting ship Index (EEXI), and the Carbon Intensity Indicator (CII), which will require the maritime industry to transition to lower carbon operations. However, the issue of how this transition is to be achieved remains unresolved. Against this background, this paper proposes a simulation-based approach for predicting how a selected fleet of merchant ships may develop over time under various decarbonization strategies. The aim is to make it possible to identify and evaluate feasible decarbonization strategies, accounting for potential bottlenecks, for instance in terms of the supply and availability of individual low-carbon fuels and technologies. A case study is presented in which the approach is applied to a fleet of 254 ships, which is assumed to be roughly representative of ships above 400 gross tonnage serving German ports.
Numerical Study on the Hydrodynamic Characteristics of a Small High-Speed Craft
Authors: Lv Huizi , Wei Chengzhu , Liang Xiaofeng , Yi Hong 
Published: September 2023

Abstract
Small high-speed crafts cannot resist adverse waves by using their displacement. In order to improve their ability to execute tasks in heavy sea conditions, a concept of a small highspeed craft, the shuttle vessel (SV-SJTU) is proposed by Shanghai Jiao Tong University. The angle freeboard is adopted to control hull wetness at high speed, and the slim wave-piercing design is utilized to produce smaller lift force.
Validated CFD methods were employed to calculate hull resistances and motions. The SV-SJTU hull is tested in the model scale of 1/6. Hull resistances and motions were predicted by using the overset mesh method and solving the URANS equations closed by the SST k-ω turbulence model. The VOF method is utilized to capture the complicated free surface.
Hence, the resistances and hull motions of SV-SJTU in calm water and waves at different speeds were obtained. With satisfying running attitudes and small resistances in calm water, the SV-SJTU experiences soft motions in harmful sea conditions at high speeds without slamming or instantaneous large acceleration, which is different from normal crafts. Accordingly, the concept of a small high-speed craft that performs well in calm water and maintains in waves for soft motions at adverse sea conditions is validated.
First Principle Design Load Estimation for LH2 Fuel Tanks by Means of 0D Approach
Authors: Lampe Tobias , Roß Lukas , Okpeke Bright Ebikemefa , Ehlers Sören 
Published: September 2023

Abstract
Within the framework of the Sustainable Development Goals, the United Nations (UN) General Assembly has declared its firm intention to combat climate change and the associated changes in the environment. Shipping is an important factor since its exhaust gases account for just over two percent of global greenhouse gas (GHG) emissions. This is reflected in the GHG Strategy of the International Maritime Organization (IMO), which forces the maritime industry to move away from fossil fuels towards zero-carbon alternatives. Liquid hydrogen is a promising candidate to enable this transition. As of now, class approval for the required technology is based on an alternative design approach which entails operational scenario development. In this work, a simulation-based approach for the estimation of design loads with respect to liquid hydrogen fuel tanks is presented. The MATLAB software is employed to implement a 0-dimensional approach for the calculation of the bulk thermodynamic behavior. Necessary thermodynamic quantities are obtained via internal energy by means of the CoolProp package. Vapor and liquid phases are treated separately under the assumption of a saturated liquid state while the vapor is allowed to superheat. There is good correlation between validation data and simulation. In order to provide a realistic load assessment during a ship voyage, an exemplary cruise ship and corresponding power-demand profiles are utilized. The results are then analyzed with regard to occurring loads and operational efficiency.
Data Informed Model Test Design With Machine Learning – An Example in Nonlinear Wave Load on a Vertical Cylinder
Authors: Tang Tianning , Ding Haoyu , Dai Saishuai , Chen Xi , Taylor Paul H. , Zang Jun , Adcock Thomas A. A. 
Published: September 2023

Abstract
Model testing is common in coastal and offshore engineering. The design of such model tests is important such that the maximal information of the underlying physics can be extrapolated with a limited amount of test cases. The optimal design of experiments also requires considering the previous similar experimental results and the typical sea-states of the ocean environments. In this study, we develop a model test design strategy based on Bayesian sampling for a classic problem in ocean engineering — nonlinear wave loading on a vertical cylinder. The new experimental design strategy is achieved through a GP-based surrogate model, which considers the previous experimental data as the prior information. The metocean data are further incorporated into the experimental design through a modified acquisition function. We perform a new experiment, which is mainly designed by data-driven methods including several critical parameters such as the size of the cylinder and all the wave conditions. We examine the performance of such a method when compared to traditional experimental design based on manual decisions. This method is a step forward to a more systematic way of approaching test designs with marginally better performance in capturing the higher-order force coefficients. The current surrogate model also made several ‘interpretable’ decisions which can be explained with physical insights.
Experimental Study of the Draft on the Flow-Induced Motions (FIM) of a Semi-Submersible Platform With Four Square Columns
Authors: Gonçalves Rodolfo , Marques Matheus , Silva Leandro , Hirabayashi Shinichiro , Suzuki Hideyuki 
Published: September 2023

Abstract
This article aims to understand the effect of the draft condition on the FIM of a semi-submersible platform (SS) with four square section columns. Model tests of a floating system supported elastically utilizing four springs were performed in a towing tank. A parametric study based on three main dimensions: the draft, H, the pontoon height, P, and the length of the square column face, L. Two studies were conducted for different H/L conditions: first, for a constant column aspect ratio, C/L = 1.00, where C = H-P; and second, for a constant P/L = 0.25. The spacing ratio of the columns was S/L = 4; where S is the distance between column centers. Two incidence angles of the current were carried out, namely 0 and 45 degrees. The results could be summarized using the column-pontoon ratio, C/P. The amplitudes in the transverse direction decreased by decreasing the C/P.
Weakly Nonlinear Surface Wave Prediction Using a Data-Driven Method With the Help of Physical Understanding
Authors: Chen Jialun , Zhao Wenhua , Mline Ian A. , Gunawan David , Taylor Paul H. 
Published: September 2023

Abstract
Accurate surface wave prediction can potentially improve the safety and efficiency of various offshore operations, such as heavy lifts and active control of wave energy converters and floating wind turbines. Prediction of surface waves, even if only for a few periods in advance, is of value for decision-making. This study aims to predict weakly nonlinear surface waves (up to the 2nd-order) in real-time using a data-driven model based on Artificial Neural Networks (ANN), where the application of physics is investigated to aid the development of a data-driven model. Based on numerically synthesized nonlinear wave records calculated using exact 2nd-order theory, ANN models were trained to separate the nonlinear bound components at an up-wave location, propagate the linear waves and reintroduce the nonlinear components as a correction to the prediction at a down-wave location. The results show that the optimal approach is to predict each stage separately following the basic physical structure of weakly nonlinear water waves using a series of ANN rather than direct prediction in a single step using ANN. Further, the generalization of the models for different sea states and the impact of the 2nd-order bound waves on prediction accuracy is investigated.