bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unsupervised Machine Learning: A Well Planning Tool for the Future
Authors: Batruny Peter , Robinson Tim 
Published: October 2022

Abstract
In recent years, the industry has sought insights from abundant data generated by drilling operations. One of the key focus areas is the rate of penetration (ROP) which impacts costs directly, and emissions indirectly. Previous work has succeeded in predicting and optimizing ROP, however was limited to specific fields and small-scale applications. This limitation stems from unobserved information between different fields or operations that often impacts model usability. This paper provides a new way of well planning by leveraging the power of unsupervised machine learning to deliver higher drilling efficiency, lower costs, and less uncertainty.
Unsupervised machine learning techniques are used to infer information about drilling operations from real-time data that is not directly measured. Certain well types seem to be separable in low dimensions, based on qualitative interpretation of clusters visualized in 2D, and according to analyzing cluster membership based on which wells the data came from, and by associating common characteristics of wells within clusters using external information.
This work introduces a novel approach to collect, separate, and extract value from data that is otherwise unused. Data synthesized by Variational Autoencoders could be used for enhanced well planning, sold as a standalone product, or shared between industry players with reduced privacy concerns, increasing the wealth of data available.
Application of Machine Learning Algorithms for Predicting Added Resistance in Arbitrary Wave Headings of a Ship
Authors: Kim Young-Rong , Steen Sverre 
Published: October 2022

Abstract
Vessels experience additional resistance by waves during navigation, which becomes a factor that increases energy consumption and exhaust gas emissions. Proper estimation and understanding of this additional resistance is an important task in the marine industry. In this study, we propose a machine-learning model that predicts added resistance in arbitrary wave headings using basic ship parameters. First, extensive model experimental data on added resistance for different ship types and sizes of ships were acquired. To build a proper machine learning model, algorithms such as extreme gradient boosting (XGB), random forest (RF), artificial neural network (ANN), k-nearest neighbor (ANN), gaussian process regression (GPR), and support vector regression (SVR) were considered. Through nested cross-validation, the evaluation and hyperparameter tuning of algorithms were performed together. As a result, SVR was selected among the candidate models due to high accuracy with robustness to the outliers. In the validation with test data of head waves and all wave headings, the R2 scores of the selected model were 0.6738–0.7584 and 0.6744–0.7449, respectively, which was better than estimation methods for added resistance in head waves such as STAWAVE-2 and Cepowski (2020), and similar accuracy to those applicable in arbitrary wave headings. Even estimation of added resistance in irregular waves of sea states, the relative deviation with the semi-empirical methods for arbitrary waves was not large, on average 10%.
Modeling and Algorithm Development for Well Trajectory Plan and Real-Time Trajectory Control
Authors: Saavedra Jerez Luis , Sui Dan 
Published: October 2022

Abstract
Drilling automation has become one of the principal goals that the drilling industry is working to achieve in the following years. Particularly the analysis of the trajectory control in realtime is a challenging topic where a simulator can be handy. Our study has developed the Rotary Steerable System (RSS) Simulator, where the drilling calculations, including bit force, bit position, trajectory control under uncertainty, and path corrections, are handled without any human interaction. The in-house RSS Simulator, developed in Python, is based on two general functions: the Trajectory Control Optimizer (TCO) and the RSS model. The TCO builds a planned and optimized trajectory (low dogleg severity and short length), controls the bit’s location, and corrects the trajectory if it has deviated from the plan. The RSS model simulates the bit’s behavior and displacement following the three-axial rate of penetration (ROP) model developed by the University of Stavanger (UiS).
The RSS Simulator has been tested using one well from the Industry Steering Committee on Wellbore Survey Accuracy (ISCWSA) examples. The simulation results show that the proposed trajectory control algorithm can correct and steer, automatically and optimally, the bit direction. The simulations show the importance of the automated deviation control of the simulator in reaching the final target as close as possible.
Finally, implementing the RSS Simulator methods could represent a novel approach within the automation control area that would benefit the drilling industry.
Optimization and Design of Separate Layer Fracturing in Tight Low Permeability Sandstone Gas Reservoir: An Case Study
Authors: Zhang Lufeng , Li Fengxia , Wang Haibo , Wang Jie 
Published: October 2022

Abstract
Tight sandstone reservoirs, widely distributed in the Sichuan Basin of China, are the significant gas exploration and exploitation area and have a profitable development prospect. Separate layer fracturing of vertical well is an indispensable technology to unlock the production potential and enable commercial productivity for tight reservoirs. This paper takes well X located in Zhongjiang County as an example to carry out separate layer fracturing design, aiming to provide an insight for efficient development of tight sandstone reservoirs. The results of laboratory experiments mainly achieved the following findings: 1. The average porosity and permeability of target formation are 4.6% and 0.2 mD. 2. Bedding fractures are locally developed, while overall structural fractures are underdeveloped. 3. The main mineral components are quartz, rock debris, a small amount of feldspar and carbonate cement. 4. Poisson’s ratio and Young’s modulus are 0.18 and 23 GPa, respectively. Moreover, the log interpretation analysis shows that the classification of geological and engineering sweet spots are III and II, respectively. The calculated breakdown pressure is mainly distributed at 107–120 mPa. Furthermore, numerical simulation shows that temporary plugging fracturing technology can achieve the uniform propagation of fractures in segment. The post-fracturing production of well X reaches 50,000 m3/d, marking a breakthrough in exploration for tight sandstone of Xujiahe Formation.
Offshore Energy Hubs in the Decarbonisation of the Norwegian Continental Shelf
Authors: Zhang Hongyu , Tomasgard Asgeir , Knudsen Brage Rugstad , Grossmann Ignacio E. 
Published: October 2022

Abstract
This paper studies the investment planning of a decarbonised Norwegian continental shelf energy system considering the connection and interfaces with the European energy system. A multi-horizon stochastic mixed-integer linear programming model is developed for such a problem. We consider short-term uncertainties, including wind and solar capacity factors, energy load, platform production profiles, and hydro power production limits. Hydrogen based energy hubs are considered both onshore and offshore for potential renewable power generation, distribution and storage. Future hydrogen market or demand is not included in the model. The results of multi-period planning towards 2050 show that: (a) offshore energy hubs are essentially wind power generation, conversion and distribution hubs, (b) a combination of offshore wind and power from shore may be a cost-efficient pathway for cutting emissions from the Norwegian continental shelf, (c) a total of 1.6 GW offshore wind may be needed to achieve a near zero emission Norwegian continental shelf energy system, 80% of which may be added in the first investment period and (d) offshore grid design is important for decarbonisation by distributing wind power efficiently; all five offshore platform clusters are connected to at least three other clusters by 2040, and they are fully connected by 2050.
Design of the Propulsion System for the Autonomous XLUUV MUM
Authors: Greve Martin , Kurowski Martin , Ritz Sebastian , Golz Matthias , Vijayasarathi Lakshmi Narasiman , Bayazit Nursen , Rentzow Erik 
Published: October 2022

Abstract
The paper reports on one aspect in the design of the extra-large unmanned underwater vehicle (XLUUV) MUM, referring to a large Modifiable Underwater Mothership. The vessel will be highly modular and has unique features, such as hydrogen fuel cell and lithium-ion batteries. Modules can be added and rearranged to fulfill different operations. The envisaged operation scenarios pose a challenge to the design of the propulsion and maneuvering system. Due to the limited power and energy storage, it must be efficient during submerged transit, capable of safe surfaced operation in public sea routes and of dynamic positioning. A design study is presented based on an initial design of two variants. The basic hull forms are compared in terms of required forces and moments for vessel motions. Simulations of hull forces are conducted using Reynolds-averaged Navier-Stokes (RANS) equations and vessel motions are determined with an actuator force model. Different arrangements of propulsors and thrusters are investigated and compared concerning their propulsion efficiency and their agility in translatory and rotary directions. The results are presented as tabulated data and in capability plots. A final design is presented and discussed and a conclusion is presented.
Approach to Simulate Fluid-Structure Interaction of a Ship in 3-Dimensional Numerical Towing Tank
Authors: Yamada Yasuhira , Chong Ma 
Published: October 2022

Abstract
In the present study, in order to investigate structural response of ships against slamming, whipping and springing a new approach to simulate fluid structure interaction (FSI) of a ship in three dimensional numerical towing tank using ICFD (Incompressible computational fluid dynamics) methodology is explored. ICFD is the state of the art methodology to simulate both structure and incompressible fluid using finite element method (FEM) where both fluid and structure are modeled with Lagrange mesh with relatively rapid computation time.
As a case study, slamming impact of bow of a container ship is demonstrated. A numerical simulation of water entry of bow into the water is carried out, and displacement, velocity and acceleration of bow, behavior of surrounding water around bow is investigated. Moreover ongoing project of simulation of an elastic-plastic container ship in regular waves in “numerical towing tank” using a whole container ship model is shortly introduced.
Implementation of a Thorough Treatment of Chain Out-of-Plane (OPB) Bending Fatigue With Chainwheel Interaction
Authors: Jones Justin , Childs Ian 
Published: October 2022

Abstract
The effect of out-of-plane bending (OPB) on the fatigue life of moorings has been the focus of extensive study over the last 15 years. Classification societies now require it to be considered in mooring chain fatigue life calculations.
A fatigue analysis of the mooring for a North Sea FPSO was required to support life extension. This paper describes the development of a procedure for the calculation of the fatigue life of the mooring chain with a thorough treatment of fatigue stresses including out-of-plane bending and interaction with the fairlead chainwheel. To include these effects, an integrated method has been developed.
A nonlinear time-domain simulation of the vessel and mooring system is used to calculate time histories of tension, and declination and azimuth angles relative to the vessel for multiple seastates representing the wave-induced fatigue environment. A detailed finite element model of the vessel’s top chain and chainwheel is used to generate transfer functions between chain tension, azimuth and declination angles relative to the vessel, and Dang Van stress.
The mooring time history output and the stress transfer functions are combined to produce time histories of Dang Van stress at nodes across the chain link surface for each seastate. The resulting nodal stress time histories are rainflow counted. Damage is then calculated and summed across all seastates using Miner’s rule.
The results for the integrated method show good agreement with that for tension-tension using chain S-N curves if OPB is omitted, providing validation of the approach. Including the effect of OPB, the increase in annual chain fatigue damage is equivalent to the application of a stress concentration factor of 1.5. The complex history of the particular vessel, including the effect of two deployments and a chain refresh strategy, results in a slight increase in calculated life of the critical link compared to tension-tension fatigue alone when all effects are included.
Analysis of Wave Fields During Ship Accidents in the North-Western Mediterranean
Authors: Innocenti Alessio , Messeri Gianni , Onorato Miguel , Brandini Carlo 
Published: October 2022

Abstract
The occurrence of extreme waves in real sea conditions and their generation mechanisms are key elements in regional forecasts to improve the safety of navigation, especially in those severe conditions where large ships depart and adapt their routes based only on average wave parameters, as the significant wave height. In the present work we have analyzed a series of accidents occurred in the North-Western Mediterranean Sea to large passengers and cargo ships, involving injured people, damages and partial loss of cargo. We have performed phase-resolving numerical simulations based on the Higher Order Spectral Method (HOS), initialized with WaveWatch III (WWIII) directional wave spectra, to analyze in details the sea conditions during the accidents from a statistical point of view. For each case study we have repeated several 3-dimensional realizations to ensure statistical accuracy, and we have tested also the impact of the atmospherical forcing in the WWIII model as well as the nonlinear source term parametrization. The statistical analysis is based on the evaluation of statistical moments as skewness and kurtosis of the free surface elevation, which are typical indicators of nonlinearities and extreme waves, and on the reconstruction of crests distributions, from space-time analysis. Finally, we have focused the attention on spectral shapes similarities among the different case studies and on its possible effect on rogue waves formation.
Temperature Reduction on LNG Bunkering Ship Structure Under Accidental Cryogenic Gas Release Using CFD Simulation
Authors: Nubli Haris , Sohn Jung Min , Jung Dongho 
Published: October 2022

Abstract
Liquefied Natural Gas (LNG) fuel has been proven to minimize sulfur oxide, nitrogen oxide, and particulate matter emissions. LNG fuel becomes a good option to fulfill an alternative fuel demand in shipping industries. Consequently, LNG bunkering ships have to deploy in order to meet the LNG bunkering infrastructure demand. In the event of an accidental LNG release, the cryogenic exposure causes embrittlement of steel that leads to the ship’s structural failure.
The scope of this work is to establish accidental LNG release scenarios considering the leak and environment-related parameters, to observe the cryogenic flow and gas accumulation on the LNG bunkering ship’s structure. The reservoir pressure, leak size, leak directions, leak positions, and release rates are provided as the leak-related parameter. A wind rose data of Ulsan Port (South Korea) is utilized to determine the wind speed, wind direction, and ambient temperature as the environment-related parameter. The release duration is set in 15 minutes which is the emergency shutdown valve reaction time. Kameleon FireEx (KFX) was employed to execute the LNG release simulation. The grid and iteration convergence tests were presented to ensure the current model’s accuracy. Finally, the thermal footprints of structure and gas accumulation characteristics are discussed in this paper.
Data Driven Digital Twin Applications Towards Green Ship Operations
Authors: Taghavi Mahmood , Perera Lokukaluge Prasad 
Published: October 2022

Abstract
Due to the growing rate of energy consumption and its consequent emissions, the International Maritime Organization (IMO) has devised strict rules for an extensive reduction in Greenhouse Emissions (GHG), which forces the shipping industry to search for more energy-efficient solutions. Therefore, alongside with the Energy Efficiency Design Index (EEDI), improving the energy efficiency of existing ships under the Energy Efficiency Existing Ship Index (EEXI) is of considerable importance. This paper address this issue by proposing a digital twin framework supported by big data analytics for ship performance monitoring. The proposed framework is developed by the respective data sets from a selected vessel. For this purpose, a cluster analysis is implemented using the Gaussian Mixture Models (GMMs) with the Expectation Maximization (EM) algorithm. By this approach, the most frequent operating regions of the engine is detected, the shapes of these frequent operating regions are captured, and the relationships between different navigation and performance parameters of the engine are determined. That will make the basis for a digital twin application in shipping. The main objective of this research study is to develop a digital twin of a marine engine by considering the engine operational conditions that can be utilized toward green ship operations. The contribution of this paper and the outcomes can facilitate the shipping industry to meet the IMO requirements enforced by its regulations.
Analyzing Extreme Sea State Conditions by Time-Series Simulation
Authors: Vanem Erik 
Published: October 2022

Abstract
This paper presents an extreme value analysis on data of significant wave height based on time-series simulation. A method to simulate time series with given marginal distribution and preserving the autocorrelation structure in the data is applied to significant wave height data. Then, extreme value analysis is performed by simulating from the fitted time-series model that preserves both the marginal probability distribution and the autocorrelation. In this way, the effect of serial correlation on the extreme values can be taken into account, without subsampling and de-clustering of the data. The effect of serial correlation on estimating extreme wave conditions have previously been highlighted, and failure to account for this effect will typically lead to an overestimation of extreme conditions. This is demonstrated by this study, that compares extreme value estimates from the simulated times-series model with estimates obtained directly from the marginal distribution assuming that 3-hourly significant wave heights are independent and identically distributed. A dataset of significant wave height provided as part of a second benchmark exercise on environmental extremes that was presented at OMAE 2021, has been analysed.
Conceptual Design of a Prestressed Concrete Spar Floater Supporting a 10 MW Offshore Wind Turbine
Authors: Munbua Wichuda , Hasan Muhammad S. , Malta Edgard B. , Gonçalves Rodolfo T. , Fujiyama Chikako , Maekawa Koichi 
Published: October 2022

Abstract
The Government of Japan implemented a new law to promote offshore wind in 2019. However, more than 90% of the 9,074 TWh of Japanese annual wind generation potential is located in the deep ocean, requiring the development of floating platform technology. This study therefore evaluated a conceptual design for a spar-type concrete floater to support a 10 MW offshore wind turbine using precast segment prestressed concrete. This conceptual design was developed based on the economic advantages of using normal-strength concrete. The preliminary dynamic analysis considered the environmental conditions of the Sea of Japan. The stability and motion analyses considered irregular waves under operational, storm, and centenary conditions at the rated wind speed and cut-out wind speed of the wind turbine, as well as typhoon conditions. The geometry of the spar was determined using a coupled dynamic analysis to satisfy hydrostatic and hydrodynamic stabilities. A cross-spectral analysis of the rigid body was then performed to investigate the response motions of the proposed model under the input wind and wave conditions. The results show that the highest force occurred under the rated wind speed in storm conditions, serving as the dominant case for the investigated stress and strain distributions; although the typhoon conditions exhibited higher wind speeds, they corresponded to a relatively small thrust force owing to the action of the wind turbine control system. The concrete compressive stress was close to its compressive strength, with some parts exceeding the limit; thus, the use of high-strength concrete is preferable in future designs. This study thus successfully demonstrated an alternative concrete-to-steel floating spar, addressing the need for future mass production.
A Dynamical System for the Combined Performance of Innovative Biomimetic Thruster With Standard Propulsion System in Waves
Authors: Belibassakis Kostas A. , Filippas Evangelos S. 
Published: October 2022

Abstract
Dynamic wings located at the bow of the ship are investigated for wave energy extraction from ship motions, augmenting ship propulsion in waves and improving dynamic stability in waves. In the context of Seatech H2020 project (https://seatech2020.eu/) flapping-foil thrusters and Dual Fuel engine technologies are combined to provide a renewable-energy-based hybrid solution for the reduction of fuel consumption and operational cost. At first stage of analysis a simplified approximation is developed exploiting data from systematic series for modelling ship propulsion in waves including ship motions and foil loads. In the present work a novel dynamical system is developed and applied to the combined performance of innovative biomimetic thruster in waves. The proposed method exploits seakeeping analysis and unsteady foil theory for the estimation of the ship-foil dynamic system coefficients and loads. The ship steadily advances in the presence of waves that are modelled by parametric spectra corresponding to specific sea states. Appropriate time integration techniques are used for the evolution of the system responses and foil loads. To examine the feasibility of the proposed propulsion innovation in short-sea shipping industry the case of a ferry ship is examined. Numerical results indicate that significant ship performance can be obtained under realistic operating conditions. Thus, the present method can serve as a useful tool for assessment and the preliminary design of such systems extracting energy from sea waves for the augmentation of ship propulsion.