bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geotechnical Study to Design a GIS Platform Subjected to Pipeline in Permafrost Area
Authors: Kim Sewon , Kim YoungSeok 
Published: December 2020

Abstract
Construction in the extreme cold regions becomes one of the important businesses in the world. Geophysical surveys, which are effective in providing consecutive ground information, have been widely applied to the civil engineering and environmental sectors. The permafrost area covers about 14 percent of the world’s land area and the global construction market for such area is rapidly expanding. Where developed countries have already recognized the need for research of the coldest places and therefore have invested heavily in technology development, the non-arctic countries are still developing and related research has rarely been performed. The purpose of this study is to design the GIS (Geophysics Information System) platform for a construction environment with a 2,000 km-class pipeline (overland) operated under the permafrost temperature conditions (−40°C∼+20°C). The GIS platform when subjected to geotechnical engineering provides an understanding of the frozen ground and information about the geo-environment of the extreme cold regions. This paper shows the characteristics and procedures of Environmental Impact Assessment (EIA) for developing Arctic resources, and reviews how to construct a system for the systematic management of the necessary information to consider building the GIS platform. In addition, this study introduces the GIS algorithm to build the route for the pipeline path, and factors which should be considered first are safety, environment, economic feasibility and technical feasibility.
Influence of Mean Tension on Mooring Line Fatigue Life
Authors: Lone Erling N. , Leira Bernt J. , Sauder Thomas , Aksnes Vegard , Gabrielsen Øystein , Larsen Kjell 
Published: December 2020

Abstract
Studies published in recent years have documented a significant mean load effect on fatigue capacity for offshore mooring chain, and show that a reduction of the mean load gives an increase in fatigue life. However, current S-N design curves are based on fatigue tests performed at a mean load of 20% of minimum breaking load (MBL), which is well above the typical mean loads for most mooring systems.
This paper investigates the mean loads experienced during fatigue damage accumulation for the mooring system of a typical production semi-submersible, operating in Norwegian Sea conditions. The study is based on numerical, time-domain simulations, using environmental conditions defined from a series of hindcast data. A parameterized S-N design curve suggested by Fernández et al. (2019), incorporating a Smith-Watson-Topper mean stress correction model, is applied for fatigue damage calculation and compared to results for the S-N design curve prescribed by current standards.
For the semi-submersible unit considered there is negligible difference in basing the correction on 3-hour mean load compared to the mean load of individual stress cycles, due to small low frequency tension variations. On this basis, a single correction factor is proposed to allow for mean load correction based on results available from a standard fatigue analysis.
Experiment-Scale Multi-Vessel Dynamic Positioning System for the Twin-Lift Decommissioning Operation
Authors: Fu Zhenqiu , Li Wei , Sun Hao , Yuan Meng , Li Xin , Cai Liancai , Wang Andy , Guo Xiaoxian , Wei Handi , Tian Xinliang 
Published: December 2020

Abstract
In general, the lifetime of the offshore oil and gas platform is about 20–30 years, and a large number of oil and gas platforms is approaching the end of their service. So, how to decommission these oil and gas platforms safely and cleanly becomes an urgent problem for the oil and gas industry and related organizations. And the costs for decommissioning equipment and services are expected to be as low as possible. It is important to develop the innovative removal techniques to reduce the overall cost of decommissioning. In this paper, we propose a new concept to remove large and heavy structures with a single lift, utilizing three semi-submerged vessels. The main process of the twin-lift solution for decommissioning includes two semi-submerged vessels lifting the topside together, and then carrying the topside to the third semi-submerged vessel. This method is simple in principle and does not require the manufacture of new special vessels, only needs to make simple modifications to existing semi-submerged vessels. It requires high positioning accuracy especially under environmental disturbances to ensure the safety of transportation. To ensure efficiency and safety, we develop a dynamic positioning (DP) system and perform a wave tank test for such a twin-lift decommissioning solution. Some aspects of an experimental facility set-up for scaled model test with dynamic positioning system are described. It includes the topology of the experiment and details of the deck mating, DP and monitoring system.
Optimization-Based Multi-Attribute Decision Making for the 7th Generation Semi-Submersible Drilling Unit
Authors: Meng Xun , Tang Pin , Li Dejiang , Xu Yu , Fu Qiang 
Published: December 2020

Abstract
The 7th generation semi-submersible drilling units (CSDU) are characteristic of deeper drilling depth, site locations and higher operational efficiency, compared with the last generation ones. Given the enormous live loads change and increasing trend of main size dimensions, considerable optimization should be deployed to achieve a balance of economy, safety and good work performance. Trial calculation and definite assessment to check whether alternative schemes meet the requirements turns out to be ineffective, for the case by case study of hydrodynamic and structure strength analysis is time consuming. In the paper, an integrated optimal design model is formulated by merging multi-objective optimization and multi-attribute decision making into one. A predesigned parametric Finite Element Analysis (FEA) structural model of CSDU is developed and validated and then coupled with detailed hydrodynamic analysis. Three mutually conflicting design objectives are arrived by hydrodynamic solutions. They are stability, hydrodynamic performance and steel consumption, which are screened to obtain Pareto optimality. The Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) is applied to incorporate these optimal attributes into decision-making process, considering all criteria in terms of quantitative stability, hydrodynamic performance and qualitative economy. The objective entropy coefficient measuring the importance of different attributes is introduced into weight selection for the purpose of avoiding non-determinacy and optional judgements. The optimal solutions are further verified with main dimensions of CSDUs in service and also could give predictive suggestion for the new CSDUs. The study provides a more objective way of benchmarking different structural schemes of CSDU by considering multiple criteria simultaneously. It is demonstrated that the proposed structural optimization model is capable of effectively and accurately determining the optimal design of CSDU.
A Modelling System for Power Consumption of Marine Traffic
Authors: Tvete Hans Anton , Guo Bingjie , Liang Qin , Brinks Hendrik 
Published: December 2020

Abstract
The International Maritime Organization (IMO) has enforced stricter limit on the Greenhouse Gas (GHG) emission due to environment and climate concern. The measures to reduce GHG emissions from shipping can be divided into two groups. The first one is to improve ship energy efficiency through new technology, optimized operation and logistics, and the second one is to introduce alternative fuels with lower carbon intensity. However, the effectiveness and applicability of any measure depend on ship type, ship size, operation type, operation environment (wind and wave condition), as well as the cost of the measure. It is necessary to evaluate new measures in real shipping scenario. Modeling of ship fuel consumption and emission are fundamental input to evaluate the impacts of shipping on the environment and climate, and to evaluate new measures for reducing GHG emission. A modeling system is developed to estimate ship fuel consumption and emission, based on ship hydrodynamical models, information from Automatic Identification System (AIS), the IHS Fairplay database and metocean data. The modeling system aims to cover most of the ship types equipped with AIS transponders, and it will provide different hydrodynamical models to calculate fuel consumption based on the available ship information. In the paper, the modeling system will be described, and the power consumption from the modeling system are compared with the measurement data on one container ship. The comparison shows that the power consumption predicted with the modeling system agrees with measurement data well. The effects of weather data and measured speed on predicted power consumption are also analyzed.
An Analytical Method for Calculating Hydrostatics for Jacket Structures
Authors: Last Irene , Krüger Stefan 
Published: December 2020

Abstract
In response to the continuing importance of offshore structures a framework for the simulation of offshore platforms is implemented in the open software environment E4. The non-commercial suite contains various methods for the ship design so that the newly developed procedures benefit from the existing knowledge. Jacket structures are installed as fixed platforms or compliant towers and play a significant role in the offshore exploitation. They are made out of hundreds of tubular steel members and each of the cylinders or cones can be seen as a simple body compared to ships. Besides the dynamic behaviour and fatigue analysis, the examination of the installation procedure especially the launch operation is of high interest. This article presents an analytical approach for the hydrostatic calculations of partially submerged cylinders. Hydrostatic forces on jacket structures are calculated by superimposing single cylinders and the results of the newly developed method are compared with a commercial simulation software. The aim is to speed up the computation time in comparison to numerical methods which is a significant advantage in the early design stage. The presented method will be the foundation for the simulation of jacket launching manoeuvres in time domain.
Scale Effects in Heave Plates: PIV Investigation
Authors: Anglada-Revenga Elena , Bezunartea-Barrio Ana , Maron-Loureiro Adolfo , Molinelli-Fernandez Enrique , Oria-Escudero Julio , Saavedra-Ynocente Leandro , Soriano-Gomez Cristina , Duque-Campayo Daniel , Gomez-Goni Jesus , Souto-Iglesias Antonio 
Published: December 2020

Abstract
Bezunartea et al. Scale Effects on Heave Plates for Semi-Submersible Floating Offshore Wind Turbines: Case Study With a Solid Plain Plate (Journal of Offshore Mechanics and Arctic Engineering, Vol. 11, pp 1–14, 2019) studied scale effects on the hydrodynamics of heave plates by conducting model scale experimental tests. Three models with different scales of one leg of the HiPRWind platform, equipped with a plain heave plate, were built and tested with forced harmonic heave motions. They showed that the influence of the model scale on the coefficients is clearly weaker than that of the heave motion amplitude. Among the pending tasks in that work was to conduct velocity field measurements of the flow with Particle Image Velocimetry techniques (PIV). This paper discusses some of the results of such measurements, carried out forcing vertical harmonic motions. In these measurements, it is assessed how significant scale effects are also in the local kinematics of the flow, thus complementing the global ones carried out in the referred work. From velocity and vorticity graphs, the flows show great similarities across the three scales, consistent with the ones found in the prequel paper. A metric has been developed whose outcomes are aligned with these results but further work is necessary to develop key indicators to compare flow fields from PIV across different scales.
Numerical Investigation of Heaving Hydrodynamic Behavior of a Single Cylinder and a Dual Coaxial-Cylinder System Using CFD
Authors: Zhi Pengfei , Zhang Xinshu , Chen Ke , Yeung Ronald W. 
Published: December 2020

Abstract
In this paper, we apply a CFD computer code to study the hydrodynamic behavior of a stand-alone cylinder and a dual coaxial-cylinder system (DCCS) via free-decay motion tests. The geometric proportions of a stand-alone cylinder and the inner and outer cylinder of the DCCS are chosen to be the same as those in [1] and [2], respectively, as ocean wave-energy converter (WEC) devices. Overset mesh based on the commercial code ‘Star-CCM+ 11’ is used to simulate the free-decay motion of the two systems. Five parameters chosen for the CFD implementation are: turbulence model, initial displacement, time step, number of prism layers and mesh size. Results obtained from using different values of these parameters are compared so as to confirm the validity of choices made. The hydrodynamic performance of the stand-alone cylinder and outer cylinder in the DCCS are compared with the experimental results to assess and validate the CFD models. In addition, the heave hydrodynamic coefficients, namely, the added mass and total damping, and ‘resonance’ frequency of the stand-alone cylinder and those of the inner cylinder of the DCCS, with the outer cylinder being fixed, are obtained by using the CFD procedure. The hydrodynamic coefficients of another stand-alone cylinder with the same dimensions as the inner cylinder of the dual-coaxial cylinder are also obtained by simulations. The vorticity-contour plots for the stand-alone cylinder and the outer cylinder in the DCCS in free-decay motion are presented and analyzed. Finally, the results of the three cases are compared to examine the effect of the outer cylinder on the heave hydrodynamic coefficients of the inner cylinder.
Tidal Turbine Load Variability in Following and Opposing Irregular Wave Conditions
Authors: Draycott Samuel , Steynor Jeffrey , Nambiar Anup , Sellar Brian , Venugopal Vengatesan 
Published: December 2020

Abstract
Waves induce large loads on tidal turbines, yet the effect of irregular waves, particularly those which oppose the current direction, have received little attention. Here we experimentally assess the loading resulting from 24 irregular combined wave-current cases, statistically presenting the load variability acting on a 1:15 scale tidal turbine. Comparisons are made between following and opposing conditions of equivalent wave parameters, and the effect of varying frequency and amplitude is assessed. Example load distributions are also shown, along with streamwise variation of significant wave height around the turbine. It is concluded that both opposing and following conditions must be assessed to effectively de-risk tidal turbine design: large differences are observed both in terms of the nature & magnitude of the resulting loads and the wave interaction with the surrounding flow field.
Displacement Efficiency in Eccentric Annuli
Authors: Lund Bjørnar , Ytrehus Jan David , Taghipour Ali , Saasen Arild 
Published: December 2020

Abstract
A successful primary cementing job requires an efficient fluid displacement process in order to place cement in the annulus between a casing or liner and the formation around the wellbore. This operation is a critical part of the well construction and due to the hardening properties of cement there will be no second chance with this operation. Once hardened, the cement should provide zonal isolation and pressure containment and should do so through the lifetime of the well. Furthermore, the cement shall anchor and support the casing string and protect it against corrosion due to formation fluids. A good quality cement job is important both from an environmental and from an economical perspective.
In order to improve recommended cementing practices, and thus also the quality of cementing process, it is necessary to develop cementing simulation software for proper engineering. Detailed data on the displacement efficiency from practical operations are difficult or impossible to obtain. Furthermore, field operations do not allow for a systematic change in fluid properties. To be able to validate the engineering tools it is therefore necessary to perform laboratory measurements with fluids with relevant properties. It is also important to perform these experiments in laboratory equipment of sufficient diameter dimensions to facilitate scale up of the results.
The purpose of the present article is to give an overview of cement displacement experiments which were conducted using a large diameter annular flow loop using model fluids with relevant rheological properties. While some results from these experiments have been presented in previous articles, this article is intended to give an overview of all the experiments, including the setup and experimental approach, and provides in more detail results not presented previously. In particular we show results from video recordings which confirm previous conclusions based on conductivity measurements.
It is found that eccentricity affects the displacement physics significantly. In washout sections the effects of eccentricity are different and generally smaller since the eccentricity is also reduced. Drill string rotation improves displacement efficiency in all tested cases both within and outside the washout cavity.
Since the amount of publicly available experimental data of this type is very limited, the detailed information presented here should be of great interest and relevance for the development and validation of industrial cementing simulation software.
Analysing Supply Chain Phases for Design of Effective Autonomous Ship Technology in New Transport System Solutions
Authors: Wennersberg Lars Andreas Lien , Nordahl Håvard , Rødseth Ørnulf Jan , Bolbot Victor , Theotokatos Gerasimos 
Published: December 2020

Abstract
Maritime autonomous surface ships provide new capabilities for transport systems design, and by that the potential to dramatically change ship logistics. Advantages of autonomous ships include operational flexibility with more and smaller ships, combined with new ship hull and superstructure designs, allowing more cargo to be transported at lower cost and reduced emissions. It is also easier to operate smaller ships with alternative energy sources such as batteries, and by that further reducing the emissions. However, the investment cost of an autonomous ship system is perceived to be higher compared with conventional ships. Combined with limited operational experience, this creates a challenging threshold for launching new projects.
The purpose of this work is to lower this threshold by providing a better understanding for the analysis tools employed in new transport systems design. Structured analysis of the supply chain phases and tasks enables the involved stakeholders to evaluate the cost and benefits associated with the increased automation in a specific phase of the transport system. This will additionally form a basis for developing business models and priorities for gradual introduction of key enabling technologies through retrofitting of conventional ships or designing and building new smart ships.
A scalable method for the systematic supply chain analysis of waterborne transport systems is introduced. The method is developed through a mapping and analysis of one inland waterways use-case and one short sea shipping use-case, and used as a basis for the systematic identification of all the supply chain phases and all tasks carried out in each phase of the transport system. A design process for autonomous ship systems consisting of the supply chain analysis, the task distribution and the cost benefit analysis is also presented. The effectiveness of this process in the design and incorporation of autonomous ship technologies in new transport systems solutions is demonstrated.
Removal of Magnetic Contamination in Drilling Fluids: Effect on Directional Drilling
Authors: Saasen Arild , Poedjono Benny , Ånesbug Geir Olav , Zachman Nicholas 
Published: December 2020

Abstract
Magnetic debris in a drilling fluid have a significant influence on the ability of the drilling fluid to maintain its function. Down hole logging can suffer from poor signal to noise ratios. Directional drilling in areas close to the magnetic North Pole, such as in the Barents Sea, Northern Canada or Russia can suffer because of magnetic contamination in the drilling fluid. Magnetic particles in the drilling fluid introduce additional errors to the magnetic surveying compared to those normally included in the ellipsoid of uncertainty calculation.
On many offshore drilling rigs, there is mounted ditch magnets to remove metallic swarf from the drilling fluid. These magnets normally only remove the coarser swarf. In this project, we use a combination of strong magnets and flow directors to significantly improve the performance of the ditch magnets. This combination, together with proper routines for cleaning the ditch magnets, significantly helps to clean the drilling fluid. Through the combined use of flow directors and ditch magnets, it was possible to extract more than five times as much magnetic contamination from the drilling fluid as normal compared with other proper ditch magnet systems. This is verified by comparing the ditch magnet efficiencies from two drilling rigs drilling ERD wells in the North Sea area.
In the paper, it is discussed how the accuracy of directional drilling and well position effected by various interferences can be improved by the use of a drilling fluid with minimal effect to the MWD measurement.
Dynamic Analysis on Critical Responses of Pipeline and Cable During Pipeline End Termination Installation
Authors: Han Duanfeng , Huang Kuo , Zan Yingfei , Yuan Lihao , Wu Zhaohui 
Published: December 2020

Abstract
In order to figure out the dynamic characteristics of the pipeline and cable during pipeline end termination (PLET) installation based on S-laying, numerical simulation is carried out based on a practical operation project performed at Liwan oil and gas fields in the South China Sea. Four scenarios are selected from the PLET installation process in sequence for simulation. Critical responses of the pipeline and the cable in different scenarios of the operation are analyzed in this paper with a coupled model using RIFLEX module of SIMA software. Both the pipeline and the cable are modeled by the finite element method, and the pipelaying vessel is controlled by a dynamic positioning system. The simulation results are validated by the commonly used OrcaFlex software. The critical responses analyzed include static configuration, time-domain variation of axial tension at the top of the cable and bending moment variation near the touchdown point (TDP) of the pipeline. Furthermore, the time-domain variation of the tension at the top of the cable under different wave and current directions are also compared and analyzed, in order to study the effect of sea environment on the pipeline and cable during PLET installation operation. The results show that the responses of pipeline and cable vary in different operation scenarios, and the sea environment has remarkable effect on the pipeline and cable. The study in this paper is of value to the design of PLET installation based on pipelaying and can help predict the response of pipeline and cable during the operation.