bluuebunny/crossref_metadata_2025_split huggingface dataset:
Challenges and Lessons Learnt From the Design, Fabrication and Installation of Rigid Tie-in Spools
Authors: Curti Gianbattista , Pavone Diego , Pirinu Gianluigi , Qin Jianjun 
Published: November 2019

Abstract
This paper is based on the experience made during the engineering, fabrication and installation of rigid spools used to tie-in production lines (10”) to manifolds, in 650m max water depth, on a project recently completed in West Africa.
The design of tie-in spools needs to accommodate the operation and environmental loads, and the installation, fabrication, metrology and, if applicable, also stack up tolerances.
This may require spools of large sizes/weights and complex geometries, with associated fabrication and installation costs that significantly contribute to the overall costs of a project.
This paper is focused on the process that was followed during the execution of the RFI (Risers Flowlines Installation) EPCI (Engineering Procurement Construction Installation) contract.
To find workable configurations of the spools, such not to compromise the execution of the project, was a major challenge.
Horizontal connection systems were to be used.
Configurations of the spools, initially designed to be in contact with the seabed (“seabed-supported” design) turned to be by far more complex than the geometries estimated before the start of the detailed engineering, and which had been the basis for laying down the execution schedule of the project.
Spools suspended between the horizontal hubs (“free-spanning” design) were finally chosen, which significantly simplified the fabrication and the installation.
A key driver of the design was to keep the interface loads within the maximum permissible values specified for the connectors.
The feedbacks from the fabrication and the installation are included in the paper, and the lessons learned are provided.
Alternative solutions — based on use of flexible pipes — are also discussed.
A Multi-Level Approach to the Prediction of the Added Resistance and Powering of Ships in Waves
Authors: Liu Shukui , Papanikolaou Apostolos , Feng Peiyuan , Fan Sheming 
Published: November 2019

Abstract
In this paper, we present a multi-level fidelity approach and associated computational tools for the prediction of the added resistance of various types of ships in waves. Employed methods include a fully empirical formula, a semi-empirical asymptotic formula, a potential flow, 3D panel method and a CFD code. Each of them requires a different level of detail for the hull form and this enables the application to various practical scenarios. The developed software tools are here validated against recently obtained model experiments data from MARIC. Developed tools are now integrated in the design software platform of MARIC and are used in the optimisation of ship design.
Second Order Wave Propagating Along VLFS
Authors: Iijima Kazuhiro , Ma Chong 
Published: November 2019

Abstract
This paper addresses the nonlinear deflection wave which propagates along a Very Large Floating Structure (VLFS). The whole VLFS is modeled as a one-dimensional beam afloat on the water surface in a vertical two-dimensional plane. It is assumed that the deflection of the wave propagating along the VLFS has a finite amplitude. The nonlinear wave propagating along the VLFS is investigated by extending the propagation theory of the linear wave along the VLFS. The kinetic and kinematic conditions at the boundary surface between the water and VLFS are considered rigorously up to the 2nd order. The 2nd order wave is obtained as a wave associated with the 1st order wave. The characteristics of the nonlinear wave along the VLFS are elucidated by the mathematical solution. The nonlinear wave along the VLFS has characteristics slightly different from the nonlinear free surface wave, known as Stokes wave. The positive peak of the wave along the VLFS is higher than the negative peak due to the nonlinearity in some frequency range while it is the opposite in the other frequency range. The amplitude of the 2nd order wave increases divergently at the frequency range between the two frequency regimes.
Lean Global Analysis of Marine Slender Structures With Machine Learning
Authors: Ribeiro Machado da Silva Vinicius , Santos Matheus Costa dos , Vignoles Mario Alfredo 
Published: November 2019

Abstract
The new age of oil and gas industry is being driven by cost effective solutions, aiming to provide cheaper, faster and better products/services. The industry 4.0 brings an opportunity to transform systems and processes to be more efficient, making use of digitalization and new technologies, including the use of artificial intelligence algorithms applied to engineering problems.
In Brazilian offshore fields, the operating conditions for flexible riser applications (deep-water, mean wave frequencies, floating units and corrosive fluids) make the metallic layer’s fatigue failure mode one of the drivers in its design. In a daily basis, nonlinear dynamic finite element analysis uses regular wave scatter diagrams as an equivalent way to model the wave elevation, avoiding the time consuming irregular wave representation. The analysis performed with regular waves are faster but carries conservatisms with it. In a deep-water scenario, the wave height and period ranges of the wave scatter diagram can be refined to improve the fatigue results obtained, leading to a considerable increase in the total amount of wave classes that need to be evaluated.
Great part of the wave classes has a very low participation in the total fatigue damage, spending an unnecessary time to analyze them. Helped by a robust design of simulation experiment (DoSE) and machine learning regressors, a lean representation of the regular wave scatter can be done, where some of them are simulated and the rest of the results can be accurately predicted.
This paper presents the application of supervised learners that are used to predict riser fatigue damage at different riser locations, given partial simulations of a regular wave scatter diagram. The techniques support the strategy to reduce the total amount of fatigue analysis required within a project design phase. The focus stays on the evaluation of the fatigue of metallic layers at two main critical regions, bend stiffener and touch down zone. Hidden patterns inside each scatter diagram are discovered, minimizing the total number of finite element analysis (FEA) required. The amount of the wave class reduction starts from 50% going up to 75%, maintaining a good level of accuracy on the predicted damage values.
Numerical Analysis of Nonlinear Wave Loads on an Offshore Wind Turbine Monopile
Authors: Feng Xingya , Willden Richard H. J. , Zhou Binzhen , Adcock Thomas A. A. 
Published: November 2019

Abstract
Highly nonlinear extreme waves are the major, often the dominant, environmental load on offshore wind turbines. The higher-order ‘ringing’ loads associated with the nonlinear waves can cause unexpected resonance of the monopile. Hydrodynamic analysis of these harmonic loads remains a challenge due to the difficulty in extracting the bound harmonics from the force spectrum in an extreme wave event. A phase manipulation approach (four-phase combination) has been recently demonstrated to be able to separate the higher harmonic components of the wave loads in tank tests. In this work, we employ a fully nonlinear potential flow based Numerical Wave Tank (NWT) to simulate the wave diffraction by a fixed vertical column. We present a detailed study of our checks on the numerical accuracy of our model. Phase control is implemented for the wavemaker to manipulate the phase of each wave component. Focused wave groups are generated to represent the incoming extreme waves. With the four-phase decomposition, the higher harmonics of the wave loads are shown to be clearly separated. Comparisons with the existing test results show fairly good agreement at higher harmonics. The structure of the harmonic forces and moments are analysed and we reconstruct the higher harmonics based on the Stokes expansion assumption using the linear force. In addition, the effects of wave steepness on the harmonic components are discussed.
Plug and Abandonment Environment in British Columbia
Authors: Bizhani Majid , Trudel Élizabeth , Frigaard Ian 
Published: November 2019

Abstract
British Columbia (BC) has a significant oil & gas industry, with approximately 25,000 wells drilled in the province since the early 1900s. In the past few decades, the industry has changed from a balanced oil & gas production to activities dominated by unconventional gas production which is recovered by hydraulic fracturing. Concurrently, since 2000 there has been a shift from isolated vertical wells to pad-drilled horizontal wells. The older well stock at end-of-life combines with horizontal production wells and fractured reservoirs, the consequence of which is a growing wave of abandonment in BC, building over the next decade. This paper reviews the existing data on BC wells, as it is relevant to well abandonment operations. This includes the well architectures, trajectories, depths, testing procedures, etc.
Emergency Disconnect and Storm Hang-Off: Reducing Risk for Drilling Risers in Harsh Environments
Authors: Gallagher Conor , Williams Dara 
Published: November 2019

Abstract
As the search for oil and gas moves to deeper waters and more challenging environments such as the Atlantic margin and South America, the operational risks and consequences of equipment failure increase significantly.
Industry guidelines, such as API RP 16Q [1] and ISO 13624-1 [2], define standard scenarios to include in a riser analysis that cover many of the various phases of installation and operation of drilling risers. These scenarios include assessments of the riser in both connected and disconnected modes such as storm hang-off. It is industry practice, as per API RP 16Q/ISO 13624-1, to assess these scenarios independently. Unplanned disconnect of the drilling riser in a storm involves transitioning through intermediate stages to get to the final hang-off configuration. While recoil analysis (assessment of riser disconnect phase) of the riser is commonly addressed, standard industry approaches fail to address other key intermediate and transitional phases of operation required to position the riser into the storm hang-off configuration.
This paper presents a study that highlights the importance of analyzing all pertinent stages of drilling riser disconnect and hang-off operations. The study demonstrates that these intermediate phases of operation are often limiting and, if not assessed adequately, have the potential to be catastrophic in harsh environments. A detailed set of revised riser analysis requirements are generated along with the development of a comprehensive harsh environment WSOG (Well Specific Operating Guideline) that optimizes operational performance and improves safety for harsh environment drilling. These revised analysis guidelines and associated modelling that are necessary for harsh environment locations represent a level of pre-drilling assessment that is ahead of that typically undertaken by the industry today.
Experimental and Numerical Investigation of Gas-Yield Power-Law Fluids in a Horizontal Pipe
Authors: Ihmoudah Abdalsalam , Awad Mohamed M. , Rahman Mohammad Azizur , Butt Stephen D. 
Published: November 2019

Abstract
Two-phase flow of gas/yield power-law (YPL) fluids in pipes can be found in a wide range of practical and industrial applications. To improve the understanding of the effects of rheological parameters of non-Newtonian liquids in a two-phase model, experimental and Computational Fluid Dynamics (CFD) investigations of gas/yield power-law fluids in a horizontal pipe were carried out. Two Xanthan gum (XG) solutions at concentrations of (0.05% and 0.10% by weight) were used as the working liquids. The experiments were conducted in a flow loop in a 65-m open-cycle system. The horizontal test section had a diameter of 3 inches (76.2 mm). The transient calculations were conducted using a Volume of Fluid (VOF) model in ANSYS Fluent version 17.2. Slug flow characteristics were recorded and observed by a high-speed digital camera in different operating conditions. The slug velocity and slug frequency were investigated experimentally and numerically, and a comparison of results with empirical relationships found in the literature was performed. We observed that the rheological properties of non-Newtonian phase influence the flow behavior in two-phase flow with increasing XG concentrations. The results of the empirical correlation to measure the slug frequency of a gas/non-Newtonian with considered the rheology of the shear-thinning behaver gave acceptable agreement with numerical measurements at low polymer concentration. The effect of liquid superficial velocity on slug translational velocity at low gas superficial velocity was relatively high.
Coupled Numerical Analysis of a Concept TLB Type Floating Offshore Wind Turbine
Authors: Ramzanpoor Iman , Nuernberg Martin , Tao Longbin 
Published: November 2019

Abstract
The main drivers for the continued decarbonisation of the global energy market are renewable energy sources. Moreover, the leading technological solutions to achieve this are offshore wind turbines. As installed capacity has been increasing rapidly and shallow water near shore sites are exhausted, projects will need to be developed further from shore and often in deeper waters, which will pose greater technical challenges and constrain efforts to reduce costs.
Current floating platform solutions such as the spar and semi-submersible rely on large amounts of ballast and complex structural designs with active stabilisation systems for stability of the floating offshore wind turbine platform (FOWT).
The primary focus of this study is to present a design concept and mooring arrangement for an alternative floating platform solution that places emphasis on the mooring system to achieve stability for a FOWT. The tension leg buoy (TLB) is designed to support future 10MW offshore wind turbine generators.
This paper presents the numerical methodology used for a coupled hydro-elastic analysis of the floater and mooring system under combined wind, wave and current effects.
A concept TLB design is presented and its platform motion and mooring line tension characteristics are analysed for a three-hour time domain simulation representing operating and survival conditions in the northern North Sea with water depths of 110 metres. The importance of wave drift forces and the other non-linear excitation forces in the concept design stage are evaluated by comparing the motion and tension responses of three different numerical simulation cases with increasing numerical complexity.
The preliminary TLB system design demonstrated satisfactory motion response for the operation of a FOWT and survival in a 100-year storm condition. The results show that accounting for second-order effect is vital in terms of having a clear understanding of the full behaviour of the system and the detailed response characteristics in operational and survival conditions. Extreme loads are significantly reduced when accounting for the second-order effects. This can be a key aspect to not overdesign the system and consequently achieve significant cost savings.
Experimental and Numerical Investigation on Planar Motion Responses of a Single Point Moored Shuttle Tanker in Waves
Authors: He Ning , Zhang Cheng , Kang Zhuang , Kang Youwei , Wang Changhong 
Published: November 2019

Abstract
In order to ensure the safety of the single point moored shuttle tanker in waves, the numerical model of a shuttle tanker moored with a fixed point was established on the basis of radiation / diffraction theory and pressure integral method in this paper, which was further checked by a series of model tests. Then the plane motion characteristics of the tanker like fishtailing oscillation were analyzed by applying the combined approach of numerical simulation and model test. On this basis, the effects of wave and ballast conditions as well as mooring line length and stiffness on the plane motion of the single point moored tanker were investigated by means of model test. Overall, the research can provide a reference for the design and safety assessment of deep-water offloading system, and give the technical support for the engineering development of deep-water oil and gas projects.
A Closed-Form SIF Determination and Fatigue Life Investigation on Ship Construction Model
Authors: Lou Benqiang 
Published: November 2019

Abstract
Stress intensity factors (SIFs) are important parameters in brittle fracture assessment of marine notched components; in respecting of previous researches, it has found that there are several ways for SIF solutions. Following outline of LEFM based fatigue analysis; the paper has proposed a closed-form SIF solution as an alternative way for ship structural details prediction. It has shown that the stress intensity factors (SIFs) can be solved revealing the effect of the geometric parameters. Numerical tool has offered an evaluation as convergence behavior of relative SIF results between CCT (central crack) and DENT (double edge notch). Then the proposed methodology is applied onto the construction similar to HHI #1 and #2 specimens. It has be concluded in results that the SIFs and fatigue lives by the proposed method have good agreement with those by FEA calculations, furthermore, these key parameters can be expressed in formula format. For real engineering application, the main advantage of the proposed method will be useful for fatigue prediction rapidly and conveniently.
Global Performance Analysis of Deep Draft Semi-Submersible Designed for Standard GOM Application
Authors: Yuck R. H. , Kang D. H. , Kim E. S. , Kim M. S. , Kim T. M. , Kim H. J. , Lee D. Y. , Park Y. C. 
Published: November 2019

Abstract
A deep draft semi-submersible hull has been developed by SHI (Samsung Heavy Industries) and Williams as a standardization concept which can support the topside structures up to the facility weight for the specific level of daily oil production in GOM (Gulf of Mexico). The designed hull has the optimized dimensions of pontoon and column which secure the sufficient level of GM for the stability and ballast capacity for coping with the weight change of topside structures. The hull form also has the good global motion in waves to be able to use the SCR (Steel Catenary Riser) as a deep draft semi-submersible concept.
Two hull forms are designed to have 4 columns with two different cross sections and the conventional ring pontoon. The compartmentation and basic hydrodynamic analysis are performed at the hull sizing stage to achieve the sufficient stability and the motion performance as well. The mooring systems are also designed for two different water depths of 1000m and 3000m as a standard design concept of hull including mooring lines.
To verify the feasibility of the proposed hull concept with regard to the hydrostatic/hydrodynamic characteristics and mooring line design, the numerical global performance analyses are carried out. Hydrostatic stability is investigated for intact and damage condition of operational loading condition and the proper tank compartments are verified under the given topside weight and the environment condition in GOM.
The global motion is validated for all the possible combinations of wave, wind, current for a site in central GOM. Through the frequency-domain analysis and quasi-static time-domain analysis as well, the essential items such as the maximum offset, mooring line tension/fatigue, air-gap and the extreme acceleration at topside are examined and confirms that the certain design criteria of Semi FPU (Floating Production Unit) operation are satisfied. The possibility of SCR usage is also investigated with the fully coupled time domain analysis using the preliminary design of risers and confirms that the designed hull form has the suitable hydrodynamic characteristics to permit the minimum motion performance for SCR in the sense of extreme load and fatigue life.
Fatigue Life Evaluation for the Repair Methods of High Pressure Gas Pipeline
Authors: Kim Woo Sik 
Published: November 2019

Abstract
High pressure gas pipeline must maintain structural integrity during the design life. To do this, periodic pipeline inspections are carried out, and fitness-for-service assessments are performed on defects found by inspection. Defects that do not meet the evaluation criteria should be repaired and replaced to ensure the integrity of the pipeline structure at the same level as before the defect. High pressure gas pipeline repair method is applied to repair of composite reinforced sleeve and repair of steel sleeve. Although there have been many studies on the short-term structural integrity evaluation of rupture pressure in these repair methods, there is insufficient research to verify whether the long-term operation of the repair pipeline maintains the long-term structural integrity of the repaired pipe.
In this study, an optimum process to improve structural integrity was established by investigating effect of the process variables on fatigue lifetime of steel-sleeve repair welds in buried gas pipeline. Residual stresses in the repair welds were derived through sequentially-coupled temperature-stress analysis using ABAQUS, which is a commercial finite element analysis program. In addition, variations of operating stresses were derived by finite element linear elastic stress analysis. Fatigue lifetimes of the steel-sleeve repair welds were evaluated by substituting the derived weld residual stresses and operating stress variations into the structural stress/fracture mechanics approach as input. Appling this method confirms long-term integrity over 200 years in terms of fatigue the abstract here in italics.
Dynamic Response of Monopile Wind Turbine in Large Waves
Authors: Seng Sopheak , Monroy Charles , Malenica Šime 
Published: November 2019

Abstract
A strongly coupled hydroelastic code based on OpenFOAM has been applied to evaluate dynamic responses of a bottom mounted monopile in regular waves at 3 different wave periods and 3 wave steepness. The code uses a free surface RANSE solver to determine accurately the hydrodynamic loads and a modal superposition approach to describe the dynamic structural responses. Numerical simulations include both rigid and elastic monopiles and the results are evaluated against publicly available model test experiments. The discussion includes a quality control of the numerically simulated incident wave fields, mesh dependency and the quality of the numerically predicted and experimentally measured third harmonic of the inline forces.