bluuebunny/crossref_metadata_2025_split huggingface dataset:
Out-of-Plane Bending (OPB) Test of Large Diameter Mooring Chains
Authors: Barros P. , Carlberg E. , Høgsæt I. S. , Karimi M. R. , Braun J. , Gooijer E. , Vargas P. 
Published: December 2020

Abstract
Chevron Corporation and Bluewater Energy Services (BES) performed a chain out-of-plane bending (OPB) test, called OPB MAX hereafter, at DNV GL’s laboratory in Høvik-Norway. The test was performed to study the OPB phenomenon for a chain diameter which was larger than the maximum diameter tested by the OPB JIP. The goal was to understand chain OPB physics for such a large diameter, measure interlink stiffness and maximum sliding moments and validate BES’ in-house finite element model. The current study is a collaboration between all involved parties and the results will be presented in three papers. The first paper summarizes the test setup and instrumentation. The second paper describes the test results, compares them with the OPB JIP estimations and tries to describe the chain OPB physics. The third and the last paper presents the FEA results performed by BES’ in-house finite element model. This paper is the first of the three and focuses on the test setup and instrumentation.
The testing machine has been developed by DNV GL and is capable of applying tensions up to 350 t and interlink rotations in the range of ±3 degrees. Two 7-link chain specimens of R4 and R4s grades, both with the nominal diameter of 168 mm were tested at five tension levels from 150, to 350 t. Testing was performed in both wet and dry conditions. Twenty strain gauges were used to measure 3 OPB and 2 IPB moments at 5 mid-link positions. Twelve strain gauge rosettes were used on 3 links to evaluate SCF’s on the OPB hotspots. Seven inclinometers were used to monitor link rotations. DNV GL utilized a digital image processing tool to capture relative movements of chain links and developed a specific data processing tool to calculate the interlink stiffness, perform statistical analysis and provide several levels of data evaluation and comparison between the tests.
The paper will provide a description of the test matrix and test objectives are given with the background of the previously performed OPB tests. Next a detailed description of the test rig is presented including the utilized instrumentation. Finally, an explanation of the implemented real-time test monitoring and the performed post-processing on the readings, in line with the test objectives is mentioned. The initial test results are briefly provided at the end.
Do Vessels Remain Within Their Operational Limitations in Ice? Analyzing the Risks of Vessels Operating in the Kara Sea Region Using POLARIS
Authors: Panchi Nabil , Kim Ekaterina , Xu Sheng 
Published: December 2020

Abstract
This study investigates whether the vessels remain within their operational limitations in ice using the risk index calculated based on the Polar Operational Limitations Assessment Risk Indexing System (POLARIS) — an acceptable methodology for the assessment of operational limitations in ice infested waters, referenced in the Polar Code of the International Maritime Organization (IMO). The speeds and positions of the vessels in the Kara Sea region were analyzed from January through April for 2017–2019 using the navigational data provided by the Northern Sea Route Administration. For each vessel, except for the icebreakers, the risk index based on POLARIS was calculated using the open-access ice information that was provided by the Arctic and Antarctic Research Institute in Russia. The variation of risk index was analyzed with respect to various parameters such as the ice-class of the vessel, the reported operating speed of the vessel, and the built year of the vessel. Furthermore, we explored the limitations of the risk assessment system as well as the limitations of the available ice information and its implications on the risk assessment system. This paper reports preliminary results from the analysis.
Development of a Simulation Environment for Hybrid Propulsion Drive Trains: Utilization of a Holistic Approach to Predict the Dynamic Behavior in the Early Design Stage
Authors: Jannsen Leif-Erik 
Published: December 2020

Abstract
This paper covers the generic procedure for the creation and usage of a complete system simulation for propulsion systems of ships with focus on complex hybrid systems. Due to the large number of available components and challenging operational profiles, there is no longer a single best solution, especially in specialized shipbuilding. On top of that even minor changes in the propulsion system can have a substantial impact on plant performance and vessel behavior. Thus, the early design stage is crucial. The design procedure usually incorporates the selection and dimensioning of available components and concepts. Once this has been done, the dynamic behavior can be analyzed using the developed system simulation environment. With the knowledge gained the needed alterations in the concept can be identified and implemented in the subsequent design iteration circle. Based on the example of an offshore anchor handling vessel, the integration potential of a hybrid propulsion system is examined and evaluated according to the aforementioned procedure. The applied tool is a system simulation environment developed in the Department of Marine Engineering, consisting of a distributed co-simulation of the existing ship design environment E4 and Matlab® Simulink®.
Fretting Fatigue Design of Subsea Connectors: Matching Results Between Pairs of Tests
Authors: Blades L. E. , Hills D. A. , Wormsen A. , Macdonald K. A. 
Published: December 2020

Abstract
The upper end of a subsea wellhead system has an external wellhead hub profile. The standardised H4 profile is widely used. A wellhead connector is latched on the wellhead profile by use of locking devices with a matching internal profile (e.g. clamps, sections and dogs). Large contact loads are set up when latching the connector on this wellhead profile with the objective of withstanding internal pressure and wave-induced cyclic bending loads while avoiding hub separation. Fretting fatigue is an additional phenomenon to that of conventional high-cycle fatigue (fatigue crack initiation from the wellhead profile grooves) that should be addressed as part of the design documentation.
Methods have been developed to match the key parameters in this contact to a laboratory test. Here, the strength of the effect of each of the matched loading parameters was assessed. Specimens were manufactured from wellhead housing and locking dog steels. The fretting fatigue tests were performed using loads representative of a preloaded connector. Validation of these methods would enable the use of fretting fatigue data determined for one geometry to be used in fatigue life prediction of another.
MIL and MIRO Diagrams for Risk-Based Positioning of Drilling Rigs With Dynamic Positioning System
Authors: Maturana Marcos Coelho , Souza Victor Rafael , Mesa Valentina Clavijo , Martins Marcelo Ramos , Oshiro Anderson Takehiro , Schleder Adriana Miralles 
Published: December 2020

Abstract
Currently, most offshore oil exploration operations are performed by Dynamically Positioned (DP) units; in Brazil, the use of these units is traditional in drilling operations (DP drilling rigs). The advent of DP systems, which allow the vessel to maintain a certain position without the need for anchor lines, has brought great flexibility to the oil field; however, usually in drilling areas, there are a large number of operations being performed simultaneously and subject to weather conditions and a failure of the DP system may cause these vessels to drift, which may occasionally result in a collision with other field equipment or vessels, causing material, personal and environmental damage.
In this context, it is necessary to analyze what would be the best positioning points for these units according to the configuration of potential obstacles present in the area (such as risers, anchor systems and floating production systems), the characteristics of the DP unit and the expected environmental conditions. It is vital to know the risk of collision associated with the positioning of these units. The risk of collision will depend mainly on the meteo-oceanographic variables of the operating region, the hydrodynamic characteristics of the unit, the DP system reliability and its repair time, and the distribution of obstacles in the area.
The objective of the ongoing research is the development of a methodology to define the risk associated with the positioning of the DP units, through a statistical method and a validated drift mathematical model under the influence of environmental agents. The proposed methodology allows us to demonstrate compliance with a widely accepted RAC (Risk Acceptance Criterion). The developed methodology proposes the use of two instruments: Location Iso-Probability Maps (MIL) and Operational Iso-Risk Maps (MIRO), to synthesize the information to the decision making about the operation of the DP units at a specific location, considering the overall collision risk (at MIRO) and the probability of the rig being at a specific location (at MIL).
Decompression Analysis of Multi-Layered Barrier Flexible Pipes Under Catenary Configuration
Authors: Gonzalez Gabriel Mattos , de Sousa José Renato Mendes 
Published: December 2020

Abstract
Periodic shutdowns, which decompress service pressure down to atmospheric pressure, are common in offshore flexible pipe systems. In high pressure and high temperature operations, the use of multi-layer barrier flexible pipes is also common. A multi-layer barrier usually combines inner sacrificial and pressure sheaths and, under certain circumstances, the annular gap between these sheaths is filled with fluid. When this fluid is trapped in this gap, which may occur due to a rapid decompression on shutdown operations or an accidental opening of an upstream valve, the flexible pipe system may fail. The trapped fluid tends to be released slower than the fluid that transiently flows under the bore thus generating a differential pressure, which is function of the rate of decompression, and may induce the collapse of the inner carcass. Therefore, the assessment of the magnitude of this differential pressure is crucial to prevent safe decompression rates. This article describes a numerical model, based on finite differences, to predict the differential pressure magnitude for risers in catenary configurations. The model is developed considering fundamental fluid dynamics principles, such as the conservation equations, for a one-dimensional geometry. The results are compared to previously published literature data for a given 4” flexible pipes under two different geometric configurations (horizontal and catenary). The results from the proposed model agreed quite well with those from a previous proposed approach for horizontal configurations, while the catenary configuration analyses evidenced the impact of the gravity parcel on the differential pressure between the pressure sheath and the bore of the pipe.
Dynamic Analysis of a Progressing Cavity Pump System Using Bond Graphs
Authors: De Moura Jeronimo , Rideout Geoff , Butt Stephen D. 
Published: December 2020

Abstract
One commonly used pump in the petroleum sector is the Progressing Cavity Pump (PCP). The PCP is a type of positive displacement pump that is used as an artificial lifting system which consists of a helical rotor and elastomeric stator. A mathematical solution to a PCP system model requires that we solve a partial differential equation system. The solution is inherently complex and requires considerable computational time. This paper uses the bond graph formalism, which is based on energy and information flow, to implement a model of a PCP system. Its purpose is to predict the dynamic response of the PCP system when it is subjected to a specific reservoir condition. Specifically focusing on the rod string, the torsional effects are captured by a lumped segment approximation. The software 20-Sim© was used to simulate a realistic PCP system application scenario. The model presented in this paper is able to determine the prime mover, rod string, and other component requirements. This paper shows that the multi-body lumped segment model is a useful way to simulate the rod string performance. The bond graph is effective at modeling the PCP system which contains elements from different energy domains.
Time Domain Turret Load and Motion Analyses for a FPSO
Authors: Kim Hyoungchul , Koo Bonjun , Kyoung Johyun 
Published: December 2020

Abstract
Fully coupled time domain turret/FPSO simulations are conducted using TechnipFMC proprietary software MLTSIM. To analyze hydrodynamic interactions and mechanical coupling effects between an FPSO and its turret, a multi-body interaction model is developed and analyzed. In the multi-body interaction model, full coupled hydrodynamic interactions are considered, and the bearing connections are modeled with nonlinear springs and frictional damping. The global performance analysis results are systematically compared with model test results (Kim et al. [1]), and hydrodynamic loads and mechanical coupling loads on the turret are presented in this paper.
Calculating Frictional Losses in Belleville Springs by Geometrical Interpolation
Authors: Maharjan Dipesh , Shah Shaheen , Abugharara Abdelsalam , Butt Stephen 
Published: December 2020

Abstract
The use of Belleville springs has been proven to be beneficial in tackling the problems related to elastic interaction, creep, differential thermal expansion or in the isolation of seismic vibrations in bolted joints. Because of its high and easily variable spring rates, the use of these springs can also be observed in passive vibration assisted rotary drilling (VARD) tools. Because of relative movement of spring with respect to supporting surfaces and the mating spring surfaces, frictional losses in the spring take place during each compression and relaxation cycle leading to a slightly different load-deflection curve from what has been defined in the literature. The geometry of the spring combined with different stacking configurations complicate the study of frictional losses in these kinds of springs.
This work presents a new method to calculate the displacement of different points of Belleville springs during its loading and unloading using geometrical interpolation method. The results of spring displacement are then used to develop a model to calculate frictional load as a function of spring deflection, which is used to analyse load-deflection curves of springs with different dimensional and frictional parameters. The developed methodology is used to plot and understand characteristics curves of four different kind of Belleville springs; High Load, Standard, Force Limiting and Force Adjusting Belleville springs by plotting the graphs for different free-height to thickness and diameter ratios. In the later section of the paper, the proposed methodology has been used to visualize the load-deflection characteristics of Belleville springs used in the p-VARD tool of the Large Drilling Simulator, one of the state-of-the-art drilling simulators at Memorial University of Newfoundland. Results show that understanding of the characteristic curves of different spring configuration helps to plan to drill with desired WOB using a p-VARD tool.
Vessel/Stinger/Pipeline Fully Coupled Analysis for Pipelaying Operation
Authors: Koo Bonjun , Tu Qin , Wang Jiaqi , Mathakari Sachin 
Published: December 2020

Abstract
During pipelaying operations, dynamic performance of the stinger due to vessel motion has a strong impact on the stinger capacity estimation. However, the conventional stinger structural design is based on the maximum load on the roller boxes corresponding to a target top tension value. In addition, the installation analysis uses the uncoupled vessel motion Response Amplitude Operators (RAOs) to calculate the motion induced loads on the stinger and the pipeline.
Since the maximum loads on the stinger are conservatively estimated by linearly superimposing maximum forces from different loading conditions, the conventional design and analysis approach leads to either over-design of the stinger structure or underestimation of the stinger capacity.
To improve conventional pipelaying design and analysis methodologies, a time domain vessel/stinger/pipeline Fully Coupled Analysis (FCA) is presented in this study. The new analysis procedure significantly improved the stinger operation limit compared to the conventional design and analysis procedure.
Hydrodynamic Loads on Net Panels With Different Solidities
Authors: Føre Heidi Moe , Endresen Per Christian , Norvik Carina , Lader Pål 
Published: December 2020

Abstract
Drag forces on nets represent the largest contribution to hydrodynamic loads on traditional fish farms, and will have a large impact on total loads on new designs utilizing netting as containment method. Precise methods for estimation of drag loads are needed.
This paper gives new knowledge on hydrodynamic forces acting on aquaculture nets. It presents results from towing tests, including updated drag and lift coefficients for Raschel knitted netting materials used in nets for aquaculture, and quantify wake effect. The results include high solidity nets and high towing velocities.
It was found that drag loads were close to proportional with the netting solidity for netting solidities ranging from 0.15 to 0.32. The wake effect is quantified through the average velocity reduction factor, which is given as a linear function of solidity.
Much of previously published data are close to the data found through these tests. However, for high solidity nets, the deviation is significant. Therefore, previously published data and models may overestimate drag loads for high solidity nets.
Benefit From Structural Reliability Analysis in Risk Evaluation of Collapse of Externally Supported Casing
Authors: Hørte Torfinn , Bjørset Arve , Zaharie Dan Tudor , Pettersen Sune 
Published: December 2020

Abstract
Casing collapse capacity was identified by Equinor as a critical operational parameter on one of its fields in production. This led to re-evaluation and detailed studies of the overall well design, specifically the production casing’s collapse capacity, together with consequence and risk evaluations in case of a potential casing failure. As an important and useful input to the risk evaluations, the present paper presents a structural reliability analysis for casing collapse.
Initially, the casing collapse capacity was evaluated using API TR 5C3 / ISO 10400 [1], with insufficient capacity being documented. In order to investigate further, physical material testing and collapse testing were performed. Two kinds of collapse tests have been performed: i) tests of unsupported pipe and ii) test of pipes with external support from the cement and formation surrounding the pipe. While a paper from 2018 (OMAE2018-78767) considered casings without external support, the present paper pays attention towards supported pipes. Five collapse tests have been performed where test lengths of the 9 5/8” casing were installed inside a thick-walled pipe that simulates the support. A small gap leaves an annulus between the casing and the supporting pipe, allowing a controlled pressure to increase until collapse. The tests have been simulated by finite element analyses. Good correspondence was obtained, providing confidence that FE simulations can be used to predict the collapse capacity of supported pipes.
While the tests were only performed for an idealized case with support around the whole circumference, a large number of FE simulations have been carried out for different combinations of support conditions together with variations in pipe ovality and internal wear from drilling. Ideally, the space between the casing and the rock formation is filled by cement. However, in practice there may be channels where there is no cement, likely to occur if the casing is eccentric in the well bore during cementing. These results from these FE simulations have been used to generate a response surface. Subsequent structural reliability analyses have been performed, in which well specific uncertainty associated with the above parameters is considered. Measurements and logging are used to minimize the uncertainty in these inputs and thereby leading to a reduction in the calculated failure probability. The probability of casing collapse is calculated conditional on different magnitude of the differential pressure of the pipe.
By using SRA the potential over-conservatism in the conventional deterministic analysis is avoided. The SRA results were used to assist in the risk evaluation resulting in an allowance for continued production on existing wells.
Offshore Breakwaters for LNG and Bulk Terminals: A Design Methodology for Determining Breakwater Layout
Authors: Youssef Khali , El Chahal Ghassan , Saadali Nadjib 
Published: December 2020

Abstract
Over the last decades LNG and bulk terminals have been constructed in many countries. Many of these terminals have been located in sheltered sites without significant influence of swell and wind seas. As the worldwide gas market continues to grow supplying domestic, industrial and power plant projects, there is a continuous interest in new LNG terminals. With the growing gas demand LNG terminals are planned at exposed sites where the need of a breakwater is important for the ability of the facility to maintain operations and to ensure survivability of the terminal infrastructure. Studies are carried out for LNG terminal concept with the main focus on the need for a breakwater protecting the facility which will have significant impact on the CAPEX (Capital Expenditure). The mooring layout of the FSU/FSRU and LNG carrier whether perpendicular or parallel to the breakwater in addition to the planned operations determine the protection area behind the breakwater.
The objective of this study is to establish design curves relating the different environmental and terminal parameters such as wave conditions, berthing facility layout, protection area and breakwater layout. These curves are derived based on the results of numerical simulations for wave transformation process of offshore waves propagating inside the terminal area. More than 700 cases are carried out in this study considering a range of wave periods, breakwater lengths, breakwater type (caisson and rubble mound), facility area dimensions and two incoming waves direction, i.e perpendicular and oblique. The simulations are carried out using the software REFONDE which is based on resolving the mild slope equation for irregular waves. The results of the study are presented in the form of curves and generalized to be used by terminal developers, designers and contractors for general guidance in future projects.
Up to the authors’ knowledge, such curves for the design of marine terminals are not available at present. From this overview, a design methodology is developed to determine breakwater layouts during the early planning phase of project considering wave conditions, facility layout and terminal operations.
Robust Method for Wellhead Loads Estimation Based on Lower Stack Motion Measurements
Authors: Cetin Ali , Holden Harald , Solum Vegard R. 
Published: December 2020

Abstract
Estimating wellhead loads from lower stack motion measurements is a practical and cost-effective approach. In this paper, a new method is proposed, which is based on system identification techniques rather than Newtonian mechanics, thus omitting reliance on uncertain and variable quantities such as lowerflex joint stiffness/damping, riser and drill pipe tension etc. The proposed method is simple and easy to apply, while maintaining accuracy. Both simulation and real-world measurement data are utilized to demonstrate and evaluate the method.