bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time Series Prediction of the Trend of Hydrate Risk Using Principal Component Analysis and Deep Learning
Authors: Lee Nayoung , Kim Hyunho , Seo Yutaek 
Published: October 2022

Abstract
Hydrate risk strategy is a critical concern in offshore gas and oil production systems. Several empirical models were employed to predict the hydrate formation behaviors related to plugging risk. However, these empirical approaches have limitations in becoming universally used due to their dependency on geometries and fluid characteristics. Also, hydrate kinetic behaviors are statistical and nonlinear relationships on the dependent variables, which means it is difficult to develop the model to describe its behavior.
In this work, time series prediction using data-driven methods is applied rather than these model-based methods to analyze the kinetic experimental data during the hydrate formation. Deep learning models, specifically LSTM (Long Short-Term Memory) were used to be trained based on the lab-scale experiment data to make the real-time prediction. The transition trend of hydrate formation from homogenous to heterogeneous particles was predicted by using the model. The prediction was made on hydrate risk indicator, which is PCA (Principal Component Analysis) treated sensor data including pressure, temperature, relative torque, and others. The results suggested that the deep learning techniques incorporated with time series prediction could be a promising method for hydrate risk management.
Comparison of Lost Circulation Material Sealing Effectiveness in Water-Based and Oil-Based Drilling Fluids and Under Conditions of Mechanical Shear and High Differential Pressures
Authors: Klungtvedt Karl Ronny , Saasen Arild 
Published: October 2022

Abstract
A study was conducted to assess the performance of granular and fibrous lost circulation materials as preventative treatments and in remedial treatment of lost circulation in water-based and oil-based drilling fluids. For the preventative treatments, a factor which introduced increased mechanical wear on the particles were added to the hot-rolling process, to identify signs of deterioration of performance of certain materials.
The study of remedial treatments of lost circulation were conducted on slotted discs with apertures of 750 μm and up to 5 mm, and with differential pressured of up to 34.5 MPa (5000psi).
To compare the sealing pressures of the different tests, a simple statistical analysis was introduced to differentiate between the peak holding pressures and the sustainable holding pressures of the various material and fluids combinations.
The material degradation studies showed that CaCO3 based lost circulation materials rapidly experienced significant particle degradation after exposure to fluid shear and mechanical degradation and that this considerably reduced the sealing performance of the materials. Also, synthetic graphite-based products showed clear signs in particle size degradation and significant reduction in sealing performance. Cellulose-based products showed superior resistance towards mechanical wear and only small changes in sealing performance.
When comparing water-based and oil-based fluids, it was clear that granular lost circulation materials showed considerably lower sealing efficiency in oil-based drilling fluid compared to water-based drilling fluids. In contrast, cellulose-based materials showed similar sealing performance in oil-based fluids and water-based fluids.
Technical and Environmental Evaluation of a Hydrate Cold Flow Technique to Produce an Oil Reservoir Using a Long Tie-Back and Comparison Against Traditional Development Concepts
Authors: Eyni Leila , Fattahi Mostafa , Schümann Heiner , Lund Fredrik , Stanko Milan , Strømmegjerde Lars 
Published: October 2022

Abstract
In Norway, the majority of offshore oil and gas fields will be developed through tie-back solutions. Here, the produced reservoir streams are transported over long distances on irregular terrain and cold ambient temperatures to processing facilities. This might result in the formation of hydrate particles that can lead to increased pressure drop and gradual or sudden plugging of the pipe. Measures to address them tend to be expensive or have a high environmental footprint. An alternative measure less costly and more environmentally friendly is the cold flow technology. Here, hydrates are formed under controlled conditions, resulting in a stable particle slurry that does not agglomerate and plugs the pipeline downstream.
This study presents a technical and environmental evaluation of cold flow as a flow assurance technique to produce an oil reservoir using a long tie-back. The case study is a synthetic field located on the Norwegian Continental Shelf. Results show that cold flow can successfully be used to produce the reservoir with lower emissions. The advantages and limitations of the concept were identified and discussed, and a comparison is made against alternatives, considering energy consumption, emissions during operation, and carbon footprint.
Study on Large Particle Slurry Transport in Jumper for Subsea Mining
Authors: Masanobu Sotaro , Yamamoto Marcio , Takano Satoru , Murai Yuichi 
Published: October 2022

Abstract
For design and operation of subsea mining system, it is important to predict pressure loss due to the hydraulic transport of solid particles in the flexible jumper which connects the mining tool to the vertical lifting pipe via subsea slurry pump. The configurations of jumper would change according to the motions of the mining tool and the slurry pump, which may be easier to cause the pipe blockage than the vertical pipe.
In the present paper, we investigated the effects of jumper configuration on the pressure loss. We assumed the 100 m long flexible jumper of which outer and inner diameters are 0.254 m and 0.200 m, respectively. PMS ore, of which density and diameter are 3,440 kg/m3 and 0.03 m respectively, were assumed as the solid particles. We varied the slurry transport conditions such as slurry concentration and slurry velocity under the condition of a constant production rate of 5,000 t/day.
The effects of jumper configuration on internal slurry flow were studied from the viewpoint of pressure loss and specific energy consumption. The allowable slurry velocity in jumper system was also investigated considering pipe inclination by referring to the past literature. Finally, the most desirable operational slurry flow condition was discussed for the jumper system studied.
Improved Climate Change Adaptation in Port of Brisbane Using a Digital Twin Cloud-Based Modelling Approach
Authors: Karatvuo Helena , Linde Michael , Dolatshah Azam , Mortensen Simon 
Published: October 2022

Abstract
Due to their low-lying coastal location, ports are vulnerable to climate change induced increases to flooding, waves, extreme winds, and the associated costly damages to port infrastructure and operational disruptions. For these reasons, there is an increasing need for ports to undertake regular risk assessments of the vulnerability of their infrastructure and operations due to the impacts of climate change.
A digital twin, cloud-based climate change modelling solution has been developed to enable in-house risk assessments of climate change vulnerability to be undertaken for any port. Once set-up, the system supports the continued sustainable operation of ports and enhancing stakeholder confidence in corporate sustainability strategies by allowing in-house re-evaluation of the ports climate risk as new predictions are released.
The basis of the digital twin model of the port are numerical wave and hydrodynamic models, configured with the actual port geography and bathymetry enabling highly detailed simulations of the ports physical environment. The numerical model simulations are supplemented with observations of wind, rainfall, and sea level to identify trends and extreme event probabilities under the historic climate conditions. Scenarios describing the predicted impacts of climate change can be superimposed on the historical climate via a web-based interface where the user (port) selects a planning horizon (e.g., 2050), storm event frequency (e.g., 100-year storm), and climate change predictions (e.g. RCP8.5). The resulting climate change simulations shows great potential to enable port-specific predictions of future impacts of extreme occurrences of wind, waves, water levels, and currents. The ports asset portfolio is incorporated in the risk assessment through dynamic GIS layouts and damage curves identifying the damage cause and cost for each vulnerable port asset.
As new climate science becomes available, this cloud-based digital twin model enables ports to rapidly complete updated risk assessments and respond to stakeholder queries and concerns.
The capability of the tool was validated by comparing the model results against a large conventional study of the region, and a historical flood event of 2011. Both validation exercises displayed a reasonable agreement increasing confidence in the model’s capacity as a predictive tool. Additionally, six climate change scenarios were modelled for one of Australia’s fastest growing container ports, Port of Brisbane and the results were successfully incorporated in the ports overall sustainability strategy.
Fatigue Capacity of Used Mooring Chain - Results From Full Scale Fatigue Testing at Different Mean Loads
Authors: Gabrielsen Øystein , Reinholdtsen Svein-Arne , Skallerud Bjørn , Haagensen Per J. , Andersen Marius , Kane Pascal-Alexandre 
Published: October 2022

Abstract
Fatigue capacity of mooring chains is one of the important parameters in design of mooring systems for floating offshore structures. Fatigue life is often a limiting factor. With life extension of existing offshore installations, the fatigue capacity and effects of corrosion become even more important, as there will be large costs for mooring line replacements if safe life extension can not be granted, and the effect of fatigue failure can be fatal. Estimation of the fatigue capacity of mooring chains is thus of high importance both for safe and cost-effective design of new mooring systems, and for the safe life extension of older mooring systems.
The standards used for design of mooring systems outline a somewhat simplified approach for fatigue analysis, where load cycle range is the only parameter included in the analysis. The fatigue capacity curves used are based on full scale fatigue tests of new chains, where effects of heavily corroded surfaces are not considered. Further it is indirectly assumed that mean load does not have any effect on fatigue capacity. Work presented the last years has indicated a strong effect of both mean load and surface condition, where also formulas for fatigue capacity including these parameters have been developed and presented. The conclusions are based on a large set of full-scale fatigue tests of both new chains and used chains, where the used chains are tested at different mean loads and different levels of corrosion.
Equinor has run a large number of used chain fatigue tests. For these tests, each set of tests is typically made from one chain length, with similar condition on all links, and usually run at one mean load only. There are test sets with some variation in either mean load or surface condition, which have added valuable data for the understanding and verification of the effect of these parameters. The effects are well documented, but due to small variation within each set there are uncertainties regarding the quantification of the effects. The latest full-scale fatigue test results, from a chain with significant corrosion pits, include a systematic approach to quantify the effect of mean load. For the chain tested, five tests have been run at low mean load, and five tests at high mean load. This paper presents the results from these fatigue tests. The results are discussed and compared with other fatigue test results on both new and used chain, and with the formulas for fatigue capacity accounting for mean load and surface corrosion.
IMO Level 3: Parametric Roll Stability Failure Simulation Using 3D Numerical Wave Tank
Authors: Ganesan T. Shivaji , Negi Amresh , Sen Debabrata 
Published: October 2022

Abstract
In late 2020, International Maritime Organization (IMO) released interim guidelines on the second generation intact stability criteria. In this paper direct stability assessment in design situations using deterministic approach for parametric rolling failure mode is presented. A 3D nonlinear direct time domain method based on mixed-Eulerian-Lagrangian (MEL) scheme as opposed to impulse response function (IRF) method is used to simulate parametric rolling in both regular and irregular waves. Computed numerical results of roll amplitude in regular head waves is validated with other available literature results. This study further examines the influence of incident wave height and roll damping coefficient on computed heave, roll, and pitch motions in regular head wave conditions. Mean 3-hour maximum roll amplitude is obtained for design situations as recommended by the IMO guidelines.
Environmental Extreme Conditions for a Wave Energy Converter: An Integrated Wave-Structure Approach
Authors: Saeidtehrani Saghy , Lavidas George , Metrikine Andrei 
Published: October 2022

Abstract
The process of finding values of extreme waves and their impacts on wave energy converter (WEC) responses, depends on both wave resources and WEC dynamic characteristics. A wide range of waves can influence the reliability of operation and survivability of a WEC. In this paper, a methodology is described to find specific values of wave heights and periods that can be critical for a flap-type WEC, through the use of an integrated wave-structure approach.
The goodness of the fit is studied and the corresponding return periods for ranges that a selected WEC is mostly operating are evaluated. Further discussions for engineering applications and making a clear understanding of the extreme and operational conditions of the WEC are also provided. The critical wave characteristics are defined based on power production and the significant change in the nonlinear dynamic behavior of the device in various ranges.
The WEC behavior is represented by an experimentally validated numerical tool considering the nonlinear behaviour of a flap as single and in an array. The study aims to provide insights in the expected behavior and loading on the WEC, affecting its reliability, considering potential catastrophic wave return values that correspond to their power production phase. The finding can be used for determining both efficient operations and limiting environmental conditions or weather windows.
Pressure Build-Up in Closed Wells During Kick Migration and Fluid Compressibility Effects
Authors: Agonafir Mesfin Belayneh , Petersen Johnny , Fjelde Kjell Kåre 
Published: October 2022

Abstract
If a kick is migrating in a closed well, this will lead to pressures building up in the well. It has earlier been shown that for Non-Newtonian fluids, suspension effects will make it impossible to deduce a unique gas velocity from the pressure build-up behavior.
In this work, it will be shown that also for Newtonian fluids, the pressure build-up will depend on both kick size and well volumes. Both very small kicks sizes typically seen in MPD operations and larger kick sizes handled in conventional well control operations will be considered. It will be demonstrated that both the shape of the pressure build-up and the final pressure levels achieved will vary significantly. It is especially when considering very small kick sizes that one starts to see large changes in the profile of the pressure build-up. The main reason for the differences is related to the fact that the liquid phase is compressible and this will again have consequences for how much a gas kick can expand and what pressures it can bring to surface.
An analytical model will be developed that shows directly which parameters have impact on the pressure build-up behavior. Simple closure laws for gas density, fluid density and gas slip will be chosen. The model will be verified against two transient models which are based on the Drift-Flux formulation. It is demonstrated that the pressure build-up and final pressure level will depend on initial kick volume, initial fluid volume, liquid compressibility and fluid density. The effect of numerical diffusion when comparing the two transient models will also briefly be discussed.
The purpose of the paper is to increase fundamental knowledge about two phase flow dynamics and show that an analytical model for the situation considered here can give results that are comparable with the results achieved with more complex transient flow models.
An Alternative Measurement Method to Identify the Minimum Bending Radius of Locked Deformed Bend Restrictor Elements Under Load
Authors: Jordal Lars , Vermeer Erwin , Limi Morten , Karlsen Kjetil André 
Published: October 2022

Abstract
Bend restrictors (BR) are used during installation and operation of subsea power cables’ and umbilicals’ to limit the bending radius. This publication presents an alternative measurement method to qualify bend restrictors. One key parameter to qualify bend restrictors is the minimum bending radius (MBR). It is required to measure the MBR of the bend restrictor elements in lock-up position and deformed locked position under load. Existing guidelines, standards and test methods do not describe exactly how and by which means the MBR should be measured. As a result different measurement methods, models and assumptions are used in the industry. To the authors knowledge, existing measurement methods have a variety of limitations, for instance complex time consuming measurement set-up, limited accuracy and sensitive to errors. The alternative measurement method to identify the MBR, described in this publication, is based on a total station measurement technique. The total station consists of an electronic theodolite integrated with an electronic distance measurement unit, which measures the position of specified points in a 3d coordinate system. The alternative measurement method is easy to apply, less time consuming, more robust and can measure the MBR for all positions along the BR elements wirelessly.
Numerical Analysis on Model- and Full-Scale Unsteady Propeller Force for Underwater Vehicle
Authors: Takahashi Kenshiro , Arai Jun , Mori Takayuki 
Published: October 2022

Abstract
Submarines and other underwater vehicles must meet extensive specifications regarding their acoustic signatures to perform covert missions. However, marine propellers produce unsteady forces, resulting in undesirable noise. In this context, the unsteady propeller force of an underwater vehicle was analyzed at the model scale and full scale, based on computational fluid dynamics. The DARPA SUBOFF submarine and INSEAN E1619 propeller were adopted as benchmark models. The propeller rotational speeds under self-propelled conditions were determined using the body-force propeller method. The dominant harmonics of the unsteady propeller forces were analyzed using the Fourier series. The effects of pre-swirl flow generated by the helmed stern planes were investigated. Reynolds scaling was examined to predict the amplitudes of the propeller forces at full scale, based on the model-scale values.
American and European Hydrostatic Tubular Beam-Column Equation Comparisons
Authors: Ku Albert , Richmond Mark 
Published: October 2022

Abstract
For structural design engineers, there is an apparent gap on how the hydrostatic pressure is treated between the American and European systems. In API RP-2A, the beam-column equations treat the axial and bending capacities the same as there is no hydrostatic pressure. This is physically not correct, as member utilization is a combination among hydrostatic, axial, and bending actions. In contrast, the ISO and NORSOK beam-column equations include reductions of axial and moment capacities due to hydrostatic effect. In this paper, actual test data are compared with the API and ISO capacity equations. A third set of capacity equations provided by Chen et al. is also considered. Unity check (UC) results show that, although API equations lack the proper hydrostatic reduction in axial/bending capacities, it is compensated by the separate checks of hoop buckling and ultimate strength. For engineering applications similar member designs will be obtained by either the European or the American systems.
Research on the Influence of Waterjet Propulsion on the Attitude of Planing Ship
Authors: Yang Jun , Liu Liwei , Feng Dakui , He Tao , Yao Chaobang 
Published: October 2022

Abstract
Waterjet propulsion system is widely used in high-speed ships. It has the characteristics of low noise and high propulsion efficiency. In this study, the influence of waterjet propulsion system on the attitude of a planing ship is investigated by an inhouse CFD code. A series of numerical simulations are carried out for a waterjet-propelled ship which is composed of a waterjet propulsion system and a planing ship (DTMB 62 series model 4667-1). The bare hull in towing condition, waterjet hull in towing condition and waterjet hull in self-propelled condition are simulated at different volume Froude number. The ship attitude as well as the ship resistance is obtained. The numerical results of resistance, trim and sinkage of the bare hull agree with the experimental data. Furthermore, the impact of the waterjet system on the attitude of the ship is analyzed. The impact is divided into two parts: the impact of the shape changes on the hull and the impact of waterjet system operation. The impact of the shape changes on the hull makes the trim and sinkage increase under lower speed, while it makes them decrease under higher speed. The impact of waterjet propulsion operation makes the trim and sinkage tend to increase within the scope of the study.
Large-Eddy Simulation of Vortex Flow Field of the Cylinder With Variable Cross Section
Authors: He Tao , Liu Liwei , Yao Chaobang , Feng Dakui , Wang Xianzhou 
Published: October 2022

Abstract
In recent years, some scholars have proposed a pontoon tension leg platform, whose tension leg is in the form of variable cross section, but there is little research on vortex flow field of variable cross-section structure at high Reynolds number. Therefore, it is of great significance to study the vortex flow field of structures with variable cross section. In this study, the vortex flow field of the cylinder with variable cross section are studied in detail by large-eddy simulations. Structured grid is used for computation, and SIMPLEC algorithm is used to solve the pressure and velocity. Large-eddy simulation of flow past circular cylinder is carried out, and the simulation results accord well with the published experimental results, which shows that the numerical method is accurate enough. Large-eddy simulations are performed for flow past the wavy cylinders at Reynolds number of 61000. The lift and drag characteristics, pressure field structure and vortex field of the cylinder with variable cross section are analyzed. The results show that the mean drag coefficients and r.m.s (root-mean-square) of the lift coefficients of the wavy cylinders are less than those of a corresponding circular cylinder. The wavy cylinder changes the pressure field and vortex field relative to the circular cylinder.