bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrodynamic Behaviors of Aquaculture Net Cages After the Successive Mooring Lines Failure
Authors: Tang Hung-Jie , Yang Ray-Yeng 
Published: October 2021

Abstract
This paper aims to study the successive mooring line failure (also known as the domino effect) and the collision between floating collars for aquaculture net cages subjected to currents. The numerical model of this study is developed based on the Morison equation and the lumped-mass scheme in the time domain. This model is then applied to see if the domino effect of moorings will happen after releasing the anchor point #1 on the upstream side. In this study, we adopt four different current speeds (0.5, 1.0, 1.5, 2.0 m/s) and three different safety factors (SF, 1.0, 1.5, 2.0) settings to calculate the number of mooring failures, and to see whether it will cause floating collars collision. The results show that in the case of the SF is 2.0, the domino effect will not be triggered, and the floating collar collision will not occur. When the SF is 1.5, and the current speed is up to 1.0 m/s or higher, only the two anchor points on the upstream side will fail and no collision will occur. However, if the SF is not considered (that is, 1.0), the domino effect will occur under all the four current speeds, and the floating collar collision will all occur. Therefore, we suggest that in order to avoid the domino effect of the mooring system of aquaculture net cages from currents, the SF of the mooring system design must be at least 2 times.
Determination of the Welding Residual Stresses in Welded Joints and Their Effects on SIFs for Surface Cracks: A Review of Recent Progress
Authors: Qiang Bin , Wang Xin 
Published: October 2021

Abstract
In this paper, the recent progress on the determination of welding residual stresses in Q345qD steel welded structural components and their effects on stress intensity factors for semi-elliptical surface cracks has been reviewed. Two different welded structural components: butt-welded steel plate and orthotropic steel deck (OSD) are considered. First, we summarize the results from recent studies on the experimental measurements and numerical simulations of the surface and through-thickness residual stress in the welded plate and OSD; the complete longitudinal and transverse residual stress distributions are discussed. Then, the effects of the obtained welding residual stresses on the SIFs for surface cracks in the weldments are quantified. The loading conditions considered are the combinations of service loading and residual stresses on the butt-welded plate and OSD. Semi-elliptical surface cracks with a wide range of aspect ratios and relative depths are investigated. In particular, both 3D FEA and weight function method are used for the determination of SIFs for surface cracks. The effects of welding residual stresses on SIFs are illustrated thoroughly. The current results are very important for the appropriate fatigue life assessment for welded structural components.
Reconstruction of Ocean Surfaces From Randomly Distributed Measurements Using a Grid-Based Method
Authors: Desmars Nicolas , Hartmann Moritz , Behrendt Jasper , Klein Marco , Hoffmann Norbert 
Published: October 2021

Abstract
In view of deterministic ocean wave prediction, we introduce and investigate a new method to reconstruct ocean surfaces based on randomly distributed wave measurements. Instead of looking for the optimal parameters of a wave model through the minimization of a cost function, our approach directly solves the free surface dynamics — coupled with an interpolation operator — for the quantities of interest (i.e., surface elevation and velocity potential) at grid points that are used to compute the relevant operators. This method allows a high flexibility in terms of desired accuracy and ensures the physical consistency of the solution. Using the linear wave theory and unidirectional wave fields, we validate the applicability of the proposed method. In particular, we show that our grid-based method is able to reach similar accuracy than the wave-model parameterization method at a reasonable cost.
Abandonment Solution for Wells With Gauge Cables: An Engineered Self-Sealing Cement System
Authors: Rublevskyi Anton , Johnson Carl , Tay Chuang Hwee , Main Darren , Herrera Axle 
Published: October 2021

Abstract
With an increasing number of wells transitioning to their abandonment stages, associated operational efficiency and cost cutting have become a major focus in the industry. An operator had an objective to permanently abandon an offshore well that was suspended in 2016. The key challenge was to develop a long-term well abandonment solution leaving the completion tubing and gauge cables in the well. All the associated operations had to be completed utilizing a lightweight well intervention vessel.
Traditionally, retrieving the entire 5 ½-in. production tubing during plug and abandonment operations has added operational complexity and costs, which increases the risk of exposure to health, safety, and environment (HSE) hazards. Alternatively, a sealant technique placing cement through and around the completion tubing with gauge cables in situ exists. However, this technique is associated with a heightened risk of leak path development over time. Ongoing experimental work suggested that enhancements to the conventional cement sealant systems are beneficial to improve long-term sealing; thus, an active self-sealing cement (SSC) system that would seal microannuli or small fissures around the tubing and gauge cables was designed. The set cement sealant characteristics include low Young’s modulus to resist failure from wellbore stresses and the ability to regenerate the original seal upon contact with any hydrocarbons that may seep through any isolation defects through the life of the abandoned well. To achieve proper cement placement, advanced fluid simulation software and carefully tailored fluid density and rheology profiles were used.
During the operation, a plug of the SSC sealant was pumped through the production tubing and squeezed into the perforations to create a permanent barrier across the reservoir section. Next, a mechanical plug was set inside the production tubing to isolate the lower section, and the tubing was perforated to provide access to the A-annulus above; subsequently, a balanced plug of SSC system was spotted above. After 30 hours, the plug passed a 3.4-MPa [500-psi] verification pressure test. The operator estimated the operation saved 2 to 3 days of rig time, valued at approximately GBP 400,000 to 600,000. The operator also avoided the risk of leaving the well on long-term suspension with mechanical plugs while waiting for a rig to complete the isolation, and the operation minimized the number of intervention steps required for abandonment, thereby limiting scope growth.
Operators are constantly looking for ways to increase reliability, improve efficiency, and minimize risks; and therefore, abandonment techniques are evolving. The developed solution is a novel and robust alternative to conventional well abandonment using an advanced cement sealant technology for the first time and an innovative placement technique.
Transitions in Charpy Energy and Splitting for X80 Pipe Steel
Authors: Mohr William , Birchfield Neal , McGaughy Tom 
Published: October 2021

Abstract
Using data obtained for a recent production 48-inch diameter X80 PSL2 pipe, the transition in fracture behavior between fully brittle and fully ductile modes was examined to assess any effects of transverse splits or delaminations. The additional surface area formed at the splits can increase and decrease the Charpy energy by expending energy to form more fracture surface and reduce constraint on the propagating crack as it extends through the unnotched Charpy ligament. Fitting of full Charpy energy transition curves for the tested material with standard hyperbolic tangent functions does not represent the behavior well. An important transition is noted in the behavior between splitting that initiates at the initial notch tip and splitting that occurs further down in the ligament. Spitting across the notch tip increases Charpy energy by releasing constraint on crack initiation behavior at the machined notch and occurs at temperatures just above the lower shelf temperature where brittle fracture dominates. The splitting behavior can also be correlated to effects on fracture toughness in the same orientation for CTOD specimens in the base material and for correlated effects on CTOD behavior in the weld heat affected zone when the crack advance is in the through thickness direction.
Visual Flooding Experiment of Hot Water, Steam and Solvent Under SAGD and VAPEX Conditions
Authors: Li Songyan , Han Rui , Wang Qun , Wei Xuemei 
Published: October 2021

Abstract
Steam-assisted gravity drainage (SAGD) is an important method of heavy oil production, and the solvent vapor extraction (VAPEX) process is also an economically feasible, technically reliable, and environmentally friendly in situ heavy oil recovery method. In this paper, a microscopic visual flooding device was used to conduct seven groups of visual flooding experiments, including hot water, steam, liquid solvent and vapor solvent, at different temperatures. It can be directly observed that the residual oil in the hot water swept area is generally distributed in “spots”, “strips” and “clusters” of varying sizes. The residual oil after steam flooding generally has a “cluster” distribution, the residual oil after liquid solvent flooding has a “film” distribution, and there is only a little “spot” residual oil distributed after solvent vapor flooding. Additionally, we found that the sweep efficiency and displacement efficiency of hot water, steam and solvent increase with increasing temperature, and the sweep efficiency of hot water is higher than that of steam and liquid solvent. Vapor solvent has the greatest recovery factor, reaching approximately 90%. The experimental results hint at the future development trend of solvent injection and support the foundation of more general applications pertaining to the sustainable production of unconventional petroleum resources.
A Numerical Simulation of Non-Linear Air-Gap for Deepwater Semi-Submersible Platform
Authors: Kang Zhuang , Zhang Yansong , Sui Haibo , Chang Rui 
Published: October 2021

Abstract
Air gap is pivotal to the hydrodynamic performance for the semi-submersible platform as a key characteristic for the strength assessment and safety evaluation. Considering the metocean conditions of the Norse Sea, the hydrodynamic performance of a semi-submersible platform has been analyzed. Based on the three-dimensional potential flow theory, and combined with the full QTF matrix and the second-order difference frequency loads, the nonlinear motion characteristics and the prediction for air gap have been simulated. The wave frequency motion response, the second-order nonlinear air gap response and nonlinear motion response of the platform have been analyzed. By comparing the simulation results, the air gap response of the platform considering the nonlinear motion is more intense than the results simulated by the first-order motion without considering the second-order difference frequency loads. Under the heavy metocean conditions, for the heave and pitch motion of the platform, the non-linear simulation values for some air gap points and areas are negative which means the wave slam has been occurred, but the calculation results of linear motion response indicate that the air gap above has not appeared the wave slamming areas. The simulation results present that the influence of the second-order wave loads is a critical part in the air gap prediction for the semi-submersible platform.
Parametric Evaluation of Forces Due to a Passing Ship on a Moored Ship Using CFD Simulation
Authors: Radhakrishnan Sreedevi , Nallayarasu S. 
Published: October 2021

Abstract
Over the years, with advancements in the shipping industry, there has been considerable increase in size, numbers and speed of ships. Ports and harbours have to handle these larger ships and increased ship traffic within the limited space especially in matured ports. Due to the above mentioned issues at the ports and harbours, passing ship interactions with a moored ship is eventual. Pressure variations around the passing ship may cause additional forces and moments on the ship moored in the vicinity. Though there is literature from past research available on the subject, only few parameters have been investigated. The passing ship forces on a moored ship has been evaluated using Computational Fluid Dynamics (CFD), based on a double-body flow model. Simulations were carried out for three-dimensional, unsteady, inviscid flow using overset meshing technique to facilitate the movement of the vessel. The results obtained from CFD simulations were compared with the existing results obtained by experiments (Remery, 1974) for the validation of the CFD model. Detailed parametric studies were carried out for parameters such as velocity ratio and displacement ratio, spacing ratio, and water depth ratio. Empirical equations for force and moment coefficients are derived based on the present study and recommendations for passing vessel distances from moored vessel has been made in the article.
Impact of Various Nanoparticles on the Viscous Properties of Water Based Drilling Fluids
Authors: Alvi Muhammad Awais Ashfaq , Belayneh Mesfin , Saasen Arild , Bandyopadhyay Sulalit 
Published: October 2021

Abstract
Properly designed drilling fluid is a key element in achieving safe and effective drilling operations. Rheological parameters of drilling fluid determine the equivalent circulation density, the pump pressure, and hole cleaning efficiency. Also, they have a significant role in predicting the stability of drilling fluid under static and low shear rates. The chemical composition of the drilling fluid controls the rheological parameters. Recently, studies have shown that a small concentration of nanosized materials in the drilling fluid can substantially impact the rheological parameters of the drilling fluids.
In this study, various nanoparticles (NPs) with different shapes, sizes, and surface charges were used to investigate their impact on the viscous properties of water-based drilling fluid. Bentonite and KCl water-based drilling fluids were used as the base fluids. NPs such as Iron oxide, Silica (SiO2), and multi-walled carbon nanotubes (MWCNT) were added to these base fluids. Also, surface functionalization of the NPs with polymer and functional groups such as -OH and -COOH groups was done to compare the effect of bare NPs with surface functionalized NPs. Hershel-Buckley model with dimensionless shear rates was used to calculate the low and high shear curvature exponents, surplus stress, and yield stress of the samples.
Results indicate that NPs alter drilling fluid’s viscous properties based on their sizes, shapes, and surface charges. Moreover, the functionalization of NPs also modifies the properties based on the functional group attached to the NPs surface. This work shows that changing the size, shape, and surface charge of NPs has impact on viscous parameters, and NPs with different properties can fine-tune the fluid’s viscous properties based on the requirement for drilling fluid.
Investigating the Solid Transport Capability of Non-Newtonian Fluid in Annulus Bend Section
Authors: Huque Mohammad Mojammel , Butt Stephen , Zendehboudi Sohrab , Rahman Mohammad Azizur , Imtiaz Syed 
Published: October 2021

Abstract
A directional drilling operation may include one or more bending sections along the drilling profile. These bend sections are the critical segments from the hole cleaning point of view. In this study, a computational fluid dynamic (CFD) method was used to investigate the hole cleaning behaviour in annulus bending section. Eulerian-Eulerian multiphase flow model was adopted in this study. The developed CFD model was validated with experimental data. Different non-Newtonian Herschel Bulkley fluids were used to simulate the drilling mud. Solid cuttings of different sizes (2 mm, 4 mm, and 5 mm) were used to replicate the drill cuttings. Different fluid flow rate (0.5 m/s, 1.0 m/s, 1.5 m/s and 2.0 m/s) were investigated to observe the solid settling tendency in the horizontal and bending section. Cuttings accumulation behaviour at different bending radius (10 inch. and 20 inch.) and bending angle (15°, 30°, and 60° from horizontal) were investigated. The simulation study shows that higher viscous fluid performs better hole cleaning at low mud velocity. Furthermore, a turbulent flow regime performs better solid transport in the bending section. Finally, this study summarizes the hole cleaning behaviour of a bend section for a range of fluid velocity, cuttings size and radius of curvature and inclination.
Placing Off-Bottom Cement Plugs: Effects of Domain Geometry
Authors: Ghazal Abdallah , Karimfazli Ida 
Published: October 2021

Abstract
Oil wells are often abandoned when they become uneconomic. Normally, several cement plugs should be placed along cased wells to seal the producing formations. Proper placement protocols, especially for off-bottom plugs, are therefore required to prevent the seepage of oil. Often, heavy cement slurry is injected into wells filled with lighter wellbore fluids, through a centralised tube. To form the cement plug successfully, the injected cement slurry should accumulate at the target zone, over wellbore fluids that typically have a lower density. Therefore, the current practices involve a major hydrodynamic challenge that can result in failing plugs.
In a previous work, we had shown that injecting cement slurry in wellbore fluids can result in developing a cement finger that advects downstream the well. The finger then breaks and aids the formation of a mixed layer below the injection point. Consequently, the injected cement slurry starts accumulating to form the plug. These flow events were observed in a symmetrical flow domain. In this study, we consider different configurations of the injection process to investigate how the previously observed dynamics change. To that end, we consider different sizes and positions of the injector inside the well. We conduct numerical simulations based on representative hydrodynamic models using OpenFOAM, an open source CFD software.
The preliminary results reveal broadly similar dynamics for symmetrical flow domains of different injector sizes. However, marked differences are observed when the injector is not centralized in the well. The injected fluid diverts directly into the gap between the injector and casing walls, with preference to flow through the wider gap side.
Retracted: “Influence of Sea State Parameters on the Accuracy of Wave Simulations of Different Complexity” [ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering, Volume 6, Virtual, Online, June 21–30, 2021, Conference Sponsors: Ocean, Offshore and Arctic Engineering Division, ISBN: 978-0-7918-8516-1, Copyright © 2021 by ASME. Paper No. OMAE2021-62631, V006T06A061; 10 pages; doi: 10.1115/OMAE2021-62631]
Authors: ASME  
Published: October 2021

Abstract
This paper was removed at the author’s request on October 22, 2021.
Copyright © 2021 by ASME
The Harmonic Structure of the Focused Wave in a Wave Flume
Authors: Gao Huixing , Zhou Jianjun , Song Yang , Fang Qinghe 
Published: October 2021

Abstract
In recent years, extreme waves have attracted more and more attention due to its threat to offshore and coastal structures. It is essential to obtain further insight into the formation and propagation of the extreme waves. The formation of extreme waves mainly comes from the simultaneous focusing of wave group energy in the ocean. In the present study, the nonlinear characteristics of the extreme wave are experimentally investigated by the wave focusing method. The phase decomposition methods, both two-phases separation and four-phases separation methods, are used to obtain the higher harmonic elevation in the focused wave. The results show that the four-phases separation method can reasonably extract the first four harmonics. With the separated results, the nonlinear analysis of the wave elevation and velocity of the focused wave is carried out. It is found that the harmonics of the wave group focused at the same time, but the wave elevation and energy of higher-order harmonics are smaller than that of the overall wave. The Stokes wave theory can describe the variation of second-order harmonics satisfactorily. However, the Stokes wave theory cannot estimate third-order harmonics accurately. More work should be carried out to figure out the third-order wave interaction occurring during wave focusing.
With a distributed wave gauge system, the wave evolution along the wave flume is measured. The evanescent modes significantly influence the wave group’s harmonic structure near the wavemaker. The coefficients of the higher-order harmonics are obtained from the measured elevations. The nonlinear wave elevation of the focused wave can be reconstructed with those coefficients basing on the linear theoretical solution, which is in good agreement with the experimental results.
On the Validity of CFD for Simulating a Shallow Water CALM Buoy in Extreme Waves
Authors: Bandringa Henry , Jaouën Frédérick , Helder Joop , Bunnik Tim 
Published: October 2021

Abstract
The Catenary Anchor-Leg Mooring (CALM) is the most popular and widely-used type of offshore loading terminal. A CALM buoy consists of a floating buoy anchored to the seabed by catenary chain legs which are secured to anchors or piles. Due to the small inertia of CALM buoys, the mooring line responses are very sensitive to waves and considerable fatigue risk is introduced to the mooring lines. Extreme waves may even lead to mooring line failure. Therefore it is highly relevant to study the motions of the CALM buoy in (extreme) wave conditions.
This paper presents a validation study of a coupled CFD – dynamic mooring model for simulating the response of a shallow water CALM buoy in extreme waves (Figure 1). Simulations of an interactively moving CALM buoy in a horizontal mooring system were performed by coupling a Navier-Stokes based finite-volume, VoF CFD solver with a dynamic mooring model. The CFD results are validated against model tests performed in MARIN’s shallow-water basin during the ComFLOW-2 joint industry project. The validation study concentrates on the correct prediction of the coupled responses of the CALM buoy in extreme, regular shallow-water waves.
As an alternative to simulations with a fully coupled dynamic mooring set-up, also CFD simulations are presented in which the mooring system is represented by a linearly equivalent spring matrix, including cross terms. The importance of correctly modelling these cross terms is presented in the paper, and the results obtained with- and without these off-diagonal spring terms are compared.