bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cuttings Bed Removal in Deviated Wells
Authors: Ytrehus Jan David , Lund Bjørnar , Taghipour Ali , Kosberg Birgitte Ruud , Carazza Luca , Gyland Knud Richard , Saasen Arild 
Published: September 2018

A drilling fluid for drilling deviated wellbores must provide adequate hole cleaning efficiency for all well angles relevant to the operation. For angles near vertical, experience show that hole cleaning is straight forward. In wellbore angles larger than, say, 45 degrees hole cleaning is more difficult. Cuttings beds are formed and at some well angles these beds may avalanche during circulation stops etc.
This paper presents results from laboratory tests with injected cuttings using a low viscosity oil based drilling fluid with micronized grained barite as weight material. The fluid is designed for highly deviated wells with low ECD requirements and the cuttings transport performance through relevant wellbore inclinations was investigated.
The experiments have been performed under realistic conditions. The flow loop includes a 10 meters long test section with 2” OD freely rotating steel drill string inside a 4” ID wellbore made of steel, representing a cased wellbore. Sand particles were injected while circulating the drilling fluid through the test section. Experiments were performed in three wellbore inclinations: 48, 60 and 90 degrees from vertical.
Results show that hole cleaning in absence of drill pipe rotation is significantly improved if the well angle is less than a critical angle. This critical angle appears to be less than 60 degrees from vertical. Further result show that this critical inclination angle is dependent to the drill string rotation rate and the annular flow velocity.
Survey Research on Legal System of Floating Residence and on Management of Water Utilization in the United States: Case Study on Seattle, Washington and Sausalito, California
Authors: Dobashi Daisuke , Kuroyanagi Akio , Sugahara Ryo 
Published: September 2018

Effective utilization of oceanic space in Japan is just recent compared to U.S. Since the end of 19th century, water utilization and management for residence constructed on lake was promoted in U.S.
It is then the aim of this paper to comprehend the laws and regulations for floating residence as well as water utilization and management of United States.
Through web survey, each State in United States will be searched if there are existing laws and regulation on floating residence.
After searching and reading all conditions of the U.S. States regarding laws and regulation as well as legal positions on floating residence, two states in the west coast of U.S: Seattle in Washington and Sausalito, California are chosen for this study. Floating residence in U.S. are divided into two; the Floating Homes and Houseboats. Floating Homes are handled by law the same with homes built in land while Houseboats are treated as type of ship. The State managing the water will lease it to the private sector, then, building of Floating Home will be carried out. Furthermore, design and construction of Floating Homes follow the building standards of the counties and cities where it will be built.
Steady and Unsteady Hydrodynamics of Different Shapes of Slender Drift Anchors With a Lattice Boltzmann Approach
Authors: Dommergues Bénédicte , Sainte-Rose Bruno , Abiza Zaki 
Published: September 2018

The Ocean Cleanup designs floating systems to intercept and accumulate plastic marine debris by having a relative velocity towards the plastic drifting with the sea-surface current of the oceans. One of the solutions to create such a velocity difference is by the mean of drift anchors located in a deeper and slower water layer therefore slowing down the system. As a basic design, two main shapes are being investigated: a punctured cylindrical pipe and a cross shape.
In order to compare the general hydrodynamic behavior and the influence of the holes pattern of the different anchor designs, a CFD study is carried out using a Lattice Boltzmann approach in order to characterize the in-line and cross-flow hydrodynamic coefficients.
Dynamic Response Analysis on Flexible Riser With Different Configurations in Deep-Water Based on FEM Simulation
Authors: Guo Shuangxi , Li Yilun , Li Min , Chen Weimin , Kong Yue 
Published: September 2018

For case of oil/gas exploitation and mining in deep water, the length of riser is pretty large and, consequently, it brings huge challenges in both offshore installation and production operations and results in significant cost elevation due to the factors such as extreme tension loads induced from riser suspended self-weight and large structural flexibility. Therefore, there are several alternative riser configurations, e.g. lazy wave, hybrid tower and lazy-wave riser beside free hanging catenary, which have been proposed. In this paper, the dynamic characteristics and responses of several risers with typical configurations are considered and compared with each other based on our numerical simulations. Firstly, the nonlinear dynamic model of the riser systems are developed based on our 3d dynamic riser equations along with the modified FEM simulations. Then the dynamic response is analyzed based on our 3d curved flexible beam approach where the structural curvature changes with its spatial position and time in terms of vector equations. Compared with the linear approach, the nonlinear FEM method is used so as to consider large displacement/deformation, configuration geometry and structural stiffness changing with body motion. Moreover, the hydrodynamic force is considered as being related to body motion too.
Based on the FEM numerical simulations, the influences of the amplitude/frequency of the top vessel motion along with the buoyancy modules/tower distribution along structural length on riser’s dynamic responses, in terms of the temporal-spatial evolution of displacement, curvature/bending stress and dynamic tension, are studied for different riser’s configurations. Our results show that the dynamic responses, particularly the maximum top tension, of different riser systems significantly change. Among the examined riser configurations, the response of the riser with more buoyancy modules may have lower value, and buoyancy distribution along structural length can influence the top tension and curvature.
Stability of Compressive Residual Stress Introduced by HFMI Technique
Authors: Ruiz Valdes Hector Olmedo , Osawa Naoki , Murakawa Hidekazu , Rashed Sherif 
Published: September 2018

Fatigue strength of welded structures is affected by welding residual stresses, which influence crack propagation at weld toe or root, considerably reducing the effectiveness of the structure and increasing its construction and maintenance costs. A mechanical post-weld treatment such as HFMI (High-Frequency Mechanical Impact) has been found to exhibit a significant fatigue life enhancement of welded joints.
The effectiveness of this mechanical impact treatment is primarily based on the combination of three effects: improvement of the local work hardening, introduction of compressive residual stresses and closing of notches at the weld toe. However, several aspects of this treatment need to be clarified or further investigated. Many researchers are focused on HFMI-treatment, simulating the impact of the peening tool at the weld toe. The present study focuses on the stability of compressive residual stresses introduced by HFMI-treatment when a cyclic load is applied on a gusset welded joint. Peening response of a flat stress-free-plate, under different peening process parameters is also investigated. Furthermore, comparisons of HFMI with other peening techniques are carried out to clarify which technique is the most reliable.
The validity of the present study is demonstrated by comparison with experimental residual stress measurements.
A Study on the Stochastic Aspects of the Whipping Vibrations in a Container Ship
Authors: De Gracia Luis , Osawa Naoki , Iijima Kazuhiro , Fukasawa Toichi , Tamaru Hitoi 
Published: September 2018

The container carriers represent a challenge in the design process, where an important role play the estimation of design loads and their response. The wave-induced vibrations are often referred to as whipping as a transient phenomenon due to wave impacts and springing as a resonance phenomenon due to oscillating loads. These hydro-elastic vibratory phenomena’s are the most important consequences of the continuous increase in the ship length and low stiffness of the hull girder. While this is a concern in the marine industry, this phenomenon is not clearly considered in the design. Therefore, there are uncertainties associated with the wave-induced vibration intensity and the probability of occurrence of whipping to the sea state that needs to be clarified.
This paper address the effect of the relationship of the characteristics of whipping vibration to the sea state, evaluating the results of a series of time-domain computational simulations. A numerical method that combines a three-dimensional panel method and FEA proposed by one of the co-authors is employed for evaluating the load effects. The calculations are performed for the respective short-term sea states. This study presents the probability of occurrence and vibration intensity of the whipping vibration experienced by a 6500 TEU container carrier in a North Atlantic Ocean route.
An Experimental and Numerical Assessment of Moss-Type LNG Carrier Seakeeping Moored to PETRONAS FLNG in Partially Filled Condition
Authors: Auburtin Erwan , Toutin Guillaume , Bin Mahmud Ahmad Fahmi 
Published: September 2018

Moss-type LNG carriers (LNGC) — equipped with spherical LNG tanks — have successfully performed multiple side-by-side (SBS) offloading operations from the PETRONAS FLNG (PFLNG1) terminal since first gas in late 2016. Such LNGC are well suited for these operations as by essence their tanks mitigate the liquid impact risk, for any filling ratio.
However, regardless of the LNG tanks shape, the accurate assessment of the relative motion between PFLNG1 and a SBS-moored LNGC was critical for designing the mooring and offloading systems — in particular the LNG Marine Loading Arms (MLA) — and subsequently assessing the terminal operability.
While the issue has been extensively studied for LNGC equipped with prismatic tanks (SALT I & II JIPs [4]) and a good agreement achieved with numerical models using potential theory, literature available on coupling with LNG sloshing in spherical tanks in a SBS mooring configuration is rare. Compared with prismatic tanks, the axisymmetric tank geometry is not restricting the main sloshing modes direction: these modes are therefore free to rotate due to LNGC wave-induced motions.
An experimental wave basin model test campaign has been held at the MARIN facility to assess the behavior of a Moss-type LNGC with partially filled tanks and provide a good quality database for numerical model calibration and relative motion prediction. This carrier, equipped with Plexiglas spherical tanks, has been tested in free-standing conditions and SBS-moored to PFLNG1. A variety of loading conditions was covered for the LNGC including ballast, 20% and 50% filling. Sloshing modes have been captured with dedicated cameras and wave probes implemented in the LNGC tanks.
In this paper, the model test set-up is presented and a comparison is made between the experiments and numerical simulations, using the potential theory software Diodore™, accounting for the hydrodynamic interaction between the vessels and the coupling with the liquid motion in tanks. Particular attention is paid to the coupling effects between longitudinal and transverse motions induced by the longitudinal asymmetry, and their consequences on the design of the offloading system.
All Around Approach for the Design of a New Escort Tug Family
Authors: Figari Massimo , Martinelli Luca , Viviani Michele , Villa Diego , Enoizi Lucia , Piaggio Benedetto 
Published: September 2018

The aim of the paper is to describe an industrial-academic collaboration whose main goal is the design of a new escort tug family characterized by high intact/damage stability margins, good maneuvering capability and stable behavior during escort indirect assistance.
The project addresses three main research areas: hydrodynamic design of the hull with escort capability, simulation of the escort capabilities in different operational scenario, development of control logics that will allow autonomous or unmanned operations.
The paper describes the methodological approach adopted for the design and will show some preliminary results.
The results refer to the first part of the project. CFD calculations and towing tank tests have been performed onto a prototype tug hull in order to assess the hull design and to infer simulation models able to describe the behavior of a family of vessels. In particular, the propulsion and maneuverability aspects in escort operations are deeply investigated.
Results of the project will form the bases for the conceptual application to a remotely controlled or autonomous escort tug.
Using the Floating Body Symmetries to Speed Up the Numerical Computation of Hydrodynamics Coefficients With Nemoh
Authors: Ancellin Matthieu , Dias Frederic 
Published: September 2018

The open source potential flow BEM solver Nemoh (developed at École Centrale de Nantes) is widely used today, notably for the development of wave energy converters. The use of a linear potential flow theory allows quick estimations of the hydro-dynamic properties of the device, such as its added mass or its radiation damping. Nonetheless, their computation with Nemoh can still be time consuming and could be optimized to facilitate the R&D process.
Many wave energy converter concepts present symmetric shapes: for instance rotational symmetry for point absorbers or translation invariance for cylindrical shapes. These symmetries can be exploited in the BEM solver to significantly speed up the computations. In this paper, the mathematical effect of symmetries on the BEM resolution will be discussed and some results of its implementation in Nemoh will be presented.
Model Test With a Vertical Pipe to Elevate Cold Sea Water
Authors: Trigo C. C. O. , Morooka C. K. 
Published: September 2018

Vertical pipes are extensively applied on offshore petroleum operations, such as subsea wellbore drilling, wellbore re-entry, installations of equipment on the sea bottom, hydrocarbon production as the conductor for oil and gas from the wellhead at the sea bottom, among other applications. Recent oil and gas field discoveries in ultra deepwater brought an increase of the amount of produced and processed petroleum onboard of floating production system. Consequently, the process plant demands more cooling capacity. One of the alternatives is to elevate cold sea water.
The present study aims to improve the understanding of the behavior of a vertical pipe forced to move at its upper end in a water tank. Displacements along the pipe length are measured, and main features of the behavior of the pipe model with its bottom end free are observed. Motions imposed at the vertical pipe intent to represent motions of the surface from the floating platform or ship, due to waves, currents and wind. Pipe model vibrations are analyzed, and results allowed improvements for the input in numerical model simulations to Orcaflex software. Developments of the analysis procedure and evaluations of the experiment allow more reliable design of riser operations with its bottom end free in actual sea operations.
In the present work, a physical model with a pipe of small diameter has been developed for the laboratory experiment, and an optical measurement system is used to measure the pipe model displacement in the water tank. Motions are imposed at the top termination by a mechanical device. Experiment is described in details and comparative analyses between experiment and numerical simulations were carried out. Results from numerical simulations as well as from the experiment brought important contributions for description and understanding of the vertical pipe behavior.
Experimental and Numerical Characterization of the Stress-Strain Behavior of Weak Sandstone Formations for Sanding Assessment
Authors: González Molano Nubia Aurora , Vila Jacobo Canal , González Pérez Héctor , Alvarellos Iglesias José , Lakshmikantha M. R. 
Published: September 2018

In this study an extensive experimental program has been carried out in order to characterize the mechanical behavior of two weak sandstone formations of an offshore field for application to sand production modeling. The experimental tests included Scratch tests, Triaxial tests and Advanced thick wall cylinder tests (ATWC) where the sand production initiation and the cumulative sand produced were registered.
Numerical simulations of experimental tests were then performed using an advanced elasto-plastic constitutive model. Triaxial tests simulations allowed calibrating the constitutive model parameters. These parameters were employed for the numerical simulation of the ATWC in order to determine the equivalent plastic strain threshold required to the onset of sand production observed in laboratory for sanding assessment.
Results obtained highlight the importance to use a realistic representation of the rock behavior focusing on post-yield behavior in order to build confidence in model predictions.
Enhanced Integrity Management by Integrated Erosion-Corrosion and Fluid-Dynamic Calculations in Oil and Gas Systems
Authors: Rodríguez Bustamante J. , Gómez-Álvarez S. , Riquelme-Oliveira J. A. , Sanz-Sanz P. , Lema-Zúñiga R. F. , Mercado-Hurtado L. E. , Merino-García D. 
Published: September 2018

Production system integrity in remote assets is a great challenge, conventionally addressed by the application of conservative standards, leading to costly construction materials. There is evidence that API RP14E standard, accepted as standard for erosional velocity estimations and some of the most extended carbon steel CO2 corrosion models, such as NORSOK, generally lead to conservative material loss rates, with strong impact on design and capital costs [1, 2, 3, 4, 5, 6]. Additionally, there is very little description in the literature of stainless steel CO2 corrosion models.
In this work, an approach to enhanced erosion-corrosion estimations is presented, to cover this gap in material selection. Conventional approaches are incomplete, as they disregard an accurate fluid definition, geometry, flow regimes, the integration of erosion-corrosion phenomena or the validation against experimental and field data. A comprehensive workflow that starts at the fluid characterization, considers the interaction between the phases, includes fluid-dynamic simulation for computation of the flow regime vs. well completion dependence, and calibrates state of art stainless steel erosion-corrosion models with dedicated lab and Calliper field data, was applied to the erosion-corrosion analysis in a gas condensate field.
The results have identified the main material loss mechanism at different points of the well completion and predicted the remaining life of the tubing in different scenarios. This approach enables a deeper insight into erosion-corrosion interaction with the fluid system and enhances the integrity management of an asset.
Variance of Fatigue Damage During Transportation
Authors: Yang Limin , Bøe Tormod , Falkenberg Erik , Korbijn Florus 
Published: September 2018

Fatigue damage prediction of offshore structures during transportation is today commonly based on long term scatter diagram for the sea route. This gives a mean value for the expected fatigue. The deviation from the mean value may however be significant due to the large variability in metocean conditions for the typical short duration of the transport. The actual fatigue damage experienced during the voyage may therefore be much higher than predicted. Hence, it is recommended to take into account the variability of environmental conditions in the calculation of transportation fatigue.
The aim of this paper is to establish a method for estimating transportation fatigue where the fatigue damage is computed with a specified level of non-exceedance.
The fatigue damage is quantified by a measure as defined in OMAE2017 /1/. The distribution of this measure is obtained through Monte Carlo simulation of around 300 separate sea route scatter diagrams derived from hindcast data. The 90% percentile value (10% probability of exceedance) of the fatigue measure is then taken as target value and used for establishing a limited set of design fatigue sea states to be used in the structural fatigue damage calculations.
Modeling the Effect of Phase Change on LNG Impact With Open-Source CFD
Authors: Calderon-Sanchez Javier , Duque Daniel , Gómez-Goñi Jesus 
Published: September 2018

The phenomenology of loads due to sloshing impact on tanks, such as those in Liquefied Natural Gas (LNG) carriers, is a problem that is currently far from being fully assessed.
A main particularity of LNG, among others (such as compressibility or hydroelasticity) is that it is carried at cryogenic temperatures, normally at liquid-vapor equilibrium. This implies phase changes may occur during sloshing impacts. However, phase change phenomena have normally been neglected in sloshing studies. Preliminary works from Behruzi et al. [1] and Ancellin et al. [2] show that phase change may have an effect on the maximum pressure load.
The current work aims to study phase change phenomenology in pressure impact events at cryogenic conditions by implementing a phase change model in the open-source tool Open-FOAM. Results will be compared against previous work by the authors (Calderon-Sanchez et al. [3]), which did not feature phase change.
Multivariate Extreme Analysis Methodology in Function of Structural Response
Authors: Pineau Hélène , Girard Françoise , Raynaud Stéphane , Prevosto Marc , Raillard Nicolas 
Published: September 2018

Many approaches exist to build environmental contours, i.e. the ensemble of joint metocean parameters corresponding to a N-year return level. However, these contours may provide rather different curves according to their calculation process. In this work, the use of response meta-models is introduced for the inter-comparison of environmental contours for two application cases: the roll of a FPSO and the tension in a mooring line of a semi-submersible.
Some state-of-the-art methods available for modelling multivariate extremes are applied for two or more variables and in a directional context. Among the conditional models, joint parametric laws (such as Weibull, log-normal...), Heffernan and Tawn simulations and several copula are investigated. Two ways of contour building are considered in 2D and 3D: Inverse First Order Reliability Model (I-FORM) and physical-space Huseby contouring method.
The comparison between the resulting design points are presented for both applications. The combined wind, wave and current parameters statistics (including directions) are presented, in addition to the extreme loads obtained from the meta-models. The advantages and drawbacks of each method are reviewed. Some key findings are finally presented, pointing out the interest of a meta-model to determine the more realistic set of design points in function of the structure response of interest.