bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Drillstring Deflection and Rotary Speed on Annular Frictional Pressure Losses
Authors: Erge Oney , Ozbayoglu Mehmet E. , Miska Stefan Z. , Yu Mengjiao , Takach Nicholas , Saasen Arild , May Roland 
Published: November 2013

Keeping the drilling fluid equivalent circulating density in the operating window between the pore and fracture pressure is a challenge, particularly when the gap between these two is narrow, such as in offshore applications. To overcome this challenge, accurate estimation of frictional pressure loss in the annulus is essential, especially for multilateral, extended reach and slim hole drilling applications usually encountered in shale gas and/or oil drilling. A better estimation of frictional pressure losses will provide improved well control, optimized bit hydraulics, a better drilling fluid program and pump selection. Field and experimental measurements showed that pressure loss in the annulus is strongly affected by the pipe rotation and eccentricity.
Eccentricity will not be constant throughout a wellbore, especially in highly inclined and horizontal sections. In an actual wellbore, because of rotation speed and the applied weight, some portion of the drillstring will undergo compression. As a result, variable eccentricity will be encountered. At high compression, the drillstring will buckle, resulting in sinusoidal or helical buckling configurations.
Most of the drilling fluids used today show highly non-Newtonian flow behavior, which can be characterized using the Yield Power Law (YPL). Nevertheless, in the literature, there is limited information and research on YPL fluids flowing through annular geometries with the inner pipe buckled, rotating, and eccentric. Furthermore, there are discrepancies reported between the estimated and measured frictional pressure losses with or without drillstring rotation of YPL fluids, even when the inner pipe is straight.
The major focus of this project is on a horizontal well setup with drillstring under compression, considering the influence of rotation on frictional pressure losses of YPL fluids. The test matrix includes flow through the annulus for various buckling modes with and without rotation of the inner pipe. Sinusoidal, helical and transition from sinusoidal to helical configurations with and without the rotation of the drillstring are investigated. Results show a substantial difference of frictional pressure losses between the non-compressed and compressed drillstring.
The drilling industry has recently been involved in incidents that show the need for critical improvements for evaluating and avoiding risks in oil/gas drilling. The information obtained from this study can be used to improve the control of bottomhole pressures during extended reach, horizontal, managed pressure, offshore and slim hole drilling applications. This will lead to safer and enhanced optimization of drilling operations.
Validation of CFD and Simplified Models With Experimental Data for Multiphase Flow in Bends
Authors: Nennie E. , Belfroid S. P. C. , O’Mahoney T. S. D. 
Published: November 2013

In this paper details of the measurement results of the forces on the bends in a 4″ setup are compared to two models. The first model is a simple analytical model and is used to estimate the forces. In the second model, CFD is used. In the experiments only resulting forces, including upstream and downstream bends and mechanical resonance and interaction is measured. The goal of the CFD was to discriminate between flow and mechanics and to evaluate the influence of a flow disturbance as a result of a bend on the force on a downstream second bend.
For the simplified analytical model the amplitudes are underestimated, but the frequency spectra look very reasonable in case of the slug flow regime. The main advantage of the simplified analytical model is that the computational time is in the order of seconds, but the accuracy is still reasonable for the use in an engineering approach of determining the structural integrity of the complete pipe system. For the CFD the shape of the force function is similar to the experiments. The CFD results indicate that the forces on the second downstream bend are also measured on the first upstream bend. The accuracy of the CFD simulation is the advantage of this model, but the computational time is very long, especially if the multiphase flow simulation is coupled to the structural model.
Lateral Buckling Response of Subsea HTHP Pipelines Using Finite Element Methods
Authors: Haq M. Masood , Kenny S. 
Published: November 2013

Subsea pipelines are subject to load effects from external hydrostatic pressure, internal pressure, operating temperature, ambient temperature and external reactions (e.g. seabed, structural support). These parameters influence the effective axial force that governs the pipeline global buckling response. Other factors, including installation stress, seabed slope, soil type, and embedment depth, can influence the pipe effective force.
Pipelines laid on the seabed surface or with limited embedment may experience lateral buckling. The resultant mode response is a complex function related to the spatial variation in these parameters and kinematic boundary conditions.
In this paper, results from a parameter study, using calibrated numerical modelling procedures, on lateral buckling of subsea pipelines are presented. The parameters included pipe diameter to wall thickness (D/t) ratio, pipe out of straightness (OOS), operating temperature and internal pressure, external pressure associated with the installation depth, and seabed lateral and axial friction properties.
Prediction of Travelling Time and Exhaust Gas Emission of Ships on the Northern Sea Route
Authors: Reimer Nils , Duong Quang-Tan 
Published: November 2013

In order to simulate the impact of increased shipping activities to the arctic environment for a scenario with decreasing ice extent and ice volume, a simulation tool for ship travelling time was enhanced with regard to the determination of fuel consumption and exhaust emission on the Northern Sea Route (NSR).
The tool was then used to investigate the impact of ships in different periods within the years 2000 and 2007 with various ice conditions.
The transit speed is compared for different periods in the past and present by using ice records from different years together with route parameters and ship data as input for a simulation program. The program is able to calculate the ship resistance in open water and additional components due to wind, waves and ice within a speed range. By including specific propulsion data of the ship, a requested power is obtained for the speed range. The maximum speed is finally interpolated using the maximum available shaft power.
The simulations are carried out for three different ship types with different hull shapes and propulsive power. The results show a significant decrease of travelling time for 2007 compared to 2000. Further in 2007 the season in which transport via the NSR is profitable is clearly extended to the winter months.
In a second work task the program is further developed with respect to the determination of fuel oil consumption and exhaust gas emission. Due to increased resistance during ice breaking, high thrust has to be provided at low speed leading to an off design condition for propulsion arrangements which are optimised for service speed in open water.
It can be found that the resulting actual fuel consumption is closely related to the operation profile of the ship. High values for fuel consumption thereby occur at service speed in ice free water but also at very low speeds in very tough ice conditions. For moderate ice conditions the fuel consumption and related emissions can be lower especially if the ship is forced to slow steaming for safety reasons.
Prediction of the Effects of Fast Passing Vessels on Moored Vessels
Authors: Pinkster J. A. , Keuning J. A. 
Published: November 2013

An analysis method to determine the behaviour of a moored ship due to wash waves created by a passing fast vessel has been developed. The method can be used for quantitative assessment of the motions of the moored vessels due to wash waves.
In this paper a short review of the main elements of the computational method is given and comparisons made with results of model tests carried out at MARIN with the concept of a fast passenger ferry and a captive barge representing a moored vessel.
Besides having the possibility to analyse, in the design stage of a fast vessel, the effects on other waterway users, criteria are needed to determine acceptable limits for the motions and accelerations of the moored vessel as caused by the passing vessel. In this paper motion criteria developed based on a comprehensive field study carried out in the Netherlands using the experiences of crew members of moored barges are compared with results of computations of barge motions.
Experimental Study for SPAR Type Floating Offshore Wind Turbine With Blade-Pitch Control
Authors: Chujo Toshiki , Minami Yoshimasa , Nimura Tadashi , Ishida Shigesuke 
Published: November 2013

The experimental proof of the floating wind turbine has been started off Goto Islands in Japan. Furthermore, the project of floating wind farm is afoot off Fukushima Prof. in north eastern part of Japan.
It is essential for realization of the floating wind farm to comprehend its safety, electric generating property and motion in waves and wind.
The scale model experiments are effective to catch the characteristic of floating wind turbines.
Authors have mainly carried out scale model experiments with wind turbine models on SPAR buoy type floaters. The wind turbine models have blade-pitch control mechanism and authors focused attention on the effect of blade-pitch control on both the motion of floater and fluctuation of rotor speed.
In this paper, the results of scale model experiments are discussed from the aspect of motion of floater and the effect of blade-pitch control.
Metocean Data Acquisition, and Live Transmission, for Tidal Array Sites
Authors: Nicholls-Lee Rachel , Csehi Jon 
Published: November 2013

With tidal stream energy moving ever closer towards full commercialization, there is a growing requirement for environmental monitoring and acquisition of meteorological data in sites of high flow velocity. Such data is imperative for installation of devices, design of arrays and for through life environmental monitoring of farms.
Previously the typical method of obtaining accurate, live data has been to deploy a separate work vessel equipped with current monitoring equipment wasting fuel, time and money. Conventional buoys are not suitable for use on strong tidal current sites as the drag forces pull the buoy under water when the current speed increases. This work discusses the development of the Mojo Current Buoy, designed to provide tidal current profile and heading data for transmission back to land or ship in extreme tidal locations without submerging. It delivers a live data stream for the assistance of marine operations, and can also be used as a cost effective alternative to vessel or bottom mounted acoustic profilers for metocean data acquisition at tidal array sites. A case study of a recent operation based at the EMEC site, Orkneys, is used to illustrate the capabilities of the buoy.
FloVAWT: Progress on the Development of a Coupled Model of Dynamics for Floating Offshore Vertical Axis Wind Turbines
Authors: Collu Maurizio , Borg Michael , Shires Andrew , Brennan Feargal P. 
Published: November 2013

In the present article, progress on the development of an aero-hydro-servo-elastic coupled model of dynamics for floating Vertical Axis Wind Turbines (VAWTs) is presented, called FloVAWT (Floating Vertical Axis Wind Turbine). Aerodynamics is based on Paraschivoiu’s Double-Multiple Streamtube (DMST) model [1] [2], relying on blade element momentum (BEM) theory, but also taking into account three-dimensional effects, dynamic stall, and unsteady wind profiles and platform motions. Hydrodynamics is modelled with a time domain seakeeping model [3], based on hydrodynamic coefficients estimated with a frequency analysis potential method. In this first phase of the research program, the system is considered a rigid body. The mooring system is represented through a user defined force-displacement relationship.
Due to the lack of experimental data on offshore floating VAWTs, the model has initially been validated by taking each module separately and comparing it against known experimental data, showing good agreement. The capabilities of the program are illustrated through a case study, giving an insight on the relative importance of aerodynamics loads and gyroscopic effects with respect to hydrodynamic load effects.
Verification Issues Related to CFD Simulations of Flow Around Circular Cylinders
Authors: Escobar Jose , Celik Ismail , Gutierrez-Amador Albio 
Published: November 2013

The classical problem of flow around a stationary smooth circular cylinder is used to evaluate Computational Fluid Dynamics (CFD) transient simulations using two approaches; Body Fitted Grid (BFG) and Immersed Boundary Method (IBM). BFG simulations were performed using a commercial CFD code ANSYS-FLUENT and IBM simulations using an in-house CFD code DREAM. Two dimensional simulations were performed at three different Reynolds numbers; 1 × 103, 1 × 105, and 5 × 105. Each of the cases was simulated using a coarse, medium and fine mesh. CFD simulations were evaluated using the following quantities; drag coefficient, lift coefficient, pressure coefficient, separation angle and the Strouhal number of the first harmonic of the lift coefficient. Average, and amplitude of the evaluation quantities are reported for every case.
Simulations showed the grid dependence of the results, e.g. finer meshes captured higher harmonics of the drag coefficient which coarse meshes smeared due the large numerical viscosity. IBM simulations were also affected by the symmetry of the computational grid. Predicted quantities follow previously reported experimental trends fairly well except in the critical flow regime.
Two dimensional calculations using turbulence models were performed for the case of Re = 1 × 105, and Re = 5 × 105. Turbulent results showed the importance of the grid resolution near the cylinder wall in capturing the physics of the problem.
Three dimensional calculations were also performed and results are compared to those obtained from the two dimensional simulations. As may be expected, discretization error estimation methods using three grid calculations are not satisfactory for this highly unsteady flow problem, especially near the critical regime, 1 × 105 < Re < 5 × 105. This paper dwells on various issues related to verification of calculations for such highly unsteady flows.
Hydro-Elastic Modelling of an Electro-Active Wave Energy Converter
Authors: Babarit Aurélien , Gendron Benjamin , Singh Jitendra , Mélis Cécile , Jean Philippe 
Published: November 2013

Since 2009, SBM Offshore has been developing the S3 Wave Energy Converter (S3 WEC). It consists in a long flexible tube made of an Electro-Active Polymer (EAP). Thus, the structural material is also the Power Take Off (PTO).
In order to optimize the S3 WEC, a hydro-elastic numerical model able to predict the device dynamic response has been developed. The inner flow, elastic wall deformations and outer flow are taken into account in the model under the following assumptions: Euler equation is used for the inner flow. The flow is also assumed to be uniform. Elastic deformation of the wall tube is linearized. The outer flow is modeled using linear potential theory. These equations have been combined in order to build the numerical model. First, they are solved in the absence of the outer fluid in order to obtain the modes of response of the device. Secondly, the outer fluid is taken into account and the equation of motion is solved by making use of modal expansion.
Meanwhile, experimental validation tests were conducted in the ocean basin at Ecole Centrale De Nantes. The scale model is 10m long tube made of EAP. The tube deformations were measured using the electro-active polymer. The model was also equipped with sensors in order to measure the inner pressure. Comparisons of the deformation rate between the numerical model and experimental results show good agreement, provided that the wall damping is calibrated.
Eventually, results of a technico-economical parametric study of the dimensions of the device are presented.
Assessment of Capacity of Grouted Connections in Piled Jacket Structures
Authors: Lotsberg Inge , Solland Gunnar 
Published: November 2013

The design of the grouted connections in jacket structures has until recently been based on a control of capacity with respect to axial force in the pile while the effect of the bending moment has been neglected, ref. ISO 19902 (2007). In later design of grouted connections it is observed that the moments in the piles can contribute to more than two times larger stress in the pile than that due to axial load only. A significant moment can hardly be transferred from the pile to the sleeve without sliding of the steel against the grout. This sliding is considered to increase with increasing diameter of the pile. Therefore it is difficult to develop design criteria based on small scale testing. The contact pressure between grout and steel will lead to compressive and tensile stresses in the grout. This requires design criteria for compressive stress and tensile stress in the grout.
ISO 19902 do not require fatigue assessment of grouted connections subjected to wave loading. This was based on a review and assessment of jackets present in the Lloyds database at the time the design formulation was developed. It was assessed that fatigue assessment was not required as long as design was performed with respect to the Ultimate Limit State. However, it is now judged that fatigue is important for jackets with significant dynamic load that exceeds the axial and bending moment from permanent loads.
A review of design standards for grouted connections in jacket structures has shown that there is a need for more relevant test data and revisions of these standards such as ISO 19902 in order to assure reliable design with respect to all potential failure modes.
Real-Time Network of Weather and Ocean Stations: Public-Private Partnership on In-Situ Measurements in the Gulf of Guinea
Authors: Quiniou-Ramus Valérie , Estival Rémi , Venzac Pascal , Cohuet Jean-Baptiste 
Published: November 2013

Monitoring of meteorological or/and oceanographic conditions is done on many Oil & Gas platforms offshore West and Central Africa (from Nigeria to Angola), but it is often only used in real-time and not necessarily archived on a hard-drive, or it is protected by each company’s IT firewalls thus making it difficult to send the information to the “outer world”.
In 2010, TOTAL Oil & Gas Operator launched a project to give remote and public access to this real-time wind, current and also wave or other meteorological / oceanographic (“metocean”) data. The objectives of this initiative were multiple:
• Improve weather and ocean hindcasts and forecasts, which will be beneficial to all Oil & Gas operations in Africa,
• Help feed a database for future O&G developments;
• Enable design checks after ∼1 year of operation;
• Serve as a “black box” in case of an incident which could be due to environment;
• Help feed or validate ocean and oil spill drift forecast in case of emergency;
• Contribute to the international effort of monitoring the oceans in the long term (operational oceanography, climate change, etc.);
• Encourage capacity building in Africa by supporting development and maintenance of technical solutions to reach objectives
In 2013, with the support of the French Meteorological Office Météo-France, the data from half a dozen platforms offshore Nigeria, Congo and Angola will be available on the World Meteorological Organization’s (WMO) Global Telecommunication System (GTS).
This paper will present the type of metocean stations that are part of this network “MODANET”, the IT architecture that was selected to send it out of the Company’s network, the quality control undertaken by Meteo France before sending it to the GTS, and future possible use of the data that are envisaged.
OTEC Cold Water Pipe Global Dynamic Design for Ship-Shaped Vessels
Authors: Xiang Sherry , Cao Peimin , Erwin Richard , Kibbee Steve 
Published: November 2013

Ocean Thermal Energy Conversion (OTEC) technology has been considered as a renewable power generation for the tropical oceans where a thermal gradient from subsea to surface are higher than 20°C since 1980. In 2009, the OTEC technical readiness report has identified that semi-submersible, ship-shaped vessel and spar are most feasible to OTEC application. All three are technically mature and well-established floating facilities and have been widely manufactured and operated in offshore industry all over the world. A pilot OTEC development, led by Lockheed Martin (LM) Industry Team, has configured a semi-submersible floating platform. As an alternative design, SBM is developing OTEC designs based on converted ships. Ship shapes provide good access to facilities for practical operation and maintenance activities. Our study focused on demonstrating the feasibility of constructing and installing a 4 meter outer diameter Cold Water Pipe (CWP) based on conventional land-based manufacture of Fiberglass Reinforced Plastics (FRP) followed by installation with SBM marine equipment. Based on insights gained from this exercise, we will continue to develop the installation methods for larger diameter CWPs.
The CWP is a key design challenge for OTEC since it must be strong enough to withstand the forces and motions while being light enough to be installed with available marine equipment. This paper focuses on the cold water pipe global dynamic performance hosted by a converted ship for a 10MW OTEC plantship offshore Hawaii. The offshore Hawaii location was selected for purposes of comparison rather than the existence of any specific prospective projects. The CWP is connected to the vessel via a sealed gimbal device that allows the CWP’s angular motions to be decoupled from the vessel. The fundamental understanding of CWP vibrations is discussed. The CWP global dynamic responses to extreme storms and operational fatigue environments are presented. Vortex Induced Vibration (VIV) and other design issues are discussed. The key global design considerations of CWP for the ship-shaped vessel are identified and summarized.