bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Advances on Concrete Coating Impact on Pipeline Strength
Authors: Battistini Alberto , Catena Luca , Mancini Adelina , Marchionni Lorenzo , Parrella Antonio , Vitali Luigino 
Published: October 2017

Concrete Weight Coating is used in offshore industry to provide for pipeline vertical and lateral stability against waves and currents and to guarantee protection against fishing activities. Reinforced concrete coating of adequate strength, especially in case of thick coatings for stringent in-place stability requirements, entails additional bending stiffness and consequently strain concentration at field joints, thus significantly affecting the state of stress and strain on the pipe steel during laying firstly, and then during operations.
Attention of the offshore pipeline industry has been focused in the development of experimental and theoretical activities in a more scientific way, which aimed to satisfy the need of a better knowledge in this field. Both analytical and FEM solutions are available in the free literature and relevant standards to predict the contribution of concrete coating layer on global pipeline strength and deformation capacity and simplified threshold values for the concrete damage are provided, as well.
Generally, for installation analysis purpose, a pipeline with equivalent mechanical behavior (bending moment-curvature relationship) and physical (weight) properties is used in installation and operation analyses. No assumptions are typically made on concrete damage evolution to evaluate the decay of pipe capacity beyond the elastic range.
In this paper new advances in modelling the mechanical behavior of concrete coated joints are discussed. In particular an advanced ABAQUS finite element model is proposed to take into account the effect of concrete coating damage on the overall capacity. The following effects have been accounted:
• Non-linear stress-strain relationship of the steel at large usage factors/curvatures on the strain concentration at the field joint.
• Concrete coating damage evolution on global pipeline bending stiffness.
In this paper:
• The state-of-the-art about published materials, numerical studies and design approaches on concrete material modelling and concrete coated pipes is briefly presented;
• A FEM based analysis methodology is drawn and proposed for the strength and deformation capacity assessment of a concrete coated pipe;
• The FEM model is calibrated on available full scale tests;
• The results of a project case study performed with ABAQUS FE Model are given.
The Influence of SiO2 and TiO2 Nanoparticles on the Properties of Water-Based Mud
Authors: Mijić Petar , Gaurina-Međimurec Nediljka , Pašić Borivoje 
Published: October 2017

About 75% of all formations drilled worldwide are shale formations and 90% of all wellbore instability problems occur in shale formations. This increases the overall cost of drilling. Therefore, drilling through shale formations, which have nanosized pores with nanodarcy permeability still need better solutions since the additives used in the conventional drilling fluids are too large to plug them. One of the solutions to drilling problems can be adjusting drilling fluid properties by adding nanoparticles. Drilling mud with nanoparticles can physically plug nanosized pores in shale formations and thus reduce the shale permeability, which results in reducing the pressure transmission and improving wellbore stability. Furthermore, the drilling fluid with nanoparticles, creates a very thin, low permeability filter cake resulting in the reduction of the filtrate penetration into the shale. This thin filter cake implies high potential for reducing the differential pressure sticking. In addition, borehole problems such as too high drag and torque can be reduced by adding nanoparticles to drilling fluids.
This paper presents the results of laboratory examination of the influence of commercially available nanoparticles of SiO2 (dry SiO2 and water-based dispersion of 30 wt% of silica), and TiO2 (water-based dispersion of 40 wt% of titania) in concentrations of 0.5 wt% and 1 wt% on the properties of water-based fluids. Special emphasis is put on the determination of lubricating properties of the water-based drilling fluids. Nanoparticles added to the base mud without any lubricant do not improve its lubricity performance, regardless of their concentrations and type. However, by adding 0.5 wt% SiO2-disp to the base mud with lubricant, its lubricity coefficient is reduced by 4.6%, and by adding 1 wt% TiO2-disp to the base mud with lubricant, its lubricity coefficient is reduced by 14.3%.
Advanced 3-D FEA Modelling for a Modern and Multidisciplinary Pipeline Design Approach
Authors: Bartolini Lorenzo Maria , Marchionni Lorenzo , Spinazzè Maurizio , Vignati Giulio Claudio , Vitali Luigino 
Published: October 2017

In the last thirty years the attention of the offshore pipeline industry has been strongly focused on submarine pipelines crossing harsh environments and subject to severe operating conditions of temperature and pressure.
Pipeline structural integrity may be threaten by large free-spanning sections between rocky peaks and deep depressions that may be coupled with the pipeline propensity to develop lateral/vertical deflection due to severe service conditions (high pressure/high temperature). For short flowlines, pipeline walking is an additional issue to be verified and faced during design and the application of an integrated approach between flow assurance, installation, geotechnics and pipeline design is a must.
All these features characterize new load scenarios for which intervention works are mandatory to control the development of excessive loads and deformations within acceptance criteria. 3-Dimensional Finite Element Models permit to anticipate the pipeline global response under design loads taking into account the expected (during design phase) and/or actual (after measurements of the as-built) 3-Dimensional pipeline configuration. In case that mitigation measures are to be installed along the pipeline route, their effectiveness can be verified and optimized. Potential failure events in the most promising mitigation measure strategy can be investigated and anticipated at design stage. This paper describes the most relevant capability of the pre- and post-processing tools developed in MATLAB environment and based on ABAQUS Finite Element.
Investigation of Free Surface Damping Models With Applications to Gap Resonance Problems
Authors: Markeng Kevin , Vada Torgeir , Pan Zhi Yuan 
Published: October 2017

In this paper two methods for modelling the damping in a narrow gap are investigated. The first method is called the Pressure Damping Model. This method has been used in studies of wave energy devices. An attractive feature of this model is that the modified input is directly related to the energy dissipation in the gap, which means that if this dissipation is estimated the input to the model can be obtained directly. The idea of the method is to add a pressure input in the gap to suppress the resonant motion. A challenge with the method is that it contains a non-linear term.
The second method is the Newtonian Cooling damping model. The method is based on introducing a dissipation term in the free surface boundary condition. This dissipation term contains a coefficient which is not directly related to the energy dissipation. Hence this method is not so easy to relate directly to the estimated energy dissipation. An advantage with this method is that it is linear and hence can be expected to be more robust.
In the first part of the paper a 2-dimensional problem is investigated using both methods. In addition to the numerical performance and robustness, much focus is put on investigation of the energy balance in the solution, and we attempt to relate both models to the energy dissipation in the gap.
In the second part the Newtonian cooling method is implemented in a 3-dimensional potential flow solver and it is shown that the method provides a robust way to handle the resonance problem. The method will give rise to a modified set of equations which are described.
Two different problems are investigated with the 3D solver. First we look at a side-by-side problem, where the 3D results are also compared with 2D results. Finally, the moonpool problem is investigated by two different 3D solvers, a classical Green’s function based method and a Rankine solver. It is also shown how this damping model can be combined with a similar model on the internal waterplane to remove irregular frequencies.
Pipeline Loads and a Design Approach in Areas of Seabed Subsidence
Authors: Reed Knut , Moshagen Hermann 
Published: October 2017

Seabed subsidence may sometimes be a consequence of the drainage of the oil and gas reservoir. The subsidence process results in changes of the seabed level as well as displacements of the seabed horizontally. The horizontal displacements may impose significant axial compression or tension loads on seabed pipelines installed in the area.
This paper focuses on the engineering challenges of pipelines subject to seabed subsidence. The paper deals with the design issues of the pipelines. It will be seen that for pipelines in areas of seabed subsidence an overall design approach applies where pipeline integrity management may be an important part of the solution.
The present paper describes the phenomenon of seabed subsidence including a typical subsidence field and the time history of vertical and horizontal displacements of the seabed. An example pipeline route is defined for the purpose of illustration of displacements along the route.
A pipeline to be designed and installed in the subsidence area is defined. The load transfer mechanism from seabed to pipeline is described and the resulting compression or tension loads from seabed subsidence on the pipeline are then derived.
An approach for designing a solution for the pipeline to accommodate the loads from seabed subsidence is established and discussed. The discussion involves spool design, mitigation measures and integrity management issues. The paper concludes by recommendations for future applications in actual design cases.
Flow Induced Pulsations (FLIP) in Rough Bore Gas Flexible Pipes, Tests and Model
Authors: Legeay S. , Decuupere M. , Charliac D. 
Published: October 2017

Since the early 2000’s singing risers phenomenon has been encountered. The so called Flow Induced Pulsations (FLIP) phenomenon occurs in dry gas risers (such as Gas Export lines) and may generate high tonal noises up to 110 dB but may also lead to high vibration of adjacent equipment leading to significant fatigue failure.
This publication presents the recently developed model that aims at performing FLIP assessment for rough bore gas flexible pipes. The developed model provides the FLIP onset velocity and frequency for a given rough bore. It will also describe the main contributing factors such as the inner layer corrugation profile, the operating conditions (pressure, temperature and flow rate) and adjacent equipment’s acoustic reflection contributions.
In addition, a Flow Induced Pulsation test carried out in 2003 to 2006 will be presented. Test outcomes will be compared to model presented in the first part.
Finally, reliability of the model will be presented detailing benchmark with past tests and FLIP experienced on fields.
To conclude, the model enables predictions and recommendations to avoid FLIP at an early stage prior to project execution.
Design Aspects of Breakwaters for Cold Climate Oil and Gas Terminals
Authors: Jimenez Puente Isabel , Gudmestad Ove Tobias 
Published: October 2017

This paper focuses on design aspects regarding breakwaters for cold climate terminals, in particular, the different types of berm breakwaters, their stability, armour mobility criteria and armour size.
A methodology is analyzed in order to determine the mean weight of the heaviest armour class as a function of wave parameters such as the significant wave height and the mean wave period, both for non-reshaping and reshaping stable berm breakwaters. The influence of the wave period on the stone mass required will be of special importance in the discussion. This methodology will enable us to determine the required median armour weight for a specific wave parameter, being easily able to compare the feasibility of different concepts or availability of the required stone size at the location.
As a case study, the breakwater selection for the Melkøya terminal in the Norwegian Barents Sea, is assessed through a comparison of the necessary armour unit masses for the different berm breakwaters. The armour mobility criteria currently established is reviewed and a recommendation for an updated criterion for the statically stable non-reshaped berm breakwater category is proposed.
Fatigue Testing of Used Mooring Chain
Authors: Gabrielsen Øystein , Larsen Kjell , Reinholdtsen Svein-Arne 
Published: October 2017

In Statoil mooring chains have been inspected since the first floaters were installed in the 1990’s, and replacement of top chain started as early as year 2000. Background for replacement has been wear, surface corrosion, end of design fatigue life and check of condition for lifetime extension evaluation. For seabed chains in site inspection has been, and still are, difficult and expensive. High quality inspection data is limited. Technology development the last years has allowed for cost efficient seabed chain replacements, and presently even seabed chains have been retrieved to investigate integrity and remaining fatigue life.
Statoil started full scale fatigue testing of chains in 2011, and the results from the first tests, presented in Fredheim et al (2013), indicates that the surface condition of the chain is vital for the fatigue capacity. Fatigue test show that chain fatigue capacity varies significantly.
The surface conditions of the chains are site dependent. To ensure timely replacement, it is vital to know the remaining fatigue capacity of the chains. An extensive fatigue test program was thus initiated, and is still ongoing. As testing has proceeded, different degrading mechanisms and fatigue capacity dependencies have been revealed. Further testing is still required, and more tests are scheduled for the following years.
The paper sums up testing so far (Dec 2016), and presents the most important findings and results.
Simulating Ice-Structure Interaction With the Material Point Method
Authors: Wang Yaomei , Yang Biye , Zhang Guiyong , Jiang Yichen , Zong Zhi 
Published: October 2017

The process of ice-structure interaction is a complex problem which is influenced by the properties of both ice and the structure. In this paper, the material point method (MPM) is introduced to simulate the interaction between an ice sheet and a cylinder structure. MPM is efficient in solving history dependent and large deformation problems and has shown advantage in hyper-velocity impact and landslide issues, etc..
The constitutive relation of ice is based on elasto-viscous-plastic model with the Drucker-Pragers yield criterion. Ice follows the Maxwell elasto-viscous model before the yield criterion is reached and fails when the plastic strain surpasses the failure strain. Meanwhile, the constitutive model used in this work considers the effect of the Young’s modulus, Poisson’s ratio, density, temperature, cohesive force and internal friction angle of ice.
A series of simulations are conducted and the results are in accord with existing theories. According to the comparison, the influences of ice temperature and penetration speed of the structure on the global ice load are testified. The numerical tests have proven the feasibility of MPM in simulating the interaction between an ice sheet and a cylinder structure. Future work in ice-structure interaction problems with MPM is also discussed.
On the Design Considerations of New Offloading Hose Applied on a Turret Moored FPSO
Authors: Yin Decao , Fylling Ivar , Lie Halvor , Baarholm Rolf J. , Kendon Timothy E. 
Published: October 2017

Offloading hoses are used to transfer crude oil or liquid petroleum products from a fixed offshore production platform/floating production, storage and offloading (FPSO) unit to shuttle tankers. The hoses are subjected to environmental loads that are mainly waves, current, and vessel motions from both FPSO and the shuttle tanker.
New offloading hoses were planned to be applied in a FPSO in harsh environment, and a design analysis was done in this connection.
Numerical simulations were performed on ultimate limit state (ULS), serviceability limit state (SLS) and accidental limit state (ALS) by using the software RIFLEX [2]. Critical responses such as curvature and axial forces are checked.
The following conditions are checked:
1. Normal operation condition with oil filled hose
2. Connect operation condition, floating gas filled hose
3. Emergency disconnect condition
A SIMA [3] workflow was established to calculate accumulated fatigue damage of all the elements of the offloading hose model.
For the new offloading hose, it is important to have a combined bending-tension loading capacity check. A utilization factor is proposed that possibly may be generalized.
The results show that the specified hose has ample capacity for the considered operating conditions for the shuttle tanker to stay in any position within the 2nd emergency shut down sector (ESD2).
Effect of Weld Geometry on the Fatigue Behaviour of Umbilical Super Duplex Stainless Steel Tubes
Authors: Raji Hauwa , Fletcher Woods Jamie 
Published: October 2017

The fatigue behavior of welded components is complicated by many factors intrinsic to the nature of welded joints. The mechanical properties of the material, the welding process and position, the type and geometry of the weld and the residual stress distribution across the weld are a few factors affecting fatigue behavior. Published studies [1, 2] have shown that weld geometry is significantly important in determining the fatigue strength of the weld. For a given weld geometry, the fatigue strength is determined by the severity of the stress concentration at the weld toe or at weld defects and by the soundness of the weld metal.
The effect of external weld geometry profile on the fatigue behavior of welded small bore super duplex umbilical steel tubes is investigated. Root cause analysis consisting of fractography, metallography and weld profile measurement is carried out on pairs of fatigue failure samples which were tested at the same stress range but failed at significantly different number of cycles. The samples are selected from Technip Umbilicals Ltd (TU) fatigue database. Following the failure analysis, weld geometric profile measurements are performed on fatigue test samples that were prepared for testing. The weld profile was measured in terms of the external weld cap height, weld width and external linear misalignment. Axial fatigue tests are carried out on these samples which are pre-strained before test to simulate the plastic bending cycles typically experienced during the manufacturing and installation processes prior to operational service. The fatigue tests results are interrogated together with the measured geometric data to identify trends and anomalies. Key weld geometric fatigue performance criteria are subsequently identified.
For the welded super duplex stainless steel (SDSS) tubes studied, the height of the weld and the weld toe angle provided the best correlation with fatigue life — shorter lives were obtained from specimens with the highest weld aspect ratio (weld height to width) and lowest weld toe angle.
Geotechnical Design of Vertically Loaded Hybrid Suction-Gravity Anchors
Authors: Hesar Majid , Maciel Raquel 
Published: October 2017

The Sapinhoá and Lula North-East fields, 300km offshore Rio de Janeiro, Brazil are the two pilot fields of the Pre-salt development strategy. Field architecture consists of satellite wells connected to a spread moored FPSO in each of the fields. Through a design competition Petrobras and Partners selected the de-coupled riser system developed by Subsea 7. In each field two BSRs (Buoy Supporting Risers) anchored at 250m below waterline support the rigid risers on one side and flexible flowlines running to the FPSO on the other. Each BSR displaces close to 10,000t of water and provides a nominal net up thrust of 3,250t. This Paper highlights the engineering challenges and the solution developed for the large-scale foundation anchors that support these massive BSRs in the harsh environment of the Santos Basin in 2140m water depth.
Vertically below each corner of the BSR tank an 8m diameter by 18m penetration suction anchor houses the receptacles for the pair of tethers. Tension in the tethers was tuned to optimise the system stiffness (to minimise lateral BSR excursion orbits and avoid clash of risers and FPSO mooring lines) while requiring minimum anchor capacity. Four ballast modules of 150t each sit on top of each suction anchor to provide the remainder of the required uplift resistance. Soil conditions across both fields consist of soft silty clay. A geotechnical FE model of the suction anchor in Abaqus was used to evaluate the interaction of the structure, surrounding soil and trapped water beneath the top cap. The model was used to develop the complete load-displacement curves of the system during the undrained design current events.
A consolidation FE model using the Soft Soil model in PLAXIS showed that the hybrid anchor/ballast system under sustained uplift loading is stable throughout the design life for the level of sustained design load.
Although the LRFD verification format of suction anchors and gravity anchors are well covered in the design codes, there seems to be a gap in the coverage of this particular type of hybrid anchor. The governing condition was found to be the long term drained pull-out capacity under sustained loading with the assumption of slowly leaking suction port and air evacuation port at the top.
A Risk Assessment of a Novel Bulk Cargo Ship-to-Ship Transfer Operation Using the Functional Resonance Analysis Method
Authors: Clarke Lauchlan J. , Macfarlane Gregor J. , Penesis Irene , Duffy Jonathan T. , Matsubara Shinsuke , Ballantyne Ross J. 
Published: October 2017

Risk assessments underpin a maritime operation’s safety management system. When applied to an untested concept a risk assessment can also assist with overcoming resistance to new technology. This paper proposes the functional resonance analysis method (FRAM) as a tool for developing design recommendations and fulfilling the safety management objectives of the ISM Code. The FRAM is applied to benefit the floating harbour transhipper (FHT), a novel concept for the transhipment of bulk commodities. The FHT acts as a large floating warehouse with an aft well dock that provides shelter for a feeder vessel. The FHT’s materials handling equipment transfers bulk cargo from the feeder vessel onto its own stockpile or directly to an export vessel moored alongside, or from its stockpile to the export vessel.
Most risk assessment tools focus on identifying and addressing system components that can potentially fail. With the FRAM however, the scope, direction and recommendations are guided by a practical understanding of the variability of work undertaken rather than preconceived notions of potential failure modes. Adopting a method based on maximising resilience rather than minimising the causes of accidents promotes a shift from a blame culture to a safety culture. Applying the FRAM generated a deeper, broader and more transparent understanding of the FHT transfer operation than what would have been achievable using traditional risk assessment tools. This understanding was used to develop recommendations designed to improve the resilience of the FHT operation.