bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Numerical Investigation on Water Slamming of Stiffened Panels
Authors: Wang Shan , Guedes Soares C. 
Published: September 2018

To investigate the slamming pressure on the bottom of a wet-deck structure of a multihull vessel, the water impact problem of a stiffened steel panel is simulated by using a fully coupled ALE/FEM algorithm which is implemented in the commercial software LS-DYNA. The Lagrangian formulation is used to describe plane-strain deformations of the hull panel while the Eulerian formulation is applied to describe the fluid flow. The governing equations of this coupling problem are solved by using finite element method. The explicit finite element method is firstly validated through the comparisons of the slamming pressure and structural deflection between the numerical predictions and the published experimental data, for an elastic horizontal plate. Secondly, the parametric study of the mesh size in the impact domain of the FE model is performed. The total slamming forces obtained from three models are compared. To study the effects of the flexibility of the structure on the slamming load, the predictions of slamming pressure on several locations of the elastic panel are compared with the values obtained by using the rigid body model.
The water entries of the stiffened panel with two different deadrise angles, entry velocities, and thickness of plating are simulated. The results of the total slamming force, slamming pressure are presented and discussed.
Impact of Climate Change on the North Sea Offshore Energy Sector
Authors: Fournier Nicolas , Guentchev Galina , Krijnen Justin , Saulter Andy , Acton Caroline , Hanlon Helen 
Published: September 2018

The complex nature of the energy industry across extraction, transportation, processing, delivery and decommissioning creates significant challenges to how the sector responds, adapts and mitigates against risks posed by the changing future climate. Any disruption in this interconnected system will affect both industry and society. For example, in the summer of 2005 Hurricane Katrina and a month later Hurricane Rita had wide reaching impacts on the US offshore Oil and Gas industry which resulted in an increase in global oil prices due to loss of production and refinery shutdowns in the Gulf of Mexico.
Preparing, mitigating and adapting to these climate changes is dependent upon identifying appropriate climate indicators as well as the associated critical operational thresholds and design criteria of the identified vulnerable assets. The characterization and understanding of the likely changes in these climate indicators will form the basis for adaptation plans and mitigating actions.
The Met Office in collaboration with energy industry partners, under the Copernicus Clim4energy European project, has developed a Climate Change Risk Assessment tool, which allows the visualization and extraction of the most recent sea level and wave climate information to evaluate their future changes. This study illustrates the application of this tool for evaluation of the potential vulnerability of an offshore infrastructure in the North Sea.
The analysis shows that for this asset there is a small increase in sea level of 0.20–0.30 m at the location of interest by 2050. However, there is a small decrease or no consistent changes projected in the future wave climate. This wave signal is small compared to the uncertainty of the wave projections and the associated inter-annual variability. Therefore, for the 2050s time horizon, at the location of interest, there is no strong impact of climate change at the annual scale on the significant wave height, the sea level and thus the associated climate change driven extreme water level. However, further analysis are required at the seasonal and monthly scales.
Novel Erosion Control Technology for Production Debottlenecking
Authors: Kane Prasad Laxman , Pliszka Dominic 
Published: September 2018

Erosion of piping systems is a significant issue for many operators of Hydrocarbon infrastructure. Until now mitigation measures have been limited to detection / measurement and reducing production. For many operators this can be a significant loss in revenue and an increase in IMR costs. A novel Erosion Control Technology (ECT) is being developed that can significantly reduce the impact of erosion on piping infrastructure. This technology has the potential of adding immense value when it is used to debottleneck and optimize flow rates. The patented ECT has been designed to control sand erosion in real-time by deflecting and redistributing sand in the product flow stream.
Preliminary laboratory testing of the ECT has been very successful. The ECT inserts designed for the ambient test conditions have shown substantial reduction in erosion (both global and local). Computational Fluid Dynamics (CFD) has been the key enabling factor allowing the critical breakthrough in this technology. Experimental results have shown very good correlation with the CFD sand erosion model results. A roadmap in line with industry practices and standards has been developed for project implementation of the ECT solution in the near future.
Methodology for Calculating Floating Offshore Wind Foundation Internal Loads Using Bladed and a Finite Element Analysis Software
Authors: Alexandre Armando , Urbano Ricard Buils , Roadnight John , Harries Robert 
Published: September 2018

In the recent years, the floating offshore wind industry has developed quickly and most authors are now converging towards the need of a coupled loads analysis using aero-hydro-servo-elastic software on time domain simulations for floating foundations design. Different hydrodynamic theories still exist and their application depends on the floating platform characteristics. The Morison equation and the boundary element method (BEM, not to be confused with the Blade Element Momentum theory) theory approaches are often used in combination on the same platform model, sometimes applied to different elements of the same structure depending on their shape.
When using the potential flow theory approach calculating internal distributed loads and later on transferring them to stress for hull design purposes is still a challenge due to the large ammount of load cases needed and the complexity of the structure. Furthermore, accounting for platform flexibility is also difficult in most codes using BEM theory due to the same reasons. Different approaches have been proposed by different authors, and currently there is not a single best industry practice for this.
This paper presents a method for accounting for platform flexibility when using BEM theory. A range of methods for the load to stress transfer are also presented and the advantages and disadvantages between them are discussed. The choice of one or another method will depend heavily on the platform structure, and different methods might be used and combined for the same platform depending on the shape of the different elements within it.
The different methods presented here involve performing coupled loads analysis using the aero-elastic software Bladed and multiple bodies to represent the floating platform in order to obtain internal loads at different points in the structure, as well as allowing for platform flexiblity modelling. Bladed can model multiple hydrodynamic bodies including the hydrodynamic effects between (e.g. coupled terms in the radiation force). The approach used in the current study is based on a platform modelled with the hydrodynamic loading distributed over independent sections, but originally computed from a single body BEM calculation. This simplification offers significant gains in computational efficiency and is expected to be valid for many types of floating structure, whist still allowing for some platform flexiblity to be modelled.
The simulation resultant time series can later on be postprocessed to obtain distributed pressure forces on the platform wetted surface and transfer those onto a Finite Element code. Different options are presented here on how to perform this last step for both extreme and fatigue analysis of the hull structure. A couple of examples are shown using the OC3 spar and OC4 semisubmersible, focusing on a subsection of the structures to demonstrate the methodology.
Fatigue Strength of Heavy Wall Line Pipe Girth Weld for J-Lay Installation
Authors: Marines-Garcia Israel , Pelcastre Mauricio , Garcia Enrique , Darcis Philippe P. , Yang Guangqiang , Bourgeois Desmond , Visco Tyler 
Published: September 2018

Tenaris and ExxonMobil conducted a qualification program focused on Heavy Wall Seamless Line Pipe (HW SMLS LP) and its girth welds, to experimentally demonstrate and validate the material potential to be used as riser or fatigue sensitive flowline for the development of challenging deep and ultra-deep offshore fields. The qualification program was divided in three phases.
Phase I [1] included: 1) HW SMLS LP, X65QS, 273 mm OD, 46 mm WT plain pipe qualification; and 2) development and qualification of a WPS (STT® process for root pass and GMAW process for hot, fill & cap passes, narrow groove J-bevel type, 1G welding torch position) and full scale fatigue testing qualification.
Phase II [2] was focused on evaluating the root girth weld fatigue endurance, taking into account the fatigue behavior observed in Phase I (fatigue crack initiation mainly occurred from the outer surface). The fatigue strength of the weld root surface is needed as the weld root surface is in direct contact with corrosive fluids and is the most sensitive area for sour service applications. Thus, to obtain the root girth weld fatigue endurance, full scale fatigue specimens were manufactured with their caps fully removed (by grinding and flapping) to generate weld cap toe free of stress raisers/imperfections. In addition, pipe outer surface was grinded to mitigate the fatigue crack nucleation from outer pipe surface. With this special preparation, the fatigue strength of weld root surface was able to be assessed.
This paper presents Phase III qualification outcomes. The objective was to develop and qualify a WPS representative of J-Lay installation, meaning 2G welding torch position (CMT® for the root pass and pGMAW process for hot, fill and cap passes, Narrow groove J3°-bevel type). The qualification included full scale fatigue assessment as well. The LP material was from the same batch used in Phase I & II (HW SMLS, X65QS, 273 mm OD, 46 mm WT).
The WPS was successfully developed and qualified. The full scale resonant fatigue testing included three specimens with cap smoothed similarly to Phase I, and three specimens with full cap removal plus outer pipe surface grinding similar to Phase II. The fatigue results surpassed the expectations (Class D, S-N curve). Most of the specimen’s fatigue lifetime is above the class B, S-N curve classification (reference for plain material). Obtaining a smooth root weld overfill was key to delaying the fatigue crack nucleation from the weld root toe.
Recent Development and Validation of the Latest FlawPRO™ ECA Methodology
Authors: Bezensek Bostjan , Chell Graham , Popelar Carl , Luo Meng 
Published: September 2018

The graphical user interface driven engineering software tool FlawPRO™ has been extensively used for subsea pipeline design and installation under high strain or fatigue intense applications. The methodology included in the program has evolved since its inception in 2002 through a series of JIPs involving major oil and gas operators and installation contractors. This paper summarises the fracture mechanics concepts incorporated in the methodology of the latest version of FlawPRO™ and the results of an extensive full scale flawed pipe testing programme that included over 45 reeling simulations and other fracture tests performed to validate the methodology.
It is shown that the program’s crack growth predictions under large strain reeling are consistent with test data obtained from reeled pipes containing centreline flaws in over-matched welds, with the majority of the predicted results obtained using average material property data scattering around the mean 1:1 line consistent with uncertainties in the mechanical property values used in the validation. The results of an assessment of some of the reeling test data using the DNV ECA methodology (DNV-RP-F108) are also presented.
It is concluded that the FlawPRO™ methodology is consistently more accurate in assessing the test data compared with the DNV methodology which may yield some non-conservative results.
Both methodologies require suitable factors of safety or adjustments to either material and / or load inputs to maintain conservatism in applications to the pipeline projects.
Simulating the Response of Untrenched Flowlines due to Iceberg-Flowline-Soil Interaction
Authors: Pike Kenton , Blundon Andrew 
Published: September 2018

As offshore oil and gas fields mature on the Grand Banks, offshore Newfoundland and Labrador, marginal field subsea tie-backs are necessary to maintain production levels. Existing untrenched flowline lengths have been limited by the assumption that iceberg contact equates to flowline failure. However, extended tie-backs will be necessary to develop stranded resources. To potentially reduce the number of failure cases, we can consider a better definition of failure that accounts for the pipeline response due to iceberg-soil-pipeline interaction events. Reducing the failure rate from free-floating iceberg contacts alone can significantly increase safe tie-back lengths.
This paper examines the flowline response from impacts with free-floating icebergs using large deformation finite element analysis. The plane strain pipe-soil interaction response is first simulated for pure vertical loading and compared against analytical bearing capacity theory. The influence of non-associativity in the soil constitutive model is demonstrated with respect to predicting the pipe drained penetration resistance in dense sands. Oblique vertical-horizontal plane strain pipe-soil interaction is also investigated, and it is shown that the vertical penetration resistance is reduced when the pipe trajectory deviates from pure vertical, consistent with published interaction diagrams. Lastly, the fully coupled interaction scenario of free-floating iceberg-pipe-soil interaction is simulated, showing the effects of the pipe wall thickness and soil strength. The numerical modelling procedures are described and the soil constitutive model that incorporates dense sand behavior is detailed.
A Study on the Added Resistance Performance of Catamarans in Waves
Authors: Ageno Emanuela , Bonfiglio Luca , Bruzzone Dario , Vernengo Giuliano , Villa Diego 
Published: September 2018

The added resistance of a catamaran advancing in waves is investigated in the framework of a non-viscous potential theory. A linear Boundary Element Method (BEM) is used for the first order seakeeping prediction and the mean longitudinal component of the second-order steady-state force is computed by using a near-field method.
Both methods are briefly presented and preliminary validations on both a mono-hull and a catamaran are shown. A systematic analysis of the added resistance of the so-called DUT catamaran is presented highlighting the effects of the advancing speed and those of the ship-wave heading angle.
State of the Art in 3D Seismic Survey Design for Petroleum Exploration in the Arctic Regions
Authors: Munoz P. A. , Sanabria Nestor , Ocampo German , Uribe Juan , Rodríguez Luis , Parrado Roberto 
Published: September 2018

3D seismic acquisition for Petroleum Exploration in the Artic Region is typically restricted to four operational months during the winter season. The area of the survey and the acquisition parameters need to be optimized and constrained to match the narrow time frame. Seismic operations must follow environmental regulations to avoid adverse impacts to the wildlife and sensitive terrains, including lakes, rivers, abandoned meanders, and the flora able to grow in the region. No vehicles or seismic equipment is allowed to operate above them in winter regardless of their protection by the snow cover. Furthermore, only vehicles and machinery are allowed to work on the frozen tundra or over frozen lakes and rivers with grounded ice. However, the ice thickness in the frozen lakes and rivers is not capable of supporting the heavy seismic vibrator. Therefore, many source points must be relocated which finally results in irregular source point distribution over the survey acquisition area.
The conventional method to recover source points around obstructions causes a concentrated redistribution of source points in the vicinity around the obstructions. An alternative operational method to recover source positions is presented in this paper. We used different types of geophysical analysis to evaluate the proposed optimized method for source recovery including traditional geophysical attribute analysis, illumination studies and attribute analysis of seismic data acquired in the Horse Shoe 3D project.
The proposed method can be implemented in areas with significant surface obstructions, either due to environmental restrictions, population, industrial or oilfield areas, or natural obstructions, etc.
An important conclusion is that the improvement in S/N and attributes obtained by the implementation of the proposed method for source recovery did require only a marginal increase in the work volume or resources for the project and so the cost and time of execution were not affected.
Consideration of the Human Element in Cementing Operations and Well Integrity
Authors: Shenold Chad , Teodoriu Catalin , Salehi Saeed 
Published: September 2018

The recent Macondo tragedy changed the health and safety landscape throughout the petroleum industry. Through such incidents, oil well cementing operations have gained widespread attention. Detailed technical reports of the Macondo well control incident outline the significance of the competent and efficient cementing operations.
The voluntary API RP 75 standard was recently modified into the current mandatory offshore Safety and Environmental Management Systems (SEMS II) regulations. The regulatory guidelines in the United States, dormant over the past 20 years, are finally being updated to meet current industry and public expectations. The human factor, overlooked for decades in the petroleum industry, serves as the catalyst behind the newly adopted offshore regulations.
This paper provides a brief overview of well integrity, and the pivotal role of cementing operations in well control. The critical role of human and organizational factors in cementing operations and well control is addressed. Furthermore. an outline of the newly implemented SEMS II regulations is also offered, with insight into adjustments that could enhance this program’s modest requirements.
Application of Fine Water Plugging Technology With Coiled Tubing in High Water Cut Wells
Authors: Wang Jie , Zhou Fujian , Zhang Lufeng , Fan Fan , Yang Hong 
Published: September 2018

Water logging problem in late production reservoir with abundant edge-bottom water and water-gas layer stagger is one of the main factors that lead to production wells stop flow. For the water plugging problem during gas well production, the common operation is coiled tubing through casing. So, coiled tubing technology without moving production string is explored.
X oilfield is located in Sichuan basin of China southwest and belongs to the origin of gas pipeline from Sichuan to China east. Its main gas producing area is carbonatite full of edge water and controlled by structural and lithology. The relationship between water and gas is complex and water-gas system is independent of different blocks and different layers. Because the main gas producing layer is close to the water layer, lots of gas producing wells stop spray for high water cut. At the meantime, the difficulty and risk of water plugging increases for its high depth of main gas producing layer and high temperature at the well bottom.
To solve the problem above, cement slurry system with the characteristics of high temperature and sulfur resistant and channeling preventing is developed. At the same time, the cement slurry system has low friction and high liquidity and is easy to flow through the coiled tubing. Besides, cement slurry pollution is reduced and the success rate of gas well produced water plugging is improved by the combination of coiled tubing and cementing process and the construction technology optimization, software simulation and laboratory evaluation is carried out. The key step is that log analysis of water and gas distribution is done first. Then, tubing-expansion bridge plug is placed under the water layer and the cement slurry is sent to the desired location. At last, coiled tubing is put down after cement solidification and gas production is recovered.
The measurement of coiled tubing and cement slurry system is positive for water plugging in gas wells with high depth and temperature. The oilfield test results show that daily gas production is improved largely and liquid production is reduced by 90% of 4 wells with high water cut through water plugging. Besides, operation cost is reduced and the pollution problem caused by produced water is also solved, which can provide certain significance for the same type wells need water plugging operation.
Numerical Investigation of Regular Waves Interaction With Two Fixed Cylinders in Tandem Arrangement
Authors: Liu Zhenghao , Wan Decheng , Hu Changhong 
Published: September 2018

The interaction of waves with fixed or floating structures involves complex wave radiation, wave diffraction and free surface deformation. In this work, the interaction of waves with a pair of cylinders in tandem arrangement is investigated using a numerical wave tank. The numerical simulation is first validated by comparing numerical results and experimental data for regular wave interaction with a single cylinder. Wave interaction with tandem cylinders is investigated for different center-to-center distances between the cylinders.
All the numerical simulations are carried out by the in-house CFD solver naoe-FOAM-SJTU which is developed on the open source platform OpenFOAM. The incompressible unsteady Reynolds averaged Navier-Stokes (URANS) equations are adopted as the governing equations. The volume of fluid (VOF) method is applied to capture the free surface. The surface elevation around the cylinders is probed by a series of wave gauges and analyzed using transfer function. The wave forces of upstream and downstream cylinder are discussed in detail. The wave forces experienced by the tandem cylinders is highly influenced by the distance between the cylinders. The local surface elevation and the scattered wave field around the cylinders are also investigated. The results show that the present CFD solver can be an alternative tool to deal with wave-structure interactions.