bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basic Design of a Semi-Submersible Rig for Experimental Drilling of Methane Hydrate by “Harmonic Design Tool”
Authors: Taniguchi Tomoki , Yukawa Kazuhiro , Otsubo Kazuhisa , Sato Hiroshi 
Published: August 2013

For the growth of demand for utilization of the vast Japanese Economic Exclusive Zone (EEZ), Ministry of Land, Infrastructure, Transport and Tourism of Japan (MLIT) started the R&D project of offshore platform technologies in 2007. National Maritime Research Institute (NMRI) had developed the integrated design support tool, called “Harmonic design tool” for evaluating economical, safety and environmental aspects of the offshore platforms. The tool conducts conceptual design of offshore platforms for seafloor massive sulphides mining, experimental drilling of methane hydrate, combined application of food and energy production. Using the tool, basic design of semi-submersible rig type platform for experimental drilling of methane hydrate is carried out and optimum hull size, predicted steady environmental forces acting on the platform (current, wave, wind forces), thruster specification for Dynamic Positioning System (DPS) such as required thrust force, construction cost are estimated.
The purpose of this paper is to evaluate the feasibility of proposed basic design of the platform aspects of stability and position keeping ability. From results of experiments and numerical calculation, it is confirmed that the basic design of the platform proposed by the “Harmonic design tool” is appropriate.
Offloading Operability With Heading Control of Side-by-Side Moored FLNG and LNGC
Authors: Kim Hyun Joe , Kwak Hyun-Uk , Lee Jonghun , Kim Se Eun , Seo Jong Soo 
Published: August 2013

In this study, a series of model tests was performed and the effect of the heading control on the offloading operability of side-by-side moored vessels in multidirectional environments was investigated. During the tests, hawser tensions, fender loads, and relative motions between two vessels were focused, which are the key factors defining the offloading operability. Basically, the heading control is designed to maintain the FLNG (LNG FPSO)’s heading at between wind wave and swell. In the model tests, several heading angles were selected to investigate the impact of the heading control on the offloading operability, which includes the heading angles aligned with swell and between swell and wind wave. The loading conditions of the FLNG and LNGC were chosen to have a similar roll natural period, and the period of swell was also selected close to the roll natural period, which realizes an worst situation.
The model tests proved that heading control improves the offloading operability in the multi-directional environments. However, in the test, as vessel’s heading angle approaches to the direction of swell, the LNGC is exposed to wind wave as much as to increase the relative motion between the two vessels and deteriorate the offloading operability. In the model test campaign, the motion RAOs and horizontal drift forces/moment due to waves for the side-by-side moored vessels were measured and compared with the analytical calculations, which show the strong shielding effect on the wind wave by the FLNG.
Monitoring Campaign on Sub-Sea Installation
Authors: Navarro Jesus Rodriguez , van Drunen Joris , de Bruin Ruben 
Published: August 2013

The Deepwater Construction Vessel (DCV) Balder performed an one-and-half year deep water construction project in west Africa. The project started in 2010 and consists of multiple oil fields located in water depths ranging from 1800m to 2100m. Heerema Marine Contractors (the Contractor) has successfully installed a large number of sub-sea structures, flow lines and Risers. Installation procedures were optimized, new deck equipment has been installed and passive heave compensation is designed. These measures enabled the crew to achieve an excellent performance in the swell dominated seas West of Africa. To accurately capture the experiences with the new equipment and procedures, an extensive Offshore Monitoring Campaign (OMC) was performed.
To achieve this goal three areas of interest were identified:
• Lowering structures to the seabed at deepwater
• Offloading of barges alongside the DCV Balder
• Motion behavior of DCV Balder in swell environment
The objectives of the monitoring campaign were:
• Validation of the models and performance of the equipment
• Verification of the operability limits for different installation activities
• Transfer of knowledge between engineering and operations
The paper describes how the Contractor executed the different measurements and how the results from the measurements were fed back into the execution of the project. The challenges which were faced to obtain high quality measurement data will be dealt with. Finally it shows the benefits of performing full-scale measurement to engineer safe and efficient deep water operations.
Evacuation From Petroleum Facilities Operating in the Barents Sea
Authors: Jacobsen Sigurd R. , Gudmestad Ove T. 
Published: August 2013

The purpose of this paper is to examine conditions relevant to evacuation and rescue of personnel from facilities operating in the Barents Sea. The paper considers the area from the Norwegian coast to Bjørnøya (Bear Island) in the north and the new border with Russia in the east. This corresponds roughly to the area that is open for exploration and exploitation of petroleum resources in the Norwegian sector of the Barents Sea.
Pertinent meteorological observation data is collected from the Norwegian Meteorological Institute. The data is used to evaluate evacuation and rescue under the observed conditions. The probability and effect of ice accretion on vessels, in particular lifeboats, is considered. Ice accretion on lifeboats is possible and could threaten stability if the lifeboat has to ride off a storm while waiting for a weather window that allows rescue of the passengers.
Meteorological conditions in the Barents Sea are such that existing equipment like life rafts, escape chutes, davit launch lifeboats and 1st and 2nd generation standby vessels may not be appropriate for the prevailing conditions during winter. Access to reliable weather forecasts is paramount for operating in the Barents Sea. Responsible personnel onboard facilities operating in the Barents Sea should be competent in the interpretation and understanding of weather forecasts and the implications the conditions may have in an evacuation and rescue situation.
Primary Conversion Efficiency of OWC Type WECs Installed on a Large Floating Structure
Authors: Ikoma Tomoki , Masuda Koichi , Rheem Chang-Kyu , Maeda Hisaaki , Watanabe Yuka 
Published: August 2013

This paper describes the performance of wave power conversion. A large scale floating system on which oscillating water column type wave energy convertors installed is proposed and the efficiency of primary conversion of wave power is estimated.
In this paper, a boundary condition due to OWC is theoretically modeled in order to consider influence of wave energy absorption to hydrodynamic forces on the floating structure into the three-dimensional singular point distribution method based on the linear potential theory. In the modeling, a boundary condition on a free water surface and an equation of state within an air-chamber above OWC are mathematically and linearly formulated. Air-pressures and variation of water elevation within OWC areas can be simultaneously and directly solved by setting both the variables and by solving the simultaneously equations of the air-pressure and the vertical displacement.
The damper effect of OWC devices is taken into account. The validity of the prediction method proposed is proven by comparing with experimental results. There are three types of large scale wave energy platform which is a pontoon type in the paper. Each performance of the efficiency of primary conversion of wave power is estimated. It is shown that the performance is very good.
Environment–Induced Cracking in Weld Joints in Subsea Oil and Gas Systems: Part I
Authors: Dodge M. F. , Dong H. B. , Milititsky M. , Barnett R. P. , Marques V. F. , Gittos M. F. 
Published: August 2013

In subsea oil and gas systems, steel linepipes (typically API X65) have been welded to 8630M low alloy steel hubs, using a buttering technique and nickel alloy filler materials (e.g. Alloy 625). After buttering, postweld heat treatment (PWHT) is carried out to temper the heat-affected zone of the low alloy steel. However, while the vast majority of subsea joints provide successful service, a small number of in-service failures has had significant ramifications. During PWHT of the buttered joints, carbon migrates from the ferritic steel to the high alloy ‘austenitic’ weld metal. The resulting microstructures and consequent localised hardening cause sensitivity to hydrogen induced cracking.
Subsea systems employ cathodic protection (CP) using aluminium based anodes in order to prevent corrosion. However, while cathodic protection has proved successful as a means of preventing corrosion of the steel components, complications can arise due to hydrogen charging.
This paper describes the detailed characterisation of such dissimilar interfaces from several joint types, including examples recovered from the seabed after exposure under CP and newly fabricated joints, using electron microscopy, microanalysis and nanohardness testing.
Review of Approximations to Evaluate Second-Order Low-Frequency Load
Authors: de Hauteclocque Guillaume , Rezende Flávia , Waals Olaf , Chen Xiao-Bo 
Published: August 2013

The second order low-frequency loads are one of main sources of excitation for moored systems. These loads are usually decomposed into the quadratic part, contributed only by first order quantities and potential part contributed by the second order potentials. In shallow water the second order incoming and diffracted potentials give a significant contribution to the low frequency forces. Therefore, the accuracy on the determination of this parcel of the low-frequency loads is a key issue for the assessment of mooring lines and operability of systems moored in shallow water area, as for example LNG terminals.
Due to the complexity in computing the second order diffraction potential, which would involve a non-homogeneous free surface boundary condition, the so-called Pinkster approximation has been proposed. This approximation is based on the assumption that the major contribution to the potential part of low-frequency loads is given by the second order potential of the undisturbed incoming waves. The methods to compute the wave forces related to the second order potentials are based on scaling of the first order wave induced forces.
Another approximation recently formulated in Chen and Rezende consists of developing the second-order bi-frequency load into a series of different orders of the difference frequency. The potential contribution to the term proportional to the difference-frequency can be evaluated efficiently by involving an integral over a small zone on the free surface around the body.
In the present paper, the existing approximations are revisited and compared to analytical solution of exact second-order load on a vertical cylinder and for the case of floating body (LNG) in shallow water. Some guidelines in the practical use of different approximations will be derived.
Methodology for Determining Remnant Fatigue Life of Flexible Risers Subjected to Slugging and Irregular Waves
Authors: Gundersen Paul , Doynov Krassimir , Andersen Torgrim , Haakonsen Rune 
Published: August 2013

Operational experience has shown that flexible risers producing different combinations of oil, gas and water can be subjected to increased dynamic motions due to slugging — a cyclic accumulation of finite volumes of liquids at a low point of the riser (e.g. sag point of a lazy-S riser) until sufficient pressure is built up behind the slug to push the liquids up through the riser. It has been observed that the slug induced dynamic riser motions can cause riser displacements larger than those generated by moderate and some extreme waves in the absence of slugging. A major impact of the slug induced riser motions is the increased fatigue damage of the tensile wires — the cross-sectional component that most frequently defines the fatigue resistance of flexible riser systems. While international standards like ISO 13628-2 & -11 require and recommend that the effects of slug flow on riser response are considered, they provide no guidance on how to practically incorporate potential slugging effects in pipe design or analysis.
A methodology has been developed to determine the remnant fatigue life of a riser subjected to slug induced motions combined with the normally considered vessel motions and wave loading. The methodology is based on using commercially available global and local riser analysis tools. The global analysis tool is used to determine the riser response induced by continuous and regular slug loading combined with loading from different irregular waves, vessel offsets and motions. The slug loading parameters are determined through an iterative process calibrating riser displacements and frequencies with those observed in the field. The local analysis tool is used to determine wire stress transfer functions, which in turn are used to derive wire stress time series from the riser tension and curvature time histories. Stress ranges are identified through rain-flow counting applied on all the calculated stress time series and fatigue performance is estimated using the Palmgren Miner summation of damage using an appropriate wire S-N curve. In a case study, the combined slug and first order wave induced fatigue damage increased by a factor of approximately two compared to the wave induced damage alone.
This methodology can be used for: a) riser fitness for service assessments by bounding the impact of slug-induced riser motions observed in the field, and b) new riser design when slugging parameters are adequately bounded by flow assurance calculations.
Hybrid Spool to Meet Deepwater Hybrid Riser Bundle Tower Critical Design Drivers
Authors: Zhao Tao , Lee Dan , Willis Neil , Qiu Hui , Puliafito Marco 
Published: August 2013

“Vertical type” spool configuration is commonly adopted as riser base spool for deepwater field development. With increasing water depths and risers subject to harsher environments, the excessive lower riser assembly motions and slugging induced fatigue damage have emerged as the governing design criteria for deepwater riser base spool design. Conventional vertical spool has inherent shortcomings to handle such design conditions. A new “hybrid” concept is therefore proposed, which extends beyond the “traditional” spool concept by integrating both vertical and horizontal spools into a 3D configuration. It inherits the vertical spool’s strength on handling large spatial expansion and utilise the pipe-soil interaction to dampen the potential resonance caused by slug flow.
Several prototypes have been examined and the hybrid spool expansion-mechanism is discussed together with an optimisation procedure proposed. An advanced FEA technique using both Abaqus/Flexcom has been employed as part of the hybrid spool development, which consists of rigorous 3D dynamic analysis, bespoke non-linear soil interaction model and utilising the global riser dynamic behaviour. An in-house spool automation tool is developed to optimise the iterative analyses required to obtain a satisfactory hybrid spool configuration. This paper described a successful case study in recent deepwater hybrid riser bundle (multibore hybrid riser) tower development project, where the need to accommodate large lower riser assembly motion and slugging fatigue damage are the two main design drivers. This presentation provides a creative insight into this innovative technology.
Numerical Simulation of a Floater in a Broken-Ice Field: Part II — Comparative Study of Physics Engines
Authors: Metrikin Ivan , Borzov Andrey , Lubbad Raed , Løset Sveinung 
Published: August 2013

Numerical simulation of a floater in ice-infested waters can be performed using a physics engine. This software can dynamically detect contacts and calculate the contact forces in a three-dimensional space among various irregularly shaped bodies, e.g. the floater and the ice floes. Previously, various physics engines were successfully applied to simulate floaters in ice. However, limited attention was paid to the criteria for selecting a particular engine for the simulation of a floater in broken-ice conditions.
In this paper, four publicly available physics engines (AgX Multiphysics, Open Dynamics Engine, PhysX and Vortex) are compared in terms of integration performance and contact detection accuracy. These two aspects are assumed to be the most important for simulating a floater in broken ice. Furthermore, the access to code, documentation quality and the level of technical support are evaluated and discussed. The main conclusion is that each physics engine has its own strength and weaknesses and none of the engines is perfect. These strength and weaknesses are revealed and discussed in the paper.
On the Collision Safety of a Gas Fuelled 6500 TEU Container Vessel
Authors: Uhlenbrock Santiago , Scholz Benjamin , Würsig Gerd-Michael 
Published: August 2013

Scheduled international environmental regulations are resulting in an increasing interest to use Liquid Natural Gas (LNG) as fuel for ships. However, the well known potential of LNG to reduce emissions must not increase the potential risks compared to conventional fuels.
The Maritime Safety Committee has published an Interim Guidelines MSC.285(86) which includes a collision safety rule for gas fuelled vessels which requests a minimal distance of the LNG storage tanks from the ship outer shell (B/5-Rule). However, research work is needed regarding the actual crashworthiness of alternative ship designs with an LNG tank position closer to the ship shell than the B/5-Rule.
A minimum safety concept actually discussed requires that LNG fuelled vessels shall have a collision resistance at least similar to the one of LNG carriers. In the present paper a case study is presented where the collision resistance of a gas fuelled 6500 TEU Container Vessel is investigated based on the GL-Rules I-1-33. The Container Vessel has an alternative design to the B/5-Rule exploiting more cargo hold space for LNG bunckering by placing the LNG tanks at 8% of B from the side shell. The crashworthiness of the Container Vessel is compared to the one of an LNG tanker of approximately the same size.
Numerical computations indicate that the critical collision speed up to penetration of the inner hull is larger for the LNG carrier. For the more relevant case of LNG spill the Container Vessel with alternative design has an increased crashworthiness compared to the LNG tanker. It is shown that the critical collision speed for the Container Vessel is almost twice the one of the LNG tanker in case of an LNG spill.
DYPIC - Dynamic Positioning in Ice: First Phase of Model Testing
Authors: Haase Andrea , van der Werff Solange , Jochmann Peter 
Published: August 2013

DYPIC (Dynamic Positioning in Ice) is a research and development project within the MARTEC ERA-NET project of the European Union. Its objective is to contribute to the closure of the gap between DP in open water being an industry standard, and DP in ice which has some extra challenges to tackle.
Two phases of model testing in ice form the back bone of the project and are facilitated by HSVA (Hamburg Ship Model Basin, Germany). The first test phase, which was executed from May to July 2011, involved two different model ships. Both were tested in free floating mode (where the model sailed solely by its own propulsion system) and fixed mode (where the model was connected to a carriage). In the free floating mode the controlling was performed by a prototype DP system scaled to model parameters.
Four different managed ice fields with systematically varied ice concentration and ice floe size were prepared in the ice tank in order to investigate the influence of the relevant parameters. Tests were executed for several velocities and headings with respect to the approaching ice floes.
In the free floating case ice loads on the hull were derived from the measured loads on the thrusters. The behavior of the model ship was captured by the position and heading tracking system Qualisys and several installed video cameras. The fixed mode tests serve well as a reference measurement.
The results will be used to develop a model scale DP system for ice that is adjustable to different kinds of vessels and ice conditions and eventually to develop testing procedures for the assessment of the DP performance of a vessel in managed ice. A second phase of model testing for fine tuning and benchmarking the developed system will be carried out in August 2012.
Within the scope of the paper is the description of the performed tests speaking of test setup and ice conditions. Analyses of results are not covered.
Higher-Harmonic Response of a Slender Cantilever Beam to Fully Nonlinear Regular Wave Forcing
Authors: Bredmose Henrik , Schløer Signe , Paulsen Bo Terp 
Published: August 2013

The higher-harmonic response of a vertical cantilever beam to fully nonlinear wave loads is investigated. Such responses are also known as ‘ringing’ and is of practical interest in the context of offshore wind turbine foundations which, in contrast to the classical incidents of ringing at deep water, are placed at intermediate or shallow water.
The purpose of the study is to provide generic results which can be of later use for the interpretation of more complex cases of irregular wave forcing. To this end, the problem parameters are defined and reduced by dimensional analysis. A simple numerical model is proposed, based on linear beam theory and fully nonlinear regular stream function waves. The hydrodynamic forces are determined from the extended Morison equation.
Parametric studies of the response dependence to relative forcing period, wave height and depth are presented and discussed. A central finding of the paper is that for waves of 85% maximum height, the third-harmonic response increases substantially when the depth is reduced from deep-water conditions into intermediate depth.
High Toughness API 5L X70MS Pipe Grade Development for Deep and Ultradeep Water Application
Authors: Ponciano Marcos , Chad Luis Claudio C. , Teixeira Marcelo Jose B. , de Abreu Lima Vinicius R. , Ferreira Helder Heleno , Ribeiro Monica C. Riccio 
Published: August 2013

The offshore deep and ultra deep water explorations summed to the distant points of the Brazilian coast bring to national industry important technological challenges. Considering production and transportation need of large volumes of natural gas and oil in a safe condition from offshore installations, the use of large diameter steel pipes produced by UOE-SAWL process is an important alternative and already applied in some important projects. However, due to the hostile environment in which the new fields are placed, it is necessary to develop new products in order to meet the rigorous mechanical properties and Sulfide Stress Cracking (SSC) and Hydrogen Induced Cracking (HIC) resistance requirements. This work presents the evaluation of mechanical properties and SSC resistance of OD 20 inches, WT 25,4 mm APL 5L X70MS line pipe, for both pipe material and girth weld joints.
For this work, plates were produced with very restrict metallurgical control, including chemical control and state of art rolling as Thermo-Mechanical Controlled Process with Accelerated Cooling — TMCP-ACC. Very good CHARPY and CTOD values were achieved at −20°C and −40°C respectively, in both conditions, and the pipes presented good (SSC and HIC) resistance even for the girth weld joint performed with a low and high heat inputs simulating the range of conditions that an operator would find in offshore welding operations.