bluuebunny/crossref_metadata_2025 huggingface dataset:
Ocean Current Profiles for Subsea Installation and Design Analysis
Authors: Hagen O̸istein , Mo̸rk Kim J. , Eide Lars Ingolf
Published: May 2009

The paper describes different strategies for establishing current design profiles from sea bed to water surface, for use in analysis of subsea installation activities, e.g. during a pipe laying process or for dynamic analysis of risers. Measured data covering a period of 3–4 years for more than 20 measurement depths are used in the study. We investigate 4 strategies for depth profiles: General Purpose Profile: an envelope of the set of n-year speeds for individual depths, with unidirectional current at all depths. Empirical Event Profile: essentially a measured current profile which is deemed to be “serious,” i.e. potentially governing for design, scaled to adequately reflect a required return period. Whether a profile is “serious” or not would depend on the application. Response Based Profile: defined as the most probable profile causing an extreme response. It is obtained from design point current speeds from a reliability analysis of a selected response, while applying a detailed stochastic current model. Alternatively, an envelope of most probable profiles might be used.
The Impact of Stress Redistribution on Structural Reliability Predictions of Deepwater Jackets
Authors: Schneider Ronald , Sanderson David J. , Thurlbeck Simon D.
Published: May 2009

Structural reliability predictions for fixed jacket structures often involve calculating the probabilities of structural members failing and the overall collapse probabilities of the jackets existing in the corresponding damaged condition. It is current best practice to consider only single member failure conditions and to ignore multi member failure conditions since the probability of more than one member failing has been considered to be negligibly small. This approach assumes that the failure of a member is in no way related to the failure of another member, which implies that the two events are statistically independent. However, in reality the two events are not statistically independent since the failure of one member changes the stress state and therefore the failure probability of the remaining members. Two studies conducted to investigate the effects of stress redistribution on platform reliability predictions concluded that, by ignoring the effects of stress redistribution, platform reliability predictions could be significantly overestimated. However, they both concentrated on shallow water jackets and consequently a further study was performed to extend the existing work on stress redistribution to consider jacket structures in greater water depths. The study considered single and dual member failure conditions and compared the effects of including and excluding stress redistribution in reliability calculations. The findings of this work suggest that including stress redistribution reduces the predicted platform reliability. From the results, generic correction factors were derived for different inspection intervals, which account for stress redistribution and dual member failure. These correction factors can be applied to the probabilities derived using current best practice to determine a more realistic estimate of a structure’s reliability.
Generation of Large Angle Bimodal Sea States Using a Single Segmented Wavemaker
Authors: Roux de Reilhac P. , Bonnefoy F. , Ferrant P.
Published: May 2009

In the present work we study the capabilities of a single segmented wavemaker to generate multidirectional sea states. We want to reproduce typical West Africa sea conditions in a rectangular basin, that is two spectra representing swell and wind waves with ±45 degrees main directions relative to the axis basin. To that extent we study two generation techniques proposed respectively by Dalrymple and Molin which relie on the control of sidewall reflections in order to enlarge the testing zone. Both numerical and experimental results show that the use of such methods in combination with a single wavemaker provides high quality wavefields as well as large extent testing area. The Molin method appears to be more efficient in terms of wavefield quality within the testing area although the tuning of its setting parameters requires more care than the Dalrymple method.
Probabilistic Analysis of Hull Girder Stresses Using an Analytical Approach Verified by the Monte Carlo Simulation
Authors: Ivanov Lyuben D. , Wang Ge , Foster Joe
Published: May 2009

The paper presents a probabilistic study of the hull girder bending stresses using an analytical approach verified by the Monte Carlo simulation method. Comparison of these two approaches was performed for the calculations of the still water, wave-induced and total bending moments and the deck stresses. The analytical methods are simple for application, especially when the application of Monte Carlo simulation requires an excessively long computational time, especially in the asymptotic tails of the probabilistic distributions of loads and stresses that are most important for assessing the hull structure reliability.
Application of Constraint Multi-Objective Optimization to the Design of Offshore Structure Hulls
Authors: Birk Lothar
Published: May 2009

The paper reports on the continuous development of an automated optimization procedure for the design of offshore structure hulls. Advanced parametric design algorithms, numerical analysis of wave-body interaction and formal multi-objective optimization are integrated into a computer aided design system that produces hull shapes with superior seakeeping qualities. By allowing multiple objectives in the procedure naval architects may pursue concurrent design objectives, e.g. minimizing heave motion while simultaneously maximizing deck load. The system develops a Pareto frontier of the best design alternatives for the user to choose from. Constraints are directly considered within the optimization algorithm thus eliminating infeasible or unfit designs. The paper summarizes the new developments in the shape generation, illustrates the optimization procedure and presents results of the multi-objective hull shape optimization.
A Maneuvering Test Platform Conceptual Design
Authors: Levi Carlos Antoˆnio , Pinto Waldir Terra , Gomes Sebastia˜o C. P. , Sales Junior Joel Sena , da Costa Paulo Roberto , Matter Gerson Beraldo , Miliante Thiago Reis , da Rosa Vagner Santos , Gervini Vitor Irigon
Published: May 2009

This work discusses the conceptual design of a maneuvering test platform to be installed at the LABOCEANO ocean basin. The platform features a 35m long main bridge, crossing over the whole basin width. A secondary trolley runs along the main bridge, connected to the model. The combination of the bridge and trolley motions can impose a very flexible range of trajectories to the model. The trolley will be equipped with special devices which enable the imposition of harmonic motion up to four degrees of freedom simultaneously. The platform technical specification includes longitudinal and transversal velocities up to 1 m/s, acceleration up to 0.2 m/s, and maximum trajectory diameter of 26m. The amplitude and frequency of the forced harmonic motion may read 0.5 m and 0.2 Hz for surge and sway; 0.15 m and 2 Hz in heave; 10 degrees and 2 Hz in roll and pitch; and 30 degrees and 0.5 Hz in yaw. The work features a general description of the platform design with special emphasis in the structural, mechanical, control and safety aspects.
Microhole Coiled Tubing Drilling: A Low Cost Reservoir Access Technology
Authors: Perry Kent F.
Published: May 2009

Although The Microhole Coiled Tubing Drilling rigs have been used extensively in Canada, their application in the U.S. has been very limited. In an effort to introduce this technology to the U.S. operators; GTI, with the support of DOE/NETL has completed successful field testing of coiled tubing microhole drilling technology. In this paper we report results of field testing of the system in 25 wells drilled in the Niobrara unconventional gas play of Kansas and Colorado. The objective of the field test was to measure and document the rig performance under actual drilling conditions. In these tests, a coiled tubing drilling rig (designed and bulit by Tom Gipson with Advanced Drilling Technologies Inc. (ADT)) was utilized. The rig operations have continued to improve to the point where it now drills a 3,100-foot well in a single day. Well cost savings of approximately 30% over conventional rotary well drilling have been documented. A description of the rig and a summary of its performance in the Niobrara unconventional gas play are included. In addition, an estimate of economic advantages of widespread application of microhole drilling technology in the Lower 48 States is presented.
Floatover Deck Installation on Spars
Authors: Edelson David , Halkyard John , Chen Liyong , Chabot Luc
Published: May 2009

Deck installation is always a major installation challenge for floating structures, particularly deep draft floaters like the spar which must be installed in relatively deep water. Derrick barges have been used for spar deck installations until now. The 4000 mt deck for the Kikeh Spar was successfully installed using the floatover method in November 2006, off the coast of Sabah in the South China Sea. This demonstrates the feasibility of this concept and opens the door for more floatover decks on spars in the future. This paper will review the technical challenges associated with this type of installation. In particular, the authors will review past studies, which included analysis and model testing of similar deck floatovers for decks up to 30,000 t, and the analysis methods use to validate the procedures and equipment which was successfully used on the Kikeh project. The requirements for application of this technology in the Gulf of Mexico will be highlighted.
Marine Current Turbines: Moving From Experimental Test Rigs to a Commercial Technology
Authors: Fraenkel Peter L.
Published: May 2009

This presentation will discuss the background to the development of Marine Current Turbines Ltd’s pioneering technology for the exploitation of tidal stream energy. This will include details of: • the 1994, 15kW Loch Linnhe “Proof of Concept” Project, and earlier work, • the 300kW 2003 Seaflow Project, • the present 1.2MW Seagen Commercial Demonstrator Project, • future plans for scaled up “Second Generation” technology to follow Seagen. The paper will then give the rationale and an outline of the essential features of MCT’s technology and an overview of the predicted performance and economics of the planned commercial technology together with an indication of MCT’s time-line for its development. The discussion will cover nontechnical issues such as consent requirements (and environmental impact issues) and an outline of MCT’s Business Plan and how it is to be implemented.
Global and Structural Performance of a TEMPSC in Pressured Ice
Authors: Igloliorte Gareth , Kendrick Andrew , Fredj Abdelfettah
Published: May 2009

In the winter of 2002 BMT Fleet Technology undertook a full scale test program as part of a Joint Industry Project to assess the survivability of a Totally Enclosed Motor Propelled Survival Craft (TEMPSC) in ice covered water. The project was provided a Schat-Harding KISS 800 TEMPSC that was subsequently outfitted with a set of instrumentation to measure strain, hull deflection, heave, pitch and roll of the hull. The TEMPSC was launched in Northumberland Strait between PEI and Nova Scotia. Strain and deflection data was successfully recorded for a period of 9 days, which included several significant pressure events. After the completion of the trials, a non-linear finite element model of the TEMPSC was developed, using material properties developed from destructive testing of the TEMSPC. The model was used to estimate the line loads placed on the hull and to investigate the role of the hull construction in the TEMPSC’s ability to resist ice loading during pressure events. This paper discusses the general conduct of the trials and the findings from both the trials measurements and the finite element model.
Polyamide 11 in Offshore Conditions: Hydrolytical Ageing, Mechanical Behaviour in Flexible Pipes
Authors: Hochstetter G. , Amouroux N. , Hugon L. , Dang P. , Werth M.
Published: May 2009

The polyamide 11 is in use since more than 30 years in offshore applications, in particularly for the manufacturing of the pressure sheath in flexible pipes.
Hydroelastic Tailoring of Composite Naval Propulsors
Authors: Young Yin Lu , Liu Zhanke
Published: May 2009

Recently, there is an increased interest to use composites as alternative materials for naval structures. In addition to the important advantage of weight reduction, the deformation of the structure can be tailored to improve the hydrodynamic and/or elastodynamic performance. For naval propulsors in particular, hydroelastic tailoring can help to reduce load variations, delay cavitation inception, and improve propeller efficiency by allowing each blade to automatically adjust its shape with the local inflow. In this work, a coupled boundary element method (BEM)-finite element method (FEM) is presented for the hydroelastic analysis of flexible composite propellers in wake inflow. An overview of the formulation for both the fluid and solid domains, and the fluid-structure interaction algorithms are presented. Experimental validation studies are shown for two 0.6096 m (24 inch) model-scale composite propellers: a flexible composite propeller and a rigid composite propeller. The deformed shape of the flexible composite propeller was designed to match the rigid propeller so both propellers yield the same thrust and efficiency under the design condition. The propellers were manufactured by A.I.R. Fertigung-Technologie GmbH and designed in cooperation with the Naval Surface Warfare Center Carderock Division (NSWCCD). The experimental studies were conducted by NSWCCD. The numerical predictions compared well with experimental measurements. Additional numerical results were also shown for a different rigid and flexible composite propeller pair using the same strategy. Both steady (open water flow) and unsteady (wake inflow) results show that the flexible composite propeller achieved higher efficiency than the rigid propeller at off-design conditions by tailored load-dependent deformations that changes with the local inflow. Moreover, the enhancement in propeller efficiency due to load-dependent deformations increases when the operating condition is moved further away from the design condition for both open water inflow and wake inflow.
Reliability Assessment and Management Lessons From Hurricane Katrina
Authors: Bea Robert
Published: May 2009

Hurricane Katrina disclosed a wide variety of flaws and defects that were embedded in the flood protection system for the greater New Orleans area (NOFPS). One of the primary reasons for this catastrophe was failure in risk assessment and management (RAM). Based on results from several extensive forensic studies, this paper details how RAM failed. Critical limitations in current RAM methodologies and results intended to help rehabilitate and further develop the NOFPS are highlighted. Recommendations are advanced to address these limitations.
Investigation of Carbon Budget Around Artificial Upwelling Generator by a Coupled Physical-Biological Model
Authors: Tabeta Shigeru , Yoshimoto Haruki
Published: May 2009

There are several projects of generating upwelling by artificial structures to enhance the primary production expecting fish catch increase. From the view point of global environment, CO2 budget between atmosphere and ocean due to such technologies are also interesting. In this study, a coupled physical-biological model was developed to simulate the nitrogen and carbon cycles around artificial upwelling generator. The model is focusing on the degradation of particulate organic matter, because the process should much affects on the efficiency of the biological pump. The model is tuned by using the experimental data and applied to simulate the material cycle in the target area which is located north of Ikitsuki Island located northwest of Kyusyu, Japan, where an artificial seabed mound is installed to generate upwelling. The long-term carbon budget is also estimated by vertical one-dimensional ecosystem model using the parameters determined from the results of the three-dimensional coupled physical-biological model.
The Effect of Directionality on Northern North Sea Extreme Wave Design Criteria
Authors: Ewans Kevin , Jonathan Philip
Published: May 2009

The characteristics of hindcast data for extreme storms at a Northern North Sea location are shown to depend on storm direction, reflecting storm strength and fetch variability. Storm peak HS over threshold is modelled using a generalised Pareto distribution, the parameters of which are allowed to vary smoothly with direction using a Fourier form. A directionally-varying extreme value threshold is incorporated. The degree of smoothness of extreme value shape and scale with direction is regulated by roughness-penalised maximum likelihood; the optimal value of roughness selected by cross-validation. The characteristics of 100-year storm peak HS, estimated using the directional model differ from those estimated when ignoring the directionality of storms. In particular, the extreme right hand tail of omnidirectional HS100 is longer using the directional model, indicating in this case that ignoring directionality causes underestimation of design criteria. Although storm peak data alone are used for extreme value modelling, the influence of a storm, in directional design sectors other than that containing its storm peak direction, is incorporated by estimating the storm’s directional dissipation directly from the data. An automated approach to selection of directional design sectors is described. Directional design criteria are developed using three different approaches, all consistent with an omni-directional storm peak HS non-exceedence probability of 0.5. We suggest a risk-cost criterion, which minimises design cost for a given omni-directional design specification, as an objective basis for optimal selection of directional criteria.
Using a Netting Geometry Simulator to Develop Smart Fishing and Smart Gear
Authors: Takagi Tsutomu , Shimizu Takashi , Suzuki Katsuya , Korte Holger
Published: May 2009

As fishing gear consists mainly of netting and rope, and lacks a definite geometry of its own, external forces acting on the netting and other rigging determine its geometry. The underwater geometries and loads of most fishing gear cannot be grasped in detail. However, the versatile simulation technique that we have developed for fishing gear allows us to understand the physical properties of dynamic fishing gear underwater. This will allow companies to design optimal fishing gear, based on scientific research and avoiding empirical procedures. In addition, it will allow fishermen to evaluate and improve their standard operating techniques, and to develop optimal techniques. The calculation model assumes that the net consists of lumped point masses that are interconnected by mass-less springs. The equations of motion of these point masses can be expressed in a local coordinate system, which simplifies the treatment of the hydrodynamic forces acting on each mass using the inertia transformation algorithm. The computer simulation not only estimates the overall shape of fishing gear but also its mesh geometry, the tension on the netting, and the impact force on the sea bed. This will allow the development of smart gear and smart fishing. Users will be able to develop and operate fishing and aquaculture gear based on a sound understanding of the physical parameters, and design gear that is economical, efficient to operate, and less harmful to the ecosystem. In this paper, we introduce the net geometry simulation system (NaLA) and discuss how to apply the system to developing smart gear and smart fishing.
The Effects of Tank Sloshing on LNG Vessel Responses
Authors: Lee S. J. , Kim M. H. , Lee D. H. , Shin Y. S.
Published: May 2009

The coupling and interactions between ship motion and inner-tank sloshing are investigated by a potential-viscous hybrid method in time domain. For the time domain simulation of vessel motion, the hydrodynamic coefficients and wave forces are obtained by a potential-theory-based 3D diffraction/radiation panel program in frequency domain. Then, the corresponding simulations of motions in time domain are carried out using the convolution-integral method. The liquid sloshing in a tank is simulated in time domain by a Navier-Stokes solver. A finite difference method with SURF scheme assuming the single-valued free surface profile is applied for the direct simulation of liquid sloshing. The computed sloshing forces and moments are then applied as external excitations to the ship motion. The calculated ship motion is in turn inputted as the excitation for liquid sloshing, which is repeated for the ensuing time steps. For comparison, we independently developed a 3D panel program for linear inner-fluid motions and it is coupled with the vessel motion program in the frequency domain. The developed computer programs are applied to a barge-type FPSO hull equipped with two partially filled tanks. The time-domain simulation results show reasonably good agreement when compared with MARIN’s experimental results. The frequency-domain results qualitatively reproduce the trend of coupling effects but the peaks are in general over-predicted. It is seen that the coupling effects on roll motions appreciably change with filling level. The most pronounced coupling effects on roll motions are the shift or split of peak frequencies. The pitch motions are much less influenced by the inner-fluid motion compared to roll motions.
High Accuracy Flow Rate Measurements: An Entire Multiphase Solution at the Well Site
Authors: Pinguet Bruno , Guieze Paul , MacWilliam Dave , Martin Brad
Published: May 2009

Representative reservoir fluid sampling and characterization has become increasingly important over the years. With exploration, appraisal and development activities moving into marginal fields and more challenging environments, accurate fluid characterization becomes more critical. This can be said for the formation tester, DST and multiphase sampling and fluid characterization environments with the most challenging area in recent years arguably being the multiphase environment. Multiphase flow meters have been accepted for several years now by the industry. Their use in permanent or well testing applications has been growing rapidly. In many cases, multiphase flow meters have replaced the separator for flow rate evaluation, but some fundamental needs from the client were not addressed properly, such as the ability to collect representative samples for phase-behavior characterization. Moreover, metering accuracies has been questionable in many cases (at very high GVF or in wet gas conditions, high pressure or /and high temperature).This paper focus on the Multiphase Active Sampling Device Service (MASS), a fluid sampling and analysis service that can be provided with the Vx multiphase metering technology with the objective of collecting representative samples, isolating and analyzing each fluid phase, and providing data from the analysis to input to the Vx acquisition software data to obtain more accurate flow rates. The collection of phase representative samples also opens the opportunity for a full recombination PVT study to be performed using the improved recombination ratio at line conditions from the multiphase flow meter. This dedicated multiphase fluid sampling and analysis system, combined with Vx technology provides flow rate better and fluid property than to a conventional test separator system.
Modelling and Investigation of Competition for Space and Food Among Blue Mussels in Tokyo Bay
Authors: Kitazawa Daisuke , Fujimoto Shuhei
Published: May 2009

A mathematical model is developed to describe the competition for space and food among blue mussels, which adhere on cylindrical substrata. In order to develop and validate the model, field investigation is carried out for mussels growing on ropes installed around the mouth of Sumida River in Tokyo Bay. In addition to monitoring of environmental factors such as water temperature, salinity, and the concentration of dissolved oxygen, the relationship between the position of each mussel and its size in the mussel bed is examined precisely. The position of each mussel in the bed is specified by how much the gape of the shells comes out from the bed. As a result, the growth of the mussels in the inner layer is obviously slow and they are considered to continue living by consuming the reserved materials accumulated in their bodies. On the contrary, mussels can grow faster if only a part of the gape of their shells comes out from the mussel bed. These observed features are taken into account in the mathematical model. The model can predict well the size structure of mussels in the bed; the faster growth of the surface mussels and the slower growth of the inner mussels, which corresponds to observations. In the future the model will be also applied to mussels on the cylindrical substrata such as cultivation ropes, piers, and piles for aquaculture management and environmental impact assessment of the coastal structures.
Research on System Management Corresponding to Natural Damage in Marina
Authors: Koizumi Yusuke , Kondo Takeo , Yamamoto Kazukiyo , Hashikawa Takashi
Published: May 2009

There are about 500 places marinas in Japan. In late years it is got close to many people as marine recreation space. However, there are problems in our country with many disasters because there is much damage such as a typhoon and high tide, a tsunami. This study is aimed at grasping the natural disaster damage, the regime situation. Therefore I performed a questionnaire and listening comprehension investigation for a marina. As a result, it is the present conditions that there is the anti-disaster measures manual which original, few marinas make. In addition, at the time of a disaster, a support system system on a fund side for the damage of a marina is not made clear. I will think that rebuilding of a system to manage, substantiality of a support system are necessary in future to make a marina good air space.
Laboratory Investigation on Response Behaviour of SeaStar Mini Tension Leg Platform Against Regular Water Waves
Authors: Ketabdari Mohammad Javad , Ardakani Hamid Alemi , Ardakani Mohammad Alemi
Published: May 2009

Among the compliant platforms, TLP is a vertically moored structure with excess buoyancy, used for deep water oil exploration. In this structure tethers can be tensioned to such an extent that heave, roll and pitch motions of the platform induced by ocean waves are virtually eliminated. SeaStar is new generation of mini tension leg platforms which is similar to a spar and has favorable response features of a TLP. This paper illustrates the results of experimental work performed on a 1/100 scaled model of SeaStar TLP in a wave flume. The investigation refers to the induced tension in different tendons of the model and the motion response behaviour of the model on different degrees of freedom under several directional impinging regular water waves. The results are presented in the frequency domain and the response amplitude operator for each motion of the platform has been calculated.
Experimental Study on the Response Behaviour of SeaStar Mini Tension Leg Platform Against Random Water Waves
Authors: Alemi Ardakani Hamid , Ketabdari Mohammad Javad
Published: May 2009

Among the compliant platforms, TLP is a vertically moored structure with excess buoyancy, used for deep water oil exploration. In this structure tethers can be tensioned to such an extent that heave, roll and pitch motions of the platform induced by ocean waves are virtually eliminated. SeaStar is new generation of mini tension leg platforms which is similar to a spar and has favorable response features of a TLP. This paper illustrates the results of experimental work performed on a 1/100 scaled model of SeaStar TLP in a wave flume. The study refers to the induced tension in different tendons of the model and the motion response behaviour of the model on different degrees of freedom under several directional impinging random water waves. The results are presented in the frequency domain and the response amplitude operator for each motion of the platform has been calculated.
The Fundamental Study on the Optimum Design of Shrimp Pot for the Coon-Stripe Shrimp (Pandalus Hypsinotus Brandt) in Hokkaido
Authors: Kim SeongHun , Yamamoto Katsutaro , Hiraishi Tomonori , Lee JuHee
Published: May 2009

This study was conducted to develop an optimally designed pot that is capable of controlling catch selectively. To achieve the optimum design for the shrimp pot, tank experiments were conducted to investigate the catch mechanism and catch selectivity of differently shaped pots. In this study, the catch selectivity of pots was estimated with different slope lengths. The experiments were conducted using model shrimp pots with five different slope lengths (24, 34, 44, 54, and 64cm) in an experimental tank (2 m × 2 m × 1 m). The catch mechanism was analyzed through a video recording system and catch selectivity was estimated using the SELECT model and master curve method. Two models using the likelihood ratio test and Akaike’s information criterion (AIC) evaluated the goodness of fit of the selectivity curve. That results, the slope length with 50% retention of individuals with carapace length of 25 mm (about 1 year old) was 60.1cm, which is about 16 cm longer than the commercial pot design.
Basin Analog Investigations Answer Characterization Challenges of Unconventional Gas Potential in Frontier Basins
Authors: Singh Kalwant , Holditch Stephen A. , Ayers Walter B.
Published: May 2009

To meet the global energy demand of the coming decades, the energy industry will need creative thinking that leads to the development of new energy sources. Unconventional gas resources, especially those in frontier basins, will play an important role in fulfilling future world energy needs. To develop unconventional gas resources, we must first identify their occurrences and quantify their potential. Basin analog assessment is a technique that can be used to rapidly and inexpensively identify and quantify potential unconventional gas resources. We have developed a basin analog methodology that is useful for rapidly and consistently evaluating the unconventional hydrocarbon resource potential in exploratory basins. The center of this approach is computer software, Basin Analog Systems Investigation (BASIN), which is used to identify analog basins. This software is linked to a database that includes geologic and petroleum systems information from intensely studied North America basins that contain well characterized conventional and unconventional hydrocarbon resources. To test BASIN, we selected 25 basins in North America that have a history of producing unconventional gas resources and began populating the database with critical data from these basins. These North American basins are “reference” basins that will be used to predict resources in other North American or international “target” or exploratory basins. The software identifies and numerically ranks reference basins that are most analogous to the target basin for the primary purpose of evaluating the potential unconventional resources in the target basin. We validated the software to demonstrate that it functions correctly, and we tested the validity of the process and the database. Accuracy of the results depends on the level of detail in the descriptions of geologic and petroleum systems. Finding a reference basin that is analogous to a frontier basin may provide critical insights into the frontier basin. Our method will help predict the unconventional hydrocarbon resource potential of frontier basins, guide exploration strategies, provide insights to reservoir characteristics, and help engineers make preliminary decisions concerning the best practices for drilling, completion, stimulation and production.
Ice Blockage Tests With a Podded Propulsor: Effect of Recess
Authors: Sampson R. , Atlar M. , Sasaki N.
Published: May 2009

Propeller ice interaction is a complex phenomenon, which relies on innovative and complex experimental research in dedicated ice tank facilities. Whilst ice tanks model the contact forces with good agreement, the possible effect of the cavitation on the hydrodynamic propulsor loading is often assumed due to the inability to scale atmospheric pressure during these experiments. This paper reports on tests performed in the Emerson Cavitation Tunnel (ECT) examining effect of performance of an ice class propulsor operating in an ice cavity (or recess), a typical phase of bollard pull manoeuvres of podded icebreakers. The findings reported herein are part of a PhD study into the phenomenon and represent the early analysis of the findings. Further analysis is ongoing to better understand the phenomena.
Numerical Simulation of Offshore Pipeline Installation by Lateral Deflection Procedure
Authors: da Silva Danilo Machado Lawinscky , Bahiense Rodrigo Almeida , Jacob Breno Pinheriro , da Silva Torres Fernando Gomes , Medeiros Antonio Roberto , Vaz da Costa Marcos Nadalin
Published: May 2009

Conventional offshore pipeline installation operations in Brazil have been performed in an S-Lay procedure employing the BGL-1 barge, owned by Petrobras. However, this procedure has some limits, and may not be feasible in some particular scenarios. Therefore, the objective of this work is to present the numerical simulation of an alternative pipeline installation procedure. This procedure basically consists of performing the pipeline assembly on shore, and deflecting it to the sea using a tug boat. The numerical simulations employ the SITUA-Prosim computational tool, which is able to incorporate the correct definition of the seabed and shore from bathymetric curves. An actual pipeline installation by this lateral deflection procedure is analyzed and discussed. The characterization of the procedure passes through the determination of the better velocity and direction of the tug boat in order to minimize the efforts on the pipeline (especially due to the curvatures).
Laboratory Simulation of Drill Bit Dynamics Using a Model-Based Servo-Hydraulic Controller
Authors: Raymond David W. , Elsayed M. A. , Polsky Yarom , Kuszmaul Scott S.
Published: May 2009

Drilling costs are significantly influenced by bit performance when drilling in off-shore formations. Retrieving and replacing damaged downhole tools is an extraordinarily expensive and time-intensive process, easily costing several hundred thousand dollars of off-shore rig time plus the cost of damaged components. Dynamic behavior of the drillstring can be particularly problematic when drilling high strength rock where the risk of bit failure increases dramatically. Many of these dysfunctions arise due to the interaction between the forces developed at the bit-rock interface and the modes of vibration of the drillstring. Although existing testing facilities are adequate for characterizing bit performance in various formations and operating conditions, they lack the necessary drillstring attributes to characterize the interaction between the bit and the bottom hole assembly (BHA). A facility that includes drillstring compliance and yet allows real rock/bit interaction would provide an advanced, practical understanding of the influence of drillstring dynamics on bit life and performance. Such a facility can be used to develop new bit designs and cutter materials, qualify downhole component reliability, and thus mitigate the harmful effects of vibration. It can also serve as a platform for investigating process-related parameters which influence drilling performance and bit-induced vibration to develop improved practices for drilling operators. Sandia National Laboratories is pursuing the development of an advanced laboratory simulation capability which allows the dynamic properties of a BHA to be reproduced in the laboratory. This simulated BHA is used to support an actual drill bit while conducting drilling tests in representative rocks in the laboratory. The advanced system can be used to model the response of more complex representations of a drillstring with multiple modes of vibration. Application of the system to field drilling data is also addressed.
On the Transient Response of a Two-Dimensional Floating Runway During Airplane Take-Off
Authors: Xia Dingwu , Ertekin R. Cengiz
Published: May 2009

The transient response of a two-dimensional floating runway subject to dynamic moving load due to airplane landing and take-off is studied in this paper. This hydroelastic problem is formulated by directly coupling the structure with fluid, by use of the Level I Green-Naghdi theory for the fluid motion and the Kirchhoff thin plate theory for the runway. The coupled fluid-structure system, together with the appropriate jump conditions are solved by the finite difference method. The results, including hydroelastic deformation of the runway and the drag force on the airplane are predicted and compared with the available results. Favorable agreements are observed. Parametric studies are carried out to identify the important factors for the design of floating runways.
Challenges for Offshore Transport of Anthropogenic Carbon Dioxide
Authors: Race Julia M. , Seevam Patricia N. , Downie Martin J.
Published: May 2009

Carbon Capture and Storage (CCS) is recognised as having a significant role to play in reducing carbon dioxide emissions and tackling climate change. In CCS schemes, carbon dioxide is captured from anthropogenic sources and transported to suitable sites either for EOR (Enhanced Oil Recovery) or storage. Globally, the largest source of CO2 is from power generation, therefore the initial projects proposed for CCS in the UK are from power plant. There are various technologies for capturing CO2 from power stations, however the captured CO2 can contain significant amounts of impurities. The presence of the impurities in the CO2 stream has an effect on the requirements for pipeline transportation and can change such factors as the flow properties, the decompression characteristics and the solubility of water in the mixture. Although transport of CO2 by pipeline is not new technology, and has been implemented in the USA for over 30 years, the effect of these impurities is not fully understood. The UK is in the advantageous position of having natural sinks for CO2 available offshore in the North and Irish Sea, which can be used for either EOR or storage. Therefore CCS implementation in the UK will involve transport of anthropogenic carbon dioxide from power stations to offshore sinks. All of the current experience with CO2 pipeline transport has been onshore, predominantly from near pure natural sources and therefore this is also a new challenge. This state-of the-art review paper will: • discuss the key technical factors presented by the transport of CO2 from power plant, including the effects of impurities on the design and operation of pipelines, • compare and contrast the current experience of transporting CO2 onshore with the proposed transport onshore and offshore in the UK and identify the technical and regulatory challenges, • present the results of initial modelling work to demonstrate the effects of the key variables on the development of a CO2 transport system in the UK.
Numerical Study of the Wave Impact on a Square Column Using Large Eddy Simulation
Authors: Pedro H. T. C. , Leung K.-W. , Kobayashi M. H. , Riggs H. R.
Published: May 2009

This work concerns the numerical investigation of the impact of a wave on a square column. The wave is generated by a dam break in a wave tank. Two turbulence models were used: Large Eddy Simulations (LES) and Unsteady Reynolds Averaged Navier-Stokes (URANS). The numerical simulations were carried out using a finite volume approximation and the SIMPLE algorithm for the solution of the governing equations. Turbulence was modeled with the standard Smagorinsky-Lilly subgrid-model for the LES and the standard κ-ε model for the URANS. The results are validated against experimental data for the wave impact on a square column facing the flow. The results, especially for LES, show very good agreement between the predictions and experimental results. The overall accuracy of the LES, as expected, is superior to the URANS. However, if computational resources are limited, URANS can still provide satisfactory results for structural design.
Exothermic Additions in a Tubular Covered Electrode and Oxidizing Reactions Influence on Underwater Wet Welding
Authors: Pessoa Ezequiel C. P. , Bracarense Alexandre Q. , Liu Stephen
Published: May 2009

During Underwater Wet Welding (UWW), the water that surrounds the arc decomposes liberating large amount of hydrogen and oxygen. As a consequence of the presence of these gases in the arc atmosphere and weld pool, porosity in the weld metal occurs. In the past years, many research programs had been carried out with the objective to reduce or eliminate porosity in wet welds. A simple way to accomplish this goal is using chemical elements or ingredients to promote or avoid certain chemical reactions in the weld pool. In conventional stick (shielded metal arc - SMA) electrodes, it is possible to add alloying elements or other ingredients through the external covering. A tubular covered electrode (TCE) (a hybrid process between SMA and flux cored arc - FCA welding) allows the addition of reactive elements in the hollow rod, separate from the other ingredients used in the flux covering. This way, it is possible to use exothermic elements, placed inside the tube, to control the oxidation reactions, but limiting these reactions to the arc plasma and in the weld pool. Exothermic additions in welding consumables can promote desirable oxidation reactions, change the metal transfer mode, reduce the cooling rate, and decrease the electrical dependence of the welding process. Theoretically, the application of flux cored shielded metal arc (FC-SMA) welding with exothermic additions will permit better control the weld metal composition and reduce the porosity in wet welds. This paper describes underwater wet welding with tubular covered electrodes that contain exothermic additions such as (CaC2) and aluminum (A1), and the influence of these ingredients on weld metal composition and porosity.
Bit Dysfunction Characterization Using a Sensor System at the Bit
Authors: Teodorescu Sorin G. , Sullivan Eric C. , Pastusek Paul E.
Published: May 2009

Drilling operations represent a major cost in discovering and exploring new petroleum reserves. Poor drilling performance, for example low ROP, can lead to high cost per foot. In order to optimize the performance of drill bits, the dynamic behavior of the bit and the drillstring has to be monitored. In recent developments, we have deployed a sensor / data acquisition (DAQ) system that is mounted at the bit, which can monitor the behavior of the drill bit and dynamic dysfunctions associated with the operating parameters, different rock formations and rock/bit interactions. A modified shank accommodates the sensor / DAQ system. Its location was determined based on extensive analysis of the bit’s structural integrity. Initial tests verified the ability of the system to identify PDC bit dysfunctions, such as backward whirl — one of the most bit damaging events in the drilling operation. Placing a sensor system in the bit allows for accurate pattern recognition and severity determination in terms of dynamic dysfunctions of the bit and can aid in optimizing drilling parameters in pursuit of increased ROP and reduced drilling costs.
Comparison of Bivariate Models of the Distribution of Significant Wave Height and Peak Wave Period
Authors: Soares Catarina S. , Guedes Soares C.
Published: May 2009

This paper presents the results of a comparison of the fit of three bivariate models to a set of 14 years of significant wave height and peak wave period data from the North Sea. One of the methods defines the joint distribution from a marginal distribution of significant wave height and a set of distributions of peak period conditional on significant wave height. Other method applies the Plackett model to the data and the third one applies the Box-Cox transformation to the data in order to make it approximately normal and then fits a bivariate normal distribution to the transformed data set. It is shown that all methods provide a good fit but each one have its own strengths and weaknesses, being the choice dependent on the data available and applications in mind.
Corrosion Modelling of Single Hull Crude Oil Tanker Subjected to Multiple Deterioration Environments
Authors: Zayed Ahmed , Garbatov Yordan , Guedes Soares C.
Published: May 2009

This work aims to study the corrosion deterioration of crude oil single hull tankers, considering the corrosion degradation process from both the internal and external sides of plating. The corrosion degradation of the external side of the tanks is modelled as corrosion degradation under atmospheric conditions or under immersion conditions or under repetitive atmospheric and immersion conditions, depending on the location of the plate elements. The corrosion degradation of the internal side of the crude oil tank is estimated as corrosion under tank environment considering the chemical and physical conditions of the crude oil. The different corrosion deterioration mechanisms under the different environments and the corresponding factors affecting it are modelled based on recently proposed models.
Numerical Methods for the Prediction of the Bilge Keel Effects on the Response of Ship-Shaped Hulls
Authors: Kinnas Spyros A. , Yu Yi-Hsiang , Vinayan Vimal
Published: May 2009

This paper addresses the hydrodynamic interaction and response of typical FPSO/FSO and LNG hull-forms with bilge keels. The hull-forms are assumed to be slender with the longitudinal length-scale exceeding the other two physical dimensions. This assumption allows the modeling of the flow around the hull-form in a 2-D strip-wise manner. A Finite Volume Method (FVM) based numerical model is developed to analyze the flow around the 2-D hull-sections, with and without bilge keels. The effect of the bilge keels in the damping of hull motions is presented with the application of the numerical scheme to a hull in forced roll motion, and its transient response in roll and heave decay.
Response-Based Evaluation of Design Sloshing Loads for Membrane-Type LNG Carriers
Authors: Kim J. W. , Kim K.
Published: May 2009

Sloshing model test and dynamic structural analysis of a membrane-type LNG tank is performed to determine design sloshing loads for LNG containment system. Spatial, temporal and statistical characteristics of the measured sloshing loads are investigated. Dynamic structural analysis of a LNG containment system is performed to obtain structural responses at predefined critical locations under short duration triangular pulse, which is referred to as triangular impulse response function (TIRF). The TIRFs are synthesized with time history of measured sloshing loads to obtain dynamic response of the LNG containment system. Statistical analysis of peak stress values are used as basis of determining design sloshing loads for the structural assessment of LNG containment system.