bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic Additives Used as Binders and Pore-Forming Elements of TIO2 Ceramics
Authors: Santana Jerusa Góes Aragão , de Campos Elson , de Melo Francisco Cristóvão Lourenço
Published: November 2016

When starches / proteins are added to the ceramic matrix, they originate pores whose morphology and sizes are varied. However, ceramic final properties are influenced by the interaction kinetics amongst particulate materials. This work was designed to analyze the interactions between proteins and disaccharides and their influence on the properties of TiO2 ceramics. Compositions containing protein and protein-sucrose were added to TiO2 powder. Rheological parameters, shear stress and viscosity were studied in order to understand the protein behavior. Furthermore, sintered ceramics were characterized as for porosity, roughness and image analysis by light microscopy. The dispersions produced with sucrose-protein showed lower viscosity and shear stress values and characteristics of a Newtonian fluid. The samples, from compositions which used 40% solids (80 wt% protein and 20 wt%), showed a higher apparent porosity (23.28%) and larger pore sizes (4947.07 μm2).
Processing of Aqueous Tape Casting of Glass-Ceramic in the SiO2-Al2O3-MgO-Li2O System with ZrO2 and B2O3 Addition
Authors: da Silveira Mariane Silva , Lopes Cristina Moniz Araujo , Melo Francisco C.L. , Rocha Rosa Maria
Published: November 2016

The aim of this work was to fabricate glass-ceramic substrates using aqueous tape casting technique of the parent glass powder in the SiO2-Al2O3-MgO-Li2O system with addition of ZrO2 and B2O3. The powder mixture was melted at 1650°C/1h and the obtained glass (frit) was milled and processed by tape casting in thin substrates with 700 μm thickness. Suspensions were prepared by aqueous medium and latex emulsion binder. Flexible green tapes with few defects were obtained using suspensions prepared with 7 and 10 wt% of binder in relation to glass powder. Substrates were submitted to burn out at 700 °C and thermal treatment at 950 oC/30min, 950 oC/4h and 1000 °C/1h. The green density of the substrates was around 1.55 g/cm3 and 2.10 g/cm3 after sintering/crystallization. Microstructure in all treatments showed high porosity. The major crystalline phases identified by XRD were Li0,6Al0,6Si2,4O6, ZrO2 and ZrSiO4.
Rapid Access Ice Drill for Sampling Antarctic Bedrock
Authors: Nielson D. L. , Delahunty C. , Goodge J. W. , Severinghaus J. P.
Published: November 2016

The Rapid Access Ice Drill (RAID) was designed and built to rapidly drill through the Antarctic ice cap, and then core the ice-rock transition zone and underlying bedrock. The system is designed to be mobile and to operate autonomously near the South Pole at elevations of 3000 to 4000 m and at air temperatures as low as −40°C. The anticipated drilling environment consists of about 100 m of firn that must be cased, followed by 2500 to 3300 m of glacial ice before reaching bedrock. The ice temperature at the surface is about −55°C warming to near 0°C at the base of the ice (warm ice). Previous work has focused on ice drilling and coring, and individual holes have required more than one drilling season. Our objective is to drill and complete a hole in approximately two weeks.

Firn will be drilled using a conventional auger system at 177.8 mm diameter until impermeable ice is encountered. Casing of 114.3 mm outer diameter will be placed in the hole and sealed against the ice with an inflatable packer. The next stage of drilling utilizes a 88.9 mm bit and 69.9 mm flush joint NRQ V-wall core rod to drill the ice section with penetration rates of 3 m/minute. The bottom hole assembly includes an outer bit and wireline-retrievable inner bit. After experimenting with a number of designs, we chose an outer bit with steel cutters to optimize penetration through the ice. In order to collect core in the transition zone or bedrock, the inner bit is removed by wireline and replaced with a coring assembly that utilizes an impregnated diamond bit.

The drilling system consists of five modules that will be mounted on skis for traversing the ice. These are a Drilling Rig Module, Rod Handling Module, Fluid Recirculation System (FRS) Module, a Power Module and a Shop/Inventory Module. The rig is a Boart Longyear LF-230 that we have modified to operate with an electric prime mover. The drilling fluid is ESTISOL-140 that is recycled through the FRS. The drilling system is powered by a 500 kW diesel generator. Two of these units are mounted in a power module to provide redundancy.
Comparison of SAR Strategies in Norwegian and Russian Part of the Barents Sea
Authors: Berg T.E. , Selvik Ø. , Rautio R. , Bambulyak A. , Marichev A.
Published: November 2016

The rising level of industrial activity in the Barents Sea region will result in more SAR operations. Oil and gas companies develop their own emergency response organizations in order to obtain the governmental permits required to operate. Where commercial shipping and fisheries are concerned, emergency response operations will depend on the availability of governmental resources and vessels of opportunity when an accident occurs. Low sea and air temperatures require rapid response in the event of a maritime emergency. Transit speed of rescue units, improved search technology and improved technology for transfer of personnel from lifesaving appliances to rescue units all affect the probability of survival of personnel involved in a maritime emergency in the Barents Sea region
Pack Ice Loads on Seasonally Operating Semi-Submersible in the Labrador Sea
Authors: Thijssen Jan , Fuglem Mark , Dolny John
Published: November 2016

Semi-submersible drilling platforms are typically moved off site given any threat of pack ice incursion. Operations in icy waters requires considerations of, amongst others, ice interations with the facility. The offshore industry will benefit from a standardized methodology to evaluate the capability of semi-submersibles in ice during drilling operations. Operators and drilling contractors are particularly interested in understanding how the drilling season may be extended into the shoulder season. This requires an understanding of variability in site-specific ice conditions throughout the year.

Ice load analysis is needed for semi-submersible rigs operating in ice prone regions to determine ice strengthening requirements. Ship-based ice class rules can be considered for the design loads of the pontoons in transit conditions, but there is no standardized methodology for determining ice loads for the operational conditions. This paper focusses on the operational phase, where loads act on the vertical-faced columns. ISO 19906 (2010) offers a framework for determining sea ice loads in the form of a deterministic equation that has been established for fixed structures mainly operating on a year-round basis. The results will generally be quite conservative for seasonal operations. Consideration of ice exposure, to account for the limited drilling season, is permitted by ISO 19906 using probabilistic approaches, though no specific guidance is provided. Seasonal operations can be planned to avoid the most severe winter conditions, allowing for a reduction of the design level ice conditions. This reduction in the severity of sea ice that impacts semi-submersible columns should be accounted for in determining design ice loads. This paper demonstrates application of an analytical approach to include exposure considerations to estimate extreme ice loads for various drilling season extensions.

An approach is demonstrated here for determining design sea ice loads to evaluate the capability of a semi-submersible in pack ice conditions. The approach considers the possibility of extended season drilling operations, rather than year-round operations, and may permit more efficient exploration in Arctic and sub-Arctic regions in the future. A study case is presented for a semi- submersible operating in the early ice season at a selected location in the Labrador Sea. The approach can be easily adopted for operations in other regions and other structure types, but is dependent on the availability of reliable data on ice conditions.
Near-Field Ice Management Tactics for Floating Drilling in Arctic Pack Ice
Authors: Hamilton Jed , Kokkinis Ted , Holub Curtis , Matskevitch Dmitri , Cheng Tao , Harris Matthew , Shafrova Svetlana
Published: November 2016

In order to be economically viable, Arctic floating drilling in high concentration pack ice requires very high confidence that ice interaction does not lead to costly, unanticipated emergency disconnections of the rig from the well. One of the foremost near-field ice management challenges is to maintain the station-keeping drilling rig within the managed ice channel throughout periods of complex changes in ice drift direction and speed. This entails precise, continuous re-positioning of the ice management fleet, which may be located up to several kilometers up-drift of the station-keeping drilling rig, in response to changing drift. While it may seem plausible to position up-drift ice management operations based on ice drift forecasts, forecasting unfortunately has insufficient precision to achieve the necessary level of reliability. To remedy this problem, ExxonMobil has developed systematic ice management command and control tactics that maintain the station-keeping drilling rig within the managed ice channel with high confidence. The tactics are based solely on the recent drift time history, and therefore eliminate any need for ice drift forecasting for near-field ice management operations. The tactics were proven in a series of near-field ice management tests conducted during the Oden Arctic Technology Research Cruise (OATRC 2015). OATRC2015 was performed by the Norwegian University of Science and Technology in cooperation with the Swedish Polar Research Secretariat and support and participation by ExxonMobil. Over a period of ten days during September, 2015, in which there were many complex Coriolis-driven ice drift loops and cusps and rapid drift direction changes, the methodology was able to successfully manage ice ahead of a fixed way point such that the point remained well within the managed ice channel at all times. The key features of the approach are described herein and include the use of variable length "arched racetrack" icebreaking patterns and an algorithm for continuously adjusting the position and size of the racetracks based on the measured ice drift speed and direction.
Design of a Shipboard Local Load Measurement System to Collect Managed Ice Load Data
Authors: Piercey Gerald , Ralph Freeman , Barrett John , Macneill Andrew , Jordaan Ian , Younan Adel , Fenz Daniel
Published: November 2016

Due to a lack of data, currently (and justifiably) conservative ice load assumptions are made in rig assessments allowing only very small floe sizes to contact non-Polar classed drilling rigs. In September 2015, in cooperation with the Norwegian University of Science and Technology (NTNU) and the Swedish Polar Research Secretariat (SPRS), ExxonMobil and C- CORE participated in the Oden Arctic Technology Research Cruise. A distinguishing aspect of this Cruise was: (a) performing ice management trials using two icebreakers, the Oden and the Frej; and (b) instrumenting the Frej, i.e. the secondary icebreaker and therefore collecting first-of-a-kind local ice load data during stationkeeping in managed ice. Unlike all prior data behind code pressure-area curves, which are based on transit in unmanaged ice and ship ramming, the new data are in managed ice field, representing true pressures and forces on a drilling or production vessel in a stationkeeping mode (moored, dynamically positioned (DP) or DP assist). This paper describes the design, installation and calibration of the Frej load measurement system. The system consists of an array of over 160 strain gauges installed over three panels on the bow and shoulder of the vessel. Prior to sailing, physical calibrations were performed as quality checks of the gauge installation and to benchmark finite element (FE) models used afterwards to convert measured strains into hull local ice pressures. More than 260 hours of local ice load data were collected throughout the program including measurements while stationkeeping in managed ice conditions in addition to actively managing ice and transit. The system remained operational through the entire field program without loss or damage to a single strain gauge. The data collected can contribute toward demonstrating the ability of existing rigs to resist some degree of managed ice, and hence can open the possibility for drilling season extension beyond open water, which can have a significant economic impact on arctic drilling. The resulting pressure-area curves will be the subject of a follow-up publication.
Improved Added Mass Modeling for Ship-Ice Interactions Based on Numerical Results and Analytical Models
Authors: Huang Yujian , Qiu Wei , Ralph Freeman , Fuglem Mark
Published: November 2016

Global ice loads at different locations on a ship during rams into ice are a function of ship motions and added mass in addition to the failure mode and strength of the ice. In the literature, various analytical added mass models have been used for ship-ice interactions, which could lead to significant differences in the prediction of global ice loads on ships. In this work, an improved added mass model has been developed based on numerical results and existing analytical models. Added mass coefficients of three ice-going ships, CCGS Amundsen, CCGS Louis S. St-Laurent and MVArctic, were estimated using four analytical added mass models. It was found that the differences in added mass coefficients predicted by these models are significant and enhancements can be made. A body-exact numerical simulation tool based on the potential-flow theory, MAPS0, has been used to compute the added mass coefficients of the three vessels in the frequency domain and the results were used for the development of the improved added mass model. The improvement in the load predictions has been demonstrated by applying the new added mass model to the three vessels.
Application of Upcrossing Rate Methodology to Local Design of Icebreaking Vessels
Authors: Ralph Freeman , Jordaan Ian , Manual Mike
Published: November 2016

Design of icebreaking vessels or ice-capable vessels must include consideration of extreme local ice pressures and exposure. Application of probabilistic methods used for data analysis, and then directly applied in design, with consideration of exposure is most useful. The Maximum Event (ME) Method is formulated for cases where ramming of ice is the dominant event. The peak pressures on a hull panel through the ram duration for each ram event is modelled. Data for each panel area are ranked and an exponential distribution fit to the tail of the ranked data. For design, we are then concerned with the maximum of n events expected in a specified period of time (e.g., a year). The random occurrence of ice along a route will also translate in to an annual number of expected impacts depending on ice and vessel dimensions. Vessel Ice classes would correspond to an annual number of impact events. This approach was used during the Arctic Shipping Pollution Prevention Regulation (ASPPR) revisions to validate maximum forces for different class vessels (e.g., a CAC4 vessel would be designed for 10-15 rams per year). For continuous-type interactions (e.g., a large floe crushing around a stationary vessel, or continuous icebreaking) an alternative approach is to use the Up-crossing Rate (UCR) Method. The number of local pressure upcrossings above a specific threshold on a particular panel area within a specified time (e.g., one year of operation) is determined. Exceedance curves for the UCR for increasing pressures on incremental panel areas are determined including an exponential fit to the tail of the distribution. For design, one only needs duration of interactions with the specified ice conditions through the year. The methodology was exercised to estimate local pressure parameters for transit segments during the ODEN 1991 trials. The greater the number of impact events and the longer the event duration, the greater the local pressures on panel areas. These high pressure zones occur and disappear, randomly shifting in location and intensity as fracture and spalling processes reshape the interaction area. For future development of the ISO design code, it is recommended that two modeling approaches be considered, the traditional ME method for short duration events and the UCR method for continuous interactions. The UCR method provides a simple means to design icebreaking vessels for extreme local pressures during continuous interactions. The method is also attractive for design of a stationkeeping vessel operating in broken ice where modeling individual floe interactions is not practical.
Using the Event Maximum Method to Further Analyze Full Scale Local Pressure Data
Authors: Manuel Mike , Ralph Freeman , Jordaan I. J.
Published: November 2016

Extreme values for local ice pressure are a primary consideration in the design of local structure for ships and offshore structures in arctic environments. ISO 19906 (2010) includes guidelines for a probabilistic approach in determining the local design pressure for Arctic offshore structures. However, the standard is vague in how it should be used. The probabilistic method employed in the standard is the event maximum method developed by Jordaan et al. (1993). It accounts for the expected exposure of the local structure to ice pressure and includes a constant, a, used to describe the relationship between local pressure and area. The constant a is derived in Jordaan et al. (1993) and extended in Jordaan et al. (1997) and reported in Taylor et al. (2010). The a-area relationship is based on the local pressure values from the very aggressive multi-year ridge rams of the CANMAR Kigoriak trial (1982). This leads to a very conservative a-area relationship and may be excessive for some ice conditions. This paper includes an explaination of the use of the event maximum method in ISO 19906. Local pressure data obtained through shear strain gauge systems from Polar Sea (1983) and Oden (1991) have been reanalyzed using the event maximum method (Jordaan et al. 1993, 1997). The data has been sorted by both ice thickness and ice concentration to investigate the existence of a trend between ice thickness and local pressure.
A Revised Basis for Iceberg Areal Density Values for Risk Analysis
Authors: Habib Kashfi , Hicks Michael , Stuckey Paul , King Tony
Published: November 2016

Iceberg areal density is one of the most important and challenging parameters to define accurately for offshore petroleum exploration. The two data sources for iceberg areal density considered here are aerial reconnaissance data collected by the International Ice Patrol (IIP) and iceberg charts which merge aerial reconnaissance data with other observations and model output. The IIP operates regular flights to monitor iceberg hazards to transatlantic transportation off the Canadian East Coast. The IIP and Canadian Ice Service (CIS) work together to generate daily ice charts year-round to provide the most reliable and timely information about the iceberg distribution by defining an iceberg limit to minimize risk of iceberg collision to transportation. The purpose of the iceberg charts is to promote safe maritime operations and to inform mariners about the latest ice conditions in navigable Canadian waterways and transatlantic shipping lanes in international waters. With navigational safety as its primary goal, the IIP develops the iceberg limit and distribution for vessels planning to avoid encountering icebergs completely. These warnings therefore are generally more conservative than on-site observations. The daily ice chart is created based on the data provided by various sources and is modified regularly by adding new sightings and applying drift and deterioration models to previous sightings. Among all the sources, aerial reconnaissance provides the most up-to-date information on iceberg conditions, and are generally conducted between February and July. For a better understanding of the influence of the data sources, iceberg frequency values using aerial reconnaissance data and charts were compared for a common period of time for several locations. Comparing the results, it was observed that results from aerial reconnaissance data analysis are typically lower than results from chart data i.e., more icebergs were reported in the ice charts than were sighted by aerial reconnaissance. This is consistent with IlP's conservative approach in reporting iceberg hazards to transatlantic mariners. Using the most appropriate source of data to identify the risk that icebergs pose for offshore petroleum production facilities is essential. The objective of this paper is to assess the discrepancies between data provided through aerial reconnaissance and that included in the daily iceberg charts.
Grand Banks Bundle
Authors: Hopkins D.
Published: November 2016

Oil and gas exploitation continue in two key harsh environment regions: Grand Banks, Newfoundland and Barents Sea, Norway. Although these regions have different challenges in terms of ice, cold temperatures, and winter storms; one common obstacle is short offshore installation windows. Mitigating a short installation window is a key motivator in considering the use of Pipeline Bundle technology.

Within the UK North Sea, Pipeline Bundles has been a key technology for Subsea 7 in many offshore field developments and expansions over the past 35 years. With the unique ability to be utilised in a number of applications, including: congested lay-down corridors, challenging seabed conditions, and the efficient incorporation of subsea processing elements; the technology offers a flexible design for any subsea field.

To export this key technology differentiator from the UK North Sea, Subsea 7 has conducted a feasibility study to investigate the use of Pipeline Bundles in the Grand Banks region. This paper discusses the various design considerations and installation options needed for the area as well as the technical readiness of the components of the Pipeline Bundle when matched against these requirements.

A way forward is then presented regarding the necessary Pipeline Bundle design and installation option for use in the Grand Banks.
Geohazards in Deepwater Sectors Offshore Newfoundland and Labrador Available for Parcel Nomination in 2016-2019
Authors: Piper David J. W. , Saint-Ange Francky , MacKillop Kevin , Campbell Calvin , Mosher David C. , Rashid Harunur
Published: November 2016

Several deep-water sectors offshore Newfoundland and Labrador are available for parcel nomination in the next few years. This paper summarizes the current availability of geohazard information from Geological Survey of Canada (GSC) data holdings, Open Files and published papers. It presents background geological information on controls on geohazards, and summarizes the significance of existing published geological and geotechnical data. It focuses on sectors NL01-LS, NL02-LS (southern Labrador Slope), NL02-EN (northern Orphan Basin), and NL01-SEN (Carson and Salar basins), with brief mention of NL-01-SN. It is based on field surveys by the GSC in the past decade, including multibeam bathymetry, high-resolution seismic, and piston cores. The information is applicable to E&P companies considering nominating parcels or submitting bids for leases and to the regulator as a guide to geohazards and sea-floor constraints to exploration and production.
Estimation of Ice Loads Using Mechanics of Ice Failure in Compression
Authors: Jordaan Ian , O’Rourke Brian , Turner Joshua , Moore Perry , Ralph Freeman
Published: November 2016

In the calculation of ice loads, reliance is generally placed on analysis of empirical data. The main reason for this is that the complex behaviour of ice under stress makes it difficult to use calculations based on mechanics directly in design. Ice is extremely brittle and prone to fracture, and develops areas of very high compression and confinement during compressive failure, which result in substantial changes in the microstructure and behaviour of the material. These are termed highpressure zones.

Progress in the analysis of ice failure using advanced methods of mechanics is reported. This has included studies aimed at understanding the behaviour of high-pressure zones. All work includes analysis of time-dependent effects, essential for a proper analysis of ice failure. The paper includes a discussion of the role of fracture and the development of high-pressure zones. Fracture processes are understood but the randomness of the flaw structure of ice in the field suggests that there is a strong variation in magnitude and position of high-pressure zones. This is supported by observations in the field on vessels operating in ice.

The analysis of high-pressure zones is outlined; these produce the high local pressures of great importance in design. As noted, very high pressures occur at the centre of the zones on small areas, of the order of 70 to 100 MPa, accompanied by very high confinement and shear. The response of the ice is profoundly altered under these conditions, as compared to virgin ice. Methods of damage mechanics have been used successfully to analyze the failure of high-pressure zones, and a distinct failure load has been obtained. The methods of mechanics require a non-classical approach that recognizes changes of material behaviour with time. A scaling rule related to the mechanics allows modelling on a smaller scale in the laboratory. Fracture events make the process of interaction highly variable in time. In the view of the writers of the present work, full time domain simulation of the process of interaction is not possible. A reasonable way to move forward is to combine the progress in high-pressure zone analysis with empirical analyses of high-pressure zone areal density and intensity.
Oil Exploration and its Relationship to the World of Trapped Micron Scale Fluids: A Review of the Applications of Fluid Inclusion Microscopy to the Study of Aqueous and Hydrocarbon Fluid Dynamics in Sedimentary Basins
Authors: Feely M. , Costanzo A. , Hunt J. , Wilton D. , Carter J.
Published: November 2016

Fluid inclusions are micron scale samples of aqueous and hydrocarbon fluids trapped in annealed microfractures developed during burial, or earlier in authigenic minerals e.g. quartz and/or calcite during cementation. Microscopic studies are carried out on specially prepared doubly polished fluid inclusion wafers (~ 150 microns thick) of well core, sidewall core and cuttings. Using a combination of transmitted light and UV light microscopy, laser Raman microscopy and microthermometry, facilitates the collation and comparison of fluid inclusion data. Textural and compositional data relating to the trapping history of fluids can be further constrained using P-T modelling software. The results of fluid inclusion studies of North Atlantic offshore basins i.e. Irish, and Newfoundland and Labrador offshore sectors highlight the use of these analytical and fluid modelling techniques. For example, Porcupine Basin aqueous basinal fluids trapped in cements are consistently of low to moderate salinity (<10 eq. wt.% NaCl), comparable to those found elsewhere on the Atlantic margins e.g. UK Rockall, West of Shetland region, and in the Jeanne d'Arc Basin offshore Newfoundland and may reflect the paucity of evaporites at depth in these regions (Parnell et al., 1999, Parnell et al., 2001 and Feely and Parnell 2003). Migration of at least two chemically distinct hydrocarbon fluids occurred post cementation, as lateral flow along Jurassic sandstones with limited vertical flow along faults (Conliffe et al., 2009). In the Saglek Basin offshore Labrador both monophase (liquid) and two-phase (liquid + vapour) hydrocarbon fluid inclusions occur in the Cretaceous Markland Formation. The two-phase hydrocarbon inclusions yield homogenisation temperatures of ~80°C. The aqueous fluid inclusions represent low temperature (~100°C) and low salinity (~5 eq.wt% NaCl) fluids, and are similar to those recorded in the Porcupine Basin offshore Ireland. P-T modelling of these fluids indicate trapping pressures and temperatures of ~300 bars and ~110° C.
Characterization of Full Scale Operational Ice Pressures and Hull Response on a Large Arctic Tanker
Authors: Kim Hyunwook , Dolny John , Quinton Bruce , Yu Han , Peng Heather
Published: November 2016

The prediction of practical ice loads for ships operating in ice-covered waters is fundamental to the calibration of ice class requirements and improvement of Polar ship structural design. Data collected from full-scale instrumentation campaigns is highly valuable, not only for identifying characteristics of ice loads during actual service experience, but also for benchmarking ice class selection and informing future design decisions. This paper presents results of a study focused on utilizing full scale ice impact data for practical Arctic engineering applications. Three (3) bow-shoulder ice impact events were selected from the Varandey shuttle tanker field data set; representing both peak force and peak local pressure events. The 4D pressure method was used to apply the real-time/real-space pressure panel data directly to a finite element model of the bow in order to assess the structural response. Subsequently, these ice loads were applied to lighter structural hull configurations, to benchmark their capability under the same loading events. The results provide unique insight to the response of different ice class structures to real ice impact measurements.
Numerical Predictions of Solidification and Water Droplet Impingement
Authors: Sultana K. R. , Pope K. , Muzychka Y. S.
Published: November 2016

Ice accretion is a hazard for offshore operations on cold northern waters. Icing on vessel surfaces can be caused by a variety of phenomena, including cold air temperature, low water temperature, freezing rain, and supercooled fog, among others. A single salt water droplet's phase change behaviour after impacting on a very cold surface is numerically studied in this paper. The model used in this study solves the flow equation, composed of energy balance and the volume fraction equations. The new predictive techniques developed in this research provides important new insights on sea spray icing of arctic vessels, medium-sized fishing trawlers, and offshore structures operating in harsh offshore environments. The main objective of the study is to investigate the influence of several physical properties on droplet freezing. Important factors include liquid fraction, salinity effect, total freezing time, and rate of total heat transfer. The liquid fraction helps to understand the complete phase change behaviors by means of three distinct transition stages: fully liquid stage, mushy or transition stage, and complete ice phase. The simulated results based on salt water properties show salinity increases total freezing times. Wall heat transfer and temperature distribution help to show heat transfer rates between the droplet and object surface. Further, this research provides an important technical achievement for ice load prediction, modeling and preventation. This contribution is particularly significant for vessels and offshore petroleum industries in the Northern environment.
Full Wave Field Simulation of Flexural Waves in an Acoustic–Viscoelastic Medium
Authors: Landschulze Marcus
Published: November 2016

In this paper I present full wave field simulation results in an acoustic-viscoelastic domain and show how flexural waves interact with the surrounding air and water instead of only focusing on the flexural wave. This paper is devoted to the advantages of full wave field simulations employing viscoelastic models compared to purely elastic models. Viscoelastic simulation provides results that better resemble measured field data than equivalent elastic or 1D flexural wave simulations are capable of. Elastic full wave field simulations suffer from undesired dispersive modes and oscillations obscuring the true interaction of different wave types. Application of acoustic-viscoelastic full wave field simulation can help to test and improve planned survey geometries and the processing workflow.
State-of-the-Art Review of Research on Ice Accretion Measurements and Modelling
Authors: Mintu S. , Molyneux D. , Oldford D.
Published: November 2016

Ice accretion on vessels and offshore structures is a serious operational hazard. Heavy ice accumulation on vessel's deck can influence the stability and potentially capsize smaller vessels. It also creates unsafe operational conditions on vessel and offshore platform decks. Accurate estimation of loads due to ice accretion is thus necessary. This paper presents a state-of- the-art review of existing literature related to ice accretion on vessels and offshore structures. Existing reports for field measurements of icing are reviewed. Model scale experiments to simulate the ice accretion are also reviewed. Various numerical methods and approaches for ice accretion prediction are critically reviewed. The review covers some key factors of the icing process such as spray flux and heat transfer models.

There are few international codes and standards available that require the ice-going ships to have adequate intact stability, taking into consideration a prescribed level of icing on exposed weather decks, gangways, and projected lateral areas of the superstructure. The codes were developed based on the limited population of ships and ship types and were focused on specific geographic regions. In fact, there is little agreement among the codes. Moreover, the formulae rely mostly on data collected for smaller vessels, and extrapolation to the larger vessels used in oil and gas operations are questionable. The paper gives a brief review of the international codes and critiques the inadequate standard for ice accretion calculation for various types and sizes of vessels. The paper concludes by discussing some aspects of improved ice accretion prediction models that may be particularly relevant for larger vessels and offshore structures.
The Interaction of Multi-Year Ridges with Upward Sloping Structures
Authors: Croasdale Ken , Brown Tom , Li George , Spring Walt , Fuglem Mark , Thijssen Jan
Published: November 2016

In ISO 19906 (2010), there are no algorithms provided for calculating loads on sloping structures due to interaction with multi-year (MY) ridges; only references are provided for a range of methods; to quote from Clause A.8.2.4.5.2:"Multi-year ridge actions against conical structures can be estimated using a variety of methods [Croasdale, 1980)], [Nordgren and Winker (1989)], [Wang (1984)]."

A study was undertaken to revisit the theories for breaking and ride-up of MY ridges and if possible to improve them. A new simplified method for long ridges has been developed which includes secondary failures associated with the hinge pieces which are successively broken as the ridge is pushed higher prior to rotation of the broken pieces around the structure. For wide ridges, failure across their width has also been quantified and this mechanism can lower ridge loads compared to prior methods. The new method also recognizes the loads associated with the clearing of level ice fragments ahead of the ridge. The key findings have been incorporated into a methodology which is described by relatively simple equations and these are provided in the paper. Example calculations and sensitivities are provided.
Simulations of the Effect of the Rate of Change of Ice Direction on Stationkeeping of Drillships
Authors: Sayed Mohamed , Watson David , Kubat Ivana , Wright Brian
Published: November 2016

This paper examines the response of a drillship to the action of an ice cover undergoing a gradual change of direction of motion. For effective stationkeeping, the drillship must continuously change its heading to face the oncoming ice. The simulations consider a vessel that maintains position using Thruster-Assisted Mooring (TAM). A turret mooring system resists the surge and sway movements, while the thrusters act to correct the heading. The simulations of ice deformation and drift solve equations that describe conservation of mass and momentum, and a failure criterion. The drillship is treated as a three-degrees-of-freedom (surge, sway and yaw) rigid body. The results give distributions of ice drift, deformation and stresses around the vessel as well as the forces and offsets of the drillship. The resulting peak ice forces and moments on the drillship show clear dependence on the rate of change of ice drift direction. As may be expected, ice forces and moments increase for high rates. They also increase for higher ice velocities. Analysis of the results shows that the ratio of the length of the drillship to the radius of curvature of ice drift trajectories can be used to estimate ice forces and moments in an environment of changing ice drift direction. The present work additionally included a cursory examination of the effects of ice cover conditions; namely ice thickness and the existence of ridge fragments and icebreaking tracks, which are often formed as part of ice management operations.
An Exploratory Review of Weathering and Transport Modeling of Accidental Releases in Arctic Waters
Authors: Afenyo M. , Khan F. , Veitch B. , Yang M.
Published: November 2016

This paper describes the essence of establishing a dynamic fugacity model, mainly in the framework of assessing the potential risk posed by oil spills during Arctic shipping. Key to evaluating this risk is the fate and transport processes as they occur in ice-covered waters. A review of relevant weathering and transport processes is therefore presented. The study shows that more understanding is needed of the behavior of oil in ice for assessing the risk posed during Arctic shipping.
Hebron – Modern Iceberg Resistant GBS Solution
Authors: Knudsen Arnt , Haldorsen Kathrine R , Andersen Ellen Grete , Haereid Kåre
Published: November 2016

The Hebron Offshore platform is an oil drilling, production, living quarters and storage facility planned to be installed in the Jeanne d’Arc basin on the Grand Banks approximately 350 km east, southeast of St. John’s, Newfoundland and Labrador, Canada in 2017.

The platform has three major elements: the modular topside facilities, the reinforced concrete gravity base structure (GBS), and crude oil offloading system (OLS). This paper addresses the current engineering and ongoing construction of the Hebron modern iceberg resistant GBS solution.

Based on the relevant environmental conditions and functional requirements specific to the Hebron GBS project, the following areas will be discussed, focusing on general learnings with future applicability: HSSEDesign considerations and constructabilityProject executionConstructionLocal content

Conclusion: Significance of Subject Matter: Robust fixed and floating concrete GBS solutions are critical for development of Oil & gas facilities in iceberg prone arctic and subarctic areas. Knowledge and experience transfer are key in ensuring future successful realization of offshore oil and gas projects for demanding areas.
Shallow Water Subsea Drilling and Production Structure to Resist Sand and Ice Keel Intrusion in Arctic Environments
Authors: Prescott Neal , Mejia Felipe , Erford John , Bhardwaj Ruchika
Published: November 2016

In certain offshore shallow water production areas in cold regions the sea conditions are characterized by first year and potentially multi-year ice features. Unlike some other arctic regions, which are characterized by icebergs, there are regions where no icebergs occur. However, gouges are formed by rafted ice, pressure ridges, and multi-year ice from the polar pack that forms deep keels. Ice gouging of the seabed in these areas is caused by winds, currents and waves driving the ice sheet containing these ice keels.

As more reserves are being found in shallow water arctic and sub-arctic environments, there is a need to determine how best to develop these resources cost effectively. Recent interest has been raised for installing typical shallow water subsea drilling templates on the seabed to be drilled by jackup drilling rigs. However, these templates would be at risk of damage from sand intrusion and ice keel penetration.

This paper discusses a novel design to best protect the subsea template and its mechanical equipment. Furthermore, this paper outlines the process undertaken for designing a subsea drilling and production template and protective structure by encasing the template within a protective structure that is placed in an armored excavation, or "Glory Hole", to prevent sand intrusion and ice keel penetration.

To protect a drilling and production template in shallow water, an enclosed structure was required to be embedded in the soil at the bottom of a Glory Hole with a full-time domed protection cover to protect from ice and soil entrance. Slotted doors allow jackup access to the template during drilling. Operation of the Wellheads contained within the Subsea Template is remotely controlled by a subsea cable containing electrical, hydraulic and fiber optic cables and tubes. The operation of the facilities can be monitored and controlled at the Command and Control Center located onshore and connected to the offshore template by the control cable.
Operational Ocean Ice Prediction System Validation for the Canadian Arctic and Northwest Atlantic
Authors: Davidson F. J. M. , Xu J. , Smith G. C. , Dupont F. , Lu Y. , Higginson S. , Regnier C. , Hernandez F.
Published: November 2016

Ocean-Ice prediction systems maximize the information value of scarce in-situ ocean and ice observations. They provide assessed and forecast ocean and ice conditions that combine satellite observations and in-situ observations along with ocean and ice physics. Such information supports many applications and marine operations including navigation in open and ice covered waters, search and rescue drift prediction and oil spill drift prediction (with and without ice cover). Additional benefits include more accurate weather predictions through coupling of prediction systems and better oceanographic information support for marine resources and marine life applications.

With decreasing ice coverage and increased navigation activity in the Arctic, the availability of operational ocean and ice predictions are important for ensuring safety of marine operations as well as timely responses to marine emergencies. We review the validation methodology of ocean ice prediction systems for the Canadian North under the Canadian Operational Network of Environmental PredicTion System (CONCEPTS) activities. CONCEPTS is an MOU governing an ocean, ice and atmospheric prediction collaboration of three government departments: National Defense, Environment and Climate Change Canada and Fisheries and Oceans Canada. Validation metrics include comparisons of ice and ocean forecast parameters against satellite (AMSRE Radiometry, Cryosat Altimetry) and in-situ observations from ships, moorings and autonomous floats. Forecast performance for the years 2015 and 2016 are presented herein.

The overall goal is to estimate forecast reliability through development of vetted procedures for providing performance statistics against observations, both in real time and delayed mode for the Canadian CONCEPTS Ocean Ice Prediction systems. The approach is part of the GODAE Ocean View international collaboration network in Operational Oceanography for comparing ocean ice predictions against observations. Ultimately we aim to provide a framework by which participating ocean operators can provide in-situ observations from their assets (ships, rigs, ice camps, etc.) and receive performance stats (year in review, month in review) of ocean and ice prediction systems against the observations they provide.
Geologic and Subsea Permafrost Characterization for Buried Pipeline Design and Construction in the Alaskan Beaufort Sea
Authors: Bashaw E. , Hebeler G. , Phillips W. , Kane G.
Published: November 2016

A man-made island and buried subsea pipeline are needed for an oil production project within the Foggy Island Bay area of the Alaskan Beaufort Sea. In order to characterize the geologic and permafrost conditions in the area, field data have been collected over several winter field seasons. Multiple subsea buried pipeline alignment options and several potential island sites have been studied. Over the years, the arctic exploration teams have completed 600 boreholes, 75 piezocone penetration test (CPT) soundings, subsea temperature measurements, and performed comprehensive laboratory programs on frozen and unfrozen sediments. The shallow subsurface geologic conditions within Foggy Island Bay range from loose silty sand and soft to firm fine-grained marine Holocene deposits to stiff Pleistocene silty clay deposits. Shallow permafrost is present in Foggy Island Bay, primarily near the Boulder Patch and within the shoreline transition zone. The results of the near surface geotechnical conditions are discussed and presented with respect to subsea pipeline constructability and design parameters. Trench constructability and wall stability is discussed, as well as the frozen and unfrozen backfill properties important to resist upheaval buckling when the pipeline goes into production and begins to thaw the frozen backfill. This geotechnical summary serves as a resource for enhanced understanding of soil, permafrost, and sea-ice properties in the Alaskan Beaufort Sea.
Development of Propulsion Technology of Icebreakers
Authors: Wilkman Göran , Adviser Wilkman Arctic , Hänninen Samuli , Heideman Torsten
Published: November 2016

Icebreakers as such have been sailing for some 120 years. At first they were just a bit stronger than ordinary commercial vessels. Propulsion solution was steam engines connected to propeller. During the first decades not much development took place. As the marine diesel engines started to replace the steam engines and advances in electric devices took place, first diesel-electric icebreakers were built in the 1930ies. During the next 40 years this solution became more or less a standard for such ships. Next step was the development of the electric drive itself. New smaller AC-motors gave room for new thinking and podded drives came into the picture in the early 1990ies. Simultaneously there were also development exercises on mechanical devices like CP-propellers and Z-drives during 1970ies and −80ies. Today we have available and most commonly used; traditional fixed pitch propellers with conventional shaft lines, mechanical Z-drives and podded drives, all driven by electric motors. The operational profile and mission of the vessel will dictate how the icebreaker will be furbished. This paper discusses the development history of icebreaker propulsion.

Recently there have been delivered and designed new icebreakers, icebreaking shuttle tankers and LNG carriers. Many of these vessel concepts are relying on podded propulsion system. AZIPOD propulsion has been selected to many of these vessels as it provides excellent ice performance for the vessel, good torque characteristics for the propeller and there already exists proven track record of ice operations. This paper will outline important design considerations when developing diesel-electric podded propulsion system.