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Collaborating Authors
Results
Abstract 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.
- North America > United States (0.68)
- North America > Canada > Newfoundland and Labrador > Newfoundland (0.29)
- Transportation > Marine (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Improved Added Mass Modeling for Ship-Ice Interactions Based on Numerical Results and Analytical Models
Huang, Yujian (CARD, C-CORE) | Qiu, Wei (Department of Ocean and Naval Architectural Engineering, Memorial University of Newfoundland) | Ralph, Freeman (CARD, C-CORE) | Fuglem, Mark (Ice Engineering, C-CORE)
Abstract 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.
Abstract A floating platform in deep water Eastern Canada is required to withstand iceberg loads and/or be disconnected and towed away only in the event of very large approaching icebergs, leaving the mooring lines and risers in-place, support large topsides and provide large quantities of oil storage in the hull. Additionally, the platform should provide low motion response to storm and ice loads to maximize the operational uptime and facilitate the use of a large number of different riser systems including steel catenary risers (SCR). This paper presents the details of a Disconnectable Concrete Spar FPSO platform that has been configured to satisfy all the above requirements and is able to be constructed locally in Eastern Canada. The paper describes a number of key features of the Spar shaped hull, mooring and riser systems that are specifically designed to withstand large iceberg loads and other environment loads while maintaining the characteristic low motion response to storm environments. The design helps to minimize disconnection frequency due to approaching icebergs and disconnection may only be required for very large icebergs or ice islands. Additionally, the system has been designed to minimize disconnection and reconnection time.
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems > Mooring systems (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems > Floating production systems (1.00)
Abstract Exploitation of the Arctic's resources requires the mastery of the risks caused by extreme ice conditions. The design of offshore structures subjected to extreme ice conditions is a challenge for engineers since there are very few advanced design tools available on the market, especially those able to cope with the large variety of ice interaction and failure mechanisms. Different approaches have been used to model and study ice behavior. Among them are analytical, numerical and empirical approaches with different models being considered. Each model has its own advantages and drawbacks and is only generally dedicated to certain circumstances. In 2012 Technip, Cervval and Bureau Veritas initiated a common development program to offer a new tool for the design of offshore structures interacting with ice (Septseault, 2014, 2015) combining a variety of approaches and models. After three years, the first version of the Ice-MAS software (www.ice-mas.com) is now available. It simulates the ice loadings on a structure and the dynamic behavior of the drifting ice-sheet and floes around. Thanks to multi-agent technology, it is possible to combine in a common framework multiple phenomena from various natures and heterogeneous scales (drag, friction, ice-sheet bending failure, local crushing, rubble stack up) (Le Yaouanq, 2015). This work has been the subject of numerous validations, particularly by comparison with ice basin and in-situ results (Dudal, 2015). The Ice-MAS development program continues in 2016 with the addition of a capability to model the interaction of icebergs with offshore structures. This paper will introduce the co-simulation architecture proposed to simulate the complex interaction between an iceberg and a platform structure. It will focus on the hydrodynamic behavior of the platform and the iceberg including its stability. It will also consider the interaction between both bodies; including the non-linearity of the mooring system (in the case of a floating platform) and the local fracture mechanisms of the iceberg. The objective is to propose a new more accurate design method that will improve the overall ice management system for a project.
- North America > Canada > Quebec > Arctic Platform (0.99)
- North America > Canada > Nunavut > Arctic Platform (0.99)
Abstract Platforms operating in arctic and subarctic regions such as the Grand Banks, Labrador Sea, Barents Sea and offshore Greenland are exposed to the risk of iceberg impacts. These structures must be designed to withstand the impact from an iceberg or be designed to disconnect and move offsite to avoid the impact. Offshore Newfoundland, gravity based structures (GBS) such as the Hibernia and Hebron platforms are designed to withstand an impact from an iceberg. However, current accepted practice is not to design the topsides for impact, but to reduce impact risk to an acceptable level by varying the facility geometry (i.e., topsides elevation or footprint). An analytical model was developed to estimate the frequency of icebergs impacting the topsides using three dimensional (3D) models of the platform and the icebergs. Random shapes and sizes are simulated for each iceberg and 3D shapes are generated using a database of measured 2D iceberg profiles. The iceberg shapes are placed randomly in close proximity to the structure and are set to drift towards the structure in a straight line. The initial point of contact between the iceberg and the structure is determined. Crushing of the iceberg against the platform caisson is considered. The process is repeated a large number of times and the total number of contacts with the topsides are determined. In 2012, Hibernia Management and Development Company Ltd. (HMDC) sponsored a field program in which high resolution iceberg profile data were collected. The high resolution iceberg profiles contain detailed 3D information of the above water and below water shape of the iceberg. This paper describes updates to the existing-topsides impact model to take full advantage of the detailed 3D iceberg profiles. These updates include new iceberg shape databases for simulation, and the addition of a detailed iceberg management model and a graphical user interface (GUI) to improve the functionality of the software.
- North America > Greenland (0.89)
- North America > Canada > Newfoundland and Labrador > Newfoundland > North Atlantic Ocean > Grand Banks Basin (0.89)
- North America > Canada > Newfoundland and Labrador > Newfoundland > North Atlantic Ocean > Atlantic Margin Basin > Grand Banks Basin > Jeanne d'Arc Basin > White Rose Field > Avalon Formation (0.89)
- (5 more...)
- Information Technology > Graphics (0.55)
- Information Technology > Human Computer Interaction > Interfaces (0.54)
- Information Technology > Modeling & Simulation (0.47)
DP in Ice Environment - Improving Safety and Efficiency of Arctic Operations
Islam, Mohammed (Ocean Coastal and River Engineering of National Research Council) | Wang, John (Ocean Coastal and River Engineering of National Research Council) | Mills, Jason (Ocean Coastal and River Engineering of National Research Council) | Sayeed, Tanvir (Ocean Coastal and River Engineering of National Research Council) | Gash, Bob (Ocean Coastal and River Engineering of National Research Council) | Lau, Michael (Ocean Coastal and River Engineering of National Research Council) | Millan, David (Ocean Coastal and River Engineering of National Research Council) | Millan, Jim (Ocean Coastal and River Engineering of National Research Council)
Abstract This paper presents an overview of a five year research and development project aiming to develop dynamic positioning (DP) system technologies specifically for ice-rich environments. It has been initiated by the Centre for Marine Simulation (CMS) at the Fisheries and Marine Institute (MI) of Memorial University of Newfoundland, with its technical partner National Research Council’s Ocean Coastal and River Engineering (OCRE-NRC) and commercial partner Kongsberg Maritime Simulation Ltd. (KMS). The primary objective of the project is to develop solutions for some of the critical challenges related to safe Arctic offshore operations by dynamic positioning. More specifically, the objective is to improve the safety and efficiency of oil and gas operations in ice infested environments through the enhancement of existing DP system technologies and training of DP operators in simulated realistic ice environments for ship operations. The project is envisioned to achieve its objective through developing a modularized simulation platform for prototype integration, validation, testing and operational studies/training. Prototypes of a DP control system, a vessel model, an ice force model, and other environmental force models will be developed. The project commenced in 2013 and is set to complete in late 2018. In this first article of the project, a discussion on the contextual aspects and formation of the project, its planning and status to-date is presented. A synopsis of the scientific and engineering research performed to-date within the project scope, with a justification of their relevance to the safe DP operations in ice is given. The high level system design of the validation platform and the deployment strategies of its major components are presented. An introductory discussion on the novel ice force modeling approach is provided. Finally, an overview of the model test program of a fully DP controlled vessel in managed ice conditions, which was completed to provide a database for building and validating the ice force model, is also offered.
- North America > United States (1.00)
- North America > Canada > Newfoundland and Labrador > Newfoundland > St. John's (0.28)
- Well Drilling (1.00)
- Reservoir Description and Dynamics (1.00)
- Management (1.00)
- (3 more...)
Common Operational Picture COP Requirements for Floating Drilling in Pack Ice
Shafrova, Svetlana (ExxonMobil Upstream Research Company) | Holub, Curtis (ExxonMobil Upstream Research Company) | Harris, Matthew (ExxonMobil Upstream Research Company) | Cheng, Tao (ExxonMobil Upstream Research Company) | Matskevitch, Dmitri (ExxonMobil Upstream Research Company) | Foltz, Raymond (ExxonMobil Upstream Research Company) | Mitchell, Douglas (ExxonMobil Upstream Research Company)
Abstract A Common Operational Picture (COP) can generally be described as a system of hardware and software that produces a shared display of information to facilitate situational awareness and decision making. A brief history of the development and use of COP technology in Arctic operations is provided. Experience and learnings from ExxonMobil's research into the use of COPs in ice management and Arctic floating drilling is described. Experience gained from simulations, desktop studies, and field observations is used to frame preliminary functional requirements for such technology needed for future Arctic floating drilling operations in high concentration ice. The COP must facilitate the planning and execution of complex and remote operations with many geographically distributed assets (e.g., drilling rig; icebreakers; shore base; manned or unmanned aviation) and stakeholders (e.g., icebreaker captains, drilling management, ice analysts, weather forecasters) at times communicating over limited bandwidth channels. The COP will serve to collect, store, communicate, and display the necessary data and information. The role of COP components (e.g., databases; communication network, displays) is described and functional requirements are outlined.
- North America > United States (1.00)
- North America > Canada > Newfoundland and Labrador > Newfoundland (0.29)
- Transportation (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.94)
- North America > Canada > Newfoundland and Labrador > Newfoundland > North Atlantic Ocean > Grand Banks Basin (0.99)
- North America > Canada > Quebec > Arctic Platform (0.89)
- North America > Canada > Nunavut > Arctic Platform (0.89)
Abstract When designing oil and gas platforms for offshore arctic and subarctic regions, operators may need to consider the influence of iceberg impacts on optimal structure configuration and ice strengthening requirements. Icebergs have complex and varied shapes, are mostly underwater and are usually moving in currents and waves. Previous iceberg profiles developed from sonar profiles and above water measurements have varying limitations in accuracy, necessitating approximations in modeling both the overall and local shape of the icebergs. A field program was conducted to obtain high resolution full three dimensional (3D) iceberg profiles that allow for detailed modeling of icebergs. Following the field program, a number of studies were conducted to utilize this data to develop improved tools both for calculating design iceberg impact loads for offshore structures and for improving ice management. One of these studies, described here, entails development of a full 3D timedomain simulation model for icebergs impacting fixed and floating platforms in 6 and 12 degrees of freedom (DOF) respectively. A key requirement of the model is that existing scale dependent models for global ice crushing failure pressure can be incorporated. The main objective in developing the model was to provide a tool for evaluating specific iceberg impact scenarios that considers 3D effects and requires fewer assumptions regarding interaction mechanics than previous methods. In this paper, the basic framework of the 3D time-domain model is described, and initial model results are presented for several example applications: icebergs impacting a cylindrical GBS, a stepped cylindrical GBS and a moored spar floating production unit (FPU), the probability of iceberg pinnacles impacting a platform topsides, and subsea interactions. For the cylindrical Gravity Base Structure (GBS), sensitivity analyses are presented for ice strength, friction, drag coefficient, damping coefficients, platform diameter and iceberg velocity.
Abstract The majority of exploration, development and production offshore Newfoundland has occurred in shallow water. Currently there are two floating production, storage and offloading (FPSO) vessels and one gravity based structure producing oil on the Grand Banks. In recent years, there has been a move to deeper water offshore Newfoundland. There have been significant discoveries at Bay du Nord and Mizzen, and new licence blocks are opening up towards the north and northwest of the existing producing fields. With the move towards deeper water, new challenges arise. Supply facilities, search and rescue equipment and other required infrastructure is much further away. A GBS structure is no longer an option due to the water depth. A disconnectable concrete Spar is being considered as a concept for deep water locations off Canada’s east coast. The platform is designed to withstand iceberg impacts, or to be disconnected and moved off location to avoid impacts from very large ice features. Global design loads (ice crushing forces on the platform) and mooring systems global loads were estimated using a two-step approach. First the concrete Spar was assumed to be fixed (i.e. not able to move during an iceberg impact) and quasi-static global design loads were estimated using the Iceberg Load Software (ILS). The ILS was developed to model iceberg impacts with a fixed platform such as a gravity based structure (GBS). Assuming the concrete Spar to be fixed is a very conservative assumption for floating platforms which are free to move upon impact, albeit limited by a mooring system. Second, the inertial properties of the platform and the mooring compliance were approximated using a one-dimensional timestep model. Since the time domain model is not as efficient computationally, a subset of the simulated impacts from the quasi-static analysis was used as input into the time domain model, and dynamic design loads were estimated. The resulting design loads were used by designers to ensure that the structure meets the requirements of ISO 19906:2010. The end product is a more effective design for the platform, while not compromising the safety of the personnel onboard or the integrity of the structure, mooring system or risers.
Abstract Icebergs can pose a risk to offshore oil and gas structures in arctic and sub-arctic regions of the world. The Iceberg Load Software (ILS) was developed to determine design loads on structures following the spirit of ISO 19906:2010, helping designers better understand the impact forces and moments the structures must be designed to withstand. The ILS is a fully probabilistic model which accounts for the range of iceberg shapes, sizes and strengths, and environmental conditions expected at the platform location. The model is applicable to fixed structures such as a gravity based structure (GBS), as well as floating structures such as a floating production, storage and offloading (FPSO) vessel. Users can incorporate the effectiveness of iceberg detection, physical management, and disconnection (where applicable for floating platforms) in mitigating the risk of impact with an iceberg. The input relationships and distributions used to characterize the iceberg population are based on measured data typically collected in the region. These data include everything from basic measurements such as iceberg length, width or sail height to the more detailed shape information in the form of complete three dimensional iceberg profiles. In 2012, a major field program was carried out (Younan et al. 2016) with the objective of collecting high resolution iceberg profiles to improve the modelling of iceberg shape. Above water shapes were captured using a photogrammetry technique and were merged with below water shapes collected using multibeam sonar. The end product was a database of 28 high resolution iceberg profiles providing considerable information on iceberg shape. The objective of this study was to use the high resolution iceberg profiles to update models characterizing iceberg shape in the ILS. These includes models for area-penetration, contact location and impact eccentricity. In addition, relationships correlating iceberg draft and mass to waterline length were updated using the new profiles. Example simulations were performed for a generic structure using the ILS to demonstrate the influence of the updated models, distributions and relationships on the output design forces and moments.
- North America > Canada > Newfoundland and Labrador > Newfoundland > North Atlantic Ocean > Atlantic Margin Basin > Grand Banks Basin > Jeanne d'Arc Basin > Hebron Field (0.99)
- North America > United States > California > San Joaquin Basin > Rose Field (0.89)
- North America > Greenland (0.89)
- (3 more...)