Lars Ingolf Eide 08 December 2010
Barents 2020 Working Group 2
Barents 2020 Conference Meeting Moscow December 8, 2010
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Working Group RN02 – Guidance to ISO 19906 for design of stationary floating installations against ice-loads
Deliverables:- Agreed Guidance Document for design against ice loads on stationary floating structures that may serve
as a common Russian-Norwegian separate supplement to ISO 19906 for the Barents Sea. The Guidance Document that may be submitted, partly or in full, to ISO for their consideration in connection with the first update of ISO19906.
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Barents 2020 Phase 4 – Working Group 2 MembersRussian team Norwegian/OGP teamMarat N. Mansurov, VNIIGAZ, Coordinator
Marina M. Karulina, Krylov Shipbuilding Res. Inst
Irina A. Surikova, Russian Maritime Register of Shipping, TK 318
Sergei D. Kim, VNIIGAZ
Pavel Liferov, Shtokman Development AG
Nina Krupina, Arctic and Antarctic Res. Inst.
Yury Nemenko, Giprospetsgaz
Vakhtang M. Glonti, Gazprom
S.I Zibakin, Gazprom Shelf Production
Gleb Churkin, Agency of researches of industrial risks (observer)
Valery P. Nekrasov, Ministry of Emergency Measures of the Russian Federation (observer)
Vladimir A. Pestryaev, Sakhlinnipimorneft
Rod Allan, Transocean
Arne Gürtner, Statoil
Hans Martin Sand, Moss Maritime
Jean-Marc Cholley, Total/OGP
Graham Thomas, BP/OGP
Mike Orr, Cairn Energy/OGP
Guido Kuiper, Shell/OGP
DNV:
Per Olav Moslet,
Lars Ingolf Eide, Coordinator
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RN02 - Status In-depth review and gap analysis by SDAG and
Statoil, comments to more than 75 sub-clauses Voluntary contributions from participants; assigned tasks for topics Revised work plan Rough layout of final report
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Review of ISO 19906; example, one out of 16 pages
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Review of ISO 19906; example, one out of 16 pages
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Contribution list; one half out of four pages
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Some issues
Ice Management (IM) and impact on floater design- Can IM be used to reduce design loads? If yes, how and what are requirements to documentation?
Ice model testing, floaters- Details missing
Ice data- How to handle sparse data statistically?
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Ice Management (IM) and impact on floater design Safety level and system reliability
Barents 2020 objective is to achieve similar safety level as in the North Sea
System reliability is a function of the component reliability of the structure and the efficiency of the components in the Ice Management (IM) system
System reliability
Structure reliability IM efficiency
Taking into account the reliability of compontents in IM system
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Ice Management (IM) and impact on floater design Design, ice management and disconnection
“Any ice management approach that is intended to support the operation of an offshore system (floating, fixed, subsea or otherwise) shall be configured to achieve an acceptable level of overall system reliability, in combination with structural resistance. The acceptable level of system reliability should be determined according to the principles set out in Clause 7 over the design service life of the system(s) the ice management system is supporting.”
IM philosophy
Design philosophy Disconnectionphilosophy
Reflect overall system reliability
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Ice Management (IM) and impact on floater designManaged ice
Gap analysis:- Reduction of design ice actions resulting from design ice features (i.e EL or AL level) is not
obvious. No guidance on methodology is offered. - Adverse effect should be identified
Contributions:- Documentation of reduction of design ice actions resulting from design ice features (i.e EL or
AL level) in case of IM.- Quantification of the effect of ice management as well as the impact of the chosen design
philosophy on the overall design- Summarize general findings and learnings from managed ice to be determined from full-
scale experience from Kulluk. - Assess adverse effects arising from Ice Management (ISO requirement). A list of so-called
‘adverse effects’ to be be provided
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Ice model testing of floaters Gap:
- No particular guidance offered for testing of floating systems in ice tanks.- Details missing
Contributions:- Performance requirements
for model testing of floaters to be provided
- Assessment of deviations between two modelling approaches:- towing or pushing the model
through a stationary ice sheet; - pushing the ice sheet towards
the stationary model;- Note that ice model test results
should be corrected according to actual obtained ice characteristics in order to make them comparable to full scale
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Ice model testing of floaters (2) Contibutions:
- Outline of special requirements to mooring system;- Moored system stiffness to be
quantified in model scale and compared to prototype design;
- Pull-out tests should be performed to assess the model scale mooring system;
- Decay tests should be performed for deriving the natural periods of the model in open water;
- Note on assessment of ice-structure friction coefficient to be assessed in model scale;
- Note on importance of logging structure motions and accelerations, i.e. degrees of freedom, for various structure types
- Notice on determination of rubble parameters for ice ridge characteristics in model tests, such as rubble strength and density
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Ice data Identifed gaps:
- Estimating statistical distributions for sea ice and icebergs based on fairly limited databases should be addressed.
- How to handle limited data sets in general. Consider distributions for probabalistic calculations or define parameters or, when no data, recommend on parameters
Contributions will include improved guidance on- Considerations on data requirements- Characterization of ice drift- Defining ice properties that can not be
readily measured in the field- Definition on ice concentration- Ice berg shape coefficients, iceberg
adverse shapes and iceberg stability- Expert judgement on physical and
mechanical properties of ice
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Ice data – contributions continued
Additional guidance on handling of limited data sets. Objective shall be to define distributions (with focus on tails and cut-offs) for probabilistic load calculations and not least define deterministic parameters for deterministic load calculation checks (in particular for AL). Where no data is available, recommendations shall be provided on which parameters to use.
Additional guidance to be provided on i) interpretation of satellite data; ii) variability of ice drift; iii) geophysical scale ice pressure
Analysis of satellite imagesFast ice
ENVISAT ASAR WS subimage for March 31, covering Surovaya Bay in Hall Island, Landsat subimage of Surovaya Bay for March 20, and photo of icebergs from helicopter in Surovaya Bay. 1, 2 and 3 – marked icebergs.
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Layout of final report - proposal
Introduction- Brief Barents 2020 description and history
Description of work process
Gap analysis
Background information/justification for recommendations- For each recommended supporting text, a brief descripription on the basis/background
Recommendations on supplementary text- Organized according to clauses in ISO 19906 where we suggest supporting text
Recommendations, other
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Proposed Work Plan 2011 Early March : Text proposals received by DNV
3rd week March: Draft text for guidelines from editing group/DNV
End March: 3rd group meeting, review texts, sort out issues; workshop
May 13: Draft report from DNV, including draft text for guidelines
End May: 4th group meeting, review texts, sort out issues, detailed plan for fall
End June: Revised texts from editing group/DNV
End August: Comments to latest revision
Mid September: Texts 90-95% complete, editing group/DNV End September: Discuss additional changes
Mid October: Distribution of revised texts, editing group/DNV
Early November: Comments to last version
Mid November: Final texts distributed, only cosmetics left
December: Last group meeting, cosmetic changes, preparation of presentations to Steering Committee and Plenary
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Thank you for the attention
Safeguarding life, property and the environment
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