Post on 27-Dec-2015
SAFER SEAS 2007 - BREST 9-12 october 2007 1
Recuperation of Oil Trapped in Ship-Wrecks:
The DIFIS Concept
Jean-François Drogou
Ifremer
SAFER SEAS 2007 - BREST 9-12 october 2007 2
Issue
Maritime disasters leading to major environmental pollution happen almost regularly
AMOCO-CADIZ in 1978, TANIO in 1980, AEGEAN SEA in 1992, ERIKA in 1999, PRESTIGE in 2002
Existing wrecks all over the world with smaller or bigger quantities of hydrocarbons trapped in their tanks constitute a more or less serious threat at shorter or longer term
SAFER SEAS 2007 - BREST 9-12 october 2007 3
Need
The REPSOL YPF solution, designed and implemented under emergency conditions for the particular PRESTIGE case, constitutes the state of the art in ROV based interventions at great depths.
The PRESTIGE case has put in evidence, among other things, the lack of tools, systems and methodologies for the prompt intervention on the ship wrecks in order to confine the pollution and, successively, eliminate the source of the pollution threat.
This is exactly the aim of DIFIS project: a method of wide applicability for the prompt intervention on ship wrecks.
SAFER SEAS 2007 - BREST 9-12 october 2007 4
Objectives
Stop the pollution Rapid deployment
Eliminate pollution threat Permanent solution
At very short term contain / seal any leakages
Successively, at a longer term, remove the pollutant from the wreck
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Requirements
General: adaptable / applicable in most possible cases
Of rapid deployment / Implementation so that to contain any leaking as promptly as possible
No risk for the structural stability of the wreck
Implemented in phases allowing, with the same system / procedure, both the prompt containment of the leaks and the subsequent removal of the remaining hydrocarbons
As simple and economical as possible
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DIFISDouble Inverted Funnel for
Intervention on Ship wrecks
The scope of this project is the study, design (including costing, planning, deployment procedures etc) of an EU reference method for the prompt and cost-effective intervention and remediation of tanker wrecks dealing with eventual leaks and recuperating the fuel trapped in their tanks even at considerable depths.
The proposed method will be of general applicability as long as the trapped pollutant does not dissolve and is of lower density than sea water
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The DIFIS consortium
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DIFIS concept & main components
-Buffer Bell
-Riser Tube stiffening lines
-Riser tube
-Dome Housing Unit
-Dome
-Anchoring System
Designed by CYBERNETYX
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Conceptconceptual study initiated in the frame of ROBMAR network
Buffer Bell
Dome and Riser tube
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Main anticipated issues
Hydrodynamics & structural
Deployment (surface & bottom)
Anchoring
Operations & planning
Costs– regulations IPR
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Reference scenarios (1)
A deep water reference scenario based on the environmental conditions of the PRESTIGE accident: wreck lying at 4,000 m deep, slightly inclined seabed, low temperature, no sea current at sea-bed; strong currents near the surface and adverse sea conditions
A shallow water reference scenario based on the fact that a DIFIS system would be feasible in terms of design from around 400 m
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Reference scenarios (2)
The “PRESTIGE grade” heavy fuel oil is the reference cargo in both scenarios. Moreover, in order to accurately define a range of oils, heaviest and lightest cases of oil cargo are included, to allow for a definition of multiple cargo scenarios.
The wreck of half of a standard double hull ULCC was opted as the reference target.
Deployment time (as soon as possible) and safety of deployment operations is one of the key design criteria.
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Preliminary design
Early design and DIFIS system behaviour
Main elements evolutions
Load calculations
Preliminary Deployment
DIFIS Internal flow analysis
Scaled Model Test
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DIFIS system behaviour(4000m)
Pre-tension 1000 ton
• Horizontal displacement, 306 m
• Vertical displacement – 13.6 m
Datas from SENER
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System behaviour (400m)
Pre-tension 1000 ton
• Horizontal displacement, 4.7 m
• Vertical displacement - 0.1 m
Datas from SENER
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Flow analysis
Flow calculations (Sirehna)
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Main elements evolution
Buffer bell
Diam:14m L:20m
Rigid rings,dyneema lines
Riser Tube
PE-pipe diam.2m
6 mooring lines
Steel rings every 50 m
Dome
Geo-textile-Diam 100 & 200m
12 mooring lines diam 98 mm
SENER
SAFER SEAS 2007 - BREST 9-12 october 2007 18
DIFIS internal flow analysis
2 m
Sirehna
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Preliminary principle of deployment
Safe and rapid deployment is the main challenge, and Bulkiness, sizes, and complexity rise as depth of operation increases.
Phase 1: deployment of the mooring anchorage dead weightsPhase 2: Surface deployment of the dome and dome housingPhase 3: Lowering the Riser tubes along the guidelinesPhase 4: Surface deployment of the buffer bell.Phase 5: Connecting buffer bell to tensionning linesPhase 6: Ballasting the Buffer bellPhase 7: Clamping the buffer bell onto the guidelinesPhase 8: Anchoring the dome using mooring linesPhase 9: Tightening of the Mooring linesPhase 10: Freeing the lifting bags for anchoring tensioningPhase 11: Deploying the domePhase 12 : End of deployment and complete survey.
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Scaled model test
Scale 1:60
Marin Offshore Bassin
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DIFIS life cycle
Phase 1Readiness
Phase 2Deployment
Phase 3Intervention
Phase 4Post-intervention
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Readiness
It includes all the activities prior to an eventual accident (or the manifestation of a need for a specific DIFIS intervention).
It includes all the activities related to the readiness forintervention. The prime requirement during this phase is preparedness to intervene, within the DIFIS operational
envelope, in a) time as short as possible, while (b) tying-down the less capital and human resources as possible.
Activities like design, costing, deployment and tender procedures, eventual pre-fabrication and storage of components, integration of the system in emergency plans
and contingency procedures and training of the personnel are
included.
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Deployment
All the pre-intervention activities after an accident has taken place (or a specific DIFIS intervention need has been manifested) till the beginning of the recuperation phase. 6 broad classes of deployment operations :
1. Planning and managing the whole project of the specific intervention
2. On-site survey of the wreck, the sea-bottom and the other local
environmental conditions (i.e. sea current profiles, waves etc)
3. Engineering and implementing the case specific aspects of the
intervention
4. On-site surface deployment: vessel positioning, deployment,
assembly of submerged platform (SUP), ROV installation
5. On-site underwater deployment: anchoring, deployment, positioning, assembly of riser tube and stiffening lines, dome unfolding, buffer bell
6. Support operations
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Intervention
It covers the period after the deployment of the system, where the wreck is covered and all the trapped pollutants are channeled to the Buffer Bell.
The most important operation during this phase is the periodic recuperation of the pollutant from the Buffer Bell, most likely by means of a small, suitably equipped shuttle tanker.
Another important class of operations performed during the intervention phase has to do with the monitoring activities (of the structure and wreck) and, eventually, maintenance of the
DIFIS structure.
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Post- intervention
It covers the period after the end of the operation phase, when the pollution threat can be considered eliminated. It deals mainly with the recuperation of the system, the evaluation of the intervention as well as eventual feedback, changes and upgrading of the system and / or procedures.
Processing of recuperated pollutant is also a task that needs to be performed in this phase, but remains outside the scope of the DIFIS project. Processing of pollutant oil is most probable to take place on shore and it is something that is case specific, depending on each oil physical properties, oil/sea-water percentage mix and evaporation of oil components.
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Planning
Scaled model validation
Final design
Deployment procedures
Planning & Costing evaluation
Exploitation & promotional activities
More information
www.difis.eu