safer seas 2007 - brest 9-12 october 20071 recuperation of oil trapped in ship-wrecks: the difis...

SAFER SEAS 2007 - BREST 9-12 october 2007 1

Recuperation of Oil Trapped in Ship-Wrecks:

The DIFIS Concept

Jean-François Drogou

Ifremer


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


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.


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


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


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


The DIFIS consortium


DIFIS concept & main components

-Buffer Bell

-Riser Tube stiffening lines

-Riser tube

-Dome Housing Unit

-Dome

-Anchoring System

Designed by CYBERNETYX


Conceptconceptual study initiated in the frame of ROBMAR network

Buffer Bell

Dome and Riser tube


Main anticipated issues

Hydrodynamics & structural

Deployment (surface & bottom)

Anchoring

Operations & planning

Costs– regulations IPR


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


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.


Preliminary design

Early design and DIFIS system behaviour

Main elements evolutions

Load calculations

Preliminary Deployment

DIFIS Internal flow analysis

Scaled Model Test


DIFIS system behaviour(4000m)

Pre-tension 1000 ton

• Horizontal displacement, 306 m

• Vertical displacement – 13.6 m

Datas from SENER


System behaviour (400m)

Pre-tension 1000 ton

• Horizontal displacement, 4.7 m

• Vertical displacement - 0.1 m

Datas from SENER


Flow analysis

Flow calculations (Sirehna)


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


DIFIS internal flow analysis

2 m

Sirehna


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.


Scaled model test

Scale 1:60

Marin Offshore Bassin


DIFIS life cycle

Phase 1Readiness

Phase 2Deployment

Phase 3Intervention

Phase 4Post-intervention


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.


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


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.


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.


Planning

Scaled model validation

Final design

Deployment procedures

Planning & Costing evaluation

Exploitation & promotional activities

More information

www.difis.eu

safer seas 2007 - brest 9-12 october 20071 recuperation of oil trapped in ship-wrecks: the difis...

Documents

cybernetyxsafer seas

possiblesafer seas

wrecksafer seas

sea watersafer seas

difis consortiumsafer

riser tubesafer seas

longer termsafer seas

prompt intervention