Decommissioning of

offshore installations in

the operational phase

Kristian Lund Jepsen

Ramboll Oil & Gas

2SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Two types of installations two types decom

3SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Reasons for decom at fixed installations

Equipment redundant from day one

Equipment/system process wise outdated

Demolition

Equipment/system technological outdated

Equipment failed / worn-out

Replace with equipment / systems that fits changedprocess conditions

Replace with modernequipment / systems withnew technology

Refurbish / Repair

Replace (1 : 1)

4SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Redundant from day one - example

Gas fired heater back-upfor turbine WHRUs

Other examples:

Mud tanks

Well kill system

Runway beams

Trolleys/chain hoists

5SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Process wise outdated equipment

Increased amount of produced water

Change from HP separation to LP Mode

Change in gas composition / mole weight

Change in gas composition increase of H2S + CO2

Increased amount of oil/gas

Debottlenecking of complete process train

Debottlenecking of produced water system

Larger pipe dia, larger volume in separators

Re-bundling of centrifugal compressors and larger driver

Change piping matr. class from CS to duplex

6SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Technological outdated equipment - examples

Pneumatic analog instruments

F&G Detectors / systems

Control / ESD Systems

Control panels for gas compressors

7SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Examples worn-out equipment

8SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Heat exchangers for cleaning/refurbisment

9SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Decommissioned stay in place

Runway beams aredecommissioned to avoid periodicinspections / tests.

10SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Experiences from operational decom

Dangerous lifting operations (unknown weight+COG)

Handling of NORM (NaturalOccuring Radioactive Matr)

Handling of chemical/oil waste

No asbestos in insulation(however: Flange Insulationkits, Carbon-Asbestos filledgaskets)

Scale may be barium orstrontium sulphate which is NORM material.

11SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Estimates tons metal scrap per year

Detailed data from one platform backload to shore during one year.

Assumed a model partly based on above data from one platform for calculating the amount of equipment operational decommissioned yearly.

Assessed the Customs Authorities to obtain information about import from offshore installations.

Assessed the oil Companies (DUC/Mrsk Oil, Hess, DONG E&P)

12SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Backload Logistics and Handling

Return Goods

/ Supply Boat

Well Service

Company

Equipment

Waste skips

Chemical Tote

Tanks

Backload

Containers /

Baskets

Large scrap

items

To Service company

Not dangerous

waste

Chemicals/oil

waste

Empty - send

to Kommune

Kemi

Empty -

normal

renovation

Waste to Kommune Kemi

Tank Cleaning

Waste to Kommune Kemi

Refill Tote

Tank

Sorting /

Evaluation

To Service /

Repair

company

To be Stocked for

later use

(OIL COMPANY'S

STORE)

To be sold for

re-use

Repair /

scrap

Repaired/

To stock

Supply Goods

/ Supply Boat

Scrap Yard

Scrap

Repaird - directly return to offshore

Costums area

13SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Estimate Model. All Danish offshore fields installedpiping / decomissioned piping and totally decommissioned

Estimated piping (incl. valves) from Danish offshore platforms decommissioned yearly

Installation

year 1987 and before 1987 - 1997 1997 - 2007 Totally

Age 20 years and more 10 - 20 years 0 - 10 years

Piping (tons) 6923 4825 3400 15148Scrap/change-

out % yearly 10 5 2,5Scrapped piping

- tons yearly 692 241 85 1018

Totally decommissioned from Danish offshore platforms yearly - estimated tons:

Piping 1000

Mech. Equipm. 500

Structures 250

Elect/Instrum 200

Other 50

Totally 2000

The model is based on a life time of 20 -25 years of an installation.

14SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Estimates from the 3 operators in Danish sector

DUC/Mrsk Oil

Hess Denmark Aps

DONG E&P

Totally: 3100 tons 3400 tons yearly

Variations: 2500 4000 tons yearly

15SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Jack-up rig conversion / decom

Maersk Giant:

Converted to oil/gas production 1996.

Production package owned by Schlumberger.

Produced on Yme Field 1996 2001, operated by Maersk Contractors.

Decommissioned production packagedemolished in Esbjerg Port 2001. Packagetaken over by Hannover Company

The rig converted back to drilling.

16SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Statoil preparations to decom. HSE / NORM

Study of consequences (Konsekvensutredning Ymeavslutningsplan).

Included evaluations regarding HSE impacts.

Included evaluations regarding NORM it was concluded there was no NORM as seawater had only been injected for a short period in the initial stage of the project.

Samples of scale in the production equipment was taken.

Concluded that scale was not radioactive and that it was calciumcarbonate.

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Maersk Giant towing in 2001

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Maersk Giant at the port side

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Maersk Giant production package onboard

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Maersk Giant equipment being lifted off

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Maersk Giant 2001 Decom/Conversion

Noise / Fire Walls around package removed

Flare tower removed

Production package removed from deck

All interconnecting piping and cabling removed

Totally: 1200 tons removed

Production package, 800 tons, sold from Schlumberger to Hannover Company for possible re-use

22SlideOctober 15, 2007Basic Ramboll Oil & Gas PPT

Yme production package. Summer 2007

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Mobile offshore units. Decom status.

Yearly 2 units in the harbour.

Equipment decommissioned/scapped yearly: 500 tons 2000 tons

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Total status. Decom. Tonnes handled yearly

From fixed installations 2500 - 4000From mobile offshore units 500 - 2000

Total 3000 - 6000

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Conclusion

The amount (tonnes) of equipment decomissioned/scraped and then handled in the harbour of Esbjerg yearly corresponds to the weight of one medium size topside.

The experience exists and the companies to handle the waste and scrap are used to handle these items.

Large heavy lift cranes (Thialf) cannot go into the harbour.

Need for companies who can handle and clean scrapped piping and equipment for NORM.

Need for long-term storage facilities for NORM.