decommissioning of offshore installations in the .... ramboll. decom in operational... ·...

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


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Equipment/system process wise outdated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Equipment/system technological outdated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)


Redundant from day one - example

Gas fired heater – back-upfor turbine WHRU’s

Other examples:

•Mud tanks

•Well kill system

•Runway beams

•Trolleys/chain hoists


Process wise outdated equipment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


Technological outdated equipment - examples

� Pneumatic analog instruments

� F&G Detectors / systems

� Control / ESD Systems

� Control panels for gas compressors


Examples – worn-out equipment


Heat exchangers for cleaning/refurbisment


Decommissioned – stay in place

Runway beams aredecommissioned to avoid periodicinspections / tests.


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.


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/Mærsk Oil, Hess, DONG E&P)


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


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.


Estimates from the 3 operators in Danish sector

� DUC/Mærsk Oil

� Hess Denmark Aps

� DONG E&P

Totally: 3100 tons – 3400 tons yearly

Variations: 2500 – 4000 tons yearly


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.


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.


Maersk Giant – towing in 2001


Maersk Giant at the port side


Maersk Giant – production package onboard


Maersk Giant – equipment being lifted off


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


Yme production package. Summer 2007


Mobile offshore units. Decom status.

� Yearly 2 units in the harbour.

� Equipment decommissioned/scapped yearly: 500 tons – 2000 tons


Total status. Decom. Tonnes handled yearly

From fixed installations 2500 - 4000

From mobile offshore units 500 - 2000

Total 3000 - 6000


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.

decommissioning of offshore installations in the .... ramboll. decom in operational... ·...

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