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Danish Sustainable Offshore Decommissioning Project

Background report of Danish and other North Sea fields and platforms due for decommissioning

December 2011

� Danish Sustainable Offshore Decommissioning Project

AcknowledgementsThis Report has been prepared by Mr Robert Ohene Adu and Mr Tommy Petersen of the Offshore Centre Denmark. The Authors would like to thank Professor Jens Peter Thomsen, in charge Envi-ronmental Technology, Aalborg University, Esbjerg for his assistance and advice.

�Danish Sustainable Offshore Decommissioning Project

Executive SummaryDecommissioning

The North Sea is currently host to more than 600 offshore oil & gas installations, many of which have been standing since the 1960s and 1970s. Thus a good number of them have exceeded their opera-tional lifetime limit of 25 years and are no longer producing hydrocar-bons. Many of the steel and concrete structures have also become obsolete. As a result they have become redundant and need to be removed.

An offshore platform contains of several thousand tonnes of steel and metals of which a big large part is recyclable. At the same time the platforms pollutants such as oil residues, chemicals, gases and radioactive substances can leach into the marine environment. There are international legal requirements for removal of obsolete platforms.

Preliminary analysis of the technical aspects of offshore decommis-sioning has shown that the task will include engineering specialist at a high level, in other words knowledge workplaces in large scale. This includes competencies in design, calculation, project management, environmental planning, environmental control, purification, libera-tion, lifting and transportation, well plugging, shredding and recycling on land.

OSPAR

The Oslo/Paris agreements (OSPAR) of 1992/1998 states with re-gard to the North Sea offshore constructions that:

“No disused offshore installation or disused offshore pipeline shall be dumped and no disused offshore installation shall be left wholly or partly in place in the maritime area”

To this end OSPAR decision 98/3, this entered into force on 9th Feb-ruary 1999, prohibits dumping, and the leaving wholly or partly in place, of disused offshore installations within the maritime area. The key terms of the OSPAR convention are as follows:

The topsides of all installations must be returned to shore and all installations with a jacket weight of less than 10,000 tonnes must be completely removed for re-use, recycling or final dis-posal onshore.

Notwithstanding this, OSPAR decision No. 98/3 recognises that companies may experience difficulties in removing the footings of large steel jackets weighing in excess of 10,000 tonnes and concrete installations. Thus there are derogations for these cat-egories of installations if the internationally agreed assessment and consultation process shows that leaving these in place is justifiable.

The derogation provisions, however, apply only to installations installed prior to 9 February 1999. All installations put in place after this date must be removed completely.

It is proposed that the decommissioning of the earmarked facili-ties will be performed in a phased manner following the permanent abandonment of the platform wells, isolation and making the facilities hydrocarbon-free. The planned phases of the decommissioning are as follows:

• Pre-decommissioning inspections, surveys and engineering de-velopment studies.

• Plugging and permanent abandonment of the wells.• Removal of residual hydrocarbons from the platform facilities and

associated pipelines.• Removal to shore of the platform structures and equipment.• In-situ decommissioning of the pipelines.• Removal of the hose bundles.• Post decommissioning seabed clearance and surveys.• Onshore dismantling and disposal.

This document presents a description of a number of mature oil and gas platforms in the North Sea considered as the most likely candi-dates for decommissioning under the project “Dansk Bæredygtig Offshore Dekommissionering”. It is prepared by Offshore Centre Denmark, as part of a Consortium of Companies in the offshore sec-tor in Denmark namely Ramboll Oil & Gas, Semco Maritime A/S and Blue Water Shipping.

It is a prelude to the environmental impact assessments to be carried out on all the possible options of decommissioning for the selected oil and gas platforms. The chosen 71 platforms located in various oil and gas fields of the North Sea are listed in this project as mature and are candidates for decommissioning. The majority of the platforms are gas platforms located in the southern sector of the North Sea mainly in the UK, Dutch and Norwegian continental shelves, whereas the oil platforms are mostly found in the North/Central North Sea, in the Danish, the UK and the Norwegian continental shelves. All of the platforms are located in shallow waters from 20 to 80 meters water depth.

Offshore Center Danmark

Danish Sustainable Offshore

Decommissioning Project

Background report of Danish and other North Sea

fields and platforms due for decommissioning

December 2011

Authors: Mr Robert Ohene Adu and

Mr Tommy Petersen, Offshore Center Danmark

Publisher

Offshore Center Danmark

Niels Bohrs Vej 6

6700 Esbjerg

Tel. + 45 33 97 36 70

www.offshorecenter.dk

This is a published document where copyright rests

with the Offshore Center Denmark and consortium

members. All rights reserved.

Information contained in this document are owned

by the aforementioned parties and supplied without

liability for errors or omissions.

No part may be reproduced or used except as

permitted by contract or other written permission.


Content

Acknowledgement .............................................................4

Executive summary ............................................................5

Decommissioning .............................................................5OSPAR .............................................................................5

1.0 Introduction ...................................................................9

2.0 Description of Fields, Platforms and Pipelines ...10

2.1 General Environmental Conditions in the North Sea . 112.2 Indefatigable Gas Field ..........................................112.2.1 Environmental Parameters ....................................132.3 Leman Gas Field ...................................................142.4 Beatrice Oil Field ...................................................152.5 West Sole Gas Field ..............................................172.5.1 Environmental Parameters ....................................172.6 The Rough Gas field..............................................182.7 Viking Gas Field and Platforms ..............................182.8 L7 Field and Platforms ..........................................182.9 Dan Oil and Gas Field and Platforms ......................182.9.2 Environmental Parameters ....................................182.10 The K Gas Field and Platforms ...............................192.11 Ekofisk Oil/Gas Field and Platforms .......................192.11.1 Albuskjell field .......................................................192.11.2 Cod field ...............................................................192.11.3 Edda field .............................................................192.11.4 Booster Platform 36/22-A .....................................192.12 Auk Oil Field and Platforms ....................................19

3.0 Conclusion ...................................................................20

�.0 References...................................................................21


An emerging decommissioning industry is on the business horizon after decades of oil and gas exploration and production on the high seas. A number of oil and gas production platforms located in the North Sea reaching the end of their productive life and might thus be due for decommissioning.

The Project codenamed: “Offshore Decommissioning Project” has developed as a result of collaborative work among a number of com-panies, consultants, politicians and Aalborg University in Esbjerg, Denmark. This project is a natural development in Esbjerg and should be seen as succession of the intense oil and gas activities in Esbjerg over the past 3 -4 decades. In addition to the Danish decommis-sioning responsibilities Esbjerg could utilize its unique infrastructure, facilities and geographical location also to consider the decommis-sioning market outside the Danish part of the North Sea.

1.0 Introduction

Currently in the North Sea there are approximately 600 platforms producing oil, gas and condensate from about 100 fields. Some of these platforms have become obsolete, having exceeded their de-sign life of about 25 years. A number of selected North Sea fields and platforms under the project have been described in this report. It contains a description of the designated platforms and their fields of location.

Virtually all the platforms listed are made of steel material.

10 Danish Sustainable Offshore Decommissioning Project

2.0 Description of Fields, Platforms and Pipelines

Figure 2.0 (a) Map of North/Cen-

tral North Sea fields (Source:

Acorn Petroleum Services, 2009)

The North Sea is segmented into a number of imaginary blocks with respect to fields and platform locations. Most of the platforms are located within longitudes ranging from 00 to 50E and latitudes 520N and 620N (Figures 2.0a and 2.0b).

11Danish Sustainable Offshore Decommissioning Project

Figure 2.0 (b)

Map of Southern

North Sea fields

(Source: Acorn

Petroleum Serv-

ices, 2009)

2.1 General Environmental Conditions in the North Sea

The Southern sector of the North Sea represents the shallow regions where gas deposits are mainly found. Fields in this sector lie in the Dutch, German, and southern UK continental shelves. The seabed in this region is characterized by sandy sediments and the benthic fauna which are present are more adapted to strong tidal currents and therefore to constant movements of sand along the bottom of this region. Species usually found in the sea bed are polychaetes. The Southern North Sea are spawning grounds for fish varieties including mackerel, shellfish, cod and sprat, as well as sea birds namely kit-tiwake, fulmar, common galls, little auks and puffins, to name a few. There are also sea mammals, namely harbour porpoises and, to a lesser extent, white-beaked dolphins and common seals.

The Central and Northern sectors of the North Sea represent the deeper regions where oil deposits are mainly found. Fields in this sector lie in the Danish, Norwegian and Northern UK Continental Shelves. The tidal currents in this region are weaker, and sediments in the seabed are less sandy and less mobile. Benthic fauna found in this region are mainly corals, sponges, polychaetes, echinodermata, crustaceans and molluscs. These are found especially in the Danish sector (DMU, 2010).

2.2 Indefatigable Gas Field

The Indefatigable Gas Field is a gas production field situated in the UK Continental Shelf (UKCS) in the North Sea between latitudes 530N and 540N. Gas production platforms are located in Blocks 49/18, 49/19, 49/23 and 49/24 of the UKCS. These platforms are located at the side of the Indefatigable Gas Field operated by Shell UK and BP Amoco. Situated 75 km off the East Anglian Coast and 113 km north-east of Lowestoft, the field lies in the Norfolk banks at a water depth of around 31 meters. The area is considered typical of the offshore regions of the North Sea where, hydrographical, meteorological, geo-logical and biological characteristics are considered constant.

This field was discovered in 1966 and brought on stream in 1971 with the installation of Juliet (JD and JP), Kilo and Lima platforms. Two smaller platforms Mike and November were added in the 1980s to maximize gas production. Further upgrading, de-manning and compressor reconfiguration were carried out on the platforms in the mid 1990s. An eductor was further installed in 2001 to lower suction pressure.

At the end of its production in July 2005, the Shell/Esso side of the Indefatigable Gas Field had produced 50.8 billion Nm3 of natural gas and 0.57 million m3 of condensate.


Fig 2.2 (a) Location of Indefatigable Field

Fig 2.2 (b) Juliet

Platform (7 wells)

Fig 2.2 (c) Kilo

Platform (5 wells)

Fig 2.2(dLima

Platform (6 wells)

Fig 2.2(e) Mike

Platform (4

wells)

Fig 2.2(f) Novem-

ber (4 wells)


Platform Type Installation. Production Operator Jacket Topsides year year (tons) (tons)

Inde AC Compression 1979 1980 Amoco S. 938 6718

Inde AD Drilling 1968 1971 Amoco S. 460 1281

Inde AP Production 1971 1971 Amoco S. 493 1348

Inde AQ Accommodation 1979 - Amoco S. 241 1317

Inde AT Pipeline terminal 1971 - Amoco S. 402 1316

Inde BD Drilling 1973 1974 Amoco S. 567 803

Inde CD Drilling 1976 1977 Amoco S. 536 1165

Inde CD Production 1976 1977 Amoco S. 504 1272

Inde JD Drilling/ prod. 1970 1971 Shell N. 550 3038

Inde JP Satellite 1972 - Shell S. 187 427

Inde K Drilling/prod. 1971 1973 Shell S. 568 3114

Inde L Satellite 1977 1977 Shell S. 550 1000

Twelve platforms in the Indefatigable Gas Field are due for decommissioning under the Project Offshore Decommissioning. These platforms are listed in the table 2.2.

Table 2.2 Platforms in Indefatigable field to

be decommissioned

2.2.1 Environmental ParametersTable 2.2.1 summarises information on the characteristics of the area in which the platforms and pipelines are located and Table 2.2.2 summarises the environmental features.

Feature Data

Sea bed Sediment Predominantly silty sands

Water Depth Approximately 31m

Nearest Land 94km North East of Great Yarmouth, Norfolk Uk

Distance to Median 21 km from UK/Dutch transboundary land median line Surface currents Wind driven and variable

Tidal Currents 1.07 m/s N-S ( extreme 1 year return)

Feature Data

Benthic ( Sea Bed) Typical of the Southern North Sea Basin, communities dominated by polychaetes (worms) living in silty sediments

Fish spawning The Indefatigable Gas Field lies within extensive spawning grounds for mackerel (May-Aug), plaice (Dec-Mar), sprat (May-Aug) and nephrops (shellfish). Cod and Lemon sole also spawn within the vicinity.

Fish Nursery areas The field coincides with nursery grounds for whiting, cod, lemon sole, nephrops and sprat.

Seabirds Several species are found in the area namely fulmar, common gull, kittiwake, guillemot, razorbill, gannet, skua, black-headed gull, little auk and puffin. Seabirds vulnerability is rated high during October through April, especially high in March

Marine mammals Harbour porpoises are the most commonly observed mammals and can be found in low numbers in Feb, Apr, May and Aug and in moderate numbers in March with up to 4 sightings/month between Jan-Apr. White beaked dolphins are less common and have only been observed in Apr and May. Common seals are expected even though little information is known.

Table 2.2.1 – Physical, meteorological and oceanographic conditions,

Indefatigable Gas Field (Source: Shell UK, 2007)

Table 2.2.2 Environmental Characteristics of

Indefatigable Field (Source: Shell, UK, 2007)

1� Danish Sustainable Offshore Decommissioning Project

2.3 Leman Gas Field

The Leman field is a gas field located in United Kingdom waters at a latitude of 53.08 (53° 4’ 60 N) and a longitude of 2.17 (2° 10’ 0 E), 72 km north-east of Lowestoft. It is the largest discovered gas field in the Southern North Sea and was discovered in 1966. The field extends into blocks 49/26, 49/27, 49/28, 53/1a and 53/2 and has a reservoir depth of 1980 meter. It is a giant field with an estimated ul-timate recovery of 325.6 billion Nm3 of gas in the aeolian dune sands of the Rotliegend Group (Hillier and Williams, 1991). Shell and Amoco are the operators.

There are four platform complexes in the Leman field - Alpha, BT, Charlie and Bravo.

Figure 2.3 The Leman Bravo Platform

The Alpha complex is the nodal installation for the Leman field and comprises four bridge-linked platforms - wellhead platforms (ADI and ADII), production platform (AP) and compression platform (AK). The nodal installation produces and processes gas from the wells on ADI and ADII. Gas is also imported from the other installations for processing and is then exported through a 76.2 cm diameter subsea pipeline to the Bacton Gas Terminal.

BT complex comprises two bridge-linked platforms - terminal plat-form (BT) and helideck/redundant accommodation platform (BH).Charlie complex comprises two bridge-linked platforms - well head platform (CD) and production platform (CP).

Bravo complex comprises two bridge-linked platforms - wellhead platform (BD) and production platform (BP).

BT complex imports gas from the Bravo complex, the Charlie com-plex and the Delta platform and the Echo platform (via the Bravo complex) for processing. The gas is then exported through a 30in diameter subsea pipeline to the Alpha complex for processing.

Delta, Echo, Foxtrot and Golf are single jacket wellhead platforms.

Some 25 platforms in the Leman field have by the present project (Offshore Decommissioning Project) been earmarked for decom-missioning (Table 2.3).

1�Danish Sustainable Offshore Decommissioning Project

Platform (tons) Type Installation. year Production year Operator Jacket (tons) Topsides (tons)

Leman AC Compression 1974 1976 Amoco Southern 960 4093

Leman ‘AD’ Drilling 1967 1969 Amoco Southern 455 892

Leman ‘AP’ Processing 1968 1969 Amoco Southern 433 1879

Leman ‘AD1’ Drilling 1967 1967 Shell 994 2465

Leman ‘AD2’ Drilling 1969 1970 Shell Southern 204 100

Leman ’AK’ Compression 1975 1975 Shell Southern 609 5000

Leman ’AP’ Production 1967 1968 Shell Southern 624 1200

Leman ’BD’ well support, 1968 1968 Amoco Southern 496 692 accommodation

Leman ’BP’ Processing 1968 Amoco Southern 420 1852

Leman ’BT’ Field terminal 1970 Amoco Southern 402 558

Leman ’BD’ Drilling 1969 1970 Shell Southern 809 2173

Leman ’BT’ Shell Southern 400 1000

Leman ’BK Shell Southern 609 5000

Leman ’BH’ Helideck/accom Shell Southern 350 850

Leman ’BP’ Production 1969 1970 Shell Southern 516 1155

Leman ’CD’ well support 1967 1969 Amoco Southern 504 714

Leman ’CP’ Processing 1968 1969 Amoco Southern 442 4160

Leman ’CD’ Drilling 1971 1972 Shell Southern 927 1891

Leman ’CP’ Production 1971 1972 Shell Southern 538 1213

Leman ’DD’ well support, acc 1971 1973 Amoco Southern 433 714

Leman ’ED’ Drilling 1972 1974 Amoco Southern 634 759

Leman ’ EP’ Production 1972 1974 Amoco Southern 281 616

Leman ‘FD’ well support,acc 1973 1975 Amoco Southern 406 759

Leman F Satellite Shell Southern 2244 1781

Leman ‘G’ Wellhead Shell Southern 2121 1537

Table 2.3 Leman field Platforms designated for decommissioning


2.� Beatrice Oil Field

Beatrice field is an oilfield that lies on latitude 580 07’ 00’’ N and on longitude 30 05’ 00’’ W (National Geospatial-Intelligence Agency, Bethesda, 2004).

Beatrice was the first field to be developed in the Moray Firth Area, and at 24 km from the shore it can be seen from the shore. Beatrice comprises 4 conventional steel platforms operated by BP Explora-tion Northern. These platforms are Beatrice A and 2 single satellite platforms B and C. The Beatrice A complex consists of 2 platforms bridge-linked (50.5m): 1 drilling/quarter platform AD and 1 process-ing/power generation platform AP.

Beatrice B satellite platform was installed later and is located 3 miles north-east of the A complex.

It is a drilling and a water injection platform. Beatrice C is designated a satellite water injection facility and was installed in September 1984. It pushes oil from the south-west end of the reservoir in direction of A. B and C are linked by pipelines with A.

Beatrice oil is exported via a 40.64 cm pipeline from the A complex to a short terminal at Nigg in the Cromarty Firth, where it is stored until tanker shipment. Since 1986/87 Beatrice has a 132/33kV power ca-ble (via submarine) from Dunbeath. It connects platform to mainland power supply. It is used when the platform is fuel gas deficient.

Instead of the Beatrice platforms there is now placed new wind tur-bine foundations. And the former import power cable, from shore to the offshore platforms is now used as an export power cable to shore from the platforms.

Hence only two platforms in the Beatrice field could be earmarked in the decommissioning project. Those are the drilling/accommodation platform, Beatrice ‘AD’, and production/power generation platform Beatrice ‘AP’.

Beatrice

Figure 2.4.1 a,b. Beatrice Oil Field (Sources: www. esru.strath.ac.uk and

Google Image, 2011)


2.� West Sole Gas Field

The West Sole field is a gas field located in Block 48/6 of the Southern North Sea and 70 km off the East Yorkshire coast. The water depth is about 28 m, a reservoir depth 2,745 m and covers an expanse 19km long and 5 km wide. The field was discovered in September 1965 and was licensed to BP (Exploration Southern) in the first UK licens-ing round. Gas Production commenced in 1967. This West Sole field supplied almost all of Britain’s gas within its first 10 years of discovery as it was Britain’s first commercial discovery. Initial recoverable re-serves were 53 billion Nm3 of gas, of which 37.8 billion Nm3 had been produced by the end of 1989. By 2005, 53.8 billion Nm3 had been produced (BP, 2005).

The field has 3 satellite fields, Newsham, Hyde and Hoton whose gas supplies are exported via West Sole.

The original development plan called for:• Two fixed steel production platforms - West Sole ‘A’ (WA) and West

Sole ‘B’ (WB), with facilities to dry the water-saturated gas.• 70 km, 40.64 cm diameter pipeline from the field to a shore termi-

nal at Easington, 40 km east of Hull.

By spring of 1968 four production wells had been drilled from WA, and six from WB. In 1969 the six-well production platform WC was installed: and in 1974 the satellite platform WAS was connected to WA and two further wells drilled.

In 1978, the WE platform was removed after eleven years in produc-tion. This was the first North Sea platform to be decommissioned.

By 1980, West Sole production was in decline due to a combination of the drop in reservoir pressure and low gas prices which deterred further capital investment. Following negotiations over the gas price, the West Sole Gas Compression Project was undertaken to improve gas recovery, and involved the installation of gas compression facili-ties and additional electrical power generation plant onshore at Eas-ington: the laying of a new 60.96 cm pipeline from WB to Easington to handle the lower pressure gas: and associated modifications to all three platforms.

2.5.1 Environmental ParametersSpecies biodiversity and seabed sediment quality around the West Sole field have fairly remained constant over the 46 years since gas production was started ( BP, 2005).

Figure 2.5.1a the West Sole Field

Figure 2.5.2b the West Sole Gas Platform


2.6 The Rough Gas field

The Rough field is a gas field located in the UK sector of the Southern North Sea and lies 32 km off the East Yorkshire Coast. Discovered in 1968, gas production from this field started in 1975. The Rough platform is a gas storage platform, the largest gas storage facility in the North Sea and is owned by Centrica (Energy Business Review, EBR: 2006).

Figure 2.6 The Rough Field

The Rough field lies at a water depth of 27.7 m and a reservoir depth 1,235 m below the sea bed. Two platforms, Rough ‘AD’ and Rough ‘AP’, which stand 1 mile apart, control the flow of gas in and out of the field (BBC, 2011). The platforms have 30 wells which allow vast quantities of gas to be pumped out on cold days when demand is high and gas to be pumped back into the wells on milder days when demand is low. The Sub-sea pipeline from this field comes on shore at the Easington Gas Terminal, 32 km from Hull. At a maximum gas flow rate of 54 million Nm3 gas/day this gas supply is enough to pro-vide one-tenths of UK’s gas energy needs.

2.� Viking Gas Field and Platforms

The Viking field is a gas field located in the UK sector of the North Sea at Blocks 49/12a, 49/16, and 49/17. The Field is operated by Conoco Southern. Production from the Viking field began in 1972 with 13 platforms and 20 wells. At a peak production of 26.9 Million Nm3 per Day, this field supplied 10% of UK’s natural gas require-ments. By 1999, the figure had declined to approximately 1.13 mil-lion Nm3.

There have been 3 new developments within the Viking area follow-ing new technology applications. These developments are: the Vam-pire field on the eastern margin; Kx to the south of the Philips Alison field; and 4 previously non-producing fields, captured in the Phoenix development (Riches, 2003).

Significant volumes of new gas have been discovered after a highly successful drilling program infield in the 1990s. Accumulated pro-duction to date is 81.6 billion Nm3 of gas.

Eight of the platforms in the Viking field are due for decommission-ing. These are: Drilling platforms AD, BD and FD (wellhead drilling); Processing platforms AP and BP; compression platforms AC and BC; and the riser platform AR.

2.8 L� Field and Platforms

The L7 block is a gas production field in the Dutch sector of the North Sea. Production of gas from the L7 offshore block began in 1977, four years after gas was first discovered in the Dutch Continental shelf (Total, 2011).

Offshore gas production is broadly concentrated in a core area in the K and L blocks in this sector (MBendi information Services, 2011).

This field has exceeded the usual 10-30 year productive period for gas fields and some platforms in the Dutch offshore fields have al-ready been decommissioned (about 9 platforms). The three platforms in this field due for decommissioning are the drilling and production platform L7-C, processing platform L7-P and accommodation plat-form L7-Q.

Already at the design stage of the above-ground installations, the possibilities for recycling various parts are taken into account. The underside of the borehole and the pipes are sealed by cement plugs (Total, 2011).

2.� Dan Oil and Gas Field and Platforms

The Dan field is an oil and gas field located in the Danish sector of the North Sea, on block 5505/17. It was discovered in 1971 and came on stream the following year. Maersk Oil is the Operator and has the sole concession license. The field lies on an area of 104 km2 with a water depth of 40m and a reservoir depth of 1,850 m. It has 61 production wells and 50 water-injection wells, with more than 60 platforms in use in connection with production. As at January 2011, the Dan field had produced 101.77 million m3 of oil, 22.72 billion Nm3 of gas and 120.29 million m3 of water.

2.9.1 Production FacilitiesThe Dan field comprises 6 wellhead platforms A, D, E, FA, FB and

Figure 2.7 Viking A and B Conocco Philips Platforms in Southern North Sea

(Source: Google Images)


FE; a combined wellhead and processing platform, FF; a processing platform with a flare tower, FG; 2 processing and accommodation platforms, B and FC respectively; and 2 gas flare stacks, C and FD (Danish Energy Agency, DEA: 2011).

Simultaneous water injection into the wells was started in 1989 as a way of maintaining reservoir pressure and has gradually been ex-tended to cover the entire field. The recovery of oil is optimized by flooding the reservoir with water to a possible extent.

The Dan Field has facilities for receiving production from the adjacent Kraka and Regnar satellite fields, as well as for receiving some of the gas produced from the Halfdan field. The Dan installations, in turn, supply injection water to the Halfdan field. After final processing the oil is transported to shore via the Gorm E platform. The Gas is pre-processed and transported to Tyra East for final processing. Treated production water from Dan field and its satellite fields is discharged into the sea.

The Dan field has accommodation facilities for 5 persons on the B platform and about 100 persons on FC.

Five Dan field platforms listed in the decommissioning Project, have been earmarked for the proposed decommissioning exercise. They are the wellhead drilling platforms A, D and E (E unmanned); process-ing platform B, as well as separator and flare platform C,

2.9.2 Environmental ParametersDan field is located approximately at Longitude 5.50 E and latitude 550 and in a demarcated area of 104 km2, west of Horns Rev SW Area (Longitude – 700, Latitude – 5530) where are found benthic fauna such as polychaetes, crustaceans, echinodermata and mol-luscs (DMU, 2010). These play a vital role in maintaining the ecologi-cal balance of the oceans.

Figure 2.8.2 Map of Denmark showing stations with benthic fauna (DMU, 2010)

2.10 The K Gas Field and Platforms

The K field is a natural gas field located in the Dutch Continental shelf and operated by NAM (Nederlandse Aardolie Maatschappij B.V).

Whereas the platforms K8-FA-1 and K8-FA-2 have been in produc-tion since 1978 and 1979 respectively, new connecting pipelines

have been installed between them in 2010. It is possible that more wells will be drilled in this block to maintain or enhance gas produc-tion before the platforms are decommissioned.

2.11 Ekofisk Oil/Gas Field and Platforms

The Ekofisk field is an oil and gas field in the Norwegian sector of the North Sea. There are a number of platforms in this field which are to be decommissioned. The field also has satellite fields whose platforms are included in the Ekofisk I cessation plan. These satellite fields are Albuskjell, Cod, and Edda fields. Approval by the Norwe-gian government was given in 2001 for the platform removal part of the Ekofisk I cessation plan. Platform removal operations were due to start in 2009 and to be completed by 2013.

2.11.1 Albuskjell fieldThis field has redundant platforms which are called Albuskjell plat-forms 1/6 A and 2/4 F.

2.11.2 Cod fieldThe Cod field has platform Cod 7/11 A.

2.11.3 Edda fieldThe redundant facility here is the Edda 2/7 C.

2.11.4 Booster Platform 36/22-AThis is a booster platform which stands on the Danish sector of the North Sea.

2.12 Auk Oil Field and Platforms

The Auk oilfield, named after the ‘Auk’family of birds, is the first Brit-ish oilfield and is located in Block 30/16 of the Central North Sea, about 270 km South East of Aberdeen (Trewin and Bramwell, 1991). The field lies in a water depth of 74- 83 m and a reservoir depth of 2,316 m. It has an oil column of 123 m contained within Rotliegend sandstones, Zechstein dolomites, Lower Cretaceous breccias and Upper Creta-ceous chalk. It covers an area of about 65 km2. It is a combination of tilted horst blocks and stratigraphic traps located at the western margin of the South West Central Graben. Production started in 1975 from the Auk A platform with 80% coming from the Zechstein dolomites. The field has an estimated ultimate recovery of 14.8 million m3 of oil, with 2.1 million m3 of oil remaining at the end of 1988.

The oil produced was initially transported from the Auk A platform to the loading terminal (ELSBM). From 1986, the oil was transported to the Fulmar Alpha platform. Associated gas from the reservoir was separated and used to generate electrical power with the excess being flared.

Thus, the two platforms due for decommissioning in this field are ‘Auk ‘A’ - Drilling, production, accommodation platform and the ‘Auk’ (ELSBM) - Loading terminal.


A description of about 71 of some of the earliest platforms in the North Sea earmarked to be decommissioned, and their correspond-ing fields of location has been made in this report. As much as pos-sible, information on the environmental sensitivities and conditions prevailing around these platform locations have been included to allow a thorough assessment of the environmental impact of all the options of decommissioning to be screened.

3.0 Conclusion


1. Acorn Petroleum Services (2009). Northern/Central North Sea Map. Accessed from http://www.acorn-ps.com/web/page/oil-gas/nsfields/nnsmap.htm on 31st October 2011

2. Acorn Petroleum Services (2009). Southern North Sea Map. Accessed from http://www.acorn-ps.com/web/page/oilgas/nsfields/snsmap.htm on 31st October 2011

3. BBC (2011). The Rough Gas Facility is key to the UK’s energy needs. Accessed from http://www.bbc.co.uk/news/business-12420219 on 8th October 2011

4. British Petroleum (2005). West Sole. http://www.bp.com/live-assets/bp_internet/globalbp/STAGING/global_assets/down-loads/U/uk_asset_west_sole_factsheet.pdf accessed 7th October 2011.

5. Danish Energy Agency, DEA (2011). Denmark’s’ producing fields. Accessed from http://www.ens.dk/en-US/OilAndGas/FieldsandProduction/Documents/Denmarks%20producing%20fields.pdf on 10th October 2011

6. Danmarks Miljøundersøgelser (2010). Bund Fauna Data. Den National Database for Marine Data (MADS) http://www.dmu.dk/vand/havmiljoe/mads/bundfauna/data/ accessed 9th No-vember, 2011.

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4.0 References