The Montrose oil field is a significant crude oil producing field in the UK sector of the central North Sea, 210 km east of Aberdeen. Production of oil started in 1976 and a major upgrade in 2016 extended the field life to beyond 2030.

Montrose oil field
Montrose oil field is located in North Sea
Montrose oil field
Location of Montrose oil field
CountryUnited Kingdom
RegionCentral North Sea
Location/blocksBlocks 22/17 and 22/18
Offshore/onshoreOffshore
Coordinates57°27′02″N 01°23′16″E / 57.45056°N 1.38778°E / 57.45056; 1.38778
Operatorsee text
Ownersee text
Field history
Discovery1971
Start of production1976
Peak year1979
Production
Peak of production (oil)28,700 barrels per day (~1.4×10^6 t/a)
Recoverable oil86.4 million barrels (~1.1×10^7 t)
Producing formationsPalaeocene Sandstone
Montrose Alpha oil production platform

The field

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The Montrose oil field is located in Blocks 22/17 and 22/18 of the UK North Sea. It is named after the Scottish east coast town of Montrose. The field was discovered in November 1971 and is a Palaeocene sandstone at a depth of 8,000 feet (2,438 m).[1] The reservoir has the following characteristics:[2][3]

Montrose reservoir
Parameter Value
API gravity 38.5-40°
Gas Oil Ratio 600-700 scf/bbl
Porosity 22.8%
Permeability 39.3 md
Pressure 3,750 psi at 8,150 TVDSS
Sulfur 0.23%
Recoverable reserves 86.4 million barrels

12.8 million tonnes

Owners and operators

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The field was originally licensed to a joint venture comprising Amoco UK Petroleum Limited (30.77%), Enterprise Oil plc (30.77%), Amerada Hess Exploration Ltd (23.00%), and Texas Eastern (UK) Ltd (15.38%).[2] The field was originally operated by Amoco (UK) Exploration Company.[2][3][4] Ownership of the Montrose field passed from Amoco to BP to Paladin Resources, until Talisman Energy took over in 2012 and most recently Repsol bought the assets in joint ownership with Sinopec. In late 2023 Sinopec sold their share and it is now owned solely by Repsol Resources.[3]

Development

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The field was developed by a single integrated production platform Montrose Alpha (or Montrose A). Oil was initially exported through a pair of CALM buoys located 1.7 km from the platform.[2] In 1982 a 48 km 14-inch oil pipeline from Montrose to Forties Charlie was commissioned which provided an oil export route.[2]

Montrose field infrastructure
Installation Montrose A Montrose bridge linked platform CALM buoys
Coordinates 57°27'02"N 01°23'16"E
Water depth, metres 88 88 91
Fabrication UIE Cherbourg and St. Wandrille Heerema Fabrication, Zwijndrecht Netherlands Earl Wright Newcastle
Topside weight, tonnes 14,000 10,500
Function Drilling, production, accommodation Process and utilities Offloading oil
Accommodation 96
Type Steel jacket Steel jacket Catenary anchor leg
Legs 8 4
Piles 32 6
Well slots 24
Throughput oil, bpd 60,000 40,000 60,000
Oil storage capacity, barrels Nil Nil
Installed 1975 2016 1975
Production start June 1976 2016 1976
Oil production to CALM buoys

Forties Charlie 48 km 14-inch

Montrose A (bridge) Tankers 72,000 dwt
Gas production to Flare Montrose A (bridge)

Production

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The original processing plant on Montrose A had a nominal capacity of 60,000 barrels of oil per day. Water injection was 55,000 barrels per day. There were 16 production wellheads, and 4 water injection wells. The production of oil (in 1000s barrels) was:[2]

There were two Catenary Anchor Leg Mooring (CALM) buoys in 91 metres of water. They were used from 1976 to 1984 to load tankers. They were decommissioned in 1984 when the 48 km 14-inch oil export line from Montrose to Forties Charlie was commissioned.[2]

Montrose was a 'stranded asset' with no nearby export route for gas, the gas was therefore flared. A horizontal 455 feet (139 m) long flare bridge was installed between the platform and the flare (57.451336N 1.390825E). The bridge was supported by a tripod jacket. 

Redevelopment

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In 1990, Amoco modified the Montrose A processing equipment to receive oil from the then new Arbroath field integrated drilling and production platform. The discovery of the Wood oil field entailed the installation of the Wood and Gas Export (WaGE) processing and compression module on Montrose A and a new 6-inch pipeline delivered gas into the CATS offshore pipeline on Arbroath.[3]

Three new fields – Godwin, Cayley and Shaw – were discovered in the Montrose area. Additional process facilities were required to develop these fields. Details of the field were as follows:[3][5]

Name Block Discovered Location Water depth Developed Start-up
Cayley 22/17 2007 10 km west of Montrose 91 m 2 subsea production June 2017
Shaw 22/22 2009 17 km north of Montrose 3 subsea production, 2 injection May 2017
Wood 22/18 1996 10 km south east of Montrose 92 m 1 subsea well December 2007

A new platform was installed adjacent to Montrose A in 2016. This was known as the bridge-linked platform and provided additional process and plant support facilities. Production increased to 40,000 boe (barrels of oil equivalent) per day.[5]

References

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  1. ^ Crawford, R., R. W. Littlefair and L. G. Affleck (1 January 1991). "The Arbroath and Montrose Fields, Blocks 22/17, 18, UK North Sea". Geological Society, London, Memoirs. 14: 211–17. doi:10.1144/GSL.MEM.1991.014.01.26. S2CID 128684619.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ^ a b c d e f g Oilfield Publications Limited (1985). The North Sea Platform Guide. Ledbury: Oilfield Publications Limited. pp. 521–511.
  3. ^ a b c d e "Twin-platform complex to maximize Montrose Area resources". Offshore magazine. 11 August 2016. Retrieved 14 October 2021.
  4. ^ Department of Trade and Industry (1994). The Energy Report. London: HMSO. pp. 73 and map 9. ISBN 0115153802.
  5. ^ a b "New Montrose platform successfully installed". repsolsinopecuk.com. 2016. Retrieved 14 October 2021.