Siri, Nini and Cecilie oil fields

The Siri oil field and its satellites, Nini and Cecille, are oil producing fields in the Danish sector of the southern North Sea. Operating since 1999 and 2003 they are the most northerly of Denmark's offshore oil assets located close to the Denmark-Norway median line.

Siri oil field
CountryDenmark
RegionNorth Sea
Blocks5604/20
Offshore/onshoreOffshore
Coordinates56.482686N 4.911144E
OperatorsDONG E & P A/S
Field history
Discovery1995
Start of production1999
Peak of production2.188 million cubic metres per year
Peak year2000
Production
Producing formationsPaleocene sandstone structural trap

The fields

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The Siri field comprises a sandstone reservoir of oil with a low gas content.[1] It is in Block 5604/20 in the far north of the Danish sector near the Denmark-Norway median line.[2] The Siri reservoir comprises four areas: Siri Central; Siri North; to the north east Stine segment 2; and Stine segment 1. The field is developed through a single installation (designated SCA) located over the Siri Central formation with subsea wells exploiting Stine1 & 2.[1][3]

The Nini field is to the north east of the Siri field and is a sandstone oil reservoir. It has been developed through two platforms (Nini A and Nini B also known as Nini East and Nini West) with well fluids piped to Siri SCA installation for processing.[1]

The Cecilie field is located south west of the Siri field, it too is a sandstone oil reservoir. It has been developed by a wellhead platform with well fluids routed to Siri SCA for processing.[1]

Key parameters of the fields are given in the table.

Siri, Nini and Cecilie fields properties[1]
Field Siri Nini Cecille
Reservoir rock Sandstone Sandstome Sandstone
Trap Structural trap Structural and stratigraphic trap Structural and stratigraphic trap
Geological age Paleocene Eocene/Paleocene               Paleocene
Depth 2060 m 1700 m 2200 m
Discovery 1995 2000 2000
Field delineation 63 km2 45 km2 23 km2
Oil reserves 1.1 million m3 1.1 million m3 0.2 million m3
Gas reserves 0 0 0

Owners and operators

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The licence for the Siri field was originally owned by Dong Energy (50%), Altinex (20%) and Talisman (30%). The operator licence was taken over by Dong Energy from Statoil in 2002. The Siri, Nini and Cecilie fields are currently owned and operated by DONG E & P A/S.[3]

Production infrastructure

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The fields have been exploited by several subsea and topside installations, as shown in the table.

Siri, Nini and Cecilie installations[1][3][4][5]
Name Siri (SCA) Stine SCB-1 Stine SCB-2 Nini A

(Nini West)

Nini B

(Nini East)

Cecilie
Block 5604/20 5604/20 5604/20 5605/10 & 14 5605/10 & 14 5604/19 & 20
Coordinates 56.482686°N

4.911144°E

56.505947N

5.040943E

56.640805N

5.321124E

56.674771N

5.412430E

56.402115N

4.759621E

Water depth, m 60 60 60 60 60 60
Commissioned 1999 2004 2003 2010 2003
Type Fixed steel Subsea Subsea Fixed steel Fixed steel Fixed steel
Function Wellheads, processing, accommodation (60 beds) Wellhead Wellhead Wellheads Wellheads Wellheads
Wells, production 6 1 1 8 3 oil, 1 gas
Wells, injection 2 1 0 6 0
Substructure weight, tonnes 2000 160 2000 2000 2000
Topside weight, tonnes 8000 0 700 700 700

The Siri, Nini and Cecilie fields are stranded assets remote from export infrastructure such as pipelines. Oil from SCA is routed to a 50,000 m3 storage tank on the seabed. The tank is 50 m x 66 m and  17.5 m high. It is emptied periodically by tanker via a Single Anchor Loading (SAL) buoy mooring system.[1][5]

Pipelines

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In addition to the offshore installations there are a number of pipelines connecting and transferring fluids within the fields

Siri, Nini and Cecilie and connected pipelines[1]
From To Fluid Length, km Diameter, inches Note
SCB-1 SCA Well fluids 9 8
SCB-1 SBC-2 Injection water adjacent
SCA SCB-1 Lift gas 9 3
SCA SAL Crude oil 16
Nini B Nini A Well fluids 7 8
Nini A SCA Well fluids 32 14
Cecilie SCA Well fluids 13 12
SCA Nini A Injection water 32 10
Nini A Nini B Injection water 7 10
SCA Nini A Lift gas 32 4
Nini A Nini B Lift gas 7 4
SCA Cecilie Lift gas 13 4
SCA Cecilie Injection water 13 10

Oil production

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The oil produced across the fields is shown in the tables.

Siri, Nini and Cecilie oil production (1000 m3) 1999-2010[6]
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Siri 1,593 2,118 1,761 1,487 925 693 703 595 508 598 326 286
Cecilie 0 0 0 0 166 310 183 116 88 66 38 33
Nini 0 0 0 0 391 1,477 624 377 323 355 159 544
Siri, Nini and Cecilie oil production (1000 m3) 2011-22[6]
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Siri 161 232 131 94 200 206 189 162 124 79 60 53
Cecilie 39 32 17 10 23 39 32 31 28 25 23 23
Mini 569 454 268 336 299 310 208 141 117 89 83 75

Water and recovered gas are co-injected into the Siri and Nini reservoirs to increase oil recovery.[3] An average of 2.98 million m3 of water per year is injected.[6]

The future

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The Project Greensand[7] consortium has identified the Nini West subsea reservoir as a feasible carbon dioxide (CO2) storage facility.[8] The reservoir is suitable for injecting 0.45 million tonnes CO2 per year per well for a 10-year period and that it can safely contain the CO2 in compressed form. If successful the project could be extended to the whole Siri field. Work on the project is ongoing.[8]

See also

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References

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  1. ^ a b c d e f g h Danish Energy Agency (2013). "Oil and gas production in Denmark" (PDF). Copenhagen. Retrieved 9 November 2023.
  2. ^ "Danish oil and gas fields". 2021. Retrieved 10 November 2023.
  3. ^ a b c d "Statoil Oil and Gas Field Project". Retrieved 9 November 2023.
  4. ^ OSPAR (2021). "OSPAR Inventory of Offshore Installations - 2021". Retrieved 9 November 2020.
  5. ^ a b A Barrel Full. "Siri Oil Field". Retrieved 9 November 2023.
  6. ^ a b c Danish Energy Agency (2022). "Monthly and yearly production". Copenhagen. Retrieved 9 November 2023.
  7. ^ "Project Greensand". Retrieved 11 November 2023.
  8. ^ a b "Denmark Starting signal for successful CCS". 2023.