Capture, Transport and Storage: The Sleipner CO2 storage project partners consist of Statoil (58.35 per cent and Operator), ExxonMobil E&P Norway (17.24 per cent), Lotos E&P Norway AS (15 per cent) and Total E&P Norge (9.41 per cent).
LOCATION: Offshore Norway, Central North Sea
CO2 capture source: Natural gas from the Sleipner Vest field, via a processing facility on the Sleipner T platform, 240 km / 149 miles west-southwest of Stavanger, offshore Norway
CO2 storage site: Utsira Formation, above the Sleipner Øst field, Central North Sea
INDUSTRY (FEEDSTOCK): Natural gas processing (natural gas)
OVERALL PROJECT LIFECYCLE STAGE: Operate
CO2 CAPTURE CAPACITY VOLUME: 0.85 million tonnes per annum (Mtpa)
CAPTURE TYPE: Pre-combustion capture (natural gas separation)
CAPTURE METHOD: Absorption chemical solvent-based process (Amine)
NEW BUILD OR RETROFIT: New build
CO2 CAPTURE START DATE: September 1996
PRIMARY STORAGE OPTION: Dedicated geological storage - offshore deep saline formation
STORAGE FORMATION AND DEPTH: Sandstone at a depth approximately 800-1,100 metres / 2,625-3,610 feet below sea level
TRANSPORTATION TYPE: No transport required (direct injection)
TRANSPORTATION DISTANCE TO STORAGE SITE: Not applicable
The Sleipner area gas development is located in the middle of the Central North Sea, near the border between the UK and Norway and approximately 240 km / 149 miles west-southwest of Stavanger, Norway. The development embraces the Sleipner Øst and Sleipner Vest gas and condensate fields (and tie-ins from a number of satellite fields). Sleipner Øst came on stream in 1993, Sleipner Vest in 1996. The two Sleipner fields have produced almost 2 billion barrels of oil equivalent since inception.
Sleipner Vest produces from the Middle Jurassic Sleipner and Hugin Formations, with most reserves found in the Hugin Formation. The reservoir depth is approximately 800-1,100 metres / 2,625-3,610 feet below sea level (water depth at Sleipner Vest is at 110 metres / 361 feet).
The CO2 content of the gas stream in Sleipner Øst is within market specifications (less than 2.5 per cent). Sleipner Vest gas however has a CO2 content in the range of 4-9 per cent, which must be reduced to meet customer requirements.
Since 1991 the Norwegian government has implemented a CO2 tax on a number of sectors, including offshore petroleum production. The tax varies across sectors and time. In 1996, the CO2 tax on offshore petroleum production on the Norwegian Continental Shelf was 210 NOK (35 USD) per tonne of CO2. This has progressively been raised to 544 NOK (65 USD) per tonne in 2016. The need to process Sleipner Vest gas to meet the European market specification cap of 2.5 per cent CO2 for natural gas, the introduction of a Norwegian CO2 tax on the offshore petroleum sector, and a commitment to sustainable energy production, led Statoil to capture and store CO2 in a deep geological formation at Sleipner.
This development was the world’s first demonstration of CCS technology for a deep saline reservoir. The injection rate of almost one Mtpa also makes the project one of the largest demonstrations of CCS in the world to date.
Production from the Sleipner Vest field is tied back to the gas treatment and transportation infrastructure facilities located at Sleipner Øst 12.5 km / 7.8 miles away. The unprocessed well-stream from the Sleipner B wellhead platform on Sleipner Vest is piped to the Sleipner T gas treatment platform at Sleipner Øst where the carbon dioxide is removed using a conventional amine based process. The processed natural gas is then routed to market via the Sleipner A drilling and production platform where, together with Troll field gas, it is transported to Europe through the Zeepipe and Statpipe system. Unstabilised condensate is piped to Karstø north of Stavanger for processing to stabilised condensate and natural gas liquids for on-shipping.
The captured CO2 is compressed and also routed to Sleipner A where it is injected via well 16/9-A-16 into the Utsira Formation, a sandstone reservoir 250 metres / 820 feet thick. The reservoir unit is at a depth of 800-1,100 metres / 2,625-3,610 feet below the sea level. The seal to the reservoir is provided by a 700 metre / 2,430 feet thick gas-tight caprock above the Utsira Formation.
Approximately 0.85 million tonnes of CO2 has been injected per annum. The purity of the CO2 is at 98 per cent. The remaining 2% is mostly methane.
Around 16.2 million tonnes of CO2 have been injected since inception to June 2016. Initial development plans for Sleipner Vest indicated the amount of CO2 to be injected over the field’s expected life (25 years) was around 25 million tonnes. A lower CO2 content and a decreasing production profile for Sleipner Vest has seen this figure revised to around 17.5 million tonnes by 2020. Since 2014 the CO2 capture facilities at Sleipner T process an additional 100,000 – 200,000 tonnes per annum of CO2 associated with gas production from the Gudrun field, which ties in to the facilities at Sleipner Øst.
Subsurface CO2 storage at the Sleipner field was originally approved as part of the hydrocarbon production activities according to the Norwegian Petroleum Law. In 2016 it has received approval according to the Environmental Protection Law and its CCS-relevant regulations.
An extensive program to monitor and model the distribution of injected CO2 in the Utsira Formation has been undertaken by a number of organisations (and has been partly funded by the European Union). This program includes a baseline 3D seismic survey and eight time lapse (4D) seismic surveys, four seabed micro gravimetric surveys, one electromagnetics survey and two seabed imaging surveys.
Latitude: 57.7159 N
Longitude: 1.87866 E