Drilling ops yield fertile ground for carbon storage in North Sea

Equinor Low Carbon Solutions, a subsidiary of Norway’s state-owned energy giant Equinor, has drilled two appraisal wells in the Norwegian sector of the North Sea, which are said to possess suitable properties for the injection and storage of carbon dioxide (CO2).

The wells 32/7-1 and 32/4-4 in the North Sea, about 20 kilometers east of the Troll A platform and about 70 kilometers west of Bergen, were drilled with Odfjell Drilling’s Deepsea Stavanger semi-submersible rig in the Gamma and Alpha areas, respectively. While the wells have been permanently plugged and abandoned, the drilling results for the appraisal well duo indicate that the reservoir is suitable for the injection and storage of CO2.

According to the Norwegian Offshore Directorate (NOD), the objective of the well 32/7-1 was to investigate whether Lower and Middle Jurassic reservoir rocks in the Gamma structure are suitable as a storage site for CO2. The well is situated about 7 kilometers southwest of well 32/4-3 S, which Equinor drilled in 2019 with the partial objective of investigating whether the area was suitable for CO2 storage.

The well 32/7-1 encountered the Draupne Formation (cap rock) with 130 meters of homogeneous shale; the Sognefjord Formation (reservoir) with 146 meters of sandstone featuring good to very good reservoir quality; and the Fensfjord and Krossfjord formations (reservoir) with 145 meters of sandstone showing good reservoir quality.

In addition, it also found the Drake Formation (cap rock) with 83 meters of homogeneous shale and the Cook and Johansen formations (reservoir) with 57 meters of sandstone displaying good reservoir quality. The well 32/7-1 was drilled to a vertical depth of 2,036 meters below sea level and terminated in the Lunde Formation in the Upper Triassic. The water depth at the site is 300 meters.

On the other hand, the objective of the well 32/4-4 was to investigate whether Lower and Middle Jurassic reservoir rocks in the Alpha area are suitable as a storage site for CO2. The Norwegian Offshore Directorate explains that dry exploration wells were previously drilled in the same area.

The well 32/4-4 encountered the Draupne Formation (cap rock) with 142 meters of homogeneous shale; the Sognefjord Formation (reservoir) with 106 meters of sandstone showing good to very good reservoir quality; and the Fensfjord and Krossfjord Formations (reservoir) with 165 meters of sandstone displaying good reservoir quality.

Additionally, it found the Drake Formation (cap rock) with 47 meters of homogeneous shale and the Cook and Johansen Formations (reservoir) with 48 meters of sandstone, indicating good reservoir quality. The well 32/4-4 was drilled to a vertical depth of 1,879 meters below sea level and terminated in the Lunde Formation in the Upper Triassic. The water depth at the site is 315 meters.

The Norwegian Offshore Directorate has pointed out that the formation pressure data for both wells show indications of the rocks in the Cook and Johansen formations being somewhat depleted, while the depletion increases towards the Sognefjord Formation, where it is greatest.

Aside from extensive volumes of data acquired and samples taken from the reservoirs and cap rocks in the two wells, four injection tests were also conducted in the wells 32/7-1 and 32/4-4, with the preliminary results being positive.

These are the second and third wells drilled to investigate the possibility of commercial CO2 storage on the Norwegian Continental Shelf (NCS), which together make up a potential CO2 storage site for the Smeaheia project. The wells were the first to be drilled in the exploration license EXL 002, awarded in June 2022.

The Norwegian Offshore Directorate has confirmed that the data will now be analyzed in greater detail, as the results will form part of the basis for future investment decisions in Equinor’s Smeaheia storage project, for which the firm secured the operator role in 2022. It is scheduled to come on stream by 2030.

Envisioned to have a storage capacity of up to 20 million tonnes of CO2 per year, the project is planned to be developed with two CO2 transport and storage solutions: a 1,000-kilometer-long pipeline called CO2 Highway Europe and a CO2 ship transport solution connecting European customers with this CO2 storage site in the North Sea.

Given Equinor’s ambition to establish value chains for CO2 transport and storage with an annual capacity of 30-50 million tonnes of CO2 by 2035, the CO2 pipeline will connect to wells at Smeaheia and other potential CO2 sites, like Kinno and Abondigas, as they are matured.