From its initiation in 2008 to 2019, the Snøhvit CCS project successfully stored 6.5 MMt of CO₂ within the Tubåen (1.1 MMt) and Stø (5.4 MMt) formations (Fig.1, Fig. 2).

Between 2008 and 2011, CO₂ was injected through a single well (F-2H) into the Tubåen Formation deltaic to shallow-marine sandstones, but rapid pressure build-up of ~943 psi over initial reservoir pressure meant that the storage capacity of this formation was called into question (Fig. 3).  4-D time-lapse seismic monitoring confirmed that the CO₂ was contained within a small isolated channel thus causing the rapid pressure increase.  An alternative option was thus required, and the back-up plan was initiated.

Following the cessation of CO₂ injection into the Tubåen Formation, injection into the overlying Stø2 layer of the Stø reservoir began using the same injection well.  With a storage capacity of ~24 MMt, initial injection began at 60 t/day. This increased rapidly and by November 2011 it had reached 2150 t/day.  As injection continued reservoir pressure steadily declined to near-hydrostatic conditions.

In 2016, a new injector (G-4H) was drilled into the Stø reservoir, in a separate fault compartment to avoid contamination of the produced gas.  The original injector was shut-in.

Another alternative scenario for carbon storage would involve additional injection into the Tubåen, Stø, and Nordmela formations, giving a potential storage resource of 90 MMt.

Learn more about DAKS for Carbon Capture & Storage (CCS)