Assessing the Long-Term Risks in Subsurface Carbon Storage Projects: Snøhvit Field (CO2 Injection Project, Example 6 of 8) #15

The Snøhvit Field, located in the Norwegian Barents Sea, produces gas condensate with 5-8% CO2 from the Middle Jurassic Stø Formation. The CO2 is separated and injected back into the subsurface.

Initially, this CO2 was injected into the Tubåen Formation which is an underlying sandstone aquifer in the F Segment of the field (see Figure below). However, reservoir pressure in the Tubåen increased more rapidly than planned, due to the presence of sub-seismic faults and lenticular sand bodies. This led to the early termination of injection into the Tubåen.

Because early risk assessment had anticipated this scenario, injection was switched to the water-bearing Stø Formation in the same fault block. Injection pressure declined and stabilized as a result. As of 2019, 6.5 Mt (million metric tons of CO2) had been injected: 1.1 Mt into the Tubåen Formation with the balance into the Stø Formation.

Snøhvit is a good example of how the problem of a smaller than expected storage volume can be overcome with advance planning to create optionality.