Sleipner 26 years: How well-established subsurface monitoring work processes have contributed to successful offshore CO 2 injection

Abstract

In August 2022, the world's longest running offshore industrial CO 2 injection project celebrated its 26-year anniversary. During these years, the Sleipner CO 2 injection project has been invaluable in demonstrating that offshore CO 2 storage is feasible, safe, and efficient. We will here show how time-lapse seismic monitoring of the CO 2 plume development has revealed depositional architecture in the Utsira Formation, and how thin mudstone layers have contributed to distributing the CO 2 in a larger rock volume, promoting trapping by dissolution. The relatively shallow depth (800-1000 m) of Utsira Formation in the Sleipner area also makes the Sleipner CO 2 injection site a good proxy for understanding the effects of overburden stratigraphy for deeper injection sites, giving important knowledge of detectability of thin, shallow CO 2 accumulations. Finally, we will show how the experience from Sleipner CO 2 injection has built confidence when planning monitoring programmes for future CO 2 injection sites. Thematic collection: This article is part of the Geoscience workflows for CO 2 storage collection available at: https://www.lyellcollection.org/topic/collections/geoscience-workflows-for-CO2-storage