Energy Technologies: How They Work and Their Induced Seismicity Potential - Induced Seismicity Potential in Energy Technologies - page 76

BOX 3.8
The Sleipner, Snøhvit, and In Salah CO 2 Capture and Storage Projects
In 1996, the Sleipner oil and gas fields in the North Sea became the site of the world's first and largest
offshore commercial CO 2 capture and storage project. Carbon dioxide is captured at a plant located on one of
the field's operating offshore natural gas platforms and is stored underground in a sandstone formation at depths
of approximately 800-1,100 m below the sea bed. Motivation for the project derived from a CO 2 offshore tax
levied on offshore oil and gas operations by the Norwegian government in 1991. CO 2 is removed from the
natural gas produced at Sleipner and is reinjected into the subsurface into a very porous, permeable sandstone
and saline aquifer, the Utsira Formation (Figure 1). The Utsira Formation has an unusually high porosity and
permeability (porosity is between 0.35 and 0.4 and permeability is near 1,000 mD) compared to the CO 2 reser-
voirs in the other two Statoil CCS projects (Figure 2) and to many other potential CCS reservoirs. Approximately
1 million metric tonnes (1.1 million tons) of CO 2 have been stored per year since operations began—with the
accumulated total CO 2 in the formation at the middle of 2012 approximately 13.5 million tonnes (Eiken and
Ringrose, personal communication). The project is designed for approximately 25 years of CO 2 injection. Current
estimates for the Utsira Formation storage capacity range from 2 to 15.7 billion tonnes of CO 2 (NPD, 2011).
Figure 1 Schematic rendition of the Sleipner field with CO 2 injection into the Utsira sandstone formation oc-
curring as natural gas is extracted from the Heimdal Formation more than 1,000 m below the CO 2 reservoir.
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