Quantitative analysis of time-lapse seismic monitoring data at the Sleipner CO2 storage operation

The CO2 storage operation at Sleipner in the Norwegian North Sea provides an excellent demonstration of the application of time-lapse surface seismic methods to CO2 plume monitoring under favorable conditions. Injection commenced at Sleipner in 1996 with CO2 separated from natural gas being injected into the Utsira Sand, a major saline aquifer of late Cenozoic age. CO2 injection is via a near-horizontal well at a depth of about 1012 m below sea level some 200 m below the reservoir top, at a rate approaching 1 million tonnes (Mt) per year, with more than 11 Mt currently stored. A comprehensive time-lapse surface seismic program has been carried out, with 3D surveys in 1994, 1999, 2001, 2002, 2004, 2006, and 2008, to track plume migration, demonstrate containment within the storage reservoir, and provide quantitative information. This paper summarizes some of the quantitative methods that have been applied to the Sleipner seismic data sets.