Demonstrating Storage of CO_2 in Geological Reservoirs : the Sleipner and SACS Projects

Publisher Summary The offshore gas field Sleipner, in the middle of the North Sea, has been injecting 1 Mt CO2 per year since September 1996. The CO2 is injected into a salt water containing sand layer, called the Utsira formation, which lies 1000 meter below sea bottom. During 1998, a group of energy companies, together with scientific institutes and environmental authorities in Norway, Denmark, the Netherlands, France, and the U.K., formed the Saline Aquifer CO2 Storage (SACS) Project Consortium and started to collect relevant information about the injection of CO2 into the Utsira formation and similar underground structures around the North Sea. The SACS project involves a multidisciplinary approach. The different scientific disciplines involved in the project include: geology, geochemistry, geophysics, and reservoir engineering/simulation. The Sleipner project is the first commercial application of CO2 storage in deep saline aquifers in the world. As a part of the SACS project, 3D seismic surveying has been used to successfully monitor the CO2 in the Utsira formation, which is unprecented in the industry. Repeat seismic surveys have successfully imaged movement of the injected CO2 within the reservoir. Reservoir simulation tools have been successfully adapted to describe the migration of the CO2 in the reservoir. The simulation packages have been calibrated against the repeat seismic surveys and shown themselves to be capable of replicating the position of the CO2 in the reservoir. The possible reactions between minerals within the reservoir sand and the injected CO2 have been studied by laboratory experiments and simulations.