3.1.4 Buoyancy

Injection of CO2 into saline formations creates strong buoyancy forces because of the large density difference between CO2 and the formation water. The strength of the buoyancy forces in oil reservoirs is not as high as in saline aquifers and depends on the miscibility of the CO2 and oil. In oil reservoirs and saline formations, the buoyant CO2 plume migrates upwards. With CO2 being denser than the natural gas, the migration takes place in the opposite direction in a depleted gas reservoir.