**2.5.2 Saline aquifers**

248 Fossil Fuel and the Environment

Fig. 11. Carbon pipeline linking Beulah and Weyburn – Source: Cenovus Energy (2011)

Figure 12 presents a graph of oil production in Weyburn since the start of the operation in December 2010. The brown area represents the increase in output because of the EOR process if the process had not begun in 2000, production in December 2010 would have been approximately 10 thousand barrels per day (10 kbopd). The EOR boosted this output in

Fig. 10. Enhanced Oil Recovery (EOR) Process

December 2010 to roughly 28 kbopd.

Saline aquifers exist in the great majority of the world's regions. Since this water cannot be used for drinking or farming, the option to store CO2 in these aquifers appears very promising. The first project to capture carbon of this type was developed by Norway's Statoil in its Sleipner natural gas field in the North Sea.

According to Statoil, the percentage of CO2 in the natural gas of its Sleipner field is approximately 9% (BGS, 2011), which is above the level tolerated by its consumers. In 1991, the Norwegian government introduced a tax of US\$ 50 dollars per tonne of CO2 emitted. These two aspects combined (standards required by consumers and government taxation) prompted Statoil to develop the geological capture project.

Physically the project is composed of two platforms. On the first one the natural gas rich in CO2 is extracted. This gas is sent to the second platform where the CO2 is separated by chemical absorption, then compressed and injected into a saline aquifer located 1000 meters beneath the seabed. According to the projections of a special report of the IPCC (IPCC, 2005), the total storage capacity of the Sleipner project is 20 MtCO2, of which nearly 11 MtCO2 had already been stored by the end of 2008 according to Statoil.
