2.3 In Salah

The In Salah gas development in the central Sahara region of Algeria is a joint venture between BP, Statoil and the Algerian national oil company, Sonatrach. The development involves producing, treating and exporting gas from seven dry gas fields in the Ahnet-Timimoun Basin. The development is estimated to contain about 12 Tcf of natural gas reserves and has a CO2 content of between 8% and 10%. The first gas was produced in 2004 and the system has a capacity to produce up to 320 Bcf/yr [13].

The gas is produced from the Krechba formation and the CO2 is removed by a conventional solvent absorption system. The gas is dehydrated and then exported through a pipeline to the European market. A schematic of the project is shown in Figure 3.

Figure 3 – Gas production and CO2 reinjection for the In Salah development [15]

Source: Wright, I., (2006). CO2 Geological Storage: Lesson Learned from In Salah (Algeria), In: Proceedings of the First International Conference on the Clean Development Mechanism, Riyadh, Saudi Arabia, 19–21 September 2006.

The captured CO2 is compressed and dehydrated before being injected through three 1.2 km long horizontal wells back into the gas bearing Krechba formation. Since 2004, the injection rate of CO2 has averaged about 1 Mt/yr and the project is expected to store up to 17 Mt [16].

As well as standard monitoring techniques such as seismic surveys, the In Salah project has also used satellites to measure ground deformation [17]. This remote-sensing approach has shown a 30 mm rise is surface elevation around the injectors and subsidence near the producers. This technique has also confirmed that the CO2 is moving in the expected directions.