Gas injection (CO2, N2 or hydrocarbon) has long been used successfully as a tertiary recovery method either alone or with WAG (Water-Alternating Gas); however even when WAG is used the process can suffer from gravity override and early breakthrough due to thief zones. This leads to the need to recycle CO2 which has a negative impact on the economics of the process.
Foams can be used to mitigate those effects either through conformance control in higher permeability intervals or through gas mobility control. The Alliance has developed specific methodologies and additives for gas foam, in particular for both dense and non-dense CO2.