Laboratory Studies on Polymer Gels for CO₂ Mobility Control at Bat Raman Heavy Oilfield, Turkey

This paper is based on the laboratory studies that are performed to establish the applicability of crosslinked polymer gels for mobility control in CO₂ injection project that is going on at Bat Raman field. Two different approaches are suggested for CO₂ mobility control in this field: either a small volume, strong gel treatment for near-wellbore profile modification or a large volume, weak gel treatment for in-depth reduction of CO₂ permeability is considered. Regarding the 2 approaches, 2 different kinds of polyacrylamide, being Alcoflood 254 S for a strong gel and Alcoflood 935 for a weak gel; were used. Both of these polymers were crosslinked with Cr ⁺³ acetate. The laboratory studies consist of the bottle tests to determine the gelation times and core flooding tests to evaluate the gel performance under CO₂ injection conditions. The strong Alcoflood 254 S gel prohibited the gas flow under 2000 psi pressure drop and there was no breakthrough. At the other test with Alcoflood 935, there was gas breakthrough but still the CO₂ permeability was reduced significantly as shown by the 1800 psi pressure drop. Consequently, both of these polymer gels behaved as expected under Bat Raman reservoir conditions. Therefore; when the economic analysis is finalized, these gel compositions may be applied in the field either for in-depth treatment or CO₂ profile modification purposes.