Oil Recovery at High Brine Salinity Conditions Using Amphoteric Terpolymer

Abstract

The viscosity and the oil recovery ability of high molecular weight amphoteric terpolymer (ATP) were tested in different brines and compared with hydrolyzed poly(acrylamide) (HPAM) which is traditionally used in enhanced oil recovery (EOR). The results show that ATP provides higher viscosity at brine salinity ranging from 200 to 300 g∙L-1. This may give ATP an advantage over HPAM in high salinity reservoirs, which are abundant in Kazakhstan. Moreover, comparative polymer flooding experiments were carried out by injecting 0.25 wt.% ATP and HPAМ dissolved in 200 g∙L-1 brine into sand packs. The HPAМ flooding in high permeability (1.77 Darcy) sand pack leads to the increase of the oil recovery factor (ORF) by 18.5 % after 1 PV of brine injection. On the other hand, the injection of ATP into the low permeability (0.6 Darcy) sand pack results in the ORF increase by 28.5 %. The obtained results show that ATP has the potential to become an alternative to HPAM in 200 g∙L-1 and higher brine salinity reservoirs.