Synthesis and study of a new copolymer for polymer flooding in high-temperature, high-salinity reservoirs

We have synthesized a new terpolymer suitable for polymer flooding from acrylamide, the hydrophobic monomer N-dodecylacrylamide, and the polar monomer 2-acrylamido-2-methylpropanesulfonic acid via micellar polymerization in water. We have studied the effect of chain initiation temperature and initiator concentration on the molecular weight of the terpolymer. We evaluate the salt resistance and thermal stability of the terpolymer and its ability to improve oil recovery compared with water flooding. Our results show that the terpolymer performs best for a chain initiation temperature of 9°C and an initiator concentration of 150 mg/liter in the reaction medium. Under such conditions, we obtain a terpolymer with a molecular weight of 22∙10⁶. The viscosity of a terpolymer solution with a concentration of 1500 ppm is 18.7 mPa∙s, and it remains constant for one month at 85°C and formation water salinity of 32 000 mg/L. The new terpolymer is superior to commercially available products in terms of the improvement in oil recovery.