Rheological properties of poly(acrylamide-co-sodium acrylate) and poly(acrylamide-co-sodium vinylsulfonate) solutions

Poly(acrylamide-co-sodium acrylate) (PAM/AA-Na) and poly(acrylamide-co-sodium vinylsulfonate) (PAM/VSS-Na) were prepared by inverse emulsion polymerization. The effects of CaCl2 on PAM/VSS-Na or PAM/VSS-Na aqueous solutions were investigated by steady-flow experiments at 25, 40, 55 and 70 °. The results show that the apparent viscosities of both solutions decrease with addition of CaCl2 or increase of temperature and shear rates. PAM/VSS-Na solution has better performance on the salt tolerance, shear endurance and temperature resistance due to containing sulfonic group in the molecules. Ca2+ concentration can affect the viscous activation energy of both solutions and the reason may be that these interactions between Ca2+ and also copolymer molecules are related to temperature and competitive in solution. These results may offer the basic data for searching the flooding systems with the ability of temperature resistance, salt tolerance and shear endurance for tertiary oil recovery.