Chemical Degradation of Polyacrylamide Polymers Under Alkaline Conditions

Summary Hydrolysis of polyacrylamide (PAM) -based polymers is rapid and extensive under the alkaline conditions typical of alkaline/ surfactant-polymer (ASP) flooding. Even at room temperature, significant hydrolysis occurs within 1 to 2 months in the presence of sodium carbonate. While this implies that polymers used in ASP floods will rapidly become susceptible to precipitation with divalent cations, in most cases the alkali present will be the most sensitive component to precipitation, so this may be a moot point. Also, autoretarding kinetics under alkaline conditions limit hydrolysis at 100°C, whereas complete hydrolysis occurs under neutral conditions. Furthermore, in-situ hydrolysis of initially unhydrolyzed PAM is proposed as a promising strategy for ASP floods because the injectivity of the unhyrolyzed PAM will be greater than that of hydrolyzed PAM (HPAM) because of its lower initial viscosity. The lower initial viscosity is not a disadvantage because once it has been hydrolyzed in-situ, its viscosity will increase.