Considering the salt sensitivity of HPAM and the salt resistance of amphoteric surfactant dodecyl dimethyl betaine

this work explored the effects of the surfactant and inorganic salt concentrations and pH values on the laws of viscosities of the compound systems by using the single factor experiments.The experimental results show that the viscosities of the systems change a little while the concentrations of the amphoteric surfactant are lower than the critical association concentration (CAC)

but they increase sharply as the concentrations of the amphoteric surfactant increase above CAC

reach to a peak when the surfactant concentration equals to the polymer saturation concentration (PSP) and decrease with the network structure of the system broken by continuously adding the surfactant.Inorganic salt show a twofold effect on the viscosities of the compound systems

increasing within the low salt concentration and decreasing above the high concentration of salt.At different pH

the salt resistance is presented as alkaline (pH=11.4) acidity (pH=2.8) neutral(pH=7).In order to further explore the effect degree of the concentrations of polymer

amphoteric surfactant and inorganic salt for the system viscosities

this work has done nonlinear regression of the uniform experimental data by using SPSS software

gotten a quantitative relation of the compound system viscosity with three parameters and analyzed their effects on the salt resistance of the compound systems. The theoretical model shows that the polymer concentration is the most important factor

and the effects of the concentrations of amphoteric surfactant and inorganic salt on the system viscosities are similar to those of their single-factors.