The salt resistance of surfactants and Partially hydrolyzed polyacrylamide (anionic) ( HPAM) combined system was studied by measuring the viscosity of the combined system of HPAM with anionic surfactant (SDS)

nonionic surfactant (OP-10) and ampholytic surfactant (C

12

BE). The results show that when the concentration of inorganic salt was constant

the viscosity of the combined system of HPAM with SDS and C

12

BE increased firstly and then decreased

but with OP-10 increased firstly then became constant afterwards. When the concentration of surfactants was in the under of the critical association concentration (CAC)

the viscosity of polymer solution was little changed ; when the concentration of surfactants exceeded the CAC

the viscosity of polymer solution increased; when the concentration of surfactants reached the Polymer critical saturation concentration (PSP)

the viscosity reached to the peak value; and then if the concentration of SDS and C

12

BE increased once more

the viscosity decreased

but if the concentration of OP-10 increased again

the viscosity of polymer solution became constant. The effect of inorganic salt on the viscosity of the polymer solution changed with concentration of inorganic salt. The viscosity increased at low concentration

decreased sharply at high concentration

and then trend to be constant at last. In the same concentration range of inorganic salt

the salt resistance capacity of three surfactants was SDS

>

OP-10

>

C

12

BE.