Abstract: When hydrolyzed polyacrylamide ( HPAM) solution flows in porous medium , it will exhibit elasticity and enhanced valid viscosity if velocity reaches a critical value. But we do not have the same opinion about its valid distances of elasticity and how much contribution to oil displacement efficiency when it is flowing from injection well to producing well under changeable velocity. In this paper , the effect of injecting velocity on the elasticity of conventional HPAM has been studied. The oil displacement efficiency of HPAM is compared with nonOelastic Xanthan gum and glycerin , and the maximum distance of elasticity of the polymer solution flowing in the reservoir has been decided.

Key words: hydrolyzed polyacrylamide, elasticity, critical velocity, oil displacement efficiency