Abstract: Alkaline surfactant polymer(ASP) flooding could improve oil recovery considerably, however, scales have also been found in the injection and production systems simultaneously. Investigation shows that CaCO\-3 of scaled sample has different morphological characters such as stick and sphere, and sliver crystallographic character. Due to the existence of partial hydrolyzed polyacrylamide(HPAM), the critical micelle concentration for the heavy alkyl benzene sulfonate surfactant(HABS) decreases, i.e., micellization of HABS could be accelerated. On the other hand, the addition of HABS accelerates negative electric attract ability of HPAM and makes the steely properties of the chains stronger. Micelle and HPAM could act as template, which leads to the formation of CaCO\-3 in the scaled sample with different morphologies. In addition, the coexistence of HPAM and surfactant does not change the character of sliver CaCO\-3 in the scaled sample. This study will be helpful for deep analysis on ASP flooding scaling mechanism, scale remover and inhibitor, and thereby increase the service life of ASP flooding well, scale up and popularize the ASP flooding.

Key words: Alkaline surfactant polymer(ASP) flooding, Scaling, Calcium carbonate, Morphology, Crystallization