Rheological Properties of Hydrophobically Associating Polyacrylamide Solution

A temperature-resistant, salt-tolerant polyacrylamide, hydrophobically associating polymer (HAP), was synthesized in the State Key Laboratory of Heavy Oil Processing. The rheological behavior of HAP solution was investigated by means of flow experiments in porous media and by using a HAAKE RS600 rheometer. The results of Nuclepore membrane filtration showed that filtration time increased sharply when the critical association concentration was reached. Shear rate had a greater impact on viscosity and shear stress with increasing HAP concentration. The HAP solution with a concentration of 100 mg/L (salinity 32,868 mg/L) exhibited negative thixotropy. However, at the same salinity the HAP solution showed thixotropy and its viscosity became greater when the polymer concentration increased to 1,500 mg/L. The flow experiments in cemented core samples indicated that the resistance factor and residual resistance factor of the HAP solution were 31.8 and 12 when polymer concentration and salinity were 1,500 mg/L, 32,868 mg/L at 85℃ respectively, which is favorable for flooding application. Such factors of partially hydrolyzed polyacrylamide 3530S were merely 3.14 and 1.71, so it could not be applied to polymer flooding in the oilfield with high temperature and high salinity.