Study on gelation of partially hydrolyzed polyacrylamide with titanium(IV)

The gelation of metallic crosslinking agent titanium(IV) (Ti(IV)) with partially hydrolyzed polyacrylamide (HPAM) is reported. Factors affecting the crosslinking reaction are discussed and the dynamic properties of the gel are examined. The results indicate that crosslinking of Ti(IV) with HPAM is delayed at low concentrations of polymer and titanium tartrate. The gelling of Ti(IV)–HPAM is a strong function of titanium/tartaric acid molar ratios, HPAM concentration, initial solution pH value, solution salinity, and the hydrolysis degree of HPAM. The gel strength depends on Ti(IV) concentration in a particular way; after a maximum Ti(IV) concentration is reached gel strength decreases. The salt NaCl can accelerate the gelling rate of Ti(IV)–HPAM. A crosslinking mechanism of Ti(IV) with HPAM is proposed. Ti(IV)–HPAM gel can hold its strength at moderate temperature (50°C) for a long time making it suitable to be used in a moderate temperature oil reservoir.