Slow gelation of titanium(IV) with partially hydrolyzed polyacrylamide. Crosslinking reaction and gel properties

The gelation of metallic crosslinking agent titanium(IV) (Ti(IV)) with part ially hydrolyzed polyacrylamide (HPAM) is studied. Factors effecting the cr osslinking reaction are discussed and the dynamic properties of gel are exa mined. The results indicate that crosslinking of TI(IV) with HPAM is delaye d at low concentrations of polymer and the titanium tartrate. The gelling o f Ti(IV)-HPAM is a strong function of titanium/tartaric acid molar ratio, H PAM concentration, initial solution pH value, solution salinity, and hydrol ysis degree of HPAM. The gel strength depends on Ti(IV) concentration in a particular way, after a maximum Ti(I) concentration is reached gel strength decreases. The salt NaCl can accelerate the gelling rate of Ti(IV)-HPAM. T he crosslinking mechanism of Ti(IV) with HPAM is proposed. Ti(IV)-HPAM gel can hold its strength at moderate temperature (50 degreesC) for a long time which is suitable to be used in a moderate temperature oil reservoir.