Rheological Study of Polyacrylamide Hydrogels in Harsh Reservoir Condition for Water Shutoff

Design and preparation of hydrogel focusing on structural strength and viscoelastic properties ofthe hydrogel under reservoir conditions is essential to ensure the hydrogel’s performance in water shutofftreatment. In this study, proportionate hydrogels for the southern Iranian reservoirs was produced firstly,and their performance was studied against strain and shear rate of their placement or injection inreservoir, secondly. Designing and producing hydrogel to increase the mechanical strength of reservoirrock and its strength against mono and divalent ions available in formation water, is one of the outcomes ofthe current study. A set of experiments were performed, conducting bottle test and rheology. According tothe results, the optimized hydrogel was approved with 9500 ppm of sulfonated polyacrylamide copolymer,and 0.5 weight ratio of Cr(OAc)3 to polymer. Besides, the required value of strain to rupture the hydrogelstructure was considered as a criterion to measure the hydrogel strength. Also, the optimum hydrogel insolution with presence of 10000 ppm of Ca2+ can keep the viscoelastic properties up to 44% of strain whileit is 110% for the Na+ solution.

Keywords:

Rheology , Gelation time , Structural strength , Viscoelastic behavior , Gel strength