Versatile hydrolyzed polyacrylamide-polyethyleneimine gels reinforced with glycerol for plugging and abandonment of oil wells

•Addition of glycerol to polymeric gels improved their thermal stability.•Incorporation of anti-syneresis agents allowed a reduction of up to 80% in gelation and delayed syneresis in 110%.•Insertion of anti-syneresis agents significantly increased the thermal stability of the gels.•New gels formulations showed a superior resistance of the elastic properties.