Abstract: The cationic polyacrylamide flocculant with hyperbranched structure was synthesized by solution polymerization using N,N-methylene bisacrylamide （BisAM） as crosslinking agent,acrylamide （AM） and acryloyloxyethyl trimethylammonium chloride （DAC） as main raw materials. By optimizing the experimental conditions,the reaction temperature （55 ℃）,the optimal dosages of crosslinking agent BisAM and chain transfer agent BCPA and the optimal molar ratio of AM-to-DAC （17 : 3） were determined. The hyperbranched flocculant JR-211 with cationic degree of 24.8% was obtained. The waste drilling fluid from well Chenghai 3-2-8 is treated with JR-211. When the dosage is 250 mg/L,the dehydration rate of drilling fluid reaches 61.6%,the water content of sludge sedimentation is as low as 35.5%,and the dry basis recovery rate is as high as 98.7%.

Key words: flocculant, hyperbranched structure, cationic degree, polyacrylamide, drilling fluid