Fast-dissolving polyacrylamide for offshore oil displacement and preparation method thereof

A method for preparing a fast-dissolving polyacrylamide for offshore oil displacement, comprising the following steps:

• adding 15-45 parts by weight of a carbon-carbon double bond-containing glycidyl ester and 10-25 parts by weight of a diamino silicone oil into 500-1,000 parts by weight of an alcohol solution, stirring uniformly to obtain a mixture, adjusting a pH value of the mixture to 9-10 with an alkali, then heating to 30-50° C. for reaction to obtain a modified monomer solution;
• uniformly mixing 40-50 parts by weight of an acrylamide aqueous solution with a mass concentration of 20-40%, 10-15 parts by weight of an acrylic acid aqueous solution with a mass concentration of 10-30%, 5-10 parts by weight of an N-vinylpyrrolidone aqueous solution with a mass concentration of 0.3-0.8%, 10-20 parts by weight of a 2-acrylamide-2-methyl propanesulfonic acid aqueous solution with a mass concentration of 1-5%, and 15-25 parts by weight of the modified monomer solution, then adding 0.001-0.002 parts by weight of a shielding agent and 1-3 parts by weight of a chain transfer agent, stirring uniformly, and then purging with nitrogen to remove oxygen to obtain a mixed solution;
• and
• adjusting a temperature of the mixed solution to (−2° C.) to 5° C., then under a protection of nitrogen, dropwise adding 3-5 parts by weight of an initiator aqueous solution with a mass concentration of 0.1%-0.3% into the mixed solution, reacting for 4-8 h after addition of the initiator aqueous solution is completed, then adding a cosolvent, stirring uniformly, followed by discharging, pelletizing, and drying to obtain the fast-dissolving polyacrylamide.