Polymer gel plugging agent suitable for compact fractured reservoir and preparation method of polymer gel plugging agent

The invention discloses a polymer gel plugging agent suitable for a compact fractured reservoir and a preparation method thereof, the gel plugging agent comprises the following components in percentage by mass: 3-10% of a monomer main agent base solution, 0.2-0.5% of a cross-linking agent, 0.5-0.7% of a retarder, 0.1-0.8% of an initiator and the balance of deionized water; the monomer main agent base solution is prepared from 20-25% of three water-soluble monomers (the mass ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid to sodium acrylate is (68-78): (10-12): (12-20)), 0.05-0.2% of a polymerization inhibitor, 0.05-0.2% of a retarder and the balance of deionized water, and the mass ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid to sodium acrylate is (68-78): (10-12): (12-20). The method comprises the following steps: diluting a monomer main agent base solution, adding a cross-linking agent and a retarder, finally adding an initiator, preparing a plugging agent monomer soluti