▎ 摘　　要

NOVELTY - Preparing polymer-sand nanocomposite comprises applying a surface polymerization to the surface of sand particles by combining a polymerization initiator dissolved in a solvent with the sand particles to form a precursor sand mixture. A co-monomer and additional polymerization initiator are combined in the presence of graphene, where the graphene is not functionalized to form a precursor polymer mixture. The precursor sand mixture and the precursor polymer mixture are combined to form a sand-copolymer-graphene nanocomposite. The sand-copolymer-graphene nanocomposite is dried. A polymer hydrogel is prepared by combining a hydrogel polymer, an organic cross-linker, and a salt. The polymer hydrogel and the sand-copolymer-graphene nanocomposite are combined to crosslink the sand-copolymer-graphene nanocomposite with the polymer hydrogel to form the polymer-sand nanocomposite. DDSC: --- USE - Method for preparing polymer-sand nanocomposite for water shutoff. ADVANTAGE - The method prepares the polymer-sand nanocomposite for water shutoff in a simple, cost-effective and eco-friendly manner with enhanced oil recovery, and chemical and thermal stability, and reduced unwanted production of water in a subterranean formation utilizing the polymer-sand nanocomposite. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for forming a barrier to shut off or reduce unwanted production of water in a subterranean formation, which comprises injecting a polymer-sand nanocomposite into water producing fractures in the subterranean formation. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the fractures connecting a wellbore and a water bearing zone. Hydrocarbon bearing zone (10) 10 Water bearing zone (20) 20 Fractures (30) Wellbore (40)