TECHNICAL FIELD

The present disclosure relates to natural resource well drilling and hydrocarbon production from subterranean formations and, more specifically, to a polymer-sand nanocomposite for eliminating or reducing water production in a hydrocarbon wellbore.

BACKGROUND

The discovery and extraction of hydrocarbons, such as oil or natural gas, from subterranean formations may be impeded for a variety of reasons, such as produced water in the reservoir. Specifically, produced water is a significant concern for the oil and gas industry resulting in incurred handling costs and oil recovery costs as well as affecting productivity through scale formation, corrosion of the field equipment and potential formation failure. Before discharge or reinjection, the produced water needs to be treated to meet governmental regulations and prevent environmental pollution. To overcome these issues economically, water production is minimized for water shutoff treatments applied to zones via mechanical isolation or chemical based isolation or by drilling in a manner to avoid produced water. Polymer-based products exist for water shutoff and enhanced oil recovery, yet they lack chemical and thermal stability.

SUMMARY

Accordingly, there is an ongoing need for methods of forming a barrier to shut off or reduce unwanted production of water in a subterranean formation which possess chemical and thermal stability. The methods of the present disclosure include preparing a polymer-sand nanocomposite for water shutoff. In particular, the methods of the present disclosure include preparation of a polymer-sand nanocomposite for water shutoff in which a polymer hydrogel and sand particles having a surface polymerization are combined. Combining the water reducing properties of the polymer hydrogel with surface polymerized sand allows unwanted water production to be reduced, hydrocarbon outcome sustained, and overall extraction costs to be reduced.

According to one or more embodiments of the present disclosure, a method of preparing a polymer-sand nanocomposite for water shutoff is disclosed. The method includes applying a surface polymerization to the surface of sand particles. The surface polymerization is applied to the surface of the sand particles by combining a polymerization initiator dissolved in a solvent with the sand particles to form a precursor sand mixture, combining a co-monomer and additional polymerization initiator in the presence of graphene, where the graphene is not functionalized, to form a precursor polymer mixture, and combining the precursor sand mixture and the precursor polymer mixture to form a sand-copolymer-graphene nanocomposite. Further, the method includes drying the sand-copolymer-graphene nanocomposite. A polymer hydrogel is then prepared by combining a hydrogel polymer, an organic cross-linker, and a salt. Finally, the method includes combining the polymer hydrogel and the sand-copolymer-graphene nanocomposite to crosslink the sand-copolymer-graphene nanocomposite with the polymer hydrogel to form the polymer-sand nanocomposite.

According to one or more further embodiments of the present disclosure, a method of forming a barrier to shut off or reduce unwanted production of water in a subterranean formation is disclosed. The method includes injecting a polymer-sand nanocomposite into one or more water producing fractures in the subterranean formation. The polymer-sand nanocomposite includes sand with a surface polymerization mixed with a polymer hydrogel. The surface polymerization of the sand includes non-functionalized graphene and a co-polymer comprising two or more of polystyrene, poly(methyl methacrylate), polyacyrlonitrile, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, hydrolyzed polyacrylamide, polycarbonate, polyethylene, polyurethane, polypropylene, and acrylonitrile butadiene styrene.

Additional features and advantages of the described embodiments will be set forth in the detailed description that follows. The additional features and advantages of the described embodiments will be, in part, readily apparent to those skilled in the art from that description or recognized by practicing the described embodiments, including the detailed description that follows as well as the drawings and the claims.

