▎ 摘　　要

NOVELTY - Forming a barrier to overcome lost circulation in a subterranean formation involves injecting a polymer-sand nanocomposite into one or more lost circulation zones in the subterranean formation. The polymer-sand nanocomposite comprising sand mixed with a polymer hydrogel. The polymer hydrogel comprises a hydrogel polymer, an organic cross-linker, and a salt, where the sand comprises a surface modification. USE - Method for forming a barrier to overcome lost circulation in a subterranean formation ADVANTAGE - The method combines the water reducing properties of the polymer hydrogel with sand having surface modifications forms a stable and dense filter cake which reduces drilling fluid losses into the formation and as a result, achieves stability of the wellbore. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method of preparing a polymer-sand nanocomposite lost circulation material, which involves applying a surface modification comprising attachment of an organic cross-linker to the surface of sand particles by preparing a cross-linker solution comprising one or more organic cross-linkers, combining the cross-linker solution and the sand particles to generate a cross-linker modified sand precursor, and heating the cross-linker modified sand precursor to a temperature of 120-180degrees Celsius for at least 2 hours to generate a cross-linker modified sand, then preparing a polymer hydrogel by combining a hydrogel polymer, additional organic cross-linker, and a salt, and combining the polymer hydrogel and the cross-linker modified sand to form the polymer-sand nanocomposite.