Abstract: Water-soluble polymers comprising an N-vinyl amide such as an N-vinyl lactam are found to be useful in processes wherein the polymer is introduced into a subterranean wellbore.Polymers useful in the recovery of natural resources are prepared by polymerizing an N-vinyl lactam by free radical initiation with polymerization conducted in an aqueous solution polymerization medium preferably containing a mixture of dissolved electrolytes, or in a polymerization medium consisting essentially of a tertiary alkanol. Copolymers of such N-vinyl lactams with unsaturated amides, and terpolymers prepared by polymerizing an N-vinyl lactam and an unsaturated amide with a selected termonomer compound are also useful when prepared by these methods. The invention also broadly encompasses utilizing a water-soluble polymer comprising at least one of a hydrophilic vinyl-containing sulfonate, phosphonate or ester and/or a hydrophilic N-vinyl lactam for applications under hostile conditions.

Abstract: A water-based drilling fluid comprising a water soluble tetrapolymer in combination with clayey materials.