Method of fracturing subterranean formations penetrated by a well

Claim 1

In a method of fracturing subterranean formations penetrated by a borehole, wherein an effective amount of a particulate water soluble organic polymer selected from the group consisting of natural gums and derivatives thereof, cellulosic derivatives, derivatives of starch, and polyacrylamide, is introduced into an aqueous liquid to thicken the liquid. said thickened liquid then being employed as a fracturing fluid, the improvement which comprises: a. introducing said polymer into the aqueous liquid as a particulate coated with an effective quantity of a water soluble polyvinyl lactam, said polyvinyl lactam being selected from the group consisting of a polymer corresponding to the formula ##STR3## wherein R is an alkylene group containing a sufficient number of carbon atoms to form a heterocyclic ring containing from 5 to 7 members, R 1 is hydrogen or a lower alkyl group and n is sufficient to provide a polymer having a molecular weight ranging from about 300 to 2,000,000 or a copolymer containing at least 20 percent by weight of N-vinyl lactam corresponding to the above formula and at least one other organic monomer to provide a copolymer having a molecular weight ranging from about 300 to 2,000,000, to increase the dispersibility of the water soluble organic polymer into the aqueous liquid; and b. introducing a sufficient quantity of said resulting thickened aqueous liquid into said borehole and in contact with said formation under sufficient pressure to fracture said formation.