Tertiary recovery process

Claim 1

A process for recovering hydrocarbons from a hydrocarbon-bearing formation penetrated by an injection well and a production well which comprises first injecting into the formation via the said injection well an aqueous solution of about 0.1 to about 4.0 weight percent of a vinylpyrrolidone polymer followed by injecting into the formation via the said injection well an aqueous solution of about 0.05 to about 5.0 weight percent of a surfactant, and finally recovering hydrocarbons via the said production well, wherein the said vinylpyrrolidone polymer is selected from the group consisting of polyvinylpyrrolidone and copolymers of vinylpyrrolidone and a material selected from the group consisting of acrylamide, acrylic acid and vinyl sulfonic acid, wherein the said vinylpyrrolidone polymer has a number average molecular weight of about 50,000 to about 1,000,000, and wherein the said surfactant is selected from the group consisting of a water-soluble petroleum sulfonate and (a) polyethoxylated alkyl benzene sulfonates having the formula: ##STR8## wherein R is alkyl of from 8 to 22 carbon atoms, n is an integer of from 2 to about 10 and A is selected from the group consisting of hydrogen, sodium, potassium and the ammonium ion, (b) polyethoxylated alkyl benzene sulfates having the formula: ##STR9## wherein R and A and n have the same meaning as previously described, (c) polyethoxylated alcohol sulfates having the formula: RO(CH.sub.2 CH.sub.2 O).sub.m SO.sub.3 A, wherein R and A have the same meaning as previously described and m is an integer of from 2 to about 18 and (d) polyethoxylated alcohol sulfonates having the formula: RO(CH.sub.2 CH.sub.2 O).sub.m-1 CH.sub.2 CH.sub.2 SO.sub.3 A, wherein R, m and A have the same meaning as previously described.