High temperature profile modification agents and methods for using same

A profile modification agent for altering the fluid flow profile of a subterranean formation having reservoir temperatures up to about 200.degree. C. comprising:

• (a) water,
• (b) from about 0.5 to about 5.0%, by weight, based upon the weight of the overall composition, of a water-dispersible polymer consisting essentially of,
• (i) from about 5 to about 75 mol percent of N,N.sup.1 -dimethylacrylamide, and
• (ii) from about 5 to about 35 mol percent of acrylic acid units or salts thereof, and
• (iii) from about 10 to about 90 mol percent of 2-acrylamido-2-methylpropanesulfonic acid units or salts thereof, and acid units or salts thereof, and
• (c) an amount of a trivalent chromium or aluminum compound or a hexavalent chromium compound sufficient to crosslink said polymer to form a high temperature stable gel.

A two component composition for use as a profile modification agent in high temperature and/or harsh brine containing subterranean oil-bearing reservoirs, comprising:

• (I) a first component comprising:
• A. a water--dispersible polymer consisting essentially of:
• (i) from about 5 to about 75 mol percent of units of N,N.sup.1 -dimethylacrylamide, and
• (ii) from about 5 to about 35 mol percent of acrylic acid units or salts thereof;
• and
• (iii) from about 10 to about 90 mol percent of 2-acrylamido-2-methylpropanesulfonic acid units or salts thereof, and
• B. an oxidizing agent selected from the group consisting of ammonium dichromate and alkali metal dichromates, or
• C. a reducing agent selected from the group consisting of sodium thiosulfate and thiourea, and
• II. a second component comprising the other of (B) or (C) which is not present in Component I.