High-temperature crosslinked polymer for use in a well

1. A method comprising the steps of:

(A) forming a fluid comprising a crosslinked polymer, wherein the crosslinked polymer comprises:

(i) a first monomeric unit of one or more N-vinyl lactams;

(ii) a second monomeric unit; and

(iii) a crosslinker selected from the group consisting of: 1,3-divinylimidazolidin-2-one, divinyltetrahydropyrimidin-2(1H)-one, dienes, N-vinyl-3(E)-ethylidene pyrrolidone, ethylidene bis(N-vinylpyrrolidone), and any combination of any of the foregoing, wherein the crosslinker is present in an amount of from about 1 mol % to about 5 mol % of a total of the first and second monomeric units; and

(B) introducing the fluid into a portion of a well, wherein a design temperature of the portion of the well is at least 149° C. (300° F.).

2. The method according to claim 1 , wherein the second monomeric unit is selected from the group consisting of: acrylamide, N-substituted acrylamides, methacrylamide, N-substituted methacrylamides, acrylates, methacrylates, acrylic acid, methacrylic acid, N-vinylamides, N-allylamides, vinyl alcohol, vinyl ethers, vinyl esters, allyl alcohol, allyl ethers, allyl esters, vinylpyridine, vinyl sulfonates, allyl sulfonates, vinylimidazole, allylimidazole, diallyldimethylammonium chloride, and any combination of any of the foregoing.

3. The method according to claim 1 , wherein the fluid comprises an aqueous phase.

4. The method according to claim 3 , wherein the aqueous phase comprises one or more water-soluble salts dissolved in water.

5. The method according to claim 3 , wherein the fluid comprises a solid particulate.

6. The method according to claim 3 , wherein the fluid comprises less than 2% clay by weight of the water.

7. The method according to claim 1 , wherein the one or more N-vinyl lactams are selected from the group consisting of: N-vinylpyrrolidone (NVP), N-vinylcaprolactam, and any combination thereof.

8. The method according to claim 1 , wherein the second monomeric unit is selected from the group consisting of: acrylamide, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and any combination of any of the foregoing.

9. The method according to claim 1 , wherein the first monomeric unit is at least 5 mol % of the second monomeric unit.

10. The method according to claim 1 , wherein the second monomeric unit comprises up to 90 mol % of the monomeric units of the crosslinked polymer.

11. The method of claim 1 , wherein the crosslinked polymer is a copolymer that consists of the first monomeric unit, the second monomeric unit, and the crosslinker.

12. The method of claim 1 , wherein introducing the fluid into the portion of the well further comprises using the drilling fluid to drill a portion of a wellbore penetrating a subterranean formation.

13. A method comprising the steps of:

(A) forming a fluid comprising a crosslinked polymer, wherein the crosslinked polymer comprises:

(i) a first monomeric unit of one or more N-vinyl lactams; and

(ii) a crosslinker selected from the group consisting of: divinyl ether, 1,3-divinylimidazolidin-2-one, divinyltetrahydropyrimidin-2(1H)-one, dienes, allyl amines, N-vinyl-3(E)-ethylidene pyrrolidone, ethylidene bis(N-vinylpyrrolidone), and any combination of any of the foregoing, wherein the crosslinker is present in an amount of from about 1 mol % to about 5 mol % of a total of the first monomeric unit; and

(B) introducing the fluid into a portion of a well, wherein a design temperature of the portion of the well is at least 149° C. (300° F.).