AMMONIUM HALIDE AS GELATION RETARDER FOR CROSSLINKABLE POLYMER COMPOSITIONS

1 . A treatment fluid for use in a subterranean formation, the treatment fluid comprising:

(a) a water-soluble polymer, wherein the water-soluble polymer comprises a polymer of at least one non-acidic ethylenically unsaturated polar monomer;

(b) an organic crosslinker capable of crosslinking the water-soluble polymer;

(c) an ammonium halide; and

(d) water.

2 . The treatment fluid according to claim 1 , wherein the treatment fluid comprises a crosslinkable polymer composition.

3 . The treatment fluid according to claim 2 , wherein the crosslinkable polymer composition has a gelation time of at least about 2 hours when tested at a constant shear rate of 10 l/s, a constant pressure of 270 psi, and a constant temperature of 300° F. (149° C.).

4 . The treatment fluid according to claim 3 , wherein the crosslinkable polymer composition has a gelation time of less than 100 hours when tested at a constant shear rate of 10 l/s, a constant pressure of 270 psi, and a constant temperature of 300° F. (149° C.).

5 . The treatment fluid according to claim 1 , wherein the non-acidic ethylenically unsaturated polar monomer is acrylamide.

6 . The treatment fluid according to claim 1 , wherein the water-soluble polymer comprises:

at least one non-acidic ethylenically unsaturated polar monomer, and

(ii) at least one polymerizable ethylenically unsaturated ester.

7 . The treatment fluid according to claim 6 , wherein the polymerizable ethylenically unsaturated ester is t-butyl ester.

8 . The treatment fluid according to claim 1 , wherein the water-soluble polymer is poly(acrylamide/t-butyl acrylate).

9 . The treatment fluid according to claim 1 , wherein the water-soluble polymer is soluble in water to an extent of at least 10 g/l when measured in a sodium chloride solution of 32 g/l of sodium chloride in deionized water at 25° C.

10 . The treatment fluid according to claim 1 , wherein the organic crosslinker is selected from the group consisting of a polyalkyleneimine, a polyfunctional aliphatic amine, an aralkyl amine, a heteroaralkylamine, and any combination thereof.

11 . The treatment fluid according to claim 1 , wherein the organic crosslinker is a polyalkyleneimine.

12 . The treatment fluid according to claim 1 , wherein the organic crosslinker is polyethyleneimine.

13 . The treatment fluid according to claim 1 , wherein the ammonium halide is ammonium chloride.

14 . The treatment fluid according to claim 1 , wherein the ammonium halide is present in a concentration of at least 100 lb/Mgal of the water.

15 . The treatment fluid according to claim 1 , wherein the water is selected from the group consisting of fresh water, seawater, natural brine, formulated brine, 2% KCl solution in water, and any combination thereof.

16 . A treatment fluid for use in a subterranean formation, wherein the treatment fluid comprises:

(a) a water-soluble polymer comprising a copolymer of:

(i) at least one non-acidic ethylenically unsaturated polar monomer, and

(ii) at least one polymerizable ethylenically unsaturated ester;

(b) a polyethylene imine capable of cross-linking the water-soluble polymer;

(c) an ammonium halide; and

(d) water,

wherein the treatment fluid is a crosslinkable polymer solution.

17 . A method for blocking the permeability of a portion of a subterranean formation penetrated by a wellbore, the method comprising the steps of:

(a) selecting the portion of the subterranean formation to be treated, wherein the bottomhole temperature of the portion of the subterranean formation is equal to or greater than 250° F. (121° C.);

(b) selecting estimated treatment conditions, wherein the estimated treatment conditions comprise temperature over a treatment time;

(c) forming a treatment fluid that is a crosslinkable polymer composition comprising:

(i) a water-soluble polymer, wherein the water-soluble polymer comprises a polymer of at east one non-acidic ethylenically unsaturated polar monomer;

(ii) an organic crosslinker capable of crosslinking the water-soluble polymer;

(iii) an ammonium halide; and

(iv) water;

(d) selecting the water-soluble polymer, the crosslinker, the ammonium halide, and the water, and the proportions thereof, such that the gelation time of the treatment fluid is at least 2 hours when tested under the estimated treatment conditions; and

(e) injecting the treatment fluid through the wellbore into the portion of the subterranean formation.

18 . The method according to claim 17 , wherein the step of injecting is under actual treatment conditions that are within the limits of the estimated treatment conditions.

19 . The method according to claim 17 , further comprising the step of: allowing the treatment fluid to gel in the formation.

20 . The method according to claim 19 , further comprises, after the step of allowing, the step of producing hydrocarbons from or through the subterranean formation.